Single Vs Double base and barrel life

[dannywayoflife]

I've always been of the impression that single base powders usually give longer barrel life due to them burning cooler than double base. But I've been looking on some US forums and they seem to think that actually the reverse is true. I've seen some figures that show that Ball powders burn a fair bit cooler than extruded single base powders? Are there any thoughts on this?

 

Danny

[The Gun Pimp]

I've always been of the impression that single base powders usually give longer barrel life due to them burning cooler than double base. But I've been looking on some US forums and they seem to think that actually the reverse is true. I've seen some figures that show that Ball powders burn a fair bit cooler than extruded single base powders? Are there any thoughts on this?

 

Danny

 

I'm pretty certain that the Vihtavuori 5 series powders are noticeably harder on barrels than the single-base version. I managed to burn out a 308 Win in 1200 rounds using Vit N540 and another F/TR shooter did the same.

[dannywayoflife]

That's what I thought. But there's a fair bit on the US forums saying ball powders burn cooler. It confuses me as a newbie to reloading if I'm honest. I've been deliberately steering away from double base as there said to burn throats but now I'm not so sure.

 

I also read somewhere that Mr Ackley thought that ball powders were easier on throats due to less friction? He felt that extruded powders acted like a grit blasting on the throat? Is there anything in that?

 

I've got to say I'm really enjoying reloading but the more I read about it the more I see I'll never really know that much on the subject!

[Laurie]

All ball powders are double-base (goes with the process they're made with) and there are two issues here - ball v stick and single v double-base, especially in S-B v D-B comparisons within stick types.

 

If you take D-B stick types, the plain objective of the exercise for most people who choose them is to get more velocity out of any given cartridge-bullet combination - more energy goes into the charge, more comes out at the muzzle in terms of bullet speed, and hence MV. As a heat engine, only ~40% of the charge's energy ends up with the bullet, so 60% is lost in heat and noise. Put a higher energy powder into the breech end of the barrel and use all of the available performance and the 60% or so of the extra energy that doesn't make the bullet go faster mostly ends up giving your barrel throat more stick.

 

The percentage of the powder weight that's made up of the high energy nitroglycerine (NG) component is a major factor. Early D-B powders had exceptionally high NG contents and burned the relatively soft steel barrels of the time out very quickly. Early Cordite as used in the first smokeless .303 British military ammo had 58% nitroglycerine, 37% guncotton (nitrocellulose) and 5% mineral jelly. A long Lee's barrel was done for at under 1,000 rounds although I bet they were used until they'd had a couple of thousand through them. The original US .30-03 and .30-06 used high NG concentration D-B powder and it's said the .30-03 with its 220gn bullet at only 2,000 fps MV had an accuracy barrel life of 600 rounds. (Shades of 7mm WSM in F-Class!) A lot of the bad repuattion of D-B powders goes back to this early period. Today's rilfe powders have maybe 8-15% NG in the mix and additives to get flame temperatures down.

 

Ball powders like I said are D-B by the nature of the beast, and if you load cartridges with them to get every last possible fps of MV out of the cartridge-load combination, then you'll beat the crap out of the barrel again just like with a D-B stick powder. It's sometimes said that the life of a barrel made from any particular material is largely driven by the combination of bore diameter and powder charge weight. Any particular calibre barrel will have a life of around so many pounds of powder burned in the chamber. Divide that figure by the charge weight and you get the life in terms of rounds fired, so if we're talking .30 calibre, you get one hell of a lot more shots with a .30BR than you do with .300 Remington Ultra Mag or .300 Lapua Magnum. That's simplistic as bullet weight, powder burning speed and rate of fire / barrel temperatures attained all have an influence too, sometimes major. Increasing performance through using a D-B powder has the same effect as running with a slightly larger charge of a lower energy powder of any type, so in itself will decrease barrel life - but not by as much as going up from .308W to .30-06, or from .30-06 to .300WSM.

 

But having said that, the main users of ball powders are governments in the form of the vast amounts of ammunition they buy for their armed forces. All US ball smallarms ammunition, some sniper rounds aside, have been exclusively loaded with ball powders throughout the entire 7.62 and 5.56 era, around 60 years to date. A lot of pressure goes on manufacturers to produce consistent ammo that's clean burning and gives good barrel life. So there has been a great deal of R&D work on ball powder and major improvements made over time, in things like lowering flame temperatures and reducing fouling and muzzle flash. The other thing governments constantly bitch about is temperature sensitivity, where S-B stick is better generally better than D-B ball, but while that has given S-B stick powder manufacturers military contracts for special-purpose ammo, the movement is still towards ball for various reasons. (This will be covered in a detailed look at Ramshot powders in the June issue of TargetShooter online.)

