6.5CM Hornady Brass Life and Loose Primer Pockets?

[pugnado]

I've got a couple hundred Hornady 6.5CM cases that I've shot four to five times. Recently, a good number of them have loose primer pockets, loose enough so that when fired the primers fall out and get lodged in the chamber or where the bolt locking lugs are supposed to go = failure to chamber round. (This is a semi-automatic large frame AR platform.)

Initially, when the bolt wouldn't lock I figured I'd messed up the COAL somehow or didn't bump the neck enough, but I confirmed that wasn't the case by bringing my calipers to the range and measuring the suspects that wouldn't chamber, that's when I discovered bits of primer where they shouldn't be.

Brass is Hornady large primer, loads are 41.0g of H4350, 147g HDY ELD-M bullets, primers are the CCI 250 large magnums.
(This gives me SD of about 5 fps, the result of 50 round ladder test.)

Is there an easy way to measure these loose primer pockets, fix them with a tool etc?

I hand prime all my cases so I can feel how loose they are, I could potentially throw them out then but that's a waste of a 2 cent primer.

Should I just switch to Lapua brass now rather than waste more primers/powder/bullets on questionable brass?

Thanks!

 

[Midwestside]

Is there an easy way to measure these loose primer pockets, fix them with a tool etc?

I hand prime all my cases so I can feel how loose they are, I could potentially throw them out then but that's a waste of a 2 cent primer.

Should I just switch to Lapua brass now rather than waste more primers/powder/bullets on questionable brass?

Thanks!

Fixing is probably synonymous with throwing them away.

Here is a tool, if you don't want to waste a primer by feeling it basically "fall" into place of the loose pocket.
https://ballistictools.com/store/swage-gage-large-primer-pocket-gauge

I grew tired of the loose pockets, and switched to Lapua.

 

[Kiba]

I've had 3 6.5 Creedmoor gassers now (1x GAP-10 and 2x JP's) and 41g of H4350 behind a 147 ELD-M in Hornady cases through a semi auto immediately sounded too hot to me if you want the brass to live more than a couple of firings.

I've trashed Hornady primer pockets in my gas guns in 3 reloads with 43.2gr of H4350 pushing a 123 Scenar. Quickload says that's 51.5ksi, your 41gr H4350 147 ELD-M is hotter than that at 55.2ksi.

I've had the same lot of Hornady 6.5 Creedmoor brass that died in my gas guns in 3 reloads last 8 reloads in my bolt rifle with hotter loads-- my experience is that even with an adjustable gas block tuned to just lock back on an empty mag and heavy buffer weights to slow things down for a little more lock time and to slow the carrier down is that the gas guns are just rough on brass-- especially the Hornady stuff since it's softer. The Creedmoor seems more susceptible to this in a gasser than a 308 gasser since the Creedmoor usually uses slower burning powders which means higher port pressures impinging on the bolt and carrier-- that's why the current line of thinking is to use a +2" gas system to drop the port pressure and slow the action down.

If you want to keep pushing loads like you are now and have the brass last longer you'll have to try stronger brass, Lapua being considered the gold standard. There are other 6.5 Creedmoor brass options out there now (Norma, Prime, Peterson, Nosler, Starline, Lapua) but I don't have experience with any of them and will wait for someone else to offer a recommendation. My hunch is that the small primer Lapua brass will last the longest, but personally I don't like chewing up $1/piece brass in a gas gun. I'd be tempted to try the cheaper small primer Peterson or Starline cases in my gas guns though and may do that once I kill the current batch of Hornady brass. If you're going to try the small rifle primer Creedmoor brass in your gun, make sure it has a small firing pin or you might pierce primers.

 

[Supersubes]

Yes, do Lapua. It’s actually cheaper once you amortize it over its longer life span than Hornady.

 

[Foul Mike]

I haven't had good luck with Hornady brass either. I use Nosler now and like it.
I use bolt guns and shoot H or IMR 4350 at 41.5 grs with a CCI standard primer and a Hornady 140 HPBT-M bullet.
My kids and I have several Savages and I load this for all. I bought Nosler brass because it was there on the shelf when I needed it.

