Phantom30

The 22" and 24" 6.5 Creedmoor barrels were purchased from Primary Arms made by Bear Creek Arsenal, fluted SS, !:8 twist The 24" 6mm Creedmoor was made by Apache Arms.

All of my Creedmoor ARs have White Oak Armament gas Tubes. The one in question is an AR-10 rifle length tube. The picture below is the only one I have available which addresses your request. But it is only 6 count not 10.

I consider this a Creedmoor issue. My suspected villain is the distance between the casing shoulder and the bullet tip, which is larger than the barrel extension face to counter bore. 6mm is more suspect because it will drop down further onto the ramp and I believe increase the chances of finding the counter bore. My 6mm counter bore has copper stains aligned with the feed ramps so it appears to be a potential source of chambering impacts. (Hornady Black BTHP) I know this is a system design weakness because my 1st 6mm Creedmoor AR, the barrel maker left out the counter bore. Jammed every time, round compression. After he put the counter bore in, it works fine but the stains are evidence of the counter bores necessity. The 6.5mm ARs have stains on the feed ramps and counter bore. The stains are largely caused by the S&B FMJ ammo ogive scraping but not damaging the rounded tip. However with enough force you could end with a seating alignment when it hits the lands. Cocking the round slightly in the casing. If you look at the Hornady White Tail Target the impacts are all over. That soft lead tip will obturate at 7KPSI which apparently it is getting when the tip hits the ramp or counter bore. Enough to get all over a 7" target at 100 yards. So That round would not be good for hunting in a 308AR, at least in a Creedmoor format. All these rounds are factory loads I have been showing. Only the Tip drill ELDs were partial hand loaded. Does this apply to all AR rifles. Don't know but why does my bolt gun shoot under a dime and my AR squeak under a quarter with the same caliber and ammo?

The effects are there the magnitude of the meaning depends on the type bullet.

The chambering tip deformation is not devastating or catastrophic but it exists. The next attachments were zoomed in on the original pictures so I could provide the clearest examples. If you are hunting especially out east where 150 yards is a typical shot then no big deal, but if you are out west making a 1,000 yard shot it is going to open up the group. Can I prove it with target examples. No but aerodynamics says asymmetry will cause variations in the ballistic trajectory. That's all I am saying tip deformation from auto feeder chambering exists and it is bullet type dependent. It may not be as dramatic with an ELD round but a Hornady White Tail will be screwed up.

The ELD tests were dummy loads no primer no powder. Just a way to examine what was gong on with the tips. Yes crimping is important in an auto-feeder. The casings were new Hornady. The zero crimp became evident early so the next ones were crimped with the standard Lee Crimp die. Maybe the crimp was not strong enough but since these were just test items, the crimp was interesting but secondary to what was going on with the tips. As an aside a strong crimp has the potential to strip the coating from my objective powder coated round which is where my interest really was before this tip issue arose. As for your comment about the utility of the 147gr Hornady ELD Match, bullet that's very true in a bolt gun, as you can see I love ELDs in my 6mm Creedmoor. I have some 6mm A-Tips that just can in and awaiting their 153gr 6.5mms, expensive but they really should get out there. Hancock's 1960s history will repeat itself it they start making them with rebated boat tails, and doing that would reaffirm what CORBAN has been selling for years. Tubbs has been selling his RBT closed tip 6mm bullets for some time and they work well.

I was too slow on my edit to fix the spelling above •Granted this was a rabbit hole exercise. My objective was to see if there was a chance any of my Powder Coated Cast bullet designs would stand up to this pounding and produce reasonable long range accuracy in AR class 6mm or 6.5mm Creedmoors. •IMHO before the magazine feed lips releases the casing or the shoulder has reached the feed ramp, the bullet tip in Creedmoors has already contacted the feed ramp and or counter bore. The force is significant enough to have an impact on bullet symmetry and resultant accuracy.

Granted this was a rabbit hole exercise. May objective was to see if there was a chance any of my Powder Coasted Cast bullet would stand up to this pounding and produce reasonable long range accuracy.

