Fairy tails do happen

[Ronin]

Congratuations on everyones success, couldnt be there to compete as I was abroad.

 

 

Small primer 308 brass - "handles pressure better",,,,may do, but the pressure (or over pressure) is still there....

 

 

 

Hate to say this but I seriously wonder how long its going to be till someone from the FTR league has a massive failure as I understand several are stoking their loads way beyond safe limits...

[Danpd]

As 6mmBR mentioned it is the general consensus that the Small Primer SP handles pressure better - and even if its only a belief when you lie behind the firearm

I used the CCI-BR

 

NOTE

1. With large powder charges and/or

2. Certain powders and/or

3. Really cold conditions

You may be challenged inconsistent ignition of the SP so careful testing and validation is required

 

Here is my plot sheet from 900y on Day 2 - this is the stage that really gave me the jump on the field

 

Happy to add the rest if it adds value to anyone

 

Tim

 

Good to see you are using the plot sheets, uncle Mik will be very happy!

[Eagernoskill]

Good to see you are using the plot sheets, uncle Mik will be very happy!

 

Rumour has it that he has a glimmer of a smile under the scowl!

[Eagernoskill]

Congratuations on everyones success, couldnt be there to compete as I was abroad.

Small primer 308 brass - "handles pressure better",,,,may do, but the pressure (or over pressure) is still there....

Hate to say this but I seriously wonder how long its going to be till someone from the FTR league has a massive failure as I understand several are stoking their loads way beyond safe limits...

 

Fair comment Roonin - missed you at Bisley!

 

I reckon the MATCH rifle boys have been "thumping" charges far longer than FTR.

I am concerned about of eyes / face / life - so my primary requirement is Accuracy first - Speed second.

and a load that is safe on a cold day may be a grenade on a warm day!

[Laurie]

Small primer 308 brass - "handles pressure better",,,,may do, but the pressure (or over pressure) is still there....

 

Maybe, more likely not. The small primer changes the charge burn behaviour and pressure curve characteristics. The fact that a given powder, charge weight + bullet model loaded identically between the two types of Lapua brass (same water capacity in fired examples in my experience) produces a significantly lower MV in the 'Palma' model in a rifle tells you the two versions behave differently.

 

Personally, I'm not a fan of the Palma brass, except in one set of cicumstances - heavy (greater than 200gn) bullets plus slow burning powders (N550 + Re/Elcho 17). The Palma case allows you to produce significantly higher MVs - side by side tests show standard large primer brass will blow primers with charges producing MVs 50-100 fps below that routinely produced in Palma cases. The guys regularly shooting 210s to 230s in these cases are now into double figure loadings with their Palma brass and they are nowhere near worn out. That again says the peak pressures being produced are not excessive - no matter how good or strong a case is you simply don't get 12 or 15 or 20 loadings out of it without something starting to go awry.

 

Hate to say this but I seriously wonder how long its going to be till someone from the FTR league has a massive failure as I understand several are stoking their loads way beyond safe limits...

 

Andy, what evidence do you have for this? I see quite the opposite at both national league and local club level with bolts opening easily, people getting their cases annealed every few firings in a multi-load life. A top 10 placed league competitors asked me to look at his standard large primer Lapua brass at Bisley to see if I couild find any incipient problems. These cases had seen up to 26 firings it turned out.

[brown dog]

Maybe, more likely not. The small primer changes the charge burn behaviour and pressure curve characteristics. The fact that a given powder, charge weight + bullet model loaded identically between the two types of Lapua brass (same water capacity in fired examples in my experience) produces a significantly lower MV in the 'Palma' model in a rifle tells you the two versions behave differently.

 

Personally, I'm not a fan of the Palma brass, except in one set of cicumstances - heavy (greater than 200gn) bullets plus slow burning powders (N550 + Re/Elcho 17). The Palma case allows you to produce significantly higher MVs - side by side tests show standard large primer brass will blow primers with charges producing MVs 50-100 fps below that routinely produced in Palma cases. The guys regularly shooting 210s to 230s in these cases are now into double figure loadings with their Palma brass and they are nowhere near worn out. That again says the peak pressures being produced are not excessive - no matter how good or strong a case is you simply don't get 12 or 15 or 20 loadings out of it without something starting to go awry.

 

 

 

Andy, what evidence do you have for this? I see quite the opposite at both national league and local club level with bolts opening easily, people getting their cases annealed every few firings in a multi-load life. A top 10 placed league competitors asked me to look at his standard large primer Lapua brass at Bisley to see if I couild find any incipient problems. These cases had seen up to 26 firings it turned out.

 

 

Laurie, I think you may be forgetting the purpose of a brass cartridge; it is nothing more than a means of providing rearward obturation. It's not a pressure bearing device; that's the purpose of the steel chamber walls and the bolt&lugs.