I am sure there is a better load for all, but that is up to them to figure out.
Goes bang each time,and is close to where you expected it. and works well in the rifle I shoot, work on that--

I bought one of those no-go--- go primer pocket gauges-chingaderos or is it a clerenderm? on the internet.
I am surprised there aren't more of these things sooner and maybe there is?
I hope it works like I think it will. Wish I had had it before as I hate losing primers to bad pockets.
Simplicity is prime. FM

 

[pugnado]

So I got a hold of those pocket measurement tools and threw out a good 50 of my lot of 200 for being too big. I started priming the remaining 150 and they all just went in too easily, so rather than wasting powder and bullets and range time I just junked the whole lot.

When I go to Hodgdon's site and punch in 147g 6.5CM bullets and H4350 it amazingly gives me a max load of 41.8g which, coincidentally, is the most accurate load for my barrel according to some ladder testing. This was true for both the 147g ELD-M (paper load) and 143g ELD-X (expanding load). It is about 60,000 psi though and I think the poor Hornady brass isn't made for that more than a few times. So now I'm looking into other brass, and will probably get some Lapua. What primers does it like? CCI BR4? CCI Magnum? It's stupid nasty cold here in the midwest (polar vortex) so I haven't been out much, but would freezing temps that dictate any load/primer change with H4350?

 

[Kiba]

If you do the large primer brass, I like GM210M. I haven't played with any small primer 6.5CM brass yet, but for my 6 Dasher I use CCI450's with very good ES/SD and that's what I'd try in small primer 6.5CM brass.

You may also want to search if there's a difference in case capacities of the Lapua 6.5CM brass compared to the Hornady stuff, you may have to adjust the powder charge down if the case capacity of the Lapua brass is less than the Hornady brass.

Also, as I mentioned in my last post, if your bolt doesn't have a small diameter firing pin (0.068" max diameter, 0.062" even better) I would not recommend trying the small primer brass in it; small rifle primers with higher pressure and a large diameter firing pin is usually a recipe for pierced primers.

My GAP-10 as delivered had a DPMS BCG with a large firing pin and it would pierce around 30% of Hornady 140 A-Max factory ammo; on the second trip to the range a piece of primer stuck the firing pin and the rifle ran away full auto slam firing. Very lucky it didn't go off out of battery and damage the rifle (or me)... GAP swapped the BCG for an Armalite setup with a 0.062" firing pin and all primer problems went away.

 

[pugnado]

If you do the large primer brass, I like GM210M. I haven't played with any small primer 6.5CM brass yet, but for my 6 Dasher I use CCI450's with very good ES/SD and that's what I'd try in small primer 6.5CM brass.

You may also want to search if there's a difference in case capacities of the Lapua 6.5CM brass compared to the Hornady stuff, you may have to adjust the powder charge down if the case capacity of the Lapua brass is less than the Hornady brass.

Also, as I mentioned in my last post, if your bolt doesn't have a small diameter firing pin (0.068" max diameter, 0.062" even better) I would not recommend trying the small primer brass in it; small rifle primers with higher pressure and a large diameter firing pin is usually a recipe for pierced primers.

My GAP-10 as delivered had a DPMS BCG with a large firing pin and it would pierce around 30% of Hornady 140 A-Max factory ammo; on the second trip to the range a piece of primer stuck the firing pin and the rifle ran away full auto slam firing. Very lucky it didn't go off out of battery and damage the rifle (or me)... GAP swapped the BCG for an Armalite setup with a 0.062" firing pin and all primer problems went away.

I'll probably do another 50 round ladder speed test if I switch brass and primers. I also just noticed the headspace in my chamber (Proof Research CF wrapped 22") has grown about .008" based on brass measurements from when it was new to now, so I wonder what's up with that -- a sign of too much pressure maybe? I have about 1000 rounds through it, mostly reloads of varying charge. (New: 1.530" fireform size, now 1.538")

I have the JP High-Pressure EnhancedBolt with the titanium firing pin, it's got a tiny business end so I'm not worried about overpressure and/or piercing primers.

I also have a can in ATF jail and by the time that gets out I'll probably get another barrel and do more ladder testing along the slower/subsonic edge of reloading...

 

[Kiba]

Headspace should *not* change over the life of a barrel, there's no combustion going on in the chamber to erode the chamber. However, if your chamber headspace is on the max side of spec and you started with fresh brass that was sized to the minimum side of spec, sometimes it will take 2 firings for the brass to expand all the way out to the chamber dimensions, so if you use a comparator and measure the shoulder on once fired brass vs the twice fired brass it may show an apparent difference in headspace. For a more accurate headspace reading from fired cases in my gas guns, I shut the gas block off, fire a couple rounds, and then retain those cases as my "chamber length" samples.

