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Posted: 11/11/2015 12:23:10 PM EDT
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...I have a very accurate 7.62x39 in an AR platform. During the ammo shortage I was able to pick up 500 rounds of Tula. My AR fired these with ease up until a year ago then started having misfires (all ammo from same lot). I followed the suggestions offered here and ordered the stronger spring and correct firing pin upgrade from a company (the name escapes me now - PSE??) that was the most highly recommended. I just got around to installing it and test firing, more misfires. The round always fires on the second hammer strike. The firing pin is correct and has a longer protrusion out the firing pin hole then a stock .223 firing pin. I looked for debris inside the bolt that might be stopping the firing pin from bottoming out, nada.
Soooo, my thinking is that I need an extra strong spring to get consistent ignition...what company offers a good grade of trigger spring that won't loose its tension in a short amount of time? Bill in OR |
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For a heavier spring Wolff is the best, have not had to run one in either of my 7.62x39 builds which even run surplus Yugo reliably but is absolutely necessary in my 5.45x39 build. But it's got a 10 lb trigger pull which is pretty bad for an AR trigger
But I agree, if your was working fine before and stopped running reliably over time there's probably another issue, unless your original trigger spring was defective it should not have lost any significant force in that short a time. I also would not rule out your lot of Tula being out of spec, I'd try a box of something else. There was an earlier thread discussing FCGs and hammer force, someone posted data for various triggers and the Hiperfire (can't remember which one) had a LOT more force when using a std weight spring compared to the standard GI & other aftermarket setups. I can't say that's a fact, but I'm considering trying one in my 5.45 to get the trigger pull down to 5lbs, that is IF the sub $100 entry level unit can deliver more force than my current GI single stage & Wolff xtra power spring does. The vendor you ordered from was probably PSA (Palmetto State Armory). |
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Quoted:
The high end hyper touch trigger actually increase force as pull weight is reduced. If you want an awesome feeling trigger that will ignite 7.62x39, 5.45x39 or 50BMG, I would go that route. IIRC they have about a 2.5lb pull with the heaviest hammer force. Interesting. Do you use that? |
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Quoted: Interesting. Do you use that? Quoted: Quoted: The high end hyper touch trigger actually increase force as pull weight is reduced. If you want an awesome feeling trigger that will ignite 7.62x39, 5.45x39 or 50BMG, I would go that route. IIRC they have about a 2.5lb pull with the heaviest hammer force. Interesting. Do you use that? No, I only have one of their cheaper triggers (EDT). I have debated picking up one of their fancier versions for my .50, but I really don't shoot it that often. |
| The Hiperfire 24 trigger is really the way to go. You can choose between 3 different trigger pull weights, but you need to get the red and green springs that don't come with the trigger but are available on their web site. I have 300+ rounds through my ar47 without any light hammer strikes. Hiperfire has great customer service as well, just wish they would package a trigger with the heavier springs needed for steel cased ammo. |
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I finally got to the range after installing the Wolf Extra Power Trigger Spring - e-bay / $8.00 free shipping. I had two of the enhances firing pins in stock. I mic'd the tips on both. The OAL was the same and longer than the 5.56 firing pins. I noticed that while the length on the two 7.62x39 firing pins but the same the one I had bee having issues with was thicker. I changed out the spring and switched to the thinner tip....all is Good to Go now. 100% firing. I was also storing the firearm in the safe with a chamber flag in place. Soooo, I figured out that the hammer was cocked and the spring under tension for weeks or a month at a time. That MAY explain why with all the same equipment and parts I started with and worked fine last year was now having misfires; the spring was loosing tension. It probably would not have been an issue with a 5.56 reload with a softer primer but it sure was with the hard Tula primers.
Bill in OR |
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