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I sent these to Hornady back then....Thanks.. for your concern...Well they now offer A-tip

ELD in bolt gun very happy

This is the Fed Fusion results, same day as white tail. Notice the burr on the tip in one of the four pictured, Not every round gets damage but flyers happen. Not good for consistency. Since the ELD stuff was not range data I'll have to collect it separately here.

On a previous day this was the result with Hornady white tail, Was using it because it was cheap but was confused by wild results. it is what start the tip symmetry investigation.

same day example

OK so you think I have a hot box of ammo. Fair enough. I have been buying them in 500 rounds batches. Now granted that doesn't guarantee they are all the same lot, so'll have to go through what boxes I have left to hard number confirm that. As for the evidence, I can post it on the tips, it was a chambering drill for the ELDs, because you can't get the tips back to examine if you fire them. The other brand assessments were just based on target results. OK, test the hot box concept, I Am still at 1600 feet and have some other boxes of S&B 140gr, defense systems 142gr, and Hornady ELDs147gr, in the bag, I can fire with Chrono on all and see what happens. Thanks for the hot box info, a useful starting point. Patterns of Evidence: extracts from personal range reports: next same day with HP

Not IMHO, tested and verified, its NO BS, Facts jack. Granted the error margin is smaller for the ELD but if you shoot Hornady white tail the SP tips which obturate at 7KPSI. the accuracy is around 7 MOA instead of sub MOA. QED Questions yes, yes. So if the muzzle velocity and resultant change in pressure is not that sensitive to that small of an altitude change then what is causing the primer punch. Probably fired maybe 700 to 800 of these in various rifles with no problems until now.

I fire these in my 24" same Gas system at sea level no problem

Oak Armament. IL Standard AR-10 gas tube Rifle Length No Chrono at this altitude 2657 near sea level The ELD will deform slightly when hitting the counter bore or feed ramps, firing fast enough they don't have time enough to recover and it will add nearly a MOA to accuracy

Oak Standard AR-10, rifle length. These things are usually fairly tight in the chrono. and you can see they are loaded right up there with those nice little volcano shape primer strikes. This happened at 1600' normally I am firing at 300'MSL think the pressure altitude was enough to juice them up. I might try some other ammo, but I hate using ELDs in this tip eater.

Been using the recommended ToolCraft NiB BCG in my 22" 6.5 Creedmoor. Got about 120 S&B 140gr FMJ rounds, all same lot, thru it. Started punching the primers during firing, four times in last 8 rounds. What is happening? Measured the pin depth using recommended procedures and found the pin to protrude 0.050" the cited number in the archives for this BCG should be 0.040" so why is it screwing up now?

IR and two color lasers. For longer range stability the QD bi-pod and stock sock under pistol grip.

I do get it MIL MIL or MOA MOA is easier when you are working within the same scale system, very valid point. However, when you understand the only thing that matters is how many clicks are needed in any correction, then you can recover the simplicity with a MIL MOA and have the benefits of both. The classic MIL reticle for traditional range estimation and the more precise MOA turrets. May be I should say it this way. I have a Click reticle with click turrets so I have a Click Click scope. When I look at the reticle I see tick marks that each have a value of 7 clicks. My holdover range is 70 clicks on the reticle. My elevation limit is + 280 clicks on the turrets. There are 60 clicks per turret revolution. The value of a click is .251 inches at 100 yards. So a Click Click Scope is within the same scale system. And that's how you get cost effective utility out of a "junk" scope IMHerO

My original picture is not what I should have used the reticle image is for a 12.5 power setting not the normal 25 power. Below is the proper pairing.t .

It may have to do with the barrel extensions being either M4 or LR308, either way I don't think they match up with the Creedmoor distance between the tip and shoulder. May be 98Z5V has experience with that, but it is even worse with 6mm Creedmoor where the bullet is even thinner allowing it to fall deeper into the feed ramp.