The JP high pressure bolt is good to go with the small primer brass. I received one of the very first HP bolts from Ben @ JP several years ago as I was also having some primer cratering issues with my JP 6.5CM that I had just received from them; solved all the primer cratering issues.

I'm also considering switching to better brass once my current batch of 6.5CM Hornady is toast... but I need to do more reading to decide between Lapua or Alpha SRP brass.

 

[Rebelirons]

I had the same issue with Hornady 6.5 Creedmoor brass. I switched to small primer Lapua brass and haven’t looked back. Toss the brass with loose pockets. I have 8 firings on some of my Lapua brass and the pockets are still tight. Also in running Lapua brass my SD’s went down and my loads are more consistent than with Hornady

 

[Foul Mike]

I bought a Ballistic Tools primer pocket gauge, I am really happy with it.
My only regret is that I didn't know of them sooner.
I think they should be on every reloader's bench. FM

 

[Sniper260]

Throw them away. Hornady brass isnt quality and they are done at that point. If primer pockets are too loose you should notice it at the priming cases stage. This is why a good hand primer is important.. to feel it.

Buy lapua or peterson brass. Anneal every time, and your brass will last longer and pay for itself.

 

[Hollywood 6mm]

I've found that semi-autos in 6 and 6.5 Creedmoor are much harder on brass for whatever reason - to some extent on primer pockets, but also on case head separations. I've been very happy with Hornady brass, including having sets of brass that have easily gone 8-10 firings - but that's in a bolt gun and not pushing them to stupid velocities.

 

[Foul Mike]

You sure have had better luck than I have had.
I wonder if it isn't year of mfg? I don't think I am pushing stupid vel at the charge that I use.
How old is your brass that you have been able to reload that many times?

 

[Hollywood 6mm]

You sure have had better luck than I have had.
I wonder if it isn't year of mfg? I don't think I am pushing stupid vel at the charge that I use.
How old is your brass that you have been able to reload that many times?

I've done it across multiple vintages of Hornady brass. Hell, I just did barrel break in and load development on a new barrel using brass from 2015 that I lost count of the number of firings on it - at least 4-5 on that batch, though. The batch I shot last year in matches has at least that many on it, and they're still solid, too.
I also have only run 105 and 108s (outside of a brief flirtation with 110s), and don't try to run them stupid velocities. My go to loads have been 3080-3125 (depending on lot of H4350) and 3040-3080 with 108 ELD-Ms, all fired from a 26" Bartlein.

 

[Foul Mike]

I am using either IMR or H 4350 @ 41.5 gr. behind 140gr. Hornady BTHP Match bullets and I am almost always shooting at 1000 yds. or beyond.
Now, maybe, this is stupid velocities but I sure can get many more reloads out of Nosler brass than I can with Hornady and not loose the primer pockets.
I have not tried the lighter bullets.
Maybe that is where the differences come in?
How far can you shoot those lighter bullets without too much wind drift hassling you at 1000 and beyond?
Maybe I should shift towards these lighter loads?
At what ranges are you shooting these lighter bullets? Maybe I am missing something here and need to change my ways? FM

 

[Hollywood 6mm]

I am using either IMR or H 4350 @ 41.5 gr. behind 140gr. Hornady BTHP Match bullets and I am almost always shooting at 1000 yds. or beyond.
Now, maybe, this is stupid velocities but I sure can get many more reloads out of Nosler brass than I can with Hornady and not loose the primer pockets.
I have not tried the lighter bullets.
Maybe that is where the differences come in?
How far can you shoot those lighter bullets without too much wind drift hassling you at 1000 and beyond?
Maybe I should shift towards these lighter loads?
At what ranges are you shooting these lighter bullets? Maybe I am missing something here and need to change my ways? FM

I'm running a 6 Creedmoor, not a 6.5, but I've had it out to just shy of 1300 (only because of opportunity).