 

The manufacturers of ball powders say their products now give enhanced barrel life compared to stick types as they've got the flame temperatures down more. The stick powder manufacturers dispute these claims. Here's what Sierra Bullets says in its Ballistics round-up:

 

Some debate has ensued over the merits of ball powders vs. extruded tubular powders. Extensive testing at Lake City Ammunition Plant found “no significant difference in bore life, accuracy wise, when using either IMR propellants (extruded tubular) or spherical propellants (ball powder).” While these comments were made specifically about the 30 caliber and 7.62mm NATO Match ammunition, the same situation will hold true for most other cartridges.

 

I suspect that was written some years back, and I suspect the test referred to is ancient history now, but any changes in the two types' relative situation since are likely to be incremental, not major.

 

So .... in summary, load your 308 say to 53-57,000 psi and ensure the barrel doesn't get really hot, and I doubt if you'd see any difference to speak of between either type if they're both shooting same weight bullets.

 

Load the same cartridge up to or or a tad above CIP Maximum, let's say regularly hit 61,000, 62,000 psi and the reduction in barrel accuracy life in terms of round count will be greater than the 11% increase in peak pressures, especially if heavy bullets are being loaded. How much greater? I don't know, but I suspect substantially greater.

 

Load it up a third time with these pressures and heavy bullets but now with a double-base type that gives higher MVs at those pressures and the number of rounds needed to destroy accuracy will reduce still further.

 

I know there are spreadsheets that will give you a prediction, but real life throws up very variable results. Vince got not much more than 1,200 rounds with N540 and 155gn Scenars. I got around 2,200 rounds from a Broughton on an F/TR rifle with a lot of bench-testing loads (gets the barrel hotter than in slowfire competition) and a mixture of bullet weights, single and double-base powders, but with a lot of heavy bullets (185-210gn) over N550 and Re17. Steve Donaldson only shoots heavies (210s and 230s) over N550 in small primer Lapua brass at some impressive MVs and gets 3,000 rounds plus out of a Broughton.

[dannywayoflife]

As usual thanks for spending the time put into that reply laurie! Very very informative.

 

Many thanks

 

Danny

[Brillo]

That was a really interesting read and has given me a lot of food for thought as I use VV N550 (occasionally) in my 6.5x47 and N540 (occasionally) in my Sako TRG-22, and have started using it in my savage 6mm BR.

The science side of shooting appeals to me because I have a science and statistics background, although I'm rapidly beginning to see that a lot of statistical rules don't apply to the sport; take for example the fact that two identical guns will perform differently even with the same ammo in the same conditions. That's an odd one..

Anyway, the main reason for my reply is to ask about the statement.....

 

"As a heat engine, only ~40% of the charge's energy ends up with the bullet, so 60% is lost in heat and noise. Put a higher energy powder into the breech end of the barrel and use all of the available performance and the 60% or so of the extra energy that doesn't make the bullet go faster mostly ends up giving your barrel throat more stick."

 

I'd be interested to know where that statistic comes from and how it is derived.

[gbal]

 

 

That was a really interesting read and has given me a lot of food for thought as I use VV N550 (occasionally) in my 6.5x47 and N540 (occasionally) in my Sako TRG-22, and have started using it in my savage 6mm BR.
The science side of shooting appeals to me because I have a science and statistics background, although I'm rapidly beginning to see that a lot of statistical rules don't apply to the sport; take for example the fact that two identical guns will perform differently even with the same ammo in the same conditions. That's an odd one..
Anyway, the main reason for my reply is to ask about the statement.....

"As a heat engine, only ~40% of the charge's energy ends up with the bullet, so 60% is lost in heat and noise. Put a higher energy powder into the breech end of the barrel and use all of the available performance and the 60% or so of the extra energy that doesn't make the bullet go faster mostly ends up giving your barrel throat more stick."

I'd be interested to know where that statistic comes from and how it is derived.

