AR Sponsor
Posted: 2/3/2025 6:23:44 PM EDT
|
Okay, BCA 10.5 in 7.62x39, the buffer and spring it came with will not work, double feeds almost every shot, figure the rate is way too fast. Had a blue spring and an orange spring, and H, H2, and H3 buffers to try. It finally seemed to start to want to work with an H2 buffer and an orange spring, but would still jam after 6 or 7. I got tired of messing with it but am going to try again next week. I’ve checked the gas key, going to use 1 mag only (Uni mag) for the next test to reduce error and variables. Also going to use brass case Golden Tiger. Other suggestions? |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
|
I can take the gas block off and check the port, but I’m waiting for BCA to reply 1st, tried white spring, regular buffer, h buffer, h2, and h3, Reg buffer with blue spring, and H, H2, and H3, Orange spring with regular, H, H2, and H3’ Mags were all duramags, except for the Zheng Uni-mag I have. |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
|
Originally Posted By Normlizer: Do you have an upgraded enhanced firing pin? Have one on order, but I don’t think the firing pin is going to cause double feeds and ejection jams. |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
|
Feed ramps are good. Inconsistent when being fired, sometimes a single round would lock open on the empty mag, sometimes the bolt wouldn’t move at all. That’s why I’m only taking 1 type of ammo next time, this time I had a mix of all kinds of mil surp. |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
|
Originally Posted By CA_TX-Cop: Feed ramps are good. Inconsistent when being fired, sometimes a single round would lock open on the empty mag, sometimes the bolt wouldn’t move at all. That’s why I’m only taking 1 type of ammo next time, this time I had a mix of all kinds of mil surp. The bolt stays in battery sometimes when it’s fired? I’d just send it in for warranty. |
R.I.P. Beau 8-17-2022
Pathetic earthlings... who can save you now?
Joined:
Sep 2009
Posts:
4079
EE: 100% (28)
TX, USA
|
Saw you were trying Dura-Mags - mags make a difference in any AR-47. BCA tends to be overgassed - so in a 10.5" I'd run the heaviest buffer & spring combination until I hit no lock back on last round. Have you examined the chamber carefully? A friend had a BCA that had some really rough tooling marks in the chamber that caused all sorts of extraction issues. He sent it back, BCA sent him a new upper. I'd spray it with brake cleaner, rub & scrub it clean and see what the chamber looks like. Hope it stops giving you headaches & starts making you smile soon! Good Luck! |
Pathetic earthlings. Hurling your bodies out into the void, without the slightest inkling of who or what is out here. If you had known anything about the true nature of the universe, anything at all, you would've hidden from it in terror.
| If the bolt isn't consistently locking back, are you sure you don't have a gas issue? My BCA 7.62x39 10.5" barrel was under gassed and short stroking with Tulammo. I have an extra power hammer spring in it and I suspect it added extra resistance to the bolt cycling. |
Joined:
Nov 2022
Posts:
109
EE: 0% (0)
WA, USA
| Slow motion camera shows that the extractor is not pulling the case out properly, so next step is to replace the extractor spring with an extra power one, and then try again next week. 😬 |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
|
Originally Posted By CA_TX-Cop: Slow motion camera shows that the extractor is not pulling the case out properly, so next step is to replace the extractor spring with an extra power one, and then try again next week. 😬 That can also be a symptom of overgassing |
R.I.P. Beau 8-17-2022
We are the Knights who say Fuuuuu!
Joined:
Sep 2004
Posts:
53948
EE: 100% (665)
TX, USA
|
Originally Posted By CA_TX-Cop: Slow motion camera shows that the extractor is not pulling the case out properly, so next step is to replace the extractor spring with an extra power one, and then try again next week. 😬 Does the 7.62x39 use a special extractor? I thought it did. Is there something over stressing the extractor? Rough or dirty chamber? Ammo? I've always been told if shooting Brass cases after shooting steel cases to vigorously clean the chamber to remove crud & residue. I'm sure you have already tried the heaviest buffer and spring combination to reduce bolt speed? Would you like to try a different complete 7.62x39 Bolt & Carrier unit to see if that "fixes" your issue? Bigger_Hammer  |
LIFE'S JOURNEY IS NOT TO ARRIVE AT THE GRAVE SAFELY IN A WELL PRESERVED BODY,
BUT RATHER TO SKID IN SIDEWAYS, TOTALLY WORN OUT SHOUTING "HOLY $H!T...WHAT A RIDE"!!
