Dimple in ammo after releasing the bolt

[zeroed_in]

Hey team,
I recently noticed a "dimple" in the primer after releasing the bolt. I'm not sure if this has happened since day one of having my MP15 sport. But it sent chills up my spine to see that happened only from loading a round. I was wondering if this was normal? Thanks! (i use factory ammo, American Eagle 55gr .223)

 

[fran m]

Normal, I have seen this many times.

 

[gmiller0737]

Normal as far as I know My Colt AR does the same

 

[GMC man]

One of the reasons the primers for reloading are made different is the way our girls load can cause a slam fire. 5.56 primers are thicker and takes more force to detonate. Unless the .223 have these primers installed in them and it should have on the box made for semi's, be very careful.



CCI® No. 34 and No. 41 MILITARY RIFLE PRIMERS

Military-style semi-auto rifles seldom have firing pin retraction springs. If care is not used in assembling ammunition, a “slam-fire” can occur before the bolt locks. The military arsenals accomplish this using different techniques and components—including different primer sensitivity specifications—from their commercial counterparts. CCI makes rifle primers for commercial sale that matches military sensitivity specs that reduce the chance of a slam-fire when other factors go out of control*. If you’re reloading for a military semi-auto, look to CCI Military primers.
*Effective slam-fire prevention requires more than special primers. Headspace, chamber condition, firing pin shape and protrusion, bolt velocity, cartridge case condition, and other factors can affect slam-fire potential.

 

[oneyeopn]

I almost exclusively use #41 primers although I recently bought a box of Wolfs for .223's (supposedly harder cap)

 

[Maddmax]

Hey team,
I recently noticed a "dimple" in the primer after releasing the bolt. I'm not sure if this has happened since day one of having my MP15 sport. But it sent chills up my spine to see that happened only from loading a round. I was wondering if this was normal? Thanks! (i use factory ammo, American Eagle 55gr .223)

How big/deep was the dimple ?

 

[oneyeopn]

because the firing pin floats in the BCG when you slam the bolt home it will dimple a standard or softer primer, not enough to set it off but it does leave a mark.

 

[storeyteller]

One more reason for following grandad's advice and always keep the muzzle pointed in a safe direction.

 

[Maddmax]

One more reason for following grandad's advice and always keep the muzzle pointed in a safe direction.

It'd also keep his #10 boot off your backside

 

[zeroed_in]

How big/deep was the dimple ?

I didn't get a chance to take pics but I compared it to a spent casing from my rifle and the "dent" in the spent round was significantly larger and deeper that the "dimple". I doubt I get to the range any time soon but I'll try to get pics up asap. Thanks!

 

[zeroed_in]

Thank you all for the feedback and information. It makes it more reassuring this is normal. It was a pretty uneasy feeling when I first noticed it. Safety is rule # 1, I need to get home in one piece and and I like to make sure everyone around me is going home safely as well. And yes, gramps would be quick to put the boot on me as well as everyone else in the family. Thanks again!