Primers for an auto loader .....question.

[Lofty]

My GAP 10 gets here today and I wanted to work up some rounds for it. I've never hand loaded for a semi auto.

So I'm worried about slam fires on soft primers.

I was thinking of using Tula primers....it's a 6.5 CM. so are Tula primers hard enough to prevent a slam fire? I've heard they're a tad oversized and have a fairly hard face.

Or is there something else I should use"

 

[-Claybuster-]

My GAP-10 had a spring on the firing pin.

 

[Pinecone]

If there is a spring, should not be a problem.

But Tula are good, as are CCI Magnum primers or military primers.

 

[bigedp51]

Remington ran Lake City Army Ammunition Plant from 1941 till 1982 and never used any special "military primers", the same applies to Winchester when they ran Lake City.

The greatest probability of a slam fire is with a free floating firing pin and if a single round is loaded "WITHOUT" the magazine in place to slow down bolt velocity. The military during testing lightened the firing pins on the M14 and M16 rifles, this reduced the chance of a slamfire to a 1 in 10,000,000 chance of a slam fire.

Bottom line, Remington and Winchester "NEVER" used CCI #34 and #41 primers while running Lake City, meaning Remington 9 1/2 and 7 1/2 primers passed military requirements at Lake City. The only difference in the CCI "military type" primers is the anvil in the primer is shorter and requires more force to set it off. Now think of all the civilian contract ammunition made by all the various ammunition companies for the military that do NOT use CCI #34 and #41 primers.

The majority of slam fires are caused by improperly loaded ammunition or improperly maintained firearms and the CCI primers are an excuse to charge you more for their product.

Below all large rifle primer cups are .027 thick

Below the military requirement for seating the primer is .008 below the surface of the case.

 

[mtrmn]

I'm sure it happens, but I personally have never seen a PROVABLE slamfire. BUT at the same time I only use CCI mil primers nowdays in my rifle loads.

 

[alpine44]

Are the CCI #41 and #34 military primers any different in the primer compound composition or consistency than their CCI 400 and CCI 200 counterparts and is it possible that they have a thicker cup?

I saw mentioned above that only the anvil is supposed to be different but I found that the #41 military primers still seat tightly in tired 300AAC brass where 400 primers would fall out. Also the military primers are not in the list where the dimensions are shown.

Does anyone have the inside scoop from CCI ?

 

[mtrmn]

According to CCI website, the mil primers are magnum strength. I'm pretty sure the cup is harder.

 

[BCP]

I've never had primer problems with semis. Sizing problems are a whole other story. You need to FL size every case with some shoulder bump otherwise you can end up with a live round in the chamber and on ARs it's a pain. That big huge bolt flying forward really hammers them into the chamber and they are a PITA to extract if you fuck up your sizing process.

 

[Lofty]

Thanks for the info guys.

As far as re-sizing, I have a Redding Small Base die for re-sizing.

Jon Paul from JP strongly suggested all my brass needs to be able to drop fit in the chamber with some room to play with to be reliable.

 

[alpine44]

Thanks for the info guys.

As far as re-sizing, I have a Redding Small Base die for re-sizing.

Jon Paul from JP strongly suggested all my brass needs to be able to drop fit in the chamber with some room to play with to be reliable.

Small Base may not always necessary, IMO, but full lengths with slight shoulder bump is a good idea. For a new barrel I check how a fully sized empty shell drops in and extracts and work from there. JP is the man for ARs but all that extra wiggle room disappears anyway when the pressure blows the brass against the chamber wall. As long as an unfired case extracts easily in all my guns, I personally see no point in creating more slop. But then, my AR home builds are a whole lot less expensive than JP's creations. Maybe cheaper horses are more tolerant to what you feed them.

Edit: I should mention that I use enhanced bolts with the 'lobster tail' extractor and double springs wherever possible - just to be on the safe side. I once got a 5.45x39 lacquered steel case stuck in a piping hot AR barrel and boy was that fun to get it out after the barrel cooled and shrunk onto the case.

 

[bigedp51]

According to CCI website, the mil primers are magnum strength. I'm pretty sure the cup is harder.

The cup isn't harder, the so called CCI military primers have a shorter anvil and require more force to set the primer off.

If you are going to post information you should get your facts straight and not guess.

 

[Pinecone]

Are the CCI #41 and #34 military primers any different in the primer compound composition or consistency than their CCI 400 and CCI 200 counterparts and is it possible that they have a thicker cup?

I saw mentioned above that only the anvil is supposed to be different but I found that the #41 military primers still seat tightly in tired 300AAC brass where 400 primers would fall out. Also the military primers are not in the list where the dimensions are shown.

Does anyone have the inside scoop from CCI ?

CCI #41 (small) are almost exactly the same as CCI 450 (Small Rifle Magnum) primers. Same priming compound and amount. Same cup. There is a bit more space between teh cup and anvil in the #41 primers.

 

[SWThomas]

I use CCI 200s in my 308 loads for my GAP-10 and have never had an issue. No firing pin spring either.

 

[DT1]

Congrats on the new stick! FWIW, I've used just about every large rifle primer out there for many thousands of 308 and 260 Rem gas gun loads. Never a slam fire or problem of any sort with any of them in six different rifles including JP, Armalites, SR 25 and OBR. Small base FL die may not be necessary but certainly couldn't hurt. Use it if you've got it.