 

[Foul Mike]

With 6mm as to 6.5 the whole thing is really moot. Apples and oranges.
My nephew is shooting a 6mm Bergara and when shooting with him I know my 6.5 takes less windage to get there. He has to add more.
If you don't mind, PM me what is shooting best for you and I will pass it along to him.
Thanks and Regards, FM

 

[Hollywood 6mm]

With 6mm as to 6.5 the whole thing is really moot. Apples and oranges.
My nephew is shooting a 6mm Bergara and when shooting with him I know my 6.5 takes less windage to get there. He has to add more.
If you don't mind, PM me what is shooting best for you and I will pass it along to him.
Thanks and Regards, FM

Wind depends on conditions and distances, too. I'm in the southeast, and for PRS matches it's not usualy to see 6 Creedmoor with a slight wind advantage for much of a match due to milder winds and shorter average distances, where the speed of the 6 Creedmoor is going to hold a slight advantage. That said, even a .1 wind advantage is noticable on targets that are in the .3-.6 MIL size range.

 

[Foul Mike]

Read the Title, and 1st post.
Good info in here. FM

 

[JMGlasgow]

Hornady brass is junk. Not only do the primer pockets loosen early, but the brass is terribly inconsistent. I switched to premium brass and won't look back for my 6.5 Creedmoor.

 

[gnatmm]

I bought a Ballistic Tools primer pocket gauge, I am really happy with it.
My only regret is that I didn't know of them sooner.
I think they should be on every reloader's bench. FM

I second this and even if slightly OT I ’d add also the neck tension gauge to your cart...

 

[Subwrx300]

I've had great luck with Hornady brass overall. I've got a "mixed lot" that catches all of my practice brass and stragglers that has 7-10+ reloads on most of it. I haven't had any issues with loose pockets save for a couple of individual pieces feeling slightly loose but still holding firm.

Also have 750 Starline with 3-4 firings and it's still tight (had been run through 6.5 CM semi auto for most of those) and still working great.

I agree with @Kiba that it sounds like your load is on the warm side for a gas gun. While it may be perfectly safe to shoot, loads just below/at max charge with slow powders have more port pressure than faster burning counterparts. I usually need to back my charges down between 1-2gr for gas guns to keep bolt from unlocking early and stressing brass.

Or just accept the lower life and by brass more often.

 

[morganlamprecht]

what kiba/sub said...6.5 gassers /= 6.5 bolt guns

i cant remember ever losing a piece of hornady brass running 140s @ 2700-2750 in a 24" bolt gun barrel...and ive been thru 1000s, i lose them at matches before the brass wears out...ive got a bunch of hornady at home with 10+ firings

my gas gun usually trashes them in 5 firings or less...get the longest gas tube you can and stack the heaviest bolt/buffer components behind it to give you the biggest cushion

 

[pugnado]

It seems like Lapua 6.5cm Brass has a $120 MSRP no matter where you get it.
So I got two boxes from Brownells, %10 off & free shipping with the usual coupon code + %4 activejunky reward =~ $205 + tax shipped.
Lesson learned, I also bought 300 pcs of lapua 300 blackout for my new trunk pistol.

 

[fvalmostthere]

I'm running into the same thing with my hornady lrp brass, I buy the 100per bag bulk stuff that midsouth and grafs sell, about 45cents a piece. I haven't had any primers fall out yet but with my lee hand priming tool I can feel them getting looser even on the 3rd firing. I just loaded up a batch of 4x fired and had about 1/3 of the cases where the primer just slid in with almost no resistance, I marked a black ring around the case with sharpie and tossed it after firing. I wasn't sure if this was just hornady cases or if I was messing them up. I got a rcbs case prep machine and use the primer pocket uniform attachment to clean out the pockets, but I do notice there is some brass shavings coming out. Am I destroying my own pockets just trying to get them clean or is this normal? I am running a hotter load, 123 scenars at about 3050.

Thought about switching to starline or peterson srp if they would last longer they would pay for the price difference, but I plan on buying enough for my next barrels life after I burn out this factory barrel and buying a barrels life worth of lapua seems like a hefty price tag. How many firings are people getting from starline, peterson and lapua? At this point I wouldn't be comfortable taking anything beyond 3x fired to a match.

 

[Supersubes]

I'm running into the same thing with my hornady lrp brass, I buy the 100per bag bulk stuff that midsouth and grafs sell, about 45cents a piece. I haven't had any primers fall out yet but with my lee hand priming tool I can feel them getting looser even on the 3rd firing. I just loaded up a batch of 4x fired and had about 1/3 of the cases where the primer just slid in with almost no resistance, I marked a black ring around the case with sharpie and tossed it after firing. I wasn't sure if this was just hornady cases or if I was messing them up. I got a rcbs case prep machine and use the primer pocket uniform attachment to clean out the pockets, but I do notice there is some brass shavings coming out. Am I destroying my own pockets just trying to get them clean or is this normal? I am running a hotter load, 123 scenars at about 3050.

