Borescope - I wish I hadn't

[Ronin]

Well, I thought I would give my rifles an annual "spring clean" to make sure all was well.

 

The Bat 6.5x47 and Surgeon 308 both look nice, no undue wear - the BAT has had over 1000 rounds through it and the Surgeon getting on for 400 in load development and practice.

 

Both the above tubes are LW and show no signs of wear under quite "warm" loads.

 

I then dug out the 6.5x284 - the barrel was clean, I shot it last a few weeks ago and found that it was throwing the odd flier - it did this last year with some 140 Barnes TSX's that I got to try a different deer bullet.

 

Anyway, the throat and ten inches of barrel forward of the chamber have severe firecracking and glazing, it appears that the tube will have to be replaced sooner than I had hoped, although its done well for just over 2000 rounds and still printing half MOA (dont think for much longer,,,)

 

I then scoped the 25-06 (this rifle prints sub half MOA all day), there is evidence of firecracking but not as bad as the "284"

 

Last but not least the 22-250AI - I expected this to be the worst as its run fairly warm but to my surprise, although there is a little forward of the thraot, there is almost no cracking evident at all.

 

Could this be down to the 40 degree shoulder angle / moly bullets? Who knows, but its looks lovely (well as nice as any barrel does wit a few thousand rounds through it!

 

 

So, I think its time to source another tube for the 6.5x284, should I go cut or button, german, US or UK or even NZ????

 

 

Decisions, decisons - one thing is certain it will remain a 6.5x284 - I just love this as a deer round.

 

 

Sorry no pics - havent any digiscoping equipment.

[Guest varmartin]

MMMMM.....bore scopes........buy them , they cost loads of money....use them and they cost you more money......

 

 

Thats why I dont have one

[eldon]

Have to agree varmartin.

 

Sometimes ignorance is bliss

[Andrew]

I'll go along with that, too! ~Andrew

[Ronin]

To be honest, I cannot say I am surprised regarding the 6.5x284, the barrel has survived longer than I had expected although I dont run full house loads in it, the 140's are still running in excess of 2900 fps.

 

 

The firecracking is real alligator skin in texture in places glazed over - cannot understand how the barrel still shoots so well - must be down to the quality of the Kreiger rifling as this is almost like new beyond the damaged area.

 

 

The 22-250 AI is the mystery as I expected this to be the worst and yet it is no where near in even a "poor" condition despite it having 1000's of rounds through it.

 

I wonder if its time to have a re-think on moly and the 6.5x284 when I do the replacement barrel?

[Redfox]

Moly has never been shown to reduce fire-cracking, if you think aboiut it how could it ?

It is more likely to be to do with the calibre and the amount of powder burned each shot and weight of projectile, which has an effect on pressure/temperature.

Redfox

[Ronin]

Redfox

 

 

I realise that moly coating wont stop firecracking, but, as there are two "extras" in the 22-250 that are not present in the 6.5x284 (namely 40 degree shoulder and using nothing but moly coated bullets, I cannot say if either contributes more to the absence of firecracking over the other.

 

I strongly believe that the 40 degree shoulder has caused the main "burn" to remain within the case rather than entering the throat area - again this is supposition on my part.

 

It does make me wonder though.

 

 

Funky

 

the barrel on the 6.5 is a cut rifled Krieger, when I cleaned it (the last time it was shot), I used M-Pro 7 products first carbon cleaner and then copper solvent - both showed clean patches after 4 or 5 patches.

 

Yesterday, after "scoping" I used some Shooters Choice (the extreme stuff) and the patches were clean too.

 

Have to say that at no time were the patches feeling "garbby or rough" when pushed through the bore - which is a sign of fouling.

 

I then used JB for 20 or so cycles of the rod and cleaned again with the weaker Shooters Choice solvent to remove the JB.

 

Looking through the scope showed no difference really.

 

The barrel is toast - its still minute of deer, no problem but it wont be reaching out anymore on small targets.

 

 

I will have a think about a barrel, using the 6.5x284 with one of James' Bergara's may well be a good test, but I was thinking along the lines of using a Bartlein or Tru Flite.

 

To be decided then....

[ejg223]

Moly has never been shown to reduce fire-cracking, if you think aboiut it how could it ?

It is more likely to be to do with the calibre and the amount of powder burned each shot and weight of projectile, which has an effect on pressure/temperature.

Redfox

 

Red,

maaaybeeee if..

does moly possibly leave traces on the surface? What is the thermo-conductivity of moly? I bet worse than copper.

 

Fire cracking is caused by a very short "split second" of ultra high temp followed by longer medium temp am I right?

If a thin layer of something protects a little from the ultra high temp then we could expect a reduction in cracking.

