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Light primer strike on 9mm major load with failure to fire CK Arms Bla


sophiasmith

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I had problems with light strikes in my new CK Arms gun as well, and primarily just on major loads with rifle primers. I think the mainspring must be VERY light, (like a 15# spring.). I replaced mine with a 19# mainspring, and haven't had problems since. I would suggest at least a 17# mainspring, to get good ignition.

Did you have to adjust the trigger pull, as well?

Yes. Changing the mainspring will affect the trigger pull, because that is the spring that is applying pressure to the hammer.

IIRC, the pull went up from 2# to about 2.5#. I just tweaked the sear spring until I got it back where I wanted it.

And my primers ARE seated below flush. Pistol primers went off, but rifle primers didn't. All rounds loaded on the same press with the same die setup, (no adjustments between major and minor rounds, aside from primer type and powder), so it's NOT a primer seating issue. A 15# mainspring just isn't strong enough for reliable ignition, IMO.

Bingo---You get the Cigar. You might get away with 15# main using Federal primers.

I'd rather have a 2.5# pull with a 17# using any SRP, then chance breach face erosion with SPP primers with a 15#

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Hello: I would take it apart and clean it first. The mainspring housing may be dirty not giving a smooth motion of the mainspring and cap. I have been cleaning up the mainspring housings with a reamer to solve a lot of problems over the years. I also bevel the mainspring cap top and bottom corners. Check the firing pin hole and make sure it is clean. What works well is a 17lb ISMI mainspring, Dawson extended firing pin and a lighter firing pin spring. Lastly clean the barrel and check your rounds in the barrel to make sure they are not seated too deep or the bullet is hitting the grooves in the barrel. Thanks, Eric

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Bobby doesn't visit this forum, but he has heard and here is his reply:

Our guns feature ISMI 19lb main springs. We recommend use of Small Pistol Primers in our handguns. Small Rifle Primers are harder and may not reliably ignite. While it is possible that we could get a bad spring from time to time, we live fire function test every gun before and after refinishing. We are sending Sophia Smith a 19lb main spring to replace the 19lb main spring we originally put in her gun. She fired 450 rounds of factory ammo and had no failure to fire. It wasn't until she started using handloads with small rifle primers that she encountered the issue. We are working with her to resolve this and have a replacement spring headed her way now. We do not visit the Enos forums so if you have an issue with a CK Arms gun, you can contact us directly by emailing us at sales@ckarms.com

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I had problems with light strikes in my new CK Arms gun as well, and primarily just on major loads with rifle primers. I think the mainspring must be VERY light, (like a 15# spring.). I replaced mine with a 19# mainspring, and haven't had problems since. I would suggest at least a 17# mainspring, to get good ignition.

Did you have to adjust the trigger pull, as well?

Yes. Changing the mainspring will affect the trigger pull, because that is the spring that is applying pressure to the hammer.

IIRC, the pull went up from 2# to about 2.5#. I just tweaked the sear spring until I got it back where I wanted it.

And my primers ARE seated below flush. Pistol primers went off, but rifle primers didn't. All rounds loaded on the same press with the same die setup, (no adjustments between major and minor rounds, aside from primer type and powder), so it's NOT a primer seating issue. A 15# mainspring just isn't strong enough for reliable ignition, IMO.

Bingo---You get the Cigar. You might get away with 15# main using Federal primers.

I'd rather have a 2.5# pull with a 17# using any SRP, then chance breach face erosion with SPP primers with a 15#

I've always heard breach face erosion was caused by harder primers (SRP) not completely sealing the primer pocket sometimes with the lower pressures of pistol rounds????

Edited by fmj3
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I had problems with light strikes in my new CK Arms gun as well, and primarily just on major loads with rifle primers. I think the mainspring must be VERY light, (like a 15# spring.). I replaced mine with a 19# mainspring, and haven't had problems since. I would suggest at least a 17# mainspring, to get good ignition.

Did you have to adjust the trigger pull, as well?