Thought about switching to starline or peterson srp if they would last longer they would pay for the price difference, but I plan on buying enough for my next barrels life after I burn out this factory barrel and buying a barrels life worth of lapua seems like a hefty price tag. How many firings are people getting from starline, peterson and lapua? At this point I wouldn't be comfortable taking anything beyond 3x fired to a match.

The bottom continues to set back, which is why you continue to get shavings. Other than that, Hornady is just soft stuff. The Lapua/ Peterson/ alpha brass will last far longer. I just got out some old 6.5x47 (identical case head to 6.5cm Lapua)brass to load a new barrel. Haven’t shot this cartridge in a while. I used it to shoot out two barrels dating back to 2008 or so. After 22 firings it’s good as new. My current 6.5 cm Lapua brass has been fired nine times. No reason it isn’t going to go 20 plus. Lapua is cheaper, not more expensive.

 

[pugnado]

I'm running into the same thing with my hornady lrp brass, I buy the 100per bag bulk stuff that midsouth and grafs sell, about 45cents a piece. I haven't had any primers fall out yet but with my lee hand priming tool I can feel them getting looser even on the 3rd firing. I just loaded up a batch of 4x fired and had about 1/3 of the cases where the primer just slid in with almost no resistance, I marked a black ring around the case with sharpie and tossed it after firing. I wasn't sure if this was just hornady cases or if I was messing them up. I got a rcbs case prep machine and use the primer pocket uniform attachment to clean out the pockets, but I do notice there is some brass shavings coming out. Am I destroying my own pockets just trying to get them clean or is this normal? I am running a hotter load, 123 scenars at about 3050.

Thought about switching to starline or peterson srp if they would last longer they would pay for the price difference, but I plan on buying enough for my next barrels life after I burn out this factory barrel and buying a barrels life worth of lapua seems like a hefty price tag. How many firings are people getting from starline, peterson and lapua? At this point I wouldn't be comfortable taking anything beyond 3x fired to a match.

Good to know I'm not the only one.

I think Hornady cases just don't like being loaded near or even at their max loads as prescribed by the... Hornady reloading manual.
Three firings, maybe, but that's it. Probably a marketing/engineering tag team ploy to get you to buy more brass from them.

 

[fvalmostthere]

So if you were to buy enough lapua brass for a barrel how much would you buy, I’m at 500 hornady cases and not sure it’s going to make it all the way through haha. My goal was around 2000 for this barrel. I know it’s probably good for more but it’s just the factory barrel with a crowned end. Already fighting back the urge to buy a custom barrel and a muzzle brake.

 

[Supersubes]

So if you were to buy enough lapua brass for a barrel how much would you buy, I’m at 500 hornady cases and not sure it’s going to make it all the way through haha. My goal was around 2000 for this barrel. I know it’s probably good for more but it’s just the factory barrel with a crowned end. Already fighting back the urge to buy a custom barrel and a muzzle brake.

That depends on how much and in what way you make loss and shoot. I don’t shoot matches for example. I can get by with 100 pcs, and get 2000 plus rounds out of it with Lapua. If you were someone who goes away for multi-day shooting trips or matches, 100 ain’t gonna do it. If the criteria is just brass quantity to lay the barrel, just do the math.

 

[Juggerxxx]

Maybe I’m just lucky but I’m getting 11-13 reloads from Hornady brass before I get head separations but with the primers still being decent. That’s with 42.2gr H4350 and 140gr ELDs.

 

[morganlamprecht]

Maybe I’m just lucky but I’m getting 11-13 reloads from Hornady brass before I get head separations but with the primers still being decent. That’s with 42.2gr H4350 and 140gr ELDs.

Not uncommon for me either, just have to reload it where it’s happy...I lose it before I wear it out

I bought 500 pcs of 6creed for my current barrel in November and up to now I’m down to ~350...lapua would get expensive at that rate

 

[fxdrider]

I'm running into the same thing with my hornady lrp brass, I buy the 100per bag bulk stuff that midsouth and grafs sell, about 45cents a piece. I haven't had any primers fall out yet but with my lee hand priming tool I can feel them getting looser even on the 3rd firing. I just loaded up a batch of 4x fired and had about 1/3 of the cases where the primer just slid in with almost no resistance,

I bought 200 pieces of once-fired Hornady LRP brass from Oncefiredbrass.com to try. About every 20 pieces or so I encounter one that requires zero effort to prime. Had one go in the other day that literally fell out when I pulled it out of the riming station to look at it. I bought it because it was cheap, and as I'm shooting it through a gas gun I didn't want to spend a lot on brass that's going to get chewed up quickly. But, as they say, you get what you pay for.

