User Panel
User Panel
User Panel
|
Posted: 2/9/2024 3:12:49 PM EDT
[Last Edit: tortilla-flats]
Here's the build: Used Colt 6520 upper, new Colt BCG/CH, new Colt H2 buffer w/stock carbine buffer spring, new Colt 10.3" M4CQBR barrel. Lower is Colt M4 Carbine w/LT MBT-2S. Muzzle device is a Surefire Blast Warden and not a suppressor (Surefire A2 FH underneath). Couldn't find a Colt carbine gas tube so used a new Wilson Combat carbine gas tube.
Mags: Lancer 20rd, Surefeed aluminum 20rd. Ammo: Hornady Black 75gr Interlock HD SBR. 5.56mm Issue: With Lancer mag, will not pick up the next round. With SF mag, attempts to pick up next round but jams. Other data point: Suppressed Colt 6933 (11.5") w/H3 buffer runs fine during the session using the same ammo & mags.  |
|
|
|
|
Posted: 10/6/2011 1:37:29 PM EDT
[#1]
Topic Moved
|
|
|
|
Posted: 2/9/2024 6:59:37 PM EDT
[#2]
Did you still have issues when you removed the H2 buffer and put in an H3?
|
|
|
|
|
Posted: 2/9/2024 7:10:06 PM EDT
[#3]
I did not try that as I ran out of time. Also, I'll need to find a range that's comfortable with me making those kind of changes on the line.
Is the idea that I would need an H3 buffer (vs a standard H)? What if that doesn't work (or work well enough)? Trying to sort out all the variables so I know what I need to bring next time to see what I can do to get it working. |
|
|
|
|
Posted: 2/10/2024 10:31:00 PM EDT
[#4]
bump
|
|
|
|
|
Posted: 2/10/2024 10:54:51 PM EDT
[#5]
Shoot with one round in the mag and see if it locks back.
Swap uppers and lowers to see if the problem follows the upper. It always hand feeds without issue? How much travel behind the bolt catch do you have? Gas key feels tight? |
|
|
|
|
Posted: 2/10/2024 11:08:33 PM EDT
[Last Edit: tortilla-flats]
[#6]
Quote HistoryOriginally Posted By jaqufrost: Shoot with one round in the mag and see if it locks back. I'll try that. Swap uppers and lowers to see if the problem follows the upper. I'll try that. It always hand feeds without issue? It feeds fine if I manually rack the bolt. How much travel behind the bolt catch do you have? It goes all the way back such that I can't see it in the ejection port opening. Gas key feels tight? Yes and it looks staked properly. |
|
|
|
|
Posted: 2/11/2024 9:08:21 AM EDT
[#7]
You should be able to pull the bolt back and have 1/4" to 3/8" of room between the front of the bolt and the bolt catch.
|
|
|
|
|
Posted: 2/11/2024 11:19:15 AM EDT
[#8]
Quote HistoryOriginally Posted By jaqufrost: You should be able to pull the bolt back and have 1/4" to 3/8" of room between the front of the bolt and the bolt catch. Swapped over the entire lower (w/H3 buffer) and entire BCG/CH from the suppressed gun. I'll shoot this one unsuppressed & suppressed and see how it goes. I really want this setup to run. I'd get rid of the 6933 over this if I can get it to run. |
|
|
|
|
Posted: 2/11/2024 2:30:25 PM EDT
[#9]
Original lower with H3 buffer snd other BCG/CH will not lock bolt to rear with 1 round in either mag.
Attach suppressor and it runs fine. |
|
|
|
|
Posted: 2/11/2024 3:44:00 PM EDT
[#10]
Sounds undergassed. You may want to try a standard buffer or open the gas port a small amount.
|
|
|
|
|
Posted: 2/11/2024 6:00:09 PM EDT
[#11]
Thanks. I'll try that next trip.
|
|
|
|
OH, USA
|
Posted: 2/12/2024 3:02:29 PM EDT
[#12]
Quote HistoryOriginally Posted By tortilla-flats: Hard to get a measuring stick in there, but eyeballing it, I'd say I have at least that much if not more. Swapped over the entire lower (w/H3 buffer) and entire BCG/CH from the suppressed gun. I'll shoot this one unsuppressed & suppressed and see how it goes. I really want this setup to run. I'd get rid of the 6933 over this if I can get it to run. Quote HistoryOriginally Posted By tortilla-flats: Originally Posted By jaqufrost: You should be able to pull the bolt back and have 1/4" to 3/8" of room between the front of the bolt and the bolt catch. Swapped over the entire lower (w/H3 buffer) and entire BCG/CH from the suppressed gun. I'll shoot this one unsuppressed & suppressed and see how it goes. I really want this setup to run. I'd get rid of the 6933 over this if I can get it to run. Insert empty mag, rack bolt, let it stop on catch, pull bolt back and see how much movement it has behind the catch. Measure the charging handle movement if you want to be more accurate. |
|
|
|
Posted: 2/12/2024 3:23:39 PM EDT
[#13]
Quote HistoryOriginally Posted By jaqufrost: Sounds undergassed. You may want to try a standard buffer or open the gas port a small amount. It's probably simply too heavy buffer though. I always start with a standard carbine buffer and increase weight only if needed. Out of curiosity why did you start with H2/H3 weights? |
|
|
|
|
Posted: 2/12/2024 4:07:25 PM EDT
[#14]
Quote HistoryOriginally Posted By crazyelece: Insert empty mag, rack bolt, let it stop on catch, pull bolt back and see how much movement it has behind the catch. Measure the charging handle movement if you want to be more accurate.  |
|
|
|
|
Posted: 2/12/2024 4:08:16 PM EDT
[#15]
Quote HistoryOriginally Posted By TGE: Agree all the way up to opening the gas port lol. I'd check a lot of other things before I did that, especially if you may ever shoot this gun suppressed. I'd work from the gas block itself through alignment, the tube, gas key and interface, etc., etc. It's probably simply too heavy buffer though. I always start with a standard carbine buffer and increase weight only if needed. Out of curiosity why did you start with H2/H3 weights? Quote HistoryOriginally Posted By TGE: Originally Posted By jaqufrost: Sounds undergassed. You may want to try a standard buffer or open the gas port a small amount. It's probably simply too heavy buffer though. I always start with a standard carbine buffer and increase weight only if needed. Out of curiosity why did you start with H2/H3 weights? 
