Small primer pockets - 6mm Creedmoor

[Howa 9700]

Have noticed that Starline and Peterson offer a large or small primer pocket option for the 6CM. On Graf's site, the 6CM brass from Lapua is small primer only.

At least one of them somewhere mentions it is for dealing with max or over max pressure loads, so as to not blow out the primer pockets.

Is that a common practice or problem with a 6CM?

Or is there another reason for wanting brass for small primers?

 

[FROGO207]

Theory is that a small primer allows more meat in the web area and thus keeps the primer pocket from expanding as soon. I have not seen any hard data confirming this however. To me it is more about using a different sized primer when supplies are low for the alternate type. That is why I keep all my small primer 45ACP brass in reserve. Just in case.

 

[Blue68f100]

I use SRP on my 6.5 CM and glad I did since the LR primer has been mia for 2 yrs now in my area. All my rifles except one use SR, 7mm Mag is the odd ball. Now it's been reported that the SR has problems setting off large quantity of ball powder in cold weather. I don't think the 6mm has enough powder to be a problem, but I don't know for sure. Maybe someone shooting in extreme cold temps will have the answer.

 

[Varminterror]

Have noticed that Starline and Peterson offer a large or small primer pocket option for the 6CM. On Graf's site, the 6CM brass from Lapua is small primer only.

At least one of them somewhere mentions it is for dealing with max or over max pressure loads, so as to not blow out the primer pockets.

Is that a common practice or problem with a 6CM?

Or is there another reason for wanting brass for small primers?

Competition shooters generally favor small primer pockets. Most competition shooters using 6 creed are not shooting Benchrest or F class, and rather are shooting PRS - in which the format doesn’t allow rounds to have the velocity which would occur if 6 creed is pushed over max pressure. We can’t exceed 3200fps, and we can topple that limit with ease eve using an under max load under the bullets we’re using in the barrel lengths we’re using. For example, I shoot a load which is .6-.8grn below max, and 1-1.2grn below bolt click in my 6 Creed match rifle, and my loads range 3100 to 3185, depending upon which barrel I’m using… can’t go over pressure without going over the speed limit.

But, whether using smaller pockets actually increases brass life or not, it theoretically SHOULD increase brass life, so when we have the opportunity to get SRP brass, we want SRP brass.

LRP in 6 creed isn’t a huge penalty, and for most folks, it’s not even a tangible penalty. I have a set of ~500pc Hornady 6 creed brass, which is reputedly soft alloy, and is LRP, which has 15 firings on it, and I’m syncing it up for my match rifle to start into this new barrel for this new season. I have 8 firings on my current set of 6 Dasher brass for matches, Lapua small primer pockets, I kinda like having separate primer stocks for both so I’m not eating out of the same pile all of the time. I used to neck down Lapua Palma brass (308win with small primer pockets) for all of my 243 win/AI, 260, and 7-08rem & AI to gain that little bit of peace of mind. I was gonna be paying for Lapua brass anyway, so why not get small primer…

Anything beyond that, any comparison of 6 creed LRP vs. SRP is at the very best a claim to accurately count angels on the head of a pin…

 

[Howa 9700]

Previous response lost in the reset. Will try again.

So sounds like a lot of the games/uses 6CM is being used for can result in some taking load pressure to the max and beyond. That would explain the comments from Peterson on small rifle primers being better suited to high pressure rounds. And perhaps why Lapua is only offered with SRP option.

So what length of barrel and what bullet being used to get close to 3,200 fps?

BTW, if I were to wind up with a 6CM, normal targets and hunting is the goal, so sounds like LRP would not matter, which is good, as all other calibers I load for use LRP. The same components stash can be used for all. Powder, primers and same 6mm bullets.

 

[Kaldor]

Competition shooters generally favor small primer pockets. Most competition shooters using 6 creed are not shooting Benchrest or F class, and rather are shooting PRS - in which the format doesn’t allow rounds to have the velocity which would occur if 6 creed is pushed over max pressure. We can’t exceed 3200fps, and we can topple that limit with ease eve using an under max load under the bullets we’re using in the barrel lengths we’re using. For example, I shoot a load which is .6-.8grn below max, and 1-1.2grn below bolt click in my 6 Creed match rifle, and my loads range 3100 to 3185, depending upon which barrel I’m using… can’t go over pressure without going over the speed limit.

But, whether using smaller pockets actually increases brass life or not, it theoretically SHOULD increase brass life, so when we have the opportunity to get SRP brass, we want SRP brass.

LRP in 6 creed isn’t a huge penalty, and for most folks, it’s not even a tangible penalty. I have a set of ~500pc Hornady 6 creed brass, which is reputedly soft alloy, and is LRP, which has 15 firings on it, and I’m syncing it up for my match rifle to start into this new barrel for this new season. I have 8 firings on my current set of 6 Dasher brass for matches, Lapua small primer pockets, I kinda like having separate primer stocks for both so I’m not eating out of the same pile all of the time. I used to neck down Lapua Palma brass (308win with small primer pockets) for all of my 243 win/AI, 260, and 7-08rem & AI to gain that little bit of peace of mind. I was gonna be paying for Lapua brass anyway, so why not get small primer…

Anything beyond that, any comparison of 6 creed LRP vs. SRP is at the very best a claim to accurately count angels on the head of a pin…

My thoughts as well, but Im only a few firings in as I am not a competition guy, more of a plinker out to a 1000.
I have both Peterson SRP and Hornady LRP 6 CM brass. Both shoot fine with either a CCI BR4, BR2 or a 200 with H4350. Dont try to use a CCI 400 with 6 CM with small primers, youll blow primers. You need a BR, or Magnum primer, or even though I havent tested it, something like a CCI 41 to handle the pressure.
My velocities really dont change from large to small primers that I have seen. Im getting 3080-3120 fps with a 22" Rock Creek barrel depending on the bullet. Those velocities are safe with my brass from my gun.
Peterson brass might be a hair more accurate, but that could just be my personal bias, as the Hornady 108 ELD Match shoots fantastic from my gun. I hate buying factory ammo, but the Hornady stuff shoots and thats how I built up my pile of Hornady 6 CM brass.

 

[Varminterror]

So sounds like a lot of the games/uses 6CM is being used for can result in some taking load pressure to the max and beyond.

No. The opposite in fact.

There is only one competition format where 6 creed is popular, and in that game, we can’t push 6 creed to the max without exceeding the speed limit of the game, let alone over the max.

So what length of barrel and what bullet being used to get close to 3,200 fps?

24” will top 3200. But most of us in PRS are using 26-27” barrels, so we end up backing way down below max.

if I were to wind up with a 6CM, normal targets and hunting is the goal, so sounds like LRP would not matter

Wouldn’t matter in the least.