22" JP Barrel at 5k and dispelling 2 myths

[StoneHendge]

I thought my 22" JP Grendel barrel was finally giving up on me. It started getting wild at a practical match and I was chasing my dope as it warmed up (up to 20 shots in 90 seconds are possible at this match). Turns out the problem was a failed JP gas ring which you can't test like standard rings. As a bolt heats up, the rings bleed gas and release pressure, dropping velocity. I didn't know it at the time and thought it was shot out. In the midst of a relocation, I put the rifle in storage (as in a storage unit at a storage place). I forgot I had a few rounds leftover and my Lapua Grendel brass was at the end of its life (Lapua at 12-13x). Storage ended up lasting 6 months in AZ high country. Out of brass and thinking it was shot out had me agonizing over buying new brass for it at today's prices or getting either a Lilja AR24 or CLE Bartlein/Kreiger Varmint ARC barrel for the build.

Then 2 weeks ago I found the rounds left over from the last match. Enough for a test! Replaced the gas rings, passed a few patches with Bore Tech C4 through it to clean it and headed to the range to see what gives.

Myth #1: the cold bore. I once blamed a bad shot at a training class on a cold bore. My instructor was a Special Forces sniper and Special Forces sniper instructor. He said 'there's no such thing as a cold bore, Stone, only a cold shooter". Given that cold bore shots were pretty important for his job for many years, I took his word for it. Well, this barrel was cold for 6 months. First 5 shots at 100 yards. 123 gr Scenar at .03" jump, 12x Lapua brass, 28.5 gr Shooters World Precision. Prone off an Atlas bipod with a midweight Wiebad bag supporting the rear:

5 on a dime - Copy.jpg

I'll add that the storage unit wasn't climate controlled. Got down into the 20s at night in the winter and some warm 80+ days in the fall. I'll give the Burris XTR III kudos for holding its zero through 6 months of those fluctuations:

5 under a dime - Copy.jpg

As I said, the brass was on its last legs (now at 13 times through the wringer):

5 lapua - Copy.jpg

Myth 2: I've never annealed and probably never will anneal. The only time this brass was annealed was when it was at the factory. I've personally always thought that neck tension was overrated and that as long as the neck holds the bullet when you press the tip against the bench, the round is good to go. Some necks did crack while loading this lot in its golden years. And if they didn't crack then, many cracked on firing. This is 2 of the 3 that cracked out of these 5:

why anneal.png

why anneal 2.png

I'll note that the brass's primer pockets still won't accept a Ballistic Tools No-Go gauge so they are GTG. I won't debate that annealing could have extended the neck life, but how long and at what cost in time? But I will argue that it is a myth that it can improve accuracy and SDs (this batch of ammo held a single digit 5 shot SD while testing before the match at a slower than match cadence).

So the JP barrel lives and is going strong - 5k+ and hopefully many more. Maybe that myth that cryogenic treatment doesn't help barrel life isn't a myth after all......

[VASCAR2]

Interesting, thanks for posting!

[biodsl]

Great stuff, SH. And great shooting. I just checked the JP Rifles site and found the 22" Grendel barrel is $575. Seems like a bargain considering how it shoots.

[Zeneffect]

cryo treating is no myth. it actually restructures the grain of the metal, there is very very solid repeatable science behind it. Never considered the gas ring as a potential issue... oddly i find that during longer strings my FPS goes up not down. I attributed it to heat soak penetrating the case but now i guess it could be better seal/expansion from the added heat.

[rickt300]

Good deal. As far as annealing goes I do anneal hard to find brass. We had a stretch where 7x57 brass was impossible to find and my brass was on more than 12 firings so I annealed it with the slowly turn in the fire of a propane torch until I could feel the heat in my fingers halfway down the case and drop case on a towel. Doesn't take too long with 60 pieces of brass. That said the cases are doing fine and I am going to anneal ever 6 firings or every time I have a neck split. Of my Grendel brass only Hornady seems to split necks sometimes on the first or second firing. I anneal it pretty soon after the first firing. If it splits on the first shot I don't want it anyway.

[CJW]

Good read Stone.

