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Old 01-10-2016, 08:33 PM
284wahoo
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JNP Action Screws Question



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First of all, I'm not lodging any kind of a complaint towards JNP. I'd just like to hear if my experience has been observed by anyone else. I've replaced the action screws on all my CZ/BRNO rifles with the JNP offerings and have had no trouble with any until today. I just got back my 527 from having the action bedded. I removed the action to do a clean and inspect of all metal. Upon replacing the action, when I hand tighten the action screws (JNP), the rear hex head sheared off at about 18 inLbs. I understand these screws are not supposed to get fatigued, and have only removed that action with these screws about four or five times total. On inspection of the screw, I could see that there is very little metal holding the head to the body of the screw. Anyways, just wondering how common this is. I went ahead and ordered another set from JNP tonite.
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Old 01-10-2016, 09:00 PM
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Fella's;

I've got several set & never had a problem with them. However, I can tell you that if you get a D.I.P. trigger guard, also get the D.I.P. screws.

900F
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Old 01-10-2016, 09:03 PM
284wahoo
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Originally Posted by Big-Dummy View Post
I imagine Gerald will be along soon to tell you how wrong you are and how great J&P is. At least he can't threaten to ban you anymore for telling the truth.
Um, like I said, wasn't bashing JnP. Nothing there to be wrong about, anyway you look at it. Just passing along my experience and seeking perspective.
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Old 01-10-2016, 09:12 PM
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Call them tomorrow and tell them what happened. The hey have good customer service.
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Old 01-10-2016, 09:17 PM
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If you have a problem, call them. They are good guys.
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Old 01-10-2016, 09:17 PM
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18 inch pounds is really low. Even though it's a 5mm screw it shouldn't fail that low. Do me a favor, does your stock have pillars? Answer me that and I may have a possible cause here.
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Old 01-10-2016, 09:19 PM
284wahoo
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Originally Posted by djdilliodon View Post
18 inch pounds is really low. Even though it's a 5mm screw it shouldn't fail that low. Do me a favor, does your stock have pillars? Answer me that and I may have a possible cause here.
Yes, just installed.
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Old 01-10-2016, 09:21 PM
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Originally Posted by 284wahoo View Post
Yes, just installed.
Do the action screws make contact with the pillars? Look inside the pillars for thread marks. If you see any the screws are binding which can cause them to fail. Any pics of the bedded stock?
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Old 01-10-2016, 09:32 PM
284wahoo
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Originally Posted by djdilliodon View Post
Do the action screws make contact with the pillars? Look inside the pillars for thread marks. If you see any the screws are binding which can cause them to fail. Any pics of the bedded stock?
I'll have a look at the pillars per your suggestion. Did not discern any unusual tension but can't rule it out. Pics of the bedding aren't in the cards for tonite but will see about posting some as soon as I can.

Last edited by 284wahoo; 01-10-2016 at 09:35 PM.
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Old 01-10-2016, 09:37 PM
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I have had a couple shear at the head. Both were replaced no problem. Better to shear at the head than in the action.
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Old 01-10-2016, 09:40 PM
284wahoo
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Originally Posted by newbie2 View Post
I have had a couple shear at the head. Both were replaced no problem. Better to shear at the head than in the action.
That ain't no lie! I was greatly relieved when I could pull the trigger guard back off, and simply back out the screw shaft.

Last edited by 284wahoo; 01-10-2016 at 09:43 PM.
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Old 01-11-2016, 12:21 AM
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FWIW the screws are 6mm. A normal grade screw like this has a fatigue breaking point over 75 in/lb. If it breaks this low then several things could cause it. The material could be compromised (non homogenous in strength) or the fact its a hex head on a shallow headed screw. Hit them up for a new one...and have them cover the postage too...its defective.

As a side note, the reason cz makes it with torx (T.M.) is that the depth in the head is less than a standard hex head requires for the similar drive size. Hexolobular drive is a proven stronger drive angle than hex. It lets them make the head flush with the TG like a proper quality rifle should be, it makes the head stronger since the bottom of the drive leaves more meat between it and the flank. Hex drive on these brings the bottom of the drive to close to the screw shank comparatively.....check out the specs on each and you will see.

Last edited by Sporter; 01-11-2016 at 12:35 AM.
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Old 01-11-2016, 01:08 AM
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Quote:
Originally Posted by Sporter View Post
FWIW the screws are 6mm. A normal grade screw like this has a fatigue breaking point over 75 in/lb. If it breaks this low then several things could cause it. The material could be compromised (non homogenous in strength) or the fact its a hex head on a shallow headed screw. Hit them up for a new one...and have them cover the postage too...its defective.

As a side note, the reason cz makes it with torx (T.M.) is that the depth in the head is less than a standard hex head requires for the similar drive size. Hexolobular drive is a proven stronger drive angle than hex. It lets them make the head flush with the TG like a proper quality rifle should be, it makes the head stronger since the bottom of the drive leaves more meat between it and the flank. Hex drive on these brings the bottom of the drive to close to the screw shank comparatively.....check out the specs on each and you will see.
A 527 uses 5mm action screws. The rimfires use 6mm action screws.
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Old 01-11-2016, 01:34 AM
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You are correct DJ, my wrong.... I had assumed this was a "rimfire" site for some weird reason and just overlooked the 527 part.
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Old 01-11-2016, 07:29 AM
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dj likely is on the right track, any binding can cause a failure as I've found with a popular Torx head brand :roll eyes: a nick in the threads caused failure at a pretty low torque.
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