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CCI 41s and consistent ignition

MikeMcCasland

MikeMcCasland

Team Texas F-T/R
Hey Guys,

Running into a slight issue, and I wanted to know if there was something obvious I'm missing. I'm trying to make CCI41s work in a few bolt guns, but I'm running into a couple of issues.

I'm working up loads in a new .308 Krieger I just had spun up. I'm shooting these out of a Panda action, .260 pin-fall, .065 protrusion. Standard Kelbly spring/pin assembly, probably has 4-5k rounds on it. Never had a hint of a misfire ever, even when I was running ~.230 pinfall.

Brass is .0035 headspace; same brass with CCI/Fed fires every single time. Bullets were not jammed... .005" off.

Primers were seated with a Primal Rights CPS (please lets avoid a CPS discussion lol). Depth is the same as I'd seat standard Fed/CCI small rifle primers. The CCI 41s are also ~.001 taller than a Fed primer.

I was getting ~25% failure to fire with the CCI41s using the Panda. If I tried to re-chamber the round and shoot it (tried each misfire 5x), it wouldn't fire.

Rounds loaded with BR4s or GM205Ms all ignited perfectly; SDs were all below ~7-8 FPS like they'd normally be.

That prompted a bit of troubleshooting this evening (wife is at a work Christmas party).

10 primed cases, primed with a hand primer to "seated until the cup was deformed" depth. - All fired.
10 primed "fired headspace" cases on my CPS with same settings - All fired.
10 primed .0035 headspace cases on my CPS with same settings - All fired.
Pulled down 10 rounds from the cases that wouldn't fire today, and "shot" those - all fired.

What do you make of that? What would I even troubleshoot next?
 
The CCI 41 and 34 primers were designed to help prevent slam fires in semi-auto military rifles with free floating firing pins.
That being said when Remington ran Lake City they used 7 1/2 and 9 1/2 primers and the firing pins on both the M14 and M16 were lightened during the trials testing period and special primers were not needed.

The anvil is shorter on the CCI military primers vs standard primers and this requires more force to set them off.

To solve your problem just "STOP" using the military type primers, or get a heavier firing pin spring. Or just switch to a normal primer like the CCI400 or CCI450.

NOTE, neither Remington or Winchester used a "special" primer when they ran Lake City for our military ammunition. And the greatest chance of a slam fire happens when a single round is loaded without the magazine in the rifle to slow down bolt velocity and firing pin inertia. And you never have this problem with a bolt action rifle no matter how fast you work the action.

The mil-spec image below shows a thicker cup on the bottom and a shorter anvil.

n8TOU36.jpg
 
Uncle Ed said:
To solve your problem just "STOP" using the military type primers, or get a heavier firing pin spring. Or just switch to a normal primer like the CCI400 or CCI450.
Click to expand...

I'm aware the CCI is a military primer. It's basically just a 450 with a thicker cup and a different anvil.

There are several folks in F-Class who have them working just fine, and I've got a good bit of them. In this climate it's easier for me to "make them work" vs. finding different primers.
 
I found the issue.

You guys can laugh at my idiocy.

When I said headspace was .0035 I was grabbing measurements off 7-8 randomly selected rounds that were in that cartridge box. When I was pulling rounds down to 'test fire', I grabbed 10 from the box randomly and didn't measure headspace. Not the ones that misfired...those were sitting in my truck.

Decided to measure every round in my cartridge box, and I about 20 rounds in hit one that came up .010 headspace (ugh oh).

Grabbed the ones that misfired out of the pick-up.

.010-.012 headspace....that'll do it.

Not sure when I prepped this batch of brass, or how/why I had several that were headspaced so far back; it's not my normally tracked 'match' stuff.

Sorry for the fire-drill, and hopefully you get a laugh at my expense. :)

Merry Christmas!
 
Double check all your headspace before your next outing and if you have another misfire, set those rounds aside for re-measure.

I had problems that I think ended up being soft brass and #41’s, it was easier to set the shoulder back then to ignite the primer. They definitely require a harder hit.
 
