New 6.5 Creedmoor build---question about primers

[jonny rotton]

i just built a super light weight 6.5 (creedmore). i am still waiting on my new jp super bolt and light weight carrier. so i put in a temp from a 308 i i test fired three rounds. the indent in the primers stick up just a little bit. whats the issue??? any help would be appreciated. i already had a bussel of grendels. lol

[FLshooter]

I’m thinking you’re talking about protruding primers on your reloads.
Primer pockets are too shallow.Use a primer pocket uniformer.RCBS has one for around $30.
A protruding primer can cause a misfire or can cause the bolt not to close.

[jonny rotton]

no, i was shooting factory ammo. where the firing pin hits the primer there is some primer metal sticking up. i am thinking it may be the headspace but i really dont know. it is not the bolt i will be using. it may be in this week. i hope.

[FLshooter]

Both calibers use the same BCG.But you may have a head space problem ,which you can check with go/no go gauges.You can also try different ammo, maybe it’s the particular ammo you are you using.

[Lemonaid]

Post a pic for better info on the reply. That said, sounds like primer cratering. Could be over pressure, could be under pressure could be firing pin or the firing pin hole in the bolt. Could also look different with a different primer as some are harder/thicker than others.

[jonny rotton]

[ATTACH=CONFIG]15771[/ATTACH] this is my first attempt at posting a picture

[jonny rotton]

[ATTACH=CONFIG]15772[/ATTACH] second try

[Lemonaid]

Looks like over pressure. Primer has completely flattened. Just my opinion, others may have more help.

[jonny rotton]

i've never seen this before. the indent is cratered. it is a temp bolt and carrier. my real one hopefully comes in this week

[FLshooter]

If head space is too short it can cause excessive pressure. From the picture that’s what it looks like to me.

[jonny rotton]

thank you for your replies. i hope it goes away when i get my jp bolt and low mass carrier.

[A5BLASTER]

And that is why the 6.5 creedmoor bolt use's a smaller fireing pin hole.

What your seeing is primer flow into the fireing pin hole of the bolt.

[jonny rotton]

wow thank you!!

[Klem]

A5 has hit the nail on the head.

It's primer flow or cratering caused by lack of support around the pin. Basically the firing pin hole is too big for the pin. Flow happen with normal loads as well as hot. The next severe step is that small circle donuts start breaking off the primers and get in everywhere to jam the action.

A thicker, stronger primer will mitigate this. A tighter hole with better tolerances from a quality manufacturer will solve it.

[lazyengineer]

A5 has hit the nail on the head.

It's primer flow or cratering caused by lack of support around the pin. Basically the firing pin hole is too big for the pin. Flow happen with normal loads as well as hot. The next severe step is that small circle donuts start breaking off the primers and get in everywhere to jam the action.

A thicker, stronger primer will mitigate this. A tighter hole with better tolerances from a quality manufacturer will solve it.

This. I have been dogged by this with my 6.5 CM, with a batch of ammo using soft primers, where it would blow a punch of the primer brass back into the firing pin channel, and cause all kinds of problems. FWIW, they were S&B primers, and I no longer use S&B primers for 6.5 CM loads; as they are just too soft for the high pressures of 6.5 CM. And yet, they aren't strong enough for a small-firing pin indentation, and will pierce. Work fine in a lower pressure round with a fat round firing pin tip like an M1 Garand or 1903, but for a modern 6.5 CM, I can't make them work.

Though, I will say, I do have S&B factory ammo, and in my guns that seems to work OK, just the independent S&B primers in reloads are doing it to me.

[jonny rotton]

i .have been shooting s&b factory ammo. it does shoot very very well. i recently purchased a christensen arms ca-10 in 6.5 creedmore. it was almost a half pound heavier than the advertised weight. it does shoot. the new one is a 2a armament build with a light fluted mcgowan barrel. i have a jp low mass bolt carrier and high pressure bolt. but my number one weapon is a 2a build with a 12" mcgowan barrel. i finally broke down and bought a night force nx8 scope. it shoots so good not many would believe some of the groups i have shot with it.
thank you to everyone for your comments and advice!!!!!!

[BluntForceTrauma]

Wait. JR, you got a 6.5 CREEDMOOR with a 12" barrel? :eek:

[jonny rotton]

no. i am sorry for the confusion. the 12" is a grendel!!! i love the 12" grendels so much that ive built more than a few. but by putting the night force scope on it really brought out its potential of the caliber and barrel. recently at the range were a large group of falkor employees. my little 12" was outshooting most of their fancy high end .308's. i do have a 16" creedmore barrel on order, not sure if i will get it. i sure hope so.