BUT RATHER TO SKID IN SIDEWAYS, TOTALLY WORN OUT SHOUTING "HOLY $H!T...WHAT A RIDE"!!
|
Yeah, tried an H3 buffer and an Orange spring and it didn’t cycle back. Got down to an H2 and a blue spring and it wasn’t extracting. Used the camera and the bolt and carrier are returning without the case. Changed out the extractor spring for an extra power spring, but won’t be at the range again until next week. Yes, the 7.62x39 extractor is shaped differently due to the larger case rim. Bigger-Hammer, thanks for the offer. I’m almost about to buy another BCG from BCA they are on sale for 80. Just to have 2 and except for the bolt and firing pin I can use the cam pin and bolt carrier in regular AR’s if needed. |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Member
Joined:
Aug 2024
Posts:
692
EE: 0% (0)
TX, USA
|
It sounds to me like you're over gassed. Don't go throwing a bunch of money at it trying to get it to run. First, stick to either a white hot or blue springco spring. The extra heavy spring will help to overcome all of the friction with AR x39 magazines when feeding. The spring will also help with bolt velocity, but will have little effect on the closed bolt lock time. The only way to increase closed bolt lock time is to either increase the buffer weight or reduce the amount of gas going through the system. Increasing buffer weight only works within a certain window of gas volume. In a case of severe over gassing, the best fix is an adjustable gas block. On my setup, I used an Aero adjustable block. You can find them on sale for like $50. I tuned the rifle to run on an H2 buffer and blue spring. It runs anything I put through it with no stuck cases. As for the extractor, it doesn't hurt to be running a good spring with the insert and the o-ring. I get my upgrade kits from FCD and run them in all of my BCGs. When your extractor breaks, try running a standard extractor. They're beefier than the x39 extractor and they seem to work fine. Ive been running one for years without a problem. Actually, this is probably going to be a set it and forget thing. I just went and looked at my setup and remembered what I did. I just went with a cheap set screw gas block. I tuned it and then used red loctite on the set screw. It's been running for years. |
|
FIXED and working. Got a new 7.62x39 BCG and using an H3 buffer and standard spring, ran everything I fed it. Wolf, golden tiger, silver bear(?), and the old green box Sellier & Bellot. Now to see if I can get the old BCG up and running. |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
|
Originally Posted By CA_TX-Cop: FIXED and working. Got a new 7.62x39 BCG and using an H3 buffer and standard spring, ran everything I fed it. Wolf, golden tiger, silver bear(?), and the old green box Sellier & Bellot. Now to see if I can get the old BCG up and running. Interesting, Per my earlier post and comment about dealing with this exact upper last year, when I finally was contacted by BCA for a return after filing with the BBB, they returned a working upper with no explanation. Perhaps they swapped out the BCG... |
|
Originally Posted By RoadShow: Interesting, Per my earlier post and comment about dealing with this exact upper last year, when I finally was contacted by BCA for a return after filing with the BBB, they returned a working upper with no explanation. Perhaps they swapped out the BCG... This didn’t go back, I just got another BCG and swapped in an H3 and it worked. The original BCG had an extractor problem, which I tried to fix and ended up over-fixing to where the extractor wouldn’t even go over the cartridge rim. I’ve changed that back to a normal spring and will try again next range trip. |
A closed mouth gathers no foot.
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
Make it "Idiot Proof", along comes a better idiot.
Official Site Nickname, given by NorCal - "Smack"
AR Sponsor