.065 of pin protrusion is about .025 more than you need. Your giving away pin fall with that much protrusion. If you have a depth mic, do a test to see how much pin penetration. Empty primed case and measure the shroud to cocking piece depth. Fire the primer and measure to the cocking piece again and do the subtraction to get the penetration number. If you are less than .020 you need some attention to the ignition. Pin weight, spring weight or pin fall. I've had actions get a bit lazy and shoot flyers that were corrected by getting the primer penetration up to snuff.
 
Mike
Trouble shooting can be a pain.
I helped my neighbor fix a problem on his AR today. He finally let me try after being fed up and discouraged.
Rifle was custom built but shot like a 12 gauge.
2 different armories looked it over, gunsmith looked it over.....

I tourqed the scope base and rings that were looser than a $3 oh never mind its fixed.
 
Bc'z said:
Mike
Trouble shooting can be a pain.
I helped my neighbor fix a problem on his AR today. He finally let me try after being fed up and discouraged.
Rifle was custom built but shot like a 12 gauge.
2 different armories looked it over, gunsmith looked it over.....

I tourqed the scope base and rings that were looser than a $3 oh never mind its fixed.
Click to expand...
Yeah. Gotta check everything - including the ones that 'can't be' the problem.
 
MikeMcCasland said:
I found the issue.

You guys can laugh at my idiocy.

When I said headspace was .0035 I was grabbing measurements off 7-8 randomly selected rounds that were in that cartridge box. When I was pulling rounds down to 'test fire', I grabbed 10 from the box randomly and didn't measure headspace. Not the ones that misfired...those were sitting in my truck.

Decided to measure every round in my cartridge box, and I about 20 rounds in hit one that came up .010 headspace (ugh oh).

Grabbed the ones that misfired out of the pick-up.

.010-.012 headspace....that'll do it.

Not sure when I prepped this batch of brass, or how/why I had several that were headspaced so far back; it's not my normally tracked 'match' stuff.

Sorry for the fire-drill, and hopefully you get a laugh at my expense. :)

Merry Christmas!
Click to expand...
Stuff happens. You think you have everything lined up and then realization sets in, hard. I speak from experience as I had the exact same issues a couple years ago. I have a Redding T-7 and the dies for .308 Winchesters stay on it all the time. Somehow (my current theory is aliens from Alpha Centauri) my sizing die backed off about .010, eve though the ring was clearly on the platter. I had had a run in with a weak spring a couple years prior and I thought that was the issue this time around.

At any rate, I pulled out my Redding comparator die and measured everything in sight. I was shocked to find out that my headspace was now 0.010 or a tad more. I bought some locking rings from Hornady, installed one on my sizing die and adjusted the crap out of it and locked it down. I now have the comparator die in the slot next to the sizing die and I check at the beginning of a session, somewhere in the middle, and at the end. So far nothing has moved in over 18 months. When you said you had measured that, I just went for my other experience.

A firing pin spring is a consumable. I change mine about every 4-5000 rounds. I buy then a few at a time and I get them from Kelbly. They do a little finishing on the regular Remington spring. They cost something like $8 or $10 and I have a few. You should also get a device to pull apart the bolt, even if you don't change the spring. I clean my spring and firing pin every few cleaning sessions. It takes just a few minutes and it provides peace of mind.

This is the tool: Remington Bolt Disassembly Tool : KLEINENDORST REMINGTON BOLT DISASSEMBLY TOOL | Brownells

I also have the firing pin disassembly device. Kleinendorst Firing Pin Tool : KLEINENDORST REMINGTON FIRING PIN TOOL | Brownells

You will also need a small hammer to push out that pin. It can be a pain to do in the field, which is why I have a complete spare firing pin assembly in my repair kit. It can be a lifesaver during a big match. With the bolt disassembly tool I showed above, I can have the firing pin assembly replaced in a few minutes or less. I can then replace the spring on the replaced firing pin in the hotel room or at home.

Remind me to show you at the next match, I plan to be at the match on January 3rd.
 
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