My s and s background and foreground would suggests the two rifles are not identical,and they may be very similar,and from the same factory,and model etc,but there are usually differences in eg 'engineering tolerance'.And who measured them,and how,to establish they are clones?Maybe the ammo is another variable,to which the same applies.I don't think the laws of physics wobble too much in our macro world,so
" identical" is immediately suspect.
Gbal

[brown dog]

My s and s background and foreground would suggests the two rifles are not identical,and they may be very similar,and from the same factory,and model etc,but there are usually differences in eg 'engineering tolerance'.And who measured them,and how,to establish they are clones?Maybe the ammo is another variable,to which the same applies.I don't think the laws of physics wobble too much in our macro world,so

" identical" is immediately suspect.

Gbal

 

Ha! Beat me to it. 'Identical' rifles and ammunition are not identical.

 

As regards the topic, Laurie - interesting read; thanks.

I think, as always, it all goes back to 'no free lunch in ballistics'.

I never trusted the claims on the 5 series powders and have consciously never touched them.

Interesting to read that people who've used them do now indeed report increased barrel wear.........no free lunch.

[dannywayoflife]

The no free lunch is a logical one. I personally am interested in moderate loads not really cranking them up. I'm quite attracted to the ramshot powders as I am on a shoe string budget and can't afford the now very expensive more main stream powders.

 

Laurie what's your thoughts on the friction argument with ball and stick powders?

[Laurie]

Brillo, I've read so much internal and external ballistics stuff over the years, it's difficult to quote sources. I've seen firearms efficiency quoted as being anywhere between 30 and 40%, and a range is probably correct in that the type of firearm, barrel length, whether the case capacity and powder charge weight are optimised for the bore dia. and bullet weight will affect thermal efficiency values. Specific powder energy values are widely available, used to be in BTU / lb, now in J/G, but I've never thought about how you'd go about comparing the energy value of a charge weight to the ME in ft/lb.

 

Danny, I've seen this friction argument too, and have no great thoughts on it one way or other. It's also linked into an issue called 'Turbulence Point', abbreviated to TP. The TP thingie was very fashionable some years back, but you hardly ever hear it mentioned now. Here's how it goes:

 

The combination of case shoulder angle and neck-length in a high pressure bottleneck case design determines where the TP forms, whether inside or outside the case-neck. The TP is a sort of area or mass of super-hot gas and powder kernels still being consumed that are pushed up the case to the shoulder / neck area as combustion starts at the rear of the powder charge and pushes the front end of the powder column forward into a heavily compressed mass of burning material. If the TP event occurs inside the case it shields the barrel throat from its ravages; if outside, the barrel wears out faster for any given pressure / temperature level induced by the powder type and weight.

 

How you 'know' if you've got a 'good' or 'bad' cartridge design is simple. take an accurate case-drawing of your cartridge, lay a ruler along the line of each shoulder and extend it forwards with a pencil. If the extended lines intersect inside the case, great; if outside, hard luck!

 

The argument for this TP theory either started with or was 'validated by' experience with some pairs of ballistically similar cartridges, in particular 6mm Remington and .243 Winchester. The 6mm has a slightly larger capacity case and slightly higher SAAMI allowed PMax pressure level than the .243 Win, so all other things being equal should give slightly higher MVs (which it does), at the expense of reduced barrel life (which 6mm proponents say doesn't happen). In fact 6mm Rem lovers say it gives better barrel life than .243 Win both loading the same bullets in same length barrels and taking advantage of the 6mm's extra performance margin obtaining higher MVs. The 'proof' of the TP theory is that the 6mm has a steeper shoulder angle and considerably longer neck than the 243W, hence the shoulder lines intersect comfortably inside the neck. QED! (Or not, if you disbelieve!)

 

Now, I've no idea if there is something in this, or it's simply a load of rubbish in which apples are compared to pears to prove that bananas are blue-colour and grow straight! It looks common-sensible, but that means bugger-all in smallarms internal ballistics as so many things are actually counter-intuitive. I feel the same way about the rough sticks v the smooth balls abrading the throat (silence back there - this ins't a porn forum!). It sounds good, but even if it is valid, is probably so marginal that changing peak pressure by 25 psi or peak temperature by 25-degrees has an equal or bigger effect.