For me, every ounce of trained intuition supports the 'no free lunch in ballistics' view of physics that would indicate that all that's happening with thicker case heads/smaller primer holes is a masking of symptoms. To reason otherwise is to measure the failure strength of a hydraulic pipe by the compression of its packings; and then think the pipe has become stronger when you've installed harder packings that compress less. Obviously, the strength of the pipe itself is unchanged; its burst pressure is constant and unrelated to any of the 'signs' on the packings.

With the bullet weights and MVs being described, I think it would be interesting to see some calculations that ignore the malleability/ductility of sealing device providing rearward obturation and that look at what actually affects whether the shooter will retain the head on his shoulders - that is: bolt thrust and all the loads and shears that relate to it. Are 308 bolts / lugs/ receivers beefy enough for the the physics of what's being delivered?

[Laurie]

For me, every ounce of trained intuition supports the 'no free lunch in ballistics' view of physics that would indicate that all that's happening with thicker case heads/smaller primer holes is a masking of symptoms. To reason otherwise is to measure the failure strength of a hydraulic pipe by the compression of its packings; and then think the pipe has become stronger when you've installed harder packings that compress less. Obviously, the strength of the pipe itself is unchanged; its burst pressure is constant and unrelated to any of the 'signs' on the packings.

 

When the Palma brass first appeared, I would have agreed with you, but I've seen enough evidence to believe something other than a strengthened case-head (through less metal removed in forming the primer pocket) is involved. Look at any pressure / burn time curve and it is the early spike that determines how close the load is getting to safety margins, while it is the total area under the curve that determines total energy produced.

 

Your pipe example, while correct for component strength in handling a given amount of pressure isnn't the only factor at play in internal ballistics. Yes, the combined action and case strength determine the ultimate safe pressure, but we play around with the other components to vary the pressures, the pressure build-up behaviours and the ultimate performance obtained.

 

If every case capacity / powder / bullet / calibre equation produced an identical pressure curve then we'd use one powder and relatively small variations around a single charge weight, the sole pressure limit determinants being case wall thickness / case capacity, chamber size (this and the case characeristics affecting the effective combustion chamber volume), bullet diameter and bearing length differences affecting pressures / friction. But that's not what we have in handloading - we use powders with modified ignition burning characteristics to optimise the time-pressure curve as best we can. So a particular case-filling charge weight of Hodgdon H4350 say under a 210gn bullet in .308 Win is fine peaking at somewhere in the 50-60,000 psi range, while the same charge weight of H4198 would destroy the case and wreck the rifle. The two powders have similar, possibly even identical, specific energy/weight values, but very different burning rates giving very different pressure curves. A side result, and why we choose powder grades carefully, is that slower burning powder produces much more velocity and energy at the same or similar peak pressures because we are now able to safely stuff a larger amount of chemical energy into the cartridge.

 

I hypothesise - can't do any more than that - that the Palma brass is producing the same effect as 'improving' the powder characteristics. It's the only explanation I can see that covers how a significantly improved performance is obtained alongside an absence of normal excessive pressure signs and long case life. I really do not believe the Palma case is THAT much stromger than the standard version, such that it will take repeated severe and excessive abuse and simply hide the symptoms over multiple firings. If you repeatedly abuse a case it will fail and a slightly stronger case-head will only put the evil day off a little longer not postpone it indefinitely. I'm sure you either use 6BR or 6.5X47 Lapua yourself, or if not know several people who do. Have you heard of overloaded 6.5X47Ls to that show the classic over-pressure symptoms? I certainly have, and even saw an incident that nearly wrecked a newly built rifle over a charge weight error with Viht N550. These cases use identical case-heads to the 308W Palma case, yet I know several people who have moderated their loads after obtaining short case life. Yes, the primers don't flatten like large ones, but the pockets soon expand if you overload them and you get hard bolt lift too. They're not hiding overpressure symptoms very well here I'm afraid except initially for a firing or two.

 

 

If your argument that there is no free lunch in internal ballistics, one that I agree with in general terms, is taken too literally, then we must assume that either Winchester underloaded the original .308 Win in the 1950s and 60s, or conversely some of today's ammunition manufacturers are producing a potentially dangerous product as .308 Win MVs have risen substantially in recent years. Hornaday's Superformance load for 150gn bullets produces 3,000 fps and a very similar ME value in ft/lbs, significantly higher than the original cartridge could produce within SAAMI pressure limits. How? 'improved' powders of course with much better attuned burning characteristics, and a time-pressure curve better matched to the cartridge's internal ballistic template. In fact when the 308 was introduced in 1952 or thereabouts, handloaders could not match Winchester's factory ammo performance because the Nobel and DuPont powders available couldn't safely achieve Winchester's results which arose from the use of a ball powder specifically developed for the cartridge and which was not available to the public.

 

Another sign of how ignition characteritics have been altered by the Palma case, in this case potentially for the worse, is that the small primer / small flash-hole is only marginally effective in low temperatures. In the side by tests I ran, MVs dropped significantly, groups expanded, as did MV spreads shooting at Diggle in 3-degrees C temperatures during November '11. This applied to N140 and N550, but N150 was barely affected. Retrying the loads in spring 2012 at around 10-12 degrees C restored the MVs and performance.