 

[MarinePMI]

Some good replies in this thread, but I'll toss out a different tangent of thought here.

I don't think the brass is the culprit of premature loose primer pockets; per se, it's not just the brass, but the fact that you're using it in a gasser.

Even with adjustable gas blocks, the AR-10 sized system was timed for .308. The .65/6mm CM operates at much higher chamber pressures, which will cause the bolt to unlock prematurely. I'd wager the adjustable gas block is keeping pressures stable long enough so that accuracy is not severely affected (as shown by SD's), but at the cost of the brass taking more of the brunt of the chamber pressures (more accurately the case head is, for however briefly, unsupported by the chamber, and the gas/pressure is likely trying to force it's way out through the path of least resistance; the unsupported case head). As soon as the case shoulders and mouth disengage from the chamber walls, the remaining gas escapes down the side of the chamber wall and out of the ejection port (hence a lot of 6.5/6CM cases have sooty case neck and shoulders). This occurs almost simultaneously (but slightly before), as the pressures drop when the bullet leaves the barrel. By this time, the gas has already impulsed down the gas tube (which is what causes the bolt to unlock and BCG to move rearward).

I'd wager that if you take similar brass (same lot) and run one through a bolt gun, and one through an AR. the AR brass will have greater case head expansion. If this is so, then that is the major culprit of the premature loose primer pockets, not necessarily the brass itself. While some brass may be tougher (like Lapua with it's thicker case head section), the real cause of this is the timing of the AR, and is dictated by the time between when the bolt moves back, and when pressures lower (as a result of the bullet leaving the barrel and the BCG disengaging the case from the chamber). If the pressures remain high while the case is unsupported (for however briefly a time) then the case head will expand and contract. Enough times, and that elasticity will no longer happen (or will lessen) and the primer pocket/case head will grow.

JMTCW...

 

[MarinePMI]

As an after thought, another way to prove out this theory might be:

Purchase some higher quality brass (Nosler/Norma or Lapua for example) and use one box in a bolt gun, and another box (obviously of the same lot) and record the ratio of number of firings before primer pocket pocket expansion forces the tossing of the brass. Compare the two. If the brass from the gasser loses it's primer pocket before the bolt gun lot of brass loses it's primer pocket, you can confirm it's actually the rifle system that is causing the issue.

Now, if you get more firings from the high end brass than the Hornady brass, it then becomes a numbers game. Is the cost of the higher end brass giving you more reloadings per cost of the premium brass case, than the number of reloadings per the cost of the cheaper brass case. It might actually be a wash...

 

[knuckleballz]

Is there a tool available to purchase that crimps the primer in place after it is pressed into the pocket? Perhaps such a tool would allow more firings of brass in a bolt gun without risk of feeding failures associated with a gas gun. Or is there a tool to crimp/tighten the primer pocket prior to installing the primer?

 

[Kiba]

Is there a tool available to purchase that crimps the primer in place after it is pressed into the pocket? Perhaps such a tool would allow more firings of brass in a bolt gun without risk of feeding failures associated with a gas gun. Or is there a tool to crimp/tighten the primer pocket prior to installing the primer?

You wouldn't want to just crimp the end of the case to hold the primer in place, because if the primer doesn't fit snugly into the pocket while seating some hot gas will escape from between the primer OD and primer pocket ID during firing which will start gas cutting the bolt face. Eventually you'll have a "ring" of pitting on the bolt face where gas has been escaping around the circumference of the primer.

Here's what happens after a while... this is a more "minor" example. I've seen far uglier on some AR bolts, and a quick google image search will yield some pictures.

When you could still get them, the Wolf and Tula primers always seemed to be very slightly larger than domestic primers and would fit somewhat snugly into primer pockets that domestic primers were loose in-- so you could sneak another 2-3 firings out of the case before the Wolf/Tula primers became loose and you had to toss the brass. Unfortunately, thanks to sanctions they haven't been available here for several years now. Too bad, because they always had great ES/SD's for me.

 

[pugnado]

Some good replies in this thread, but I'll toss out a different tangent of thought here.

