i'm at my wits end trying to figure this thing out over the last 4 weeks, going to the range at least three hours a week. i am experiencing FTE's. FTF's, and light hammer strikes now! but it will run like a champ very inconsistently. this is a long write up, but please bare with me.
specs: my rfile has a dedicated ST-22 upper i got from you guys using a DPMS lower kit in a .22LR spike's lower receiver, and has a M1S 14.5" .22LR barrel (it came as a 16", but i had a gunsmith properly cut it down). during the course of my tuning, i am using 5 black dog mags with 6 types of ammo. CCI Mini Mags, Blazers, Winchester 333's, American Eagle, Winchester White Box, and Federal Bulk Pack 550rd. red box.
initially it was experiencing FTE's about 2-3 rounds per 10 round mag. (i'm in california.) i cut the spring down 3 coils and fired 60 rounds (10 rounds each of different ammo) and kept cutting until the spring was down to 7.25" all the while seeing how each type of ammo ran. this took forever! at an OAL of 7.25", i found the CCI Mini Mags, Blazers, and Winchester 333's were firing the best with 1-2 FTE's per 20 rounds each whereas the other ammo types had many FTE's. but at around the 7.25-7.50" OAL range, i had a mix of FTE's AND NOW, FTF's. i saw that i had a few hammer strikes at the 12 o'clock position on the chamber face and went and got it deburred and polished. that seemed to help some of the FTF's, but it was still doing it.
so, i ordered and installed a light JP hammer spring from you guys. now i replaced the recoil spring to a new black 9" OAL one in your spares kit and did my coil cut and firing test again, this time only with the 3 types of ammo that seemed to run the best from my last test which were CCI Mini Mags, Blazers, Winchester 333's. this time, when my recoil spring reached an OAL of 7.75", i was able to shoot 150 rounds of blazers without a single FTE or FTF! i was completely stoked.
so i cleaned it up real good and went back to the range a week later to see if it was a fluke or not. unfortunately, the ST-22 started to act up again. i got a mix of FTE's and FTF's. about 1 FTE and 1 FTF per 10 round mag. i played around with the black dog mags by pressing them directly up into the mag well, then pulling down, pushing forward, right, left, and back and the results were that it seemed to help the shells eject more powerfully with the mag pushed up, i did get a few mag loads to fire all the way with no issues, but that was only once every 3 mags. as of last night, i get about 1 FTF per 10 round mag or an FTE with a round chambered. i even had a new problem surface last night with 5 rounds out of 250 that failed to fire! (due to light hammer strikes i presume)
now i turn to you, what do you think i should do now? should i replace the stock hammer spring? could it be a mag issue? i do keep it clean and use CLP very sparingly. i've gone through over 1,000 rounds, 2 hammer springs, and 2 recoil springs trying to get this baby to work. guys at the range laugh at me now, but i refuse to give up. they say that .22LR AR's can't run right. i need to prove them wrong and show them that my Spike's ST-22 can be a beast.
please help! thanks,