 

Years back, I had a very interesting conversation with Dr Geoff Kolbe, proprietor of Border Barrels, who was an 'experimental physicist' in a research lab before he teamed up with Boots Obermeyer and learned how to make cut-rifled barrels. Geoff spent much time studying internal ballistics in his early years and wrote a rather good book on it, well good if you like lots of maths and equations which I don't! Anyway, what the good doctor said to me was that there are lots of things about rifle calibre internal ballistics that we know happen, but don't know why they happen, or how different effects interract. This is because of 'non-linear effects' - ie you can often identify that doing A results in a certain effect B, but that it either doesn't always apply (eg between different types of calibre of firearm), or make it quantifiable in that 2XA = 2XB (or more or less through a constant). It may do so, but only up to a certain value at which point the relationship changes unpredictably. Likewise, the effect may only occur in the presence or absence of factors C, D. E .. etc, etc.

 

This is very different from the internal ballistics of big stuff (20mm calibre and above where you can model the effects of changing all sorts of variables to get close to an optimum result long before you build your first prototype artillery piece or shell), and is one of the things that makes smallarms barrel chamber, throat and ammunition design, handloading etc both frustrating and fascinating.

 

As has also been pointed out, no two firearms are identical even if they have the same spec and components, so it makes validating such theories very difficult, even if we could afford the time and money to shoot two barrels out with identical shooting speeds and patterns with different types of powder. There is a well-known and excellent hobby gunsmith on this forum who decided a few years back that the the 6.5-284 Norma is a great cartridge bar one thing - its case is a bit too big so optimum powder charges don't fill all the available space completely. The 'answer' was a 'short-body' 6.5-284 wildcat, easily done in both chamber cutting and case re-forming. Anyway, he did it on a rebarrelling job. Now, you simply cannot fault the logic - BUT it didn't work! Now was that because 95-100% fill-ratio is less important than we thought? Or, was it because reducing the case volume slightly injected another unforeseen negative variable that outweighed the move from 90% fill-ratio to 100% (or whatever it actually was)? Or, was it because re-forming the brass produced an inferior case over the out of the box standard Lapua version? Or, was it just Sod's law that the wildcat's barrel was an average number while its factory spec chambered predecessor had been a 'screamer'?

[dannywayoflife]

Once again thanks for a full and informative reply Luarie.

 

Danny

[kent]

Laurie,

The TP test of drawing lines sounds like total BS to me and just a case of making circumstantial things fit. Very common to believe in strange Voodo when the facts are lacking, sound like it was suggested by a fan of the Ackerly imp. The .222 and .22 Hornet both fail the test btw (being the world renowned barrel burners) but most of the improved types fair better than std cases

[Andrew]

I have read much on the "TP" effect over the years and it doesn't pass the sniff test for me. When I was at gunsmithing school I read an old book that showed the effect of running 30-06 through barrels that were of the same billet, and cut on the same machine and fired with heavy loads. The barrels were carefully chambered to have the same throat dimensions. The difference between each barrel was the groove diameter which was increased from nominal .308" by .0002" for each barrel. Identical ammo was fired in each barrel and i can't remember the considerable number of rounds fired, but it is no surprise that the barrels showed progressively increasing amounts of wear depending on the increase in the groove diameter. The barrel that was .0006" over size showed noticably more errosion than the nominally dimensioned barrel. I remember a caption that said that hot gas at 55,000 psi can find it's way through the smallest gap. That always stuck in my head.~Andrew

[gbal]

 

 

Laurie,The TP test of drawing lines sounds like total BS to me and just a case of making circumstantial things fit. Very common to believe in strange Voodo when the facts are lacking, sound like it was suggested by a fan of the Ackerly imp. The .222 and .22 Hornet both fail the test btw (being the world renowned barrel burners) but most of the improved types fair better than std cases

I had not heard of this TP effect,but it seems rather suspect.I am struggling to find a case with shoulders that lead to their belonging to a "bad case"-esp with anything otherwise
similar enough to compare.The 6 rem and 243 both seem to pass the test,and so does the 222 rem(and 223? despite its short neck compared to the ballistically very close 222 rem mag)and I don't think the hornet has shoulders!
Since most at least cases disconfirm the TP idea,it does not seem surprising it isn't currently at the cutting edge of accurate case design.....
Gbal

[kent]

I had not heard of this TP effect,but it seems rather suspect.I am struggling to find a case with shoulders that lead to their belonging to a "bad case"-esp with anything otherwise

similar enough to compare.The 6 rem and 243 both seem to pass the test,and so does the 222 rem(and 223? despite its short neck compared to the ballistically very close 222 rem mag)and I don't think the hornet has shoulders!

