Quarterbore.Net Forums

claydunbar · #1 11-11-2006, 06:03 PM

Hi folks,

I have 2 JDJ cz-527 .300 Whisper. I am experiencing light primer strike on my reloads using CCI benchrest primers. The load is an awesome subsonic load using 220gr rn hornady bullets, and pattern well inside 1". Additionally I have about 5000 rds loaded so Im now fully comitted. I can take the same cartridges that wont fire In the CX 's and put them in my AR upper and they fire. Has anybody experienced this? Does CZ make heavier firing pin springs? I hope someone can help me because I am very frustrated at this point.

Thanks,
Clay Dunbar

prebancolt · #2 11-12-2006, 04:35 AM

I know this doesn't answer your question, but I think the CCI primers are not as soft as other primers. I had a similar experience w/CCI primers in other calibers.

I'm sure you can find a stronger replacement spring for the firing pin, though. Just might take some looking.............Wolfe?

J

keith__davis · #3 11-12-2006, 10:13 AM

Hey Clay,

Your the third people i have send have the same trouble with the CZ guns, given your shooting my brass i feel compelled to help make this right, couple things if the head space is off just a little the cased would go to fare into the chamber would only take a few thousands, and i think your firing pin spring is ok if it works some of the time, i would thing of setting the shoulder of the firing pin back a few thousnads to let it travel deeper, I can send you a set of headspace gages and have you check headspace very easily done, or chuck up your firing pin and set the shoulder back a few thousands, let me do a little pit of research, I'll get back with you on it.

DonT · #4 11-12-2006, 10:26 AM

Clay,

One other item you might check is to disassemble the bolt and remove the firing pin and spring. Get can of brake cleaner or gun scrubber and give it a good cleaning up inside the firing pin channel. It could have just enough junk in it to cause the pin not to extend far enough. I would try this before modifying the pin. Just clean it and they try some primed unloaded rounds in rifle to see if it will set them off.

DonT

keith__davis · #5 11-12-2006, 10:46 AM

I looked just for a couple minutes and found these. and i agree with Don cutting on the firing pin is the last thing we want to do.

http://www.benchrest.com/forums/show...850#post281850

http://www.thefiringline.com/forums/...93#post2116793

claydunbar · #6 11-12-2006, 12:13 PM

Guys thanks so much. David I will absolutely take you up on the headspace guage offer. Ive been looking for some on the internet and couldn't find any. The perplexing thing is my dad has a JDJ CZ .300 Whisper as well and the same thing is happening there. The gun triggers the ammo 19 times out of 20 but I missed a bobcat this past week because the same thing happened twice in a row. My firing pin has plenty of length but I think a stronger spring may help, I just have no idea where to find that. DonT, I have just put some Wilson Combat Oil lube on the spring and firing pin and fired some primed brass. It worked fine every one I shot but again Ill shoot 20 rds in the field and the 21st will fail, so its a hard test to apply. David, fyi your brass does this significantly less than resized corbon brass. Have no idea why, but it seems your brass is better. Anyway thanks so much to you all and any further direction is much appreciated.

-Clay

claydunbar · #7 11-12-2006, 05:28 PM

Yet still more perplexing....

I cleaned the entire bolt and lubed it once again, then took 60rd primed brass with the CCI benchrest primers, and did a test. 2 of 60 failed. Thats actually progress in the right direction but the thing thats different now is that of the two that failed when I reset the bolt and fired again the primers fired. This didnt happen before. Its not a bad thing, it just serves to further confuse me. Again, I appreciate everyones help.

Clay

DonT · #8 11-12-2006, 09:57 PM

Clay,

A couple of things to try or consider. One is to go to a different brand of primers. Federal seems to be the most sensitive, followed by Winchester, remington and then CCI. I would immediately jump to federals and give them a try.

Next check your seating depth. In the past, have been reloading for about 20 years now, I have found that at times I have had primers that were not totally seated. What happened when I fired the gun is the firing pin actually seated the primer the remaining distance and this took most of the momentum out of the firing pin leaving a light dimple in the primer and giving the impression of the light primer strike. This can be quickly checked with a straight edge. Holder the base of the primed round on the straight edge and see if there is an apparent difference in the depth of the primers. If there is the ones seated deeper are probably the ones that are going off and the others are hit or miss..

Also not sure how your firing pin spring is setup but you may be able to get a small washer to put behind it to increase the pressure. This isn't a permanent fix but would give you a good idea if the firing pin spring is weak.

Thats about all I have at the moment.

Good luck..
DonT

claydunbar · #9 11-13-2006, 11:16 PM

Good news for those interested. Since I have 5000 rds pressed out going to Federal Primers was a poor option but a solution seems to have been found. Hindsight is always 20/20 they say.

1. I called CZ and they have seen this problem in their 7.62x39 gun, though not before in their .223. Nonetheless they informed me they ake a heavier Wolfe spring for my gun and are shipping 2 out to me straightaway at no charge. Nice huh?
2. I ground a washer down to fit inside the bolt around the firing pin to add tension to the firing pin spring as was suggested. I fired 30rds without a hitch. That is not to say that tomorrow when I pick it up again it wont happen rd 1, but I think its a good sign that greater spring tension is the solution. FYI All 30rds patterned inside 1", plus its a 220gr rn subsonic which has had great success in the field, so you can see why Im so attached to this load.

I will report back to this forum if additional problems arise so hopefully someone else in my situation will have an easier resolution. I appreciate very much all the help you guys have been especially Mr. Davis. Anybody who hasn't dealt with him wether its buying brass or whatever, he is a 100% good dude. By the way Mr. JDJ was cantankerous and wholly unhelpful in this matter, as Im sure will come as no surprise to many.

Thanks,
Clay