Bit like the tiles on a space shuttle.

 

just a guess

 

edi

[Guest northernchris]

Redfox

 

Less fire cracking maybe a by-product of useing moly which in turn will reduce pressure???? just thinking outloud

 

 

 

EDI

You could be onto something maybe ,i see the yanks are playing with Boron Nitride instead of moly,in the past we used this on a couple of "projects" in the F1 and WRC arena.

[Ronin]

This then begs the question -

 

does anyone use moly coated bullets exclusively in their 6.5x284 and if so (and you have a high round count), can I have a look down the tube with my scope to see if there is any discernable difference?

 

 

The layer of moly put down as each bullet passes along the bore could protect the metal from the flame - is this possible?

 

I wonder if JR could comment on this one?

 

I know its not exactly scientific comparing two makes of barrel in two different calibres - but its sure interesting

[Redfox]

The introduced layer of moly is minute and not cosistent (hence the damage caused to bores by ridges of Moly build up) .

The investigations done on it showed that the best way to apply moly was to fire a plugged case with a charge of moly dust, this coated the barrel interior and lasted a number of shots ( cant remember how many but it was a few) but in each case the moly was not present until a way up the bore past the throat. Also the moly dust would vapourise and change its state in the first inch or two of bore creating the layer which is hygroscopic and with moisture from the air forms weak sulphuric acid!

I think the shoulder angle has some to do with it, the smaller bore as well possibly.

There are much better friction reducers than moly , without its drawbacks. I started to look at this, but time and a lack of interest from the UK distributor have so far prevented me doing much with it.

Interesting subject though, there are many grades of moly and some types have been shown to cause stress cracking in stainless steel when in contact under pressure, this brought about some significant changes in the use and types of moly used with the stainless grades of steels a few years back.

Some years ago I did quite a lot of work on uses of moly enhanced lubricants and their applications.

Ronin if you contact Lilja ( dan) he has looked as you might expect at this subject in detail, a little of it here http://www.riflebarrels.com/faq_lilja_rifl...m#deepcryogenic and would I'm sure share some of his knowledge with you.

Redfox

[col48]

have you ever thought that the barrels on the L/W have lasted longer because they are harder??

 

ATB

Colin

[Ronin]

Hi Colin

 

 

the LW barrels I have are on the 6.5x47 and 308.

 

They both have had relatively few rounds through them in comparision to the 284.

 

The 47 is on about 1000 and the 308 around 400 so neither are in any way near the same state as the 284.

 

So I think its a bit early to say that the LW are better with regard to longevity - ultimately all I care about is accuracy in any rifle, if the barrels shot at 500 rounds I would be a bit cheesed off but it would be changed regardless - even more so now I can "do it myself"

[col48]

Hi Colin

 

 

the LW barrels I have are on the 6.5x47 and 308.

 

They both have had relatively few rounds through them in comparision to the 284.

 

The 47 is on about 1000 and the 308 around 400 so neither are in any way near the same state as the 284.

 

So I think its a bit early to say that the LW are better with regard to longevity - ultimately all I care about is accuracy in any rifle, if the barrels shot at 500 rounds I would be a bit cheesed off but it would be changed regardless - even more so now I can "do it myself"

 

 

sorry i thought the 22 250 was a L/W (what is she??)

ATB

Colin

PS i have that kreiger up for sale in the next few days, its a #7 29" long not sure about twist i think its a 1 in 10 i will check and get back to you.

[Ronin]

22-250 Ai is a Border cut rifled job and 7 years old

 

The Krieger may be too sloooow for my needs, thanks mate.

[ejg223]

The introduced layer of moly is minute and not cosistent (hence the damage caused to bores by ridges of Moly build up) .

The investigations done on it showed that the best way to apply moly was to fire a plugged case with a charge of moly dust, this coated the barrel interior and lasted a number of shots ( cant remember how many but it was a few) but in each case the moly was not present until a way up the bore past the throat. Also the moly dust would vapourise and change its state in the first inch or two of bore creating the layer which is hygroscopic and with moisture from the air forms weak sulphuric acid!

I think the shoulder angle has some to do with it, the smaller bore as well possibly.

There are much better friction reducers than moly , without its drawbacks. I started to look at this, but time and a lack of interest from the UK distributor have so far prevented me doing much with it.

Interesting subject though, there are many grades of moly and some types have been shown to cause stress cracking in stainless steel when in contact under pressure, this brought about some significant changes in the use and types of moly used with the stainless grades of steels a few years back.

Some years ago I did quite a lot of work on uses of moly enhanced lubricants and their applications.

Ronin if you contact Lilja ( dan) he has looked as you might expect at this subject in detail, a little of it here http://www.riflebarrels.com/faq_lilja_rifl...m#deepcryogenic and would I'm sure share some of his knowledge with you.

