First time loads for my AR15

[Bear24]

I loaded some rounds up to test mainly to see if I could get the velocity high enough to justify running the 75g hpbt in my 16.5" barrel. The gun is a spikes tactical with a Geissele S3G trigger.

Components:
LC brass
75g bthp
2000MR
CCI 41's

I loaded 5 rounds each from 23g-26.5g

My big concern was that I was getting slight dents in the primers when the bolt cycled on a new round, it happened at all charge weights and had me a little freaked out about slam fires. I though that it shouldn't do that with the CCI 41's. I didn't have any slam fires but I was surprised at this result and it doesn't do that with factory ammo.

I wasn't shooting groups due to the range being busy. I don't have the velocities with me right now but will post them later.

 

[Bear24]

Is this normal with the CCI 41's?

 

[Bear24]

average velocities were:

23.5g: 2289

24g: 2303

24.5g: 2381

25g: 2458

25.5g: 2462

26g: 2586

26.5g: 2598

I am just wondering if these are reasonable numbers for the combo that I used. I am planning on using the rifle for shooting and hunting varmints out to ~400yards. Anyone using a similar load in a 16.5" barrel? Also any suggestions such as changing bullets would be appreciated.

 

[nuclear_shooter]

That looks scary. I do not see this on factory ammo (I don't reload for AR-15/223... yet). Are you sure the primer is fully seated? Its hard to tell but it looks like it might be sticking out a little. Those CCI 41 primers may have saved you from a slamfire.

 

[Bear24]

That looks scary. I do not see this on factory ammo (I don't reload for AR-15/223... yet). Are you sure the primer is fully seated? Its hard to tell but it looks like it might be sticking out a little. Those CCI 41 primers may have saved you from a slamfire.

yes the primers are seated all the way, i think the picture looks like that because I used a countersink to cut out the crimp in the primer pocket. It is seated well below flush from the base of the case.

 

[ArmyJerry]

I think you have a typo in your charge weights in this post.

I loaded some rounds up to test mainly to see if I could get the velocity high enough to justify running the 75g hpbt in my 16.5" barrel. The gun is a spikes tactical with a Geissele S3G trigger.

Components:
LC brass
75g bthp
2000MR
CCI 41's

I loaded 5 rounds each from 43g-46.5g

My big concern was that I was getting slight dents in the primers when the bolt cycled on a new round, it happened at all charge weights and had me a little freaked out about slam fires. I though that it shouldn't do that with the CCI 41's. I didn't have any slam fires but I was surprised at this result and it doesn't do that with factory ammo.

I wasn't shooting groups due to the range being busy. I don't have the velocities with me right now but will post them later.

 

[Bear24]

I think you have a typo in your charge weights in this post.

haha yes... 23-26.5g big difference. Ill edit that out

 

[wildfowler]

My understanding is that is normal for AR-15 to ding the primer like that when the bolt operates.

That's why it's recommended to use a military style primer like the CCI number 41 or a Remington 7 1/2 which have a harder primer cup.

Keep in mind also that a CCI 41 is considered a magnum primer so use caution when working with maximum loads.

 

[mwilkins]

OH oh oh....... (with my hand raised)....... Your AR has what is called a floating firing pin. When the BCG comes forward after firing a round, loading a round by use of the charging handle or releasing the BCG from the bolt release, the inertia created from the forward movement of the BCG causes the firing pin to move forward when the BCG stops from closing the breech. The firing pin will put a small ding in the primer but does not carry enough force (in most cases) to cause the primer to discharge. With soft cupped primers, this becomes more of an issue. CCI 400's have been named as such an example but I have yet to have any problems with them. As always, a properly seated primer will aid in the prevention of such issues.

Did I get it right guys?

 

[sentry1]

OH oh oh....... (with my hand raised)....... Your AR has what is called a floating firing pin. When the BCG comes forward after firing a round, loading a round by use of the charging handle or releasing the BCG from the bolt release, the inertia created from the forward movement of the BCG causes the firing pin to move forward when the BCG stops from closing the breech. The firing pin will put a small ding in the primer but does not carry enough force (in most cases) to cause the primer to discharge. With soft cupped primers, this becomes more of an issue. CCI 400's have been named as such an example but I have yet to have any problems with them. As always, a properly seated primer will aid in the prevention of such issues.

Did I get it right guys?

WRONG. When you let the bolt go forward, the magic ammo fairy swoops into your receiver and shoves a round up into the breach. Since the ammo fairy has to be pretty small to fit in there, it has a tough time handling the round, so it has to use a couple of good kicks to get the round seated in the chamber. And that, kids, is how your primer gets dented.

P.S. When the ammo fairy doesn't get out of the way fast enough, it gets smushed by the bolt, hence your bolt gets jammed in battery.

 

[Bear24]

I understand the floating pin thing and a slight ding doesn't bother me but this is a pretty significant ding.

Anyhow... What about the velocities I got? Is that about normal? I can't locate any real world data with the same combo

 

[scudzuki]

The design of the AR-15 Bolt Carrier Group prevents the firing pin from protruding from the bolt face until the breech is locked.
When the bolt locks and stops, momentum of the floating firing pin causes it to tap the primer.

Normal in AR pattern rifles.

I've fired thousands of reloads through half a dozen different AR-15s using every brand of small rifle primer I've been able to get my hands on (these days it's tough to be a primer snob) and every brand of primer gets dented by the floating firing pin.

Never had a slam fire, either.

Joe

 

[damoncali]

I think the OP's question is not "is the firing pin supposed to strike the primer", but "is it supposed to dent a CCI 41 like that". I don't know the answer to that - I have never used CCI 41's, but it is normal to put a light ding in the normal stuff.