Since most at least cases disconfirm the TP idea,it does not seem surprising it isn't currently at the cutting edge of accurate case design.....

Gbal

the hornet does not have shoulders in the classic description but it has a steeper taper of 5 degrees towards the neck, in this case relevant. I think the BAD case is the one were the shoulder taper clears the neck as in .222 were the 22-250 Ack it just touches. The theory though is BS, like many theories its meaningless without hard evidence

[gbal]

the hornet does not have shoulders in the classic description but it has a steeper taper of 5 degrees towards the neck, in this case relevant. I think the BAD case is the one were the shoulder taper clears the neck as in .222 were the 22-250 Ack it just touches. The theory though is BS, like many theories its meaningless without hard evidence

...thanks,agree on the conclusion...and we get hard evidence by that well known scientific method! (suck both equally and see)!

gbal

[Laurie]

Oh, Oh! I seem to have kicked an ant-heap over here! The reason I mentioned the TP hypothesis is that it's closely linked to the claim, or more accurately hypothesis, that nice smooth balls do less damage to the chamber throat than nasty erosive stick varieties. I also seem to remember my saying that this is, in fact both of these are, very likely examples one of those hypotheses that people come up with to compare apples and pears in order to prove that bananas are blue and straight.

 

As I pointed out, we know that certain things happen in smallarms cartridge design and internal ballistics, we often don't know why, or have trouble with the interractions betweeen various conflicting effects. The balls versus sticks issue + the TP hypothesis may or may not have legs, but I don't know which situation applies and neither does anybody else on this forum, so it's a bit presumptious for anybody to simply announce it's BS. What some of you are saying is that YOU THINK it's BS, and I'm afraid the 'reasons' given are none too supportive of this 'thought' / assertion. For instance, I'm rather surprised to see people say that 222 Rem and 223 Rem hypothetical TP locations are both inside the case, likewise the pair that started this hypothesis off, 243W and 6mm Rem.If you have a look at the accurately reproduced SAAMI cartridge drawings on this link which actually have the shoulder lines extended, you'll see that many popular and common cartridges do have the intersection point either right on the case-mouth or outside of it, but quite a few others are inside.

 

http://www.6mmbr.com/cartridgediagrams.html

 

 

In the 222 v 223 comparison, the former has the intersecting point just inside the neck, the 223 just outside. However, as we all know, the reason for any barrel life difference between this pair is driven by differences in charge size, bullet weight, and chamber pressure, all of which affect the degree of pressure and temperature afflicting the throat end of the barrel and their duration.

 

222 is nominally listed by SAAMI and CIP as loaded with 50gn bullets with a (CIP) maximum allowed average Piezo strain-gauge pressure of 53,650 psi. The 223 Rem equivalents are 55gn, 62,350 psi, a more than inconsequential increase. The heaviest maximum powder charges quoted by Viht run at 23.9gn (222) and 27.3gn (223) for the nominal 50 and 55gn bullets.

 

Moving onto the original pairing, I don't know where your cartridge drawings came from George, but I'd get a new set if I were you. Look at them in 6mmBR link and the 243 Win intersection is WELL outside and the 6mm Rem is equally WELL inside.

 

QuickLOAD gives 243W 54gn water capacity and 6mm Rem 54.4gn, so small as to be inconsequential. PMax is 60,191 psi for the former and 62,366 for the latter, a 3.6% increase. Personally, I would think that the differences are so relatively minor that other factors such as barrel make and quality would likely overturn or negate any perceived barrel life difference between them, but friendly arguments between the enthusiasts for one type or another of cartridge are the sort of pseudo-technical issue that can make shooting and handloading fun - or a complete bore, depending on the individual's point of view.