I don't think the brass is the culprit of premature loose primer pockets; per se, it's not just the brass, but the fact that you're using it in a gasser.

Even with adjustable gas blocks, the AR-10 sized system was timed for .308. The .65/6mm CM operates at much higher chamber pressures, which will cause the bolt to unlock prematurely. I'd wager the adjustable gas block is keeping pressures stable long enough so that accuracy is not severely affected (as shown by SD's), but at the cost of the brass taking more of the brunt of the chamber pressures (more accurately the case head is, for however briefly, unsupported by the chamber, and the gas/pressure is likely trying to force it's way out through the path of least resistance; the unsupported case head). As soon as the case shoulders and mouth disengage from the chamber walls, the remaining gas escapes down the side of the chamber wall and out of the ejection port (hence a lot of 6.5/6CM cases have sooty case neck and shoulders). This occurs almost simultaneously (but slightly before), as the pressures drop when the bullet leaves the barrel. By this time, the gas has already impulsed down the gas tube (which is what causes the bolt to unlock and BCG to move rearward).

I'd wager that if you take similar brass (same lot) and run one through a bolt gun, and one through an AR. the AR brass will have greater case head expansion. If this is so, then that is the major culprit of the premature loose primer pockets, not necessarily the brass itself. While some brass may be tougher (like Lapua with it's thicker case head section), the real cause of this is the timing of the AR, and is dictated by the time between when the bolt moves back, and when pressures lower (as a result of the bullet leaving the barrel and the BCG disengaging the case from the chamber). If the pressures remain high while the case is unsupported (for however briefly a time) then the case head will expand and contract. Enough times, and that elasticity will no longer happen (or will lessen) and the primer pocket/case head will grow.

JMTCW...

This makes a lot of sense, but I've done a few things to address this and still getting problems with the pockets. My particular setup has a Rifle +2" length gas tube on an adjustable gas block, the JP-VMOS Heavy BCG configured with all the tungsten weights and the JP-SCS Heavy with all the tungsten weights and the most beefiest spring. All of this is to slow things down and delay the unlock time. Mostly because I'm going to be running a can on it when it gets out of ATF-jail.

Gas block is tuned for last round bolt hold open and then a tiny bit more for a reliable semi-automatic feeding.
I can't reduce the gas force without changing the load and losing fps, which I will do if it's killing brass.

Last night I primed 200 cases of brand new never fired Lapua with CCI #450 and they all went in very nicely.
(I also primed 300 cases of Lapua 300 blackout and those were so tight I got blisters and the RCBS deluxe no-shell-holder-needed primer tool spring-launched a few cases, but I had a smile on my face the whole time.)

I need a different neck size bushing (.289) for Lapua brass though because it has thicker walls than the Hornady. (.288)
I don't turn necks or mandrel size, not yet anyway, happy with my accuracy needs without that and probably not necessary for semi.
I just got my Mitutoyo calipers, so no screwing around with dimensions this time either.

When the bushing comes in I'll be setting up for another 10 charge, 50 round ladder test with the chrono.

 

[pugnado]

Hot damn, now I know why Lapua brass rocks. Here's a chart spanning the charges from minimum to maximum from the Hornady reloading manual. Check out the stats on Load 5. unfortunately, 2350fps is a little slow so I'm going for Load 9. ALL of these are better than Hornady factory match ammo.

 

[spife7980]

Dang, is that excel?
I cant get my graphs with the labeling etc to workout like that in excel.

 

[pugnado]

Dang, is that excel?
I cant get my graphs with the labeling etc to workout like that in excel.

Here you go:

http://www.65guys.com/load-development-analysis

http://www.65guys.com/wp-content/uploads/2018/06/Load-Analysis-Model-V2.xlsm

 

[Hollywood 6mm]

Not uncommon for me either, just have to reload it where it’s happy...I lose it before I wear it out

I bought 500 pcs of 6creed for my current barrel in November and up to now I’m down to ~350...lapua would get expensive at that rate

I run into the same issue. Even when I am careful, I tend to lose 10 pieces per match, and some matches it's not unusual to lose 20-30 - and I am shooting 5+ 2-day matches a year, plus several 1-day matches. It's not worth paying for Lapua, Alpha, etc. when I'm losing that much brass per year.

