FTF problem

[fortdick]

I just built a new upper and tested it....not too good results.

It is a YHM upper with a YHM barrel, and YHM FF quadrail (not that this should matter). I put a Spikes mil spec BCG in it with a YHM charging handle. At first, I had problems with the charging handle sticking, but after lubing it real well, that seemed to fix the problem.

Put it on my S&W lower to test fire it and it FTF. Charged it again, FTF. The third round, FTF and the charging handle stuck again. Had to really yank on it to eject the round.

I took it apart, checked everything, and noticed there was a dimple on the primer of one round, the other two were clean.

Reassembled it, this time using a single round, I charged the bolt and FTF. Took it apart again and checked everything, all seemd fine. Tested my S&W to make sure it wasn't the lower and no problem.

Third try, after putting the new upper back on, I loaded the magazine into the gun with the chamber open and used the bolt release to charge the round. Fired perfectly, locking open on an empty mag.

Any ideas what my problem was with the first couple tests?

thanks in advance.

[subijitsu]

It sounds to me like the gas tube is binding or not lined up good with the key, causing it to not go fully into battery or come out easily.

Does it cycle by hand fine without ammo or does it still stick?

[torquefliteterror]

could be that it is just tight since it has never really been fired. what type of ammo did you use?
On the cheap ,Try picking up an extra heavy hammer spring like the ones used for 7.62x39 conversions. google it , they are like $2.00. I have built a ton and come across the occasional kit with a "weak" hammer spring. not saying that is the problem but it could be that your new upper requires a little more "whack" to ignite the primer.

It probably is a good idea to try another 10 or so rounds in the "single" fire method to test it to see if you get anymore light primer strikes and to allow the ammo to work the action to "loosen" up some.

[fortdick]

It sounds to me like the gas tube is binding or not lined up good with the key, causing it to not go fully into battery or come out easily.

Does it cycle by hand fine without ammo or does it still stick?

It stuck the first time I put it together, but after disassembling and a good lube it started cycling fine. I have kinda wondered if the tube was binding somehow. I might pull the whole thing apart and check that out if this continues.

Thx

[fortdick]

could be that it is just tight since it has never really been fired. what type of ammo did you use?
On the cheap ,Try picking up an extra heavy hammer spring like the ones used for 7.62x39 conversions. google it , they are like $2.00. I have built a ton and come across the occasional kit with a "weak" hammer spring. not saying that is the problem but it could be that your new upper requires a little more "whack" to ignite the primer.

It probably is a good idea to try another 10 or so rounds in the "single" fire method to test it to see if you get anymore light primer strikes and to allow the ammo to work the action to "loosen" up some.

I was using federal eagle ammo. I am hoping it will loosen up, but haven't been able to put many rounds through it yet. I live in a rural area and a few rounds out the back door is no big deal, but to many will draw unwanted attention. The weather has prevented a trip to the woods to give it a real test.

[torquefliteterror]

What did you lube the gun with. I use the red high temp bearing grease from the walmart automotive department. I heavily coat the bolt lugs and the four rails on the bolt. I spray remoil or whatever oil i have , into the gas ring holes as well.

do that and the single shot method the next chance you get . hopefully it will loosen up. It's worked for me on a few "tight" uppers.

[69powerwagon]

torquefliteterror, awesome name. GO MOPAR! A-727 ROCKS


Ok, now you may go back to topic.

[torquefliteterror]

torquefliteterror, awesome name. GO MOPAR! A-727 ROCKS


Ok, now you may go back to topic.

ha ha ha ,thanks.