 

Now, so far as .22 Hornet is concerned, just what can I say about this awkward little sod of a creature, that logic suggests should have been quietly euthed a generation or three back when the .222 Rem was introduced? Well OF COURSE it gives a long barrel life! With SAAMI nomional bullet weights of 45/46gn and maximum pressure of 43,000 CUP, it's hardly warming the barrel never mind burning it out. Viht's heaviest maximum charge weight in any powder-bullet combination is a massive 9.5gn, less than half its 222 equivalent, only a shade over a third of the 223's, and a quarter that of the 22-250 Rem's equivalent with a 55gn bullet. As nobody I've yet heard of is masochistic enough to use the troublesome insect in target shooting, it's a true sporting cartridge which in the European environment (lacking prairie-dog concentrations or equivalent requiring a lot of fast shooting) will see small round counts, usually achieved through widely spaced shots timewise. Frankly if I owned a Hornet and burned the barrel out in my remaining lifetime, I'd want my money back as having been sold a firearm with inadequate metallurgy!

 

The points about balls v sticks and inside v outside TP are that comparisons are only valid between similar designs in a single calibre which have similar powder charges and are loaded to similar pressures.

 

Thinking further on this issue in the light of responses took me onto considering the single commonly used cartridge with the longest barrel life by far, the humble .22 Long Rifle which in its standard velocity match form uses between 1.6 and 2.0gn of fast burning powder to give a 40gn lead bullet 1,050-1,140 fps (nominally). HV forms use more slower burning powder, hyper-vel types even more so, but there are a lot of people collectively known as smallbore target shooters who have a considerable stake in and knowledge of the midget's precision in a top quality rifle and barrel and also know the barrel life as they consume vast quantities of cartridges and do actually wear their barrels out. Given the affordability and availability of borescopes and precision measuring tools in recent years, there are a few mostly US based private individuals who have studied the wear characteristics that the 22LR produces on barrel throats. The concensus is that a good quality barrel fed standard vel ammo has an 80-100,0000 round life. Taking the lower figure and the higher charge weight range figure, we see that a .22LR barrel likely consumes ~160,000gn or 23 lb of fast-burning powder in its lifetime. Take that figure and divide it by a typical charge weight of N133 or N135 as used in .223 Rem, say 25gn, with a 55gn bullet, and we get a comparative 6,400 rounds for the centrefire .22 - actually not too far out from real barrel lives espeically considering SAAMI PMax for the rimfire is a piddling 24,000 psi compared to 55,000 psi (SAAMI) 62,350 psi (CIP) for the CF cartridge. However, at one time - I don't know about now - .22RF barrels were made of considerably softer steel than those used in high-pressure CF rifles. If so it's an apples and oranges comparison again!)

 

The story gets more interesting as it relates back to the TP issue, regurgitating some stuff I read years back from one of these Americans who studies the 22LR in depth. The 22LR cannot have a case-shape induced TP (if you believe the hypothesis of course, otherwise we're discussing a non-present phenomenom) obviously as it has a straight-wall case, so burning powder kernels are presumably simply blown forward into the leade behind the bullet, this factor's existence depending on how quickly the bullet moves and whether all powder present is consumed before or after the bullet enters the leade and passes through it. So, you'd think erosion would occurs around the entire circumference of the leade equally given the straight-wall case, but it doesn't. Wear starts at the bottom, the 6 o'clock position, gradually extends up each side to and through the 3 and 9 o'clock positions and finally both 'arms' meet up at 12 o' clock - that's when the barrel is shot-out and the big drop in precision occurs. Think further and the wear pattern is explicable as the .22LR SV cartridge's charge only takes up around 25% of the case volume. So, the charge will lie along the bottom of the case when chambered and fired with the rifle in the prone position, burning erosive kernels will be concentrated on the 6 o'clock position of the barrel throat / leade. It's not case-shape directing anything here, simply gravity. But, oddly enough it supports the TP hypotheis in its way.

 

 

I note that I'm 'accused' (if that's the correct term) of proselyting the Ackley Improved and similar design cartridges. Well actually I've never owned an AI chambered rifle although as I now have a variant of the 6-Dasher waiting in the wings to be used in 600yd BR next winter, I suppose that nearly counts. Actually, I've never been personally convinced by the commonly circulated hypothesis (another one!) that because the 6PPC is the world's highest precision short-range cartridge, plus the 6PP being short and fat, that the latter is the sole cause of the former, and that all super precision cartridges should therefore be given this case-shape. As one who still has a soft spot for the .30-06 Springfield, shot a Maddco stainless match barrel out using the long-tall-Sally .300 H&H Magnum in the early days of F-Class and more recently 'proved' that the comparatively long thin .223 Rem would shoot sub 5-inch 5-shot groups at 1,000 yards, briefly equalled the GB F-Class Association 1,000 yard 20-shot F/TR match record with it and successfully used it at 1,112 and 1,224 yards at Blair Atholl .......... I think it's fair to claim that I keep an open mind on the cartridge case and shape issue.