 

[pugnado]

Here's what I was getting with Hornady Brass, CCI BR2 / 250 large-primers, chasing that fps trying to get 2700 and probably killing my brass in the process. (Remember 40.3 is max load according to THE BOOK. )

 

[pugnado]

I run into the same issue. Even when I am careful, I tend to lose 10 pieces per match, and some matches it's not unusual to lose 20-30 - and I am shooting 5+ 2-day matches a year, plus several 1-day matches. It's not worth paying for Lapua, Alpha, etc. when I'm losing that much brass per year.

You can see from my charts the difference it makes. Granted, they aren't the same loads or same primers or same conditions but I'm definitely seeing an advantage with Lapua even if I have to sacrifice some fps with lighter loads. I hope it stays that way or gets better (these aren't even fire-formed cases yet.)

Edit: To get all this data I've got to strap the magnetospeed to the barrel which throws off all the harmonics and point of impact etc... but in general the most consistent load groups the best. One of my previous loads had no vertical variance and if I'd had been better on the bench horizontally they would've all gone through the same hole.

 

[Hollywood 6mm]

You can see from my charts the difference it makes. Granted, they aren't the same loads or same primers or same conditions but I'm definitely seeing an advantage with Lapua even if I have to sacrifice some fps with lighter loads. I hope it stays that way or gets better (these aren't even fire-formed cases yet.)

Edit: To get all this data I've got to strap the magnetospeed to the barrel which throws off all the harmonics and point of impact etc... but in general the most consistent load groups the best. One of my previous loads had no vertical variance and if I'd had been better on the bench horizontally they would've all gone through the same hole.

I've run Hornady brass in 6 Creedmoor since I switched to 6mm in late 2014. In all of that time, I can count on one hand (with fingers left over) the number of times I have seen an SD of 10 or higher on my hand loads. My ES is typically in the mid-teens, with the occasional low 20s - and I can probably count those on one hand, too. With 105 Hybrids, typical group sizes were .5" at 100 yards, and te 108 ELD-M s have been a little tighter.

Like I said, it's not worth it for me to switch brass brand. I've also never chased lands or powder charges across the life of a barrel. Hell, I shot out 3.5 barrels with the exact same load data. The only reason I switched half way though barrel #4 was I couldn't get any more Hybrids, and I switched to the 108ELD.

 

[pugnado]

I've run Hornady brass in 6 Creedmoor since I switched to 6mm in late 2014. In all of that time, I can count on one hand (with fingers left over) the number of times I have seen an SD of 10 or higher on my hand loads. My ES is typically in the mid-teens, with the occasional low 20s - and I can probably count those on one hand, too. With 105 Hybrids, typical group sizes were .5" at 100 yards, and te 108 ELD-M s have been a little tighter.

Like I said, it's not worth it for me to switch brass brand. I've also never chased lands or powder charges across the life of a barrel. Hell, I shot out 3.5 barrels with the exact same load data. The only reason I switched half way though barrel #4 was I couldn't get any more Hybrids, and I switched to the 108ELD.

That’s pretty cool, I’ve clocked factory around 20 S-D consistently so I figure anything over that I’ve done something wrong and less then 10 is a step in the right direction.

I was surprised to see less than 5 for the first time, so either my brass is better or I’m getting better at reloading. I do have a new scale because the old one broke, maybe that’s it..

I don’t bother trying to reach the lands anymore, I tried but couldn’t mag feed properly even with mags recommended by folks here, so that was that. I know where they are and they’re out of reach.

 

[Hollywood 6mm]

That’s pretty cool, I’ve clocked factory around 20 S-D consistently so I figure anything over that I’ve done something wrong and less then 10 is a step in the right direction.

I was surprised to see less than 5 for the first time, so either my brass is better or I’m getting better at reloading. I do have a new scale because the old one broke, maybe that’s it..

I don’t bother trying to reach the lands anymore, I tried but couldn’t mag feed properly even with mags recommended by folks here, so that was that. I know where they are and they’re out of reach.

IMO, using the right load development techniques makes the biggest difference in SD and ES. Everything else is secondary.

 

[pugnado]

So I recently got the wiser precision magnetospeed mount so I’m able to record all shots and zero without changing the point of impact.

This increases the life of my barrel/brass etc... because I can do load development and group analysis in one step.

Here is my best group of the day. 5 shots into 0.440” @ 100 yards. I was using the 39.6gn H4350@2500fps. What’s really cool is I shot 28 of them and they were all within 10 S-D for the entire set. I like this load.