[Lemonaid]

I'm a bit disappointed, I thought the thread was about a shooting a Grendel at 5000 yards or meters. Nice shooting though!

[CJW]

LMAO Lemonaid

[Zeneffect]

Most of us shoot 5000... inches.

I think annealing would have avoided that neck cracking and you would have a little more brass now. I'm on reload 15+ with zero losses (minus 1... my fault though, not a split neck) and anneal every firing. Per case it adds exactly 6 seconds to the reloading time (this includes the wait.. annealing time is only 1.86 seconds)

Lapua brass is 2 things right now. Hard to find and expensive. I don't doubt you can get more than the average life out of them by just running them until failure, but I also believe life can be extended further by annealing, thus my cost per shot goes down over time.

[Klem]

Stone,

I'll add two comments.

The idea that there's 'No such thing as a cold bore shot, only a cold shooter' is one of those neat sayings that adds its own credibility, but only because it sounds neat. Of course the first round out of a gun that has been idle for 6 months is [on average] not going to print in the same place as the previous session. Especially if it has been cleaned and/or lubed in any way. Even if not I can imagine if not touched the internal coating of carbon will change as moisture slowly works on it over the months. Then there is the external temperature difference between firing sessions, and the internal temperature difference of the breech. Your firing position on the gun may also be different. If the gun is precise enough the shooter will see a difference, and hopefully that difference is predictable... But I know you know this.

My other point is that I have never seen shoulders and necks like that on a Grendel. I anneal now but did not use to when first starting on this calibre. I know annealing is doing something as the feel when seating bullets is stiffer than before. But to be honest, I have not seen any improvement in accuracy, not even a tiny bit. The induction annealing wand cost a few hundred dollars in parts so that will have to be compared against how many more firings I get. Again to be honest, I don't know because I've never had to retire any of the original brass. The price of brass here is three times higher than when I first got it so I imagine annealing will pay for itself eventually - just when, I don't know. Plus I've paid for the setup so feel obligated to use it. As with Zene, it takes time - roughly 6 seconds per case. I set it up and over a couple of days do it in batches of about 30 at a time.

[lazyengineer]

Great post! I will say Klem is right about Cold Bore. You may not see it at 100 yards, but you definatleybwill at 600 yards. Thr bullet barrel friction etc interface of a clean barrel on that first shot, is quite different than on the second, amd will show up at distance. If it's Cold bore still fouled and last shot in the last few days, then sure - not much difference. But a cleaned rifle sitting for 6 months is fired Cold, that firstbshot can easily be at least 1 scoring ring off at 600.

As to annealing - I lean in your direction. I don't anneal, though admit of done right it's no harm and a great way to extend brass life. I run 7.62x39 at times, amd that stuff will crack quick. Ah well. It comes to me free (pickup), it goes away free. If I had easy access to an annealed, I'd run it; but otherwise haven't had the gumption to bother with the effort and expense.

I will say, I seem to have a similar correlation to brass that sits loaded for a while, tends to neck crack on me at a notably higher rate than the same lot fired shortly after reloading. I don't really know why. People don't mention this much, amd just dismiss it when it comes up; but it happens to me - and you, and I suspect others. I tend to load large volumes to exhaustion, so large portions of some of my reload lots can end up 5-10 years old, and then that 1000 rounds cycled into use for a season. In my experience it often doesn't affect anything, and I've won matches where every single neck cracked.

[JASmith]

There is a lot of evidence to suggest that the first 1 to 3 shots from a clean cold bore will print differently at longer ranges.

Much of that lore comes from the days of poorly bedded wooden stocks where a warm barrel and / or damp stock will print differently than a cold barrel.

Remember, the instructor mentioned in the OP had a mission where most, if not all, of his shots were from a cold bore and the barrels were almost certainly free floated. (We don't know his cleaning routine.).

A good way to see the effect in your rifle is to shoot the first shot of the day on a different target than the rest. (Always the same degree of cleaning, or none, depending on your preference.) Use that same first target each time for several subsequent range sessions, recording date, light, wind and weather along with impact point. At that point one will have a clear understanding of where the first shot will hit and how accurte that first shot will be -- important for the hunter.