[gbal]

...thanks,agree on the conclusion...and we get hard evidence by that well known scientific method! (suck both equally and see)!

gbal

Thanks Laurie-it was Barnes COTWorld,but it just shows that drawing quick lines isn't good enough-the 6br site is definitive and very clear.I think I was just trying to defend the 222 and 6rem,correctly,as it turns out,from their shorter neck companions,the 223 and 243.There does not seem much to support the TP hypothesis exclusively,given all the variables.What we need is a 22rf shot out from the upside down position,or some data from the antipodes.....

gbal

[Laurie]

IF (big IF) the TP hypothesis has legs, I'd think any difference between equivalent cartridges would be so small that you'd never notice it, let alone prove it one way of the other.

 

I like the idea of persuading somebody to shoot a .22LR barrel out while lying upside down to see if wear now starts at the other end of the clockface - any takers?

 

On the .22RF v CF barrel steel issue, is there anybody in the forum who knows if they're all made of the same material these days. I'd assume (dangerous word 'assume') that cheapo .22LR sporting rifles might have lower quality steel in their barrels, but that if you buy a good make, especially any of the target models, that the steel would be just as durable as in equivalent .222, .223, .22-250 Rem examples.

 

I remember that Border Barrels offered 'drop-in' chambered match barrels for Anschutz target rifles some years back and checking its website see that you can get them for Anschutz, Walther, and Ruger 10/22, as well as .22RF blanks in whatever length and profile you want. Presumably, they're made from the same steel grades as the comapany's centrefire barrels and blanks. Or, is there a technical reason to use a different specification for rimfire barrels for something or other? Just a thought.

[gbal]

IF (big IF) the TP hypothesis has legs, I'd think any difference between equivalent cartridges would be so small that you'd never notice it, let alone prove it one way of the other.

 

I like the idea of persuading somebody to shoot a .22LR barrel out while lying upside down to see if wear now starts at the other end of the clockface - any takers?

 

On the .22RF v CF barrel steel issue, is there anybody in the forum who knows if they're all made of the same material these days. I'd assume (dangerous word 'assume') that cheapo .22LR sporting rifles might have lower quality steel in their barrels, but that if you buy a good make, especially any of the target models, that the steel would be just as durable as in equivalent .222, .223, .22-250 Rem examples.

 

I remember that Border Barrels offered 'drop-in' chambered match barrels for Anschutz target rifles some years back and checking its website see that you can get them for Anschutz, Walther, and Ruger 10/22, as well as .22RF blanks in whatever length and profile you want. Presumably, they're made from the same steel grades as the comapany's centrefire barrels and blanks. Or, is there a technical reason to use a different specification for rimfire barrels for something or other? Just a thought.

Laurie,

Strictly speaking,for the rim fire 22 test,it's the rifle that needs to be upside down-we might get a volunteer more readily,if that's made clear-the shooter has free choice as to his/her orientation.

 

The major rationale for inferential statistics ( as distinct from the descriptive sort-lies,d- lies and...),is that they do give us a confidence measure for very small differences that are non the less there,if not readily apparent via the 'eyeball test',as my stats mentor used to call it.Of course we never get 'proof'-we just get 95%,99%,99.5%,99.9% and so on confidence in the result...while we are at it,sometimes a large difference isn't significant,if there are very large variations within the samples.....such as are sometimes reported here,with rather small samples,modally 'one' - as in "well,my rifle shoots...." and " I had one of them and it didn't....".These of course simply underline the case for more data to enable statistical tests.(maybe just the eyeball test)

..to see if there are meaningful differences....

But I suspect we will have to just hope for one upside down 22 test,rather than a decent sample.....

gbal

[kent]

Laurie,

I think I might have misplaced your point on the TP (hypothesis, theory or whatever) . Still I do personally "think" it is BS, we know what wears a barrel quickly and if you take away or reduce these you get longer barrel life.

Don't know about the balls thing but if its hotter it will melt metal quicker, sure as eggs is eggs and bananas are bent and yellow