 

As I said, I'm not a fan of the case type with anything other than 210gn and up bullets, and I'm not a fan of shooting such heavy bullets in F/TR or any other 308W rifle, so I've no axe to grind on this issue. Conversely, the US Palma teams undertook extensive work with the case applied to their strandard load of the 155gn Sierra MK (#2156) and 46-47gn H. VarGet and saw useful MV spread reductions in the conditions they shoot in while adjusting charges up a little to retain their 2,975-3,000 fps MVs. If they say they obtained these benefits, I'll believe these guys, but won't bother using the brass myself in my F/TR ammunition.

[brown dog]

I 'get' your take Laurie; but no matter how one tunes the pressure time curve, one has to recognise that at some point there's an upper limit; above which the shooter is tip-toeing along a 'disaster' precipice.

I think, coupled with that, is the fact that almost all the assessment of pressure in this is done by 'looking at the packings'; and really lies in the land of assumption.

 

As earlier: With the bullet weights and MVs being described, I think it would be interesting to see some calculations that ignore the malleability/ductility of sealing device providing rearward obturation and that look at what actually affects whether the shooter will retain the head on his shoulders - that is: bolt thrust and all the loads and shears that relate to it. Are 308 bolts / lugs/ receivers beefy enough for the the physics of what's being delivered?

 

I ask because we're all cognisant that 'heavy load rifles' such as magnums generally have beefier lugs, receivers etc designed into them for the loads they're designed to bear.

[Laurie]

I quite agree with your overall conclusions - anything can be overloaded, and often is especially when people are trying to get more performance out of a cartridge than the design happily allows. All I can say though is that I'm not worried by what I see from my fellow F/TR shooters using these cases with heavy bullets. The only way we'll ever know just what pressures their loads are running at though will be if somebody runs some tests using a Piezzo transducer pressure rig and publishes the results.

 

What does worry me FAR more these days is how some shooters are abusing the 6.5X47 Lapua and its 6mm wildcat offspring. While sharing the same case-head, flash-hole and small primer as the .308 'Palma', these smaller case, smaller bore cartridges are by definition more vulnerable to sudden pressure increases caused by a relatively smaller powder charge change than applies to .308 win. Contrary to common belief, they soon enough show pressure signs, but rarely on primer condition. Some users seem to think because 6.5X47 is an 'efficient, modern number', they can get full-house 6.5X55mm performance from a 25% smaller case. I've even seen claims on the AccurateShooter forum that the cartridge will match 6.5-284 Norma performance levels with 140gn bullets. The 'overloaders' here say their loads are OK as the primers look fine, but ignore other symptoms, primarily hard bolt lift and ejector housing marks on the case-head.

 

Going back to the original point about the 'Europeans' - a great result by Tim, especially his 900yd Saturday 73.3v in very hard conditions, the only F/TR shooter to break 70 and a score that would have given him 2nd F-Open match place between Maurizio Battaglino (73.8v) and the final overall winner Lee Tomlinson (73.2v). I shot 67.2v in that match and was (and still am) delighted with that score. So the small primer brass worked for Tim that weekend. On the basis of my tests though, if the much heralded early Arctic Winter spell we were initially promised for that week had turned up, there was a good chance that his ammo, and that of some of the heavy bullet shooters, wouldn't have performed given the Palma case's poor showing as temperatures drop to near freezing levels. The original 'Autumn Challenge' meeting some 5 or 6 years ago that has evolved into the European Championship meeting was shot in freezing conditions with frost on the ground for much of the day. Since then, it's been mild every year bar none - but you can't rely on that in early November!

[Eagernoskill]

Laurie, BrownD, Ronin

 

There is much value in your views and thoughts above.

 

Thank you - I have learnt several things and have noted some changes I may have to make / be aware of!

 

Thanks!

[Eagernoskill]

Hi All

 

Nice update with videos from F-Class Rifle 2012 European Championships

 

FIELD and Rural Sports Magazine did a great video at Bisley for F-Class Rifle 2012 European Championships.

 

Lots of really nice views of Bisley, various guns and the wind conditions.

It was taken on Day 2 - The Saturday.

 

Very nice interviews with:

1. Russell Symonds - FTR World Champ 2009-2013

2. John Deane - AIM

3. Mik Maksomivic - Euro Organiser / Dolphin Guns

 

 

Enjoy

TIM

[Eagernoskill]

TEAM VIDEO

 

There is also a video taken by one of the visiting teams either the Italians or Spanish (not sure)

 

It was also taken on Day 2 - The Saturday - more or less the same time I was shooting the Match 5 900y

I would be slightly down to the left in the video Lots of clean environmental shoots - so you can see the flags etc!

 

It should give you all an idea of the conditions

 

ENS