The standard of how much drift is allowable should also be set with the understanding that most hunting shots only need to print in a circle of a few inches in diameter at the maximum hunting range to have a good chance of hitting a deer's vital zone, so being off a half moa or so is not a huge deal. The precision target shooter will have a different standard and may need to be attentive to the need for fouling and warming shots.

[JASmith]

Regarding neck tension, I can't tell, as a moa-class shooter, the effect of tension, but the quarter-moa shooter may be able to.

My view is that the precise degree of neck tension not particularly important as long as all of the cases have been fired the same number of times but may be important when the brass has a variety of shots in the small lot.

Brass hardens each time it is worked and the shot, size, and resize all induce plastic work, so the tension will be greatest just before the neck cracks. Most of the work hardening happens early in the size-resize cycle. That rapid, followed by a slow, hardening rate suggests that the tension should become more uniform as the number of shots and resize cycles increases.

The first resize cycle will help iron out any anneal-induced hardness inconsistencies. That's why I advocate resizing freshly annealed brass prior to loading.

BTW my first neck cracks and base separations in the Grendel were consistent with the OP -- on the 13th to 15th reload cycle.

[VASCAR2]

I have a friend who is a retired police officer who was a sniper for a state tactical team. He kept meticulous records and was a very competent shot. Law Enforcement sniper engagements are assumed to be on a cold bore and I know snipers who used a separate target to record their cold bore shots. My Friend used to keep many of his targets in the event he was subpoenaed to court after an engagement.

I know my friend used to keep records on the environmental conditions for all his practice and knew his dope for any encounter.

[StoneHendge]

Thanks everyone and sorry - I didn't abandon the thread - just busy.

I certainly do think that annealing would have extended the case neck lives. Thing is, this lot of Lapua brass is the only brass I've owned where the primer pockets haven't started going first. I'll add that I purchased 300 pieces of Alpha 6.5CM brass that is over a buck apiece and all the rage in some circles. The primer pockets were so tight at first that I couldn't even get a Fed LR primer into them - only a BR-2 which has a slightly smaller diameter. After 5 firings they still don't fully accept a no go gauge, but some are getting close and the Feds fit easily. I'm pretty dissapointed and although I'm at a near max load (2850 with a 123 Scenar with H4350 out of a 22"), I'm not over it. So what I grapple with is investing the money and time in something that might not get me any additional brass life at the end of the day

Klem and others, I don't disagree that a clean bore will shoot faster than a dirty bore - I've tested myself and I'm sure others have and the first one to three always run a bit faster than once its fouled (20 fps for the first if I recall in my Grendel), so that will affect vertical dispersion at range, but it should have an insignificant effect on POI at 100 yards which is what I was referring to. The heat shouldn't have an impact on zero either provided a temp insensitive powder is being used. A faster bullet does tend to go lower as barrel dwell time is less as the barrel is following its natural rise - and for me it also goes slightly right - I don't know if that's normal or a function of my shoulder structure or my form. I debated about whether or not i should clean this time and did decide to for exactly the reason you said, Klem - who knows what the time and temp fluctuation could do with the residue over 6 months. Normally, I wouldn't have since its a barrel that can go to at least 150 before a cleaning is needed.

By cold shooter I mean that we get on our rifle, we run through our checkdowns and we blame the cold barrel when the shot doesn't go where we thought it should. And then we have the feel of that first shot and our muscle memory takes over and we're more relaxed and the next rounds go where we know they should go. I think that group was so good because I didn't overthink it and part of me was kind of looking forward to having it be shot out so I could buy an ARC barrel. So I think I was truly perfectly relaxed.

It would be interesting to document one's cold shots to see it there is a pattern - be it first shot pulls due overgripping or maybe pushes from too much shoulder, or maybe a little of each.

I put my remaining 13-14x brass in the tumbler and have about 3/4 lb of the lot of powder I was using left. I'm interested to see what the SD's are like and if the more brittle necks will have an impact. My 5 shot SDs were in the 5-7 range when I worked the load up when the brass was at 9x. If anyone has any ideas of any other sort of test that could be run on brittle necks, let me know!