AR Sponsor
Posted: 4/1/2010 12:34:06 PM EDT
|
I recently got back by Tac Sol M-4 style upper from having the barrel cut to 11.5 inches. After putting it all back together it shoots accurately but I am now having a functioning problem. What happens is after a round is fired, it ejects perfectly and picks up a new round without problem. The problem is about 4-5 shots out of 27 it does not reset the hammer/trigger for the next shot. A live round is chambered but there is a dead trigger and the hammer is not recocked. I am assuming I either need 1. a lighter trigger spring 2. a lighter hammer or 3. trim a couple coils off the bolt's spring to let it recoil a little harder back.
Any suggestions on which would be the most effective? By the way the hammmer on the lower is rounded and not notched so that problem is already eliminated. Thanks Bigbets |
|
On my dedicated .22LR rifles, I chose to reduce the hammer spring and bob the tail on the DPMS hammer (like the JP Enterprises speed hammer). I wanted to keep the recoil spring at full length to aid in feeding the rounds into the chamber.
I used just the yellow hammer spring from this kit. http://www.brownells.com/.aspx/pid=7582/Product/AR_15_REDUCED_POWER_SPRING_KIT |
|
It's really strange that it's happening after 4 or 5 rounds and not right away????
It sounds like a weird problem but you do need the bolt to come back farther to disconnect and reset the hammer. You could try bending one leg of hammer spring you're using to lighten it up a bit. You could try cutting tiny bits of the coil while at the range, testing as you go or you could try what was mentioned above with the yellow hammer spring and bobbing the hammer. I do not like the yellow trigger spring at all, personal preference. Good Luck, Spec |
|
It happens intermitently. It functioned perfectly before cutting the barrel. The now lack of back pressure from missing 5 inches of barrel is what has to be causing the problem. Thing is it is obviously right on the edge of functioning properly as it only fails to reset the hammer every 3-5 rounds when shooting a magazine.
BigBets |
|
Hi to Alaska, He has a rounded hammer.
I've shot 7-1/2",10-1/2" and11-1/2" AR barrels and now a dedicated 8" Beyer Barrel with no need to change the hammer spring or cut any coils off the recoil spring. I just can't quite get wrapped around this problem. Irregardless, it could be exactly what you're thinking. It gets to a round that's loaded slightly lighter and it doesn't kick the bolt back quite hard enough. Maybe Tac Sol's recoil spring is just that much stronger. But it comes the same as far as I know for their shorter SBX Barrels. Spec |
|
Yeah and when the problem occurs it does chamber a round effectively and eject the old one effectively. I also notice when the hammer doesnt reset that the live round in the chamber has a dent where the striker hit it, just not quite hard enough to set the second round off with one trigger pull. This obviously would've been a no no so I stopped right there. It appears when it happens the bolt comes back enough to eject and chamber a new round and is occasionally just not powerful enough to reset the hammer/trigger. New spring and lighter hammer it is.
Jacob |
|
Quoted:
Yeah and when the problem occurs it does chamber a round effectively and eject the old one effectively. I also notice when the hammer doesnt reset that the live round in the chamber has a dent where the striker hit it, just not quite hard enough to set the second round off with one trigger pull. This obviously would've been a no no so I stopped right there. It appears when it happens the bolt comes back enough to eject and chamber a new round and is occasionally just not powerful enough to reset the hammer/trigger. New spring and lighter hammer it is. Jacob This seems to be a fairly common problem with TacSol uppers, except it usually happens after firing the first round. My M4 upper on a RRA lower with a NM trigger did it. I sent it back to TS and they fixed the problem, but didn't specifiy what they did to cure it. It's as close to 100% as they get now. My LT upper does exactly the same thing on that RRA lower that the M4 did. It works perfectly with a Spikes and a DPMS lower with mil-spec triggers. This leads me to believe that TacSol did something to the bolt on the M4 to make it work with the NM trigger. I'm just not smart enough to figure out what it was. I guess I'm going to have to call them - this is driving me crazy. If I find out anything helpful, I'll let you know. Tom-> |
|
Quoted:
My LT and LMT lower are arriving back from TS on Monday, I sent it in for the same problem. They had it for a week and I had/have no word on what they did to it. Hope it works come Monday. This seems to be a very common problem all of a sudden. Keep us posted - hope they included a note on what they did to fix it. They did not include one when they fixed mine. |
| I talked with Lon at TacSol Friday. He said that in order to make my M4 upper work with the RRA NM trigger/hammer, they did some re-shaping of the bottom rear of the bolt. I thought it looked like it might have been polished on the bottom when I got it back. At least now I know what they did to fix the problem, but it's not something I would tackle on my own. I need to do a side-by-side comparison between the M4 and LT bolts to see if the difference is noticeable. |
|
My TS LT and LMT lower arrived back from TS yesterday.
Off to the range today. Short and sweet... No indication from TS as to what they did to the upper or lower. Trigger reset problems are gone. After about 120 flawless rounds one ftfeed, and 1fte both in same magazine. Wiped down the bolt assembly and re lubed, then 30 more rounds with no issues. Then had to get back to work. I can tell the difference in the bolt and trigger reset between HV and SV ammo. HV is more definite and certain. I am hoping that the magazine loading or some dirt was the reason for my FTF&FTE, next time at the range will tell. No question it is functioning better than it was, not sure yet if it is perfect though.... |
AR Sponsor