Yes. Changing the mainspring will affect the trigger pull, because that is the spring that is applying pressure to the hammer.

IIRC, the pull went up from 2# to about 2.5#. I just tweaked the sear spring until I got it back where I wanted it.

And my primers ARE seated below flush. Pistol primers went off, but rifle primers didn't. All rounds loaded on the same press with the same die setup, (no adjustments between major and minor rounds, aside from primer type and powder), so it's NOT a primer seating issue. A 15# mainspring just isn't strong enough for reliable ignition, IMO.

Bingo---You get the Cigar. You might get away with 15# main using Federal primers.

I'd rather have a 2.5# pull with a 17# using any SRP, then chance breach face erosion with SPP primers with a 15#

I've always heard breach face erosion was caused by harder primers (SRP) not completely sealing the primer pocket sometimes with the lower pressures of pistol rounds????

Same here fmj3

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Bobby doesn't visit this forum, but he has heard and here is his reply:

Our guns feature ISMI 19lb main springs. We recommend use of Small Pistol Primers in our handguns. Small Rifle Primers are harder and may not reliably ignite. While it is possible that we could get a bad spring from time to time, we live fire function test every gun before and after refinishing. We are sending Sophia Smith a 19lb main spring to replace the 19lb main spring we originally put in her gun. She fired 450 rounds of factory ammo and had no failure to fire. It wasn't until she started using handloads with small rifle primers that she encountered the issue. We are working with her to resolve this and have a replacement spring headed her way now. We do not visit the Enos forums so if you have an issue with a CK Arms gun, you can contact us directly by emailing us at sales@ckarms.com

Sorry, but that was NOT a 19# mainspring in the gun. I REPLACED whatever was in there with a 19#.

Also, I'll wager that MOST people shooting 9mm major are using small rifle primers. If you're building a 9mm Major open gun, you should know that and plan for it.

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I run 17lb mainsprings in my 1911s and have no trouble igniting Tula KVB-556M rifle primers. I do hand prime and am sure the primers are seated correctly. You may not be getting the primers seated correctly.

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Further input from Bobby. Hope this helps those with questions.

We try to insure the highest quality of parts go into each and every gun we manufacture. Sometimes, component parts may fail or be out of spec. The main springs we use in our guns are from ISMI and are packaged by ISMI as 19lb springs. We don't have a way of testing the springs other than through live fire function testing. No gun leaves the shop that doesn't complete test firing. As for primers, we build handguns, and we recommend use of PISTOL primers in our guns. There is zero benefit or reason to use a rifle primer other than availability during these times when components can be difficult to source.

mainspring%20pic_zpsj7ybsskx.jpg

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Hello: The hardest primers I have used are the Remington small rifle bench primers and they still work with a ISMI 17 lb mainspring. The ISMI springs I get are in a different package than the ones in the photo? When they heat treat springs they are put in a furnace all together and some could be different heat treatment depending where they are located in the furnace. The springs I have received from ISMI have been very close in listed spring weight, at least on my tester. Could be a case of miss labelled springs. Hope you get the problem solved. Thanks, Eric

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Hi Eric! Hope you have have been doing great. The springs are packaged and labeled for or by EGW and they come from ISMI. That might explain the different packaging you get.

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Let me add to this discussion...

My SVI suddenly started having light strikes - straight out of blue.

Yesterday at the range it had about 5 light strikes out of 100 rounds. All ammo is the same, from the same batch. Winchester Small Pistol primers, all loaded on the 1050, primers look perfect.

The main spring was replaced in 2012 with a 16# one, so I thought - it got tired... so last night I replaced it with a brand new Wolf 17#.

Took it to the range today - the first round had light strike... :(

The gun was cleaned last night.

What else could be happening there? Checked the hammer - moves with no obvious restriction.

WTH?

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Does your sv have the interchangeable breech face? If so my bet is the screw has worked loose a little. When that happens it stops the fp moving as far forward. You access it through the firing pin tunnel. I forget the size tool you need. Check that first. Then see if it's tight or not.

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