03-07-2020, 10:03 PM
My new build is shooting accurately, but...
After about the 1st 20 rounds, I began having FTF issues. Bolt was running over the next round and bolt was only locking open on the carrier, not the bolt face. Empties ejecting at 3-4 o'clock. Ok, I seemed under gassed.
Build is JP barrel/bolt, rifle gas on Vltor upper, RCA carrier and BCM ambi charging handle. Lower is Aero and the A2 stock, rifle buffer tube and spring came from a Bushmastet carbine gas system rifle it was previously on.
Things I've double checked. Gas block is centered on barrel port. Put some painters tape around the GB and no apparent leaks. Worked on Elander mags until they were feeding nicely and no apparent contact between mag and carrier. Cleaned up sharp edges on the extractor. Ejector pin height looks fine. Barrel port is .093 minus pin gauged. Put on a known good carbine lower from another rifle gas upper. Still short strokes and ran over next round in the mag. That lower had an H1 buffer.
So I canned the single JP gas ring in favor of standard rings and replaced buffer spring with JP enhanced spring. First round this morning, got full bolt lock on empty mag. Woohoo, problem solved, or so I thought. Cycled the next 17 rounds flawlessly. Then noticed that the bolt locked open on the carrier again. Reloaded a mag and bolt was over running the next round again. Checked that a loaded round falls freely from the chamber when upper is vertical and chamber looks nice.
So I cleaned up the receiver and relubed the BCG. Was going to shoot a jackpot tomorrow from 400-1000 yards with the rifle but my confidence in it running without the distraction of ftf issues has me second guessing using it until I can figure it out. I have 129 pills down the pipe so far. I'm thinking it might just need to wear in some more, I dunno.
I also tried my Young carrier to no avail. Have 5 other carriers I could try that are all milspec full auto carriers, but seems somewhat pointless.
Any thoughts would be appreciated. Thanks, Jeff.
After about the 1st 20 rounds, I began having FTF issues. Bolt was running over the next round and bolt was only locking open on the carrier, not the bolt face. Empties ejecting at 3-4 o'clock. Ok, I seemed under gassed.
Build is JP barrel/bolt, rifle gas on Vltor upper, RCA carrier and BCM ambi charging handle. Lower is Aero and the A2 stock, rifle buffer tube and spring came from a Bushmastet carbine gas system rifle it was previously on.
Things I've double checked. Gas block is centered on barrel port. Put some painters tape around the GB and no apparent leaks. Worked on Elander mags until they were feeding nicely and no apparent contact between mag and carrier. Cleaned up sharp edges on the extractor. Ejector pin height looks fine. Barrel port is .093 minus pin gauged. Put on a known good carbine lower from another rifle gas upper. Still short strokes and ran over next round in the mag. That lower had an H1 buffer.
So I canned the single JP gas ring in favor of standard rings and replaced buffer spring with JP enhanced spring. First round this morning, got full bolt lock on empty mag. Woohoo, problem solved, or so I thought. Cycled the next 17 rounds flawlessly. Then noticed that the bolt locked open on the carrier again. Reloaded a mag and bolt was over running the next round again. Checked that a loaded round falls freely from the chamber when upper is vertical and chamber looks nice.
So I cleaned up the receiver and relubed the BCG. Was going to shoot a jackpot tomorrow from 400-1000 yards with the rifle but my confidence in it running without the distraction of ftf issues has me second guessing using it until I can figure it out. I have 129 pills down the pipe so far. I'm thinking it might just need to wear in some more, I dunno.
I also tried my Young carrier to no avail. Have 5 other carriers I could try that are all milspec full auto carriers, but seems somewhat pointless.
Any thoughts would be appreciated. Thanks, Jeff.