Redfox

Interesting,

micronized teflon ever show up in your work? We found it did increase performance on small 2 stroke engines at very high revs.

Just like in a barrel as a short term lube.

I am convinced that the barrel steel is not at the end yet either, we where involved in testing a new tool steel which increased life span of certain areas by factor 4, the previous 15 years of searching for better materials resulted in max 30% increase of lifespan.

Every time a steel maker comes up with a new material the gunny's start crying about their reamers getting blunt... no free lunch

Any barrels ever made of sintered steel? Powder metallurgy steel. Can do magic.

edi

[silentsoulsleave308holes]

have a good read at armalon's website

 

read all that is there and you may be well shocked

 

they have parker hales bbl making hammer forge machines, they quote that many (308 probsly) bbl's dont peak in accuracy till around 10,000 rounds

 

start at £200 something

 

both my and others I know of, ph bbls shoot sub 1/4"@100 if you do your part

[Guest northernchris]

Ja

 

They may have the old PH machines but do they have the lads with the savey to use them???? + Dealing with certain people @ Armalon can be hard work

[baldie]

I,d take that claim with a large pinch of salt , silent....10,000 rounds to reach peak performance? most .308,s are getting to the shot out stage by then. Would anyone want a barrel that took that long to "come on song" ? i bloody wouldn,t.

[brown dog]

- one thing is certain it will remain a 6.5x284 - I just love this as a deer round.

 

Andy,

 

Back from Scotland today; this comment struck a chord with me. I'm thinking massively reduced wind effect but still delivering a decent bullet weight to the target. Any links to previous posts or anecdotes on the 6.5/284 on deer?

 

Thanks!

 

Matt

[Redfox]

I might believe it of 22Lr as they have no real wear due to lead bullets heavily greased, but 308! you just have to call b$%%^&it on that for an excuse. You can hear the excuses, " sorry sir you will have to shoot it in for another 2 yrs before it settles down" .

I dont see it in their adds now but Sako used to claim "up to 10000 rounds before significant loss of accuracy for their barrels which is still pretty good for a hunting rifle.

Redfox

[Guest northernchris]

I agree with Baldie and Redfox utter BS , 10,000 rnds is a hell of alot of shooting for a barrel to live with.

[Ronin]

Hi Matt

 

 

I have shot quite a few deer with the 6.5x284 - I don't post exploits of kills regularly as I choose not to for obvious reasons, possibly why some think I "do targets only" - this is far from the case.

 

I stalk in the main roe but have access to red on some difficult ground that suffers from strong wind and accessibility problems, so the range from a good and practical shooting position is extended. This is by necessity rather than choice - it simply is not possible to stalk on this ground, you have to wait for them to come to you if you will.

 

Without exception the cartridge has dropped every deer I have shot if not immediately, certainly within 50 yrds of being hit.

 

I use 140 grain bullets so the analogy and comparison bettween the two (308 and 6.5x284) is reasonable as I think in the main most hunters would use a 150 grain bullet in the 308 and a 140 in the "284"

 

Energy levels are similar when each are run around 2800 - 2900 fps.

 

But, the "284" excells where the 308 is mediochre in ballistic performance.

 

 

I chose a Nosler ballistic tip 150g (BC .43) from the massive selection of 30 cal bullets and ran that in Exbal at 2800fps;

 

In 15 mph crosswind (certainly typical of my area and no doubt a slight "breeze" in bonnie scotland!

 

at 300 (from 100 zero)

 

13" drop and 10" wind deflection.

 

at 400

 

30" drop and 20" wind deflection

 

 

For the "284" I used a Hornady SST 140g (BC.52) - again typical deer bullet from the massive selection available in this calibre.

 

Same crosswind / same zero.

 

At 300

 

11" drop and 8" deflection

 

at 400

 

26" drop and 15" deflection

 

 

Ok I chose similar (ballistic tipped) bullets so the comparision was fair. The differences are not massive, but they are certainly noticable and relevant at these ranges - I find 6.5mm easier to shoot and predict bullet placement, I know you have shot 308 for a while, so you will no dobt be on top of your game with this calibre.

 

However anything that gives an advntage in the field is a definate plus IMHO, thats why I like the "284"

There is the obvious down side to this cartridge - you need a long action to feed the cases if you use 140g bullets.

 

If you are thinking of another barrel for the AW, you wouldnt go wrong if you considered a .260" Rem, Zac Smith has done wuite a bit with this case and an AW on 6mmBR and SH (as well as 6.5x47 - but that wont handle 140's)

 

 

Andy

[brown dog]

Thanks Andy. PM inbound.