6.5mm Creedmoor - Small vs Large Primer - Charge Difference?

[TXSGFmrCWO3]

I did a search of the forum first, but didn't find an answer.

I ordered some 6.5 Creedmoor brass that takes a small rifle primer. I've always used large rifle primers in med to large rifle cases before.

Any advice on regular vs. magnum, or percentage over under the recommended powder charge?

 

[8up]

look over on rifleshooter.com

He had some good write up's on Small vs. Large

 

[TXSGFmrCWO3]

Thanks. I found the test of small magnum vs. large standard. Interesting.

There's no mention of change in powder or charge size, so I imagine I'm good to go with the recommended tables on my V-N550 and IMR4350.

Thanks.

 

[Stpilot12]

The bigger picture with switching brass vs charge weight is internal case capacity.. If you switch from say, hornady to Lapua, the Lapua has less case capacity. A reduction in charge weight would be expected. The real answer is, do a proper load work up again as youre changing multiple variables, case capacity and primers.

 

[TXSGFmrCWO3]

Thanks for that. I will, always do. I was planning to work on the moderate side of powder charge anyway. Got to make this factory barrel last as long as possible.

What I did gather from reading is that a magnum primer is not necessary, thank goodness. Don't have any. This is further mitigated by the fact that Starline cases have a standard 0.80 size flash hole even though it takes a small rifle primer.

 

[Stpilot12]

Magnums are not necessary... work up a good load with what you have.

 

[TXSGFmrCWO3]

That's my plan. I'm tempted to get a batch of Starline large rifle primer cases for 6.5 Creedmoor and do a side-by-side comparison.

If I do, I'll post it here.

 

[Rick7353]

The bigger picture with switching brass vs charge weight is internal case capacity.. If you switch from say, hornady to Lapua, the Lapua has less case capacity. A reduction in charge weight would be expected. The real answer is, do a proper load work up again as youre changing multiple variables, case capacity and primers.

Exactly! I just bought 2 boxes of Peterson Brass. I spent the morning weighing each piece, measuring case length, head space, even called Peterson to find out case volume in h2o as I have been using Hornady. The Hornady volume on 6.5 Creedmoor is 52.2 and Peterson is 50.4. Very impressed so far. All annealed and really didn't have to do much. Used a full length sizing die and it did right over, neck sized with a .290 bushing. Will turn the necks but only off about.001 if that.

 

[whiskeysierra762]

My friend and I both had 6mm CM's built and we used Lapua small primer brass. We both pierced primers quite a bit with Federal and CCI. I have switched to the Federal "AR" Gold Metal Match primers with good luck, my friend has switched to the large primer brass. Some rifles will need the firing pin bushed for the small primer brass.

 

[Hiker12]

My friend and I both had 6mm CM's built and we used Lapua small primer brass. We both pierced primers quite a bit with Federal and CCI. I have switched to the Federal "AR" Gold Metal Match primers with good luck, my friend has switched to the large primer brass. Some rifles will need the firing pin bushed for the small primer brass.

I have a question and dont mean to hijake the conversation.
In the middle of doing research to convert my 308 over to 6.5x47 Lapua. Lapua brass for this cartridge is small primer. You guys were just talking about small primers being pierced and bushing the firing pin.
Running a Defiance Deviant SA with 308 bolt face . Firing pin measures. 069" would i need to bush the pin or not. Can I get away with running a harden primer gold medal or CCI #41 Any input appreciated.

 

[Supersubes]

I have a question and dont mean to hijake the conversation.
In the middle of doing research to convert my 308 over to 6.5x47 Lapua. Lapua brass for this cartridge is small primer. You guys were just talking about small primers being pierced and bushing the firing pin.
Running a Defiance Deviant SA with 308 bolt face . Firing pin measures. 069" would i need to bush the pin or not. Can I get away with running a harden primer gold medal or CCI #41 Any input appreciated.

Youre fine, and should be able to run any primer you like. I prefer the cci srm’s, but in a custom like a defiance, it isn’t gonna matter.

 

[Hiker12]

Youre fine, and should be able to run any primer you like. I prefer the cci srm’s, but in a custom like a defiance, it
Thanks for the info and quick reply

 

[flyer]

I have ARs with standard size firing pins.

I've never had a problem with LRP ammo so I see no reason to change to a "high pressure" bolt with a smaller firing pin and to maintain compatibility I'm not going to get any SRP brass.

It seems like the best brass available with large primer pockets is Alpha Munitions brass. It's expensive but the ES and SD people are getting with their brass is very impressive. From what I've seen, the consistency of their brass has more effect than the difference between large primer and small so if I can avoid chasing that small incremental change from LRP to SRP, I'll be happy.

Alpha's 6.5 Creedmoor SRP brass seems to be as good as Lapua or damn close so I won't be giving up much. Their web site has some really good comparisons between LRP and SRP, it's good to read. I usually take website claims with a grain of salt because it's marketing but people seem to get performance that matches their claims.

Going back to the original question, as others have said, start your load development again because your case capacity probably changed.