CCI 41s and consistent ignition

[Webster]

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?

You could have excess friction where the firing pin assembly passes thru the shroud slowing down the FP fall. Take the bolt out and lube all around the shroud and wipe of excess oil. Look for rub marks on the fP assembly. Some are normal. Don't buy the crappy FP springs made from whats called music wire (plain carbon steel alloy). They lose tension quickly. Only buy the springs made from the silicon chrome alloy. They keep tension almost forever.

 

[rwj]

I’m certainly not a smith, but something still seems amiss. If CCI 41 primers are made to require a deeper strike to avoid slam fires, it would seem that Mike’s rifle was doing just that by virtue of having a large pin drop and protrusion from the bolt face.

Is the additional case headspace alone enough to explain the lack of ignition? I can understand a high primer not igniting on the first strike, but once the anvil is seated, it should ignite on the next strike but didn’t on five tries. Could it be that the primers are defective (missing anvils) and/or the primer pockets are too deep?

Now that I’m inspecting my Rem 700 style bolts, are there standard dimensions for the amount of pin drop and bolt face protrusion?

 

[XTR]

Another thing... l believe Pandas run a light-ish firing pin spring. (I’m told it’s a BR thing to make them cycle smoother) Last time mine was in the shop it got the bolt reamed and a 26# wolf spring.

 

[243winxb]

Misfires may produce shoulder set back, from the firing pin strike.

A bullet Jammed with little neck tension may absorb the firing pin strike, as the COL gets shorter.

Depends on the type of extractor.

Zero head clearance helpS fire primers.

 

[MikeMcCasland]

Its not like these primers weren't getting hit pretty hard. I doubt I'd of had this issue with non-mil primers.

 

[gunsandgunsmithing]

Misfires may produce shoulder set back, from the firing pin strike.

A bullet Jammed with little neck tension may absorb the firing pin strike, as the COL gets shorter.

Depends on the type of extractor.

Zero head clearance helpS fire primers.

Yes and virgin brass can be on the short side. Not sure if that applies here but I run into it frequently with Grendel based wildcats, often used in gas guns. The Lapua brass runs short but on top of that, if necking it up(especially) or down. you may move the shoulder a bit further and get misfires on the first firing. It's a double edged sword! Excess headspace can contribute to pierced primers, which harder primers seem to fix. But harder primers are harder to ignite and more prone to misfires. Aargh!

Not typically a big deal, though. I usually start with 205m primers because they're easier to light off. If I get misfires, I'll go to harder cci's or similar. If I still have problems, I'll make a false shoulder. This is rarely the case but I've never had any luck seating bullets long to fix it. Just a big pillow of cushion. Not a good thing.

FWIW, I have 3 different go gages for a Grendel and none measure the same. If I chamber for the shortest one, almost zero problems. The other two, is where I see it most.

Just use a light bit of lube on the case when fire forming, so it doesn't grip the chamber walls and use a moderate load on the first firing. The first firing is THE only time I've ever had a problem at all. Even then, it's rare but can happen.

 

[gunsandgunsmithing]

Its not like these primers weren't getting hit pretty hard. I doubt I'd of had this issue with non-mil primers.

View attachment 1221018

Mine look good too! Ignition is about speed and pin weight. If the blow is cushioned at all, it can do that! I've had new cases that were perfect at the datum after making them that way from running them thru a sizer to the point of moving the shoulder forward a tad. I think the shoulder rounds a tad when necking up and has a tiny contact area that doesn't give it enough "stopping power" on the first firing. Just my 2 cents

 

[243winxb]

Ignition is about speed

Yes, the firing pin velocity is most important.

The hunting rifle may misfire on a 10 degree day. Old oil in the pin channel slows the firing pin.

 

[Andy Legg]

Mike,

How do you feel the CCI 41's compare to the FED 205M's?

Any thoughts regarding effects on SD's or Accuracy? We've been getting sub 10 fps SD's using 8208 XBR and the 205M's (.223 wylde w/77 grain SMK's).

I have been using FED 205M's for years...but am close to running out. I was able to score a case of the CCI 41's thanks to a post on this forum. I guess I'll reduce my go-to loads by a 1/2 grain and work back up.

Thanks...
Andy

 

[MikeMcCasland]

Mike,

How do you feel the CCI 41's compare to the FED 205M's?

Any thoughts regarding effects on SD's or Accuracy? We've been getting sub 10 fps SD's using 8208 XBR and the 205M's (.223 wylde w/77 grain SMK's).

I have been using FED 205M's for years...but am close to running out. I was able to score a case of the CCI 41's thanks to a post on this forum. I guess I'll reduce my go-to loads by a 1/2 grain and work back up.

Thanks...
Andy

View attachment 1221100

Hey Andy,

Looks like the 205Ms are working well for you! Same story for me....these primers were from that DSA fire-sale.

I was using them to put the first 100 rounds down a new .308 barrel with some low cost bullets I use just to get the barrel sped up, so it's hard for me to say. I can definitively tell you that they don't ignite as easily as a Fed 205.

I do plan to try them again later this week in my .308 with Varget/N150/H4985 and the 200.20x.

That said, I dragged my long-throated (.169) .223 out and thought I'd see how they did with some shooters world precision and 85.5 hybrids. I don't usually place much value in chronograph numbers during load dev (esp. with heavies out of a .223), but I was getting like 30-50fps SD. The .223 ignited them 100% of them though, and they didn't show any pressure signs with powder charges I know were way too hot. (damn near 2900 out of a 28" tube; 2770-2800 is where they need to be)

If you're shooting them out of your AR-Tac gun I'm confident you'll have zero issues setting them off. I think you're wise to drop your charge a bit and work back up. I do think they'll mask pressure signs though.

Edit: I want to shoot a match in the AR Tac division one of these days.