Flattened primers

[PickettSFHunter]

I've been reloading for years but honestly have never gotten crazy about it and never done anything except very mild loads. I started loading some 300 BLK today, I noticed flattened primers during test firing. I then noticed that factory ammo was also flattened. What's the deal? I wouldn't think factory ammo would be to hot? Thanks

 

[ADR]

flatted primers never worried me. For bolt rifles I feel if I'm not getting flattened primers, I'm no where near potential velocity. I worry more about extractor marks and definitely sticky bolt lift. Never loaded for AR platform so I'll be following others ideas

 

[MUP]

Chamber may be tight? Throat a little shorter?

 

[MUP]

I agree with ADR as well, when I get a hard bolt lift is when it's time to back off most definitely for me.

 

[PickettSFHunter]

It is an AR. 21 gr CFE BLK with a 110 GMX

 

[backyardtndeer]

I started loading some 300 BLK today, I noticed flattened primers during test firing. I then noticed that factory ammo was also flattened. What's the deal? I wouldn't think factory ammo would be to hot?

First thought was not seated to properly fit the chamber.

But, I would inspect the bolt and firing pin. Doing this with factory ammo as well as your loads you could probably rule out it being a result of hot loads.

 

[Mausermeister]

How flat are they? Just squared off or flowing to completely fill the primer pocket? Any cratering around firing pin mark? What primers you using? Some are softer than others and will flatten a bit even with mild to medium loads.

 

[Tenntrapper]

Or, the headspace could be out of spec.

 

[PickettSFHunter]

How flat are they? Just squared off or flowing to completely fill the primer pocket? Any cratering around firing pin mark? What primers you using? Some are softer than others and will flatten a bit even with mild to medium loads.

No cratering. Filling the primer pocket, flush with the case head. Winchester Small Rifle and some Federal 205. I've never had much trouble reloading but this little 300 BLK is giving me fits. Winchester brass is accepting WSR primers easily. Hornady brass primer pocket will not accept a WSR.

 

[Jcalder]

Converted brass or standard 300bo brass. My other question is do you have a chrony

 

[EastTNHunter]

Depends. Headspacing can cause this. It is one of many things to watch for that MAY indicate pressure, but not concerned about some flattening by itself.

 

[PickettSFHunter]

Converted brass or standard 300bo brass. My other question is do you have a chrony

Factory 300bo brass. I do not have a chrony.

 

[Jcalder]

Factory 300bo brass. I do not have a chrony.

I have no idea how close you are to byrdstown but I'm up that way often. I could bring a chrony and let you send some over sometime.

 

[DaveB]

Since no bolt to lift you seeing any marks on case? metal shavings in chamber? Flattened but not cratered suggests your headspace is a tad off. Fire a round with just a primer-no bullet no powder---results should be telling

 

[PickettSFHunter]

Since no bolt to lift you seeing any marks on case? metal shavings in chamber? Flattened but not cratered suggests your headspace is a tad off. Fire a round with just a primer-no bullet no powder---results should be telling

I'll give that a try after work today, thanks. I'm not seeing anything unusual on the cases or in the chamber.

 

[kamml]

It is certainly a pressure sign, the primer is literally flowing back against the bolt during ignition. It could be a mechanical problem with the gun but more likely related to powder charge. Try reducing 3/10s of a grain or more to see if it goes away. Could be a tight free bore too where the pressure is coming up to quickly for the bullet entering the bore. That might explain the factory ammo showing pressure signs too. Just my .02.