|
|
|
|
|
Posted: 2/12/2024 4:37:08 PM EDT
[#16]
Quote HistoryOriginally Posted By tortilla-flats: Reading the internets. Quote HistoryOriginally Posted By tortilla-flats: Originally Posted By TGE: Originally Posted By jaqufrost: Sounds undergassed. You may want to try a standard buffer or open the gas port a small amount. It's probably simply too heavy buffer though. I always start with a standard carbine buffer and increase weight only if needed. Out of curiosity why did you start with H2/H3 weights? Some guns do benefit from the heavier weight, but I'm at about 50% of my ARs that just need a regular carbine buffer even suppressed (which is about 99% of my shooting). A couple did exactly what you describe when I tested H1/H2 buffers in them. |
|
|
|
|
Posted: 2/13/2024 12:33:54 PM EDT
[#17]
Still not picking up rounds/locking back.
At this point I'm guessing there's something wrong with this build? |
|
|
|
|
Posted: 2/13/2024 1:08:41 PM EDT
[#18]
I would look for gas leaks at the key, gas block, bell on the gas tube, and proper gas tube length. Then check for a misaligned gas block, check the gas port size and check for a misdrilled gas tube.
If the port size is small and everything else is good, open it up a little. |
|
|
|
|
Posted: 2/13/2024 1:31:27 PM EDT
[#19]
So send it to a gunsmith that knows what they are doing?
 |
|
|
|
|
Posted: 2/14/2024 3:53:29 PM EDT
[#20]
I like to set up SBR ARs with the A5 length buffer tube and 11.5" BBL. I had a lot more trouble with the shorter BBLs (<11.5")
|
|
|
|
|
Posted: 2/15/2024 6:14:38 PM EDT
[#21]
have you tried different ammo , maybe some m193 55gr ball ammo. i've had issues with that bullet feeding smoothly in usgi mags in some guns
if it does the same with m193 it sounds under gassed as has been mentioned above did the barrel come with the fsp already pinned , did you check alignment with the gas port does the wilson gas tube fully enter the gas key if you can i would go over the gas system to make sure everything is "all good". pull the fsb and pin the gas port to check it and alignment of the fsb with the gas port. measure the length of the gas tube and make sure it's going into the gas key far enough. for some reason that wilson combat gas tube is standing out as an issue to me. check your gas key to make sure it's tight and that it lines up with the gas tube good with that list of parts that thing should run like a top , it's an awesome little blaster. personally though i would have to put a set of carbine length m16 triangular style handguards on it |
|
|
|
|
Posted: 2/16/2024 3:48:12 PM EDT
[#22]
I'm not qualified to analyze the quality of the work representing this build. It's clear at this point that there is in fact something wrong.
ADCO is sorting it out for me. 
|
|
|
|
|
Posted: 2/16/2024 3:49:47 PM EDT
[#23]
Quote HistoryOriginally Posted By 1iviper: personally though i would have to put a set of carbine length m16 triangular style handguards on it  (Off to see how much more this parts build is going to cost me) |
|
|
|
|
Posted: 2/17/2024 9:33:05 PM EDT
[#24]
Quote HistoryOriginally Posted By tortilla-flats: I'm not qualified to analyze the quality of the work representing this build. It's clear at this point that there is in fact something wrong. ADCO is sorting it out for me. |
|
|
|
|
Posted: 2/17/2024 9:37:49 PM EDT
[#25]
Quote HistoryOriginally Posted By tortilla-flats: (Off to see how much more this parts build is going to cost me) shorty handguards i have a set somewhere around here i was going to cut down to work with pistol length gas fsb on a 7" kitty kat barrel |
|
|
|
NC, USA
|
Posted: 2/18/2024 4:08:35 PM EDT
[#26]
Try a H buffer or even a carbine. My MK18 will not lock back 223 pressure and H2. Runs great with H
Suppressed is a H3 all day .070 gas |
|
|
|
Posted: 2/20/2024 9:51:16 PM EDT
[Last Edit: tortilla-flats]
[#27]
Steve vetted the upper today. Confirmed .070 gas port.
Next steps... -- Check for any binding/scraping with the BCG and/or buffer assy, causing drag -- Carbine buffer (3oz) -- Lighter buffer spring -- Lower mass bolt carrier |
|
|
|
|
Posted: 2/25/2024 7:06:56 PM EDT
[Last Edit: tortilla-flats]
[#28]
Got the upper back and went to the range today.
Standard carbine buffer seems to work (3oz). Put an H buffer back in and it ran ok with the Lancer mag, but had intermittent problems locking back after the last round with the SureFeed mag. Otherwise, both fed multiple rounds without problems. It also ran with the H buffer on a mag of Mk262, but didn't run it all the way out to see if it locked back. I also had a brand new (literally arrived this morning) Colt 10.3" M5 CQC upper (complete) out today that ran perfect with both an H & H2 buffer, unsuppressed. Not sure why the 6520 upper won't run like that; not sure what I want to do with it. |
|
|
|
|
Posted: 2/25/2024 7:32:08 PM EDT
[#29]
I have a Noveske 14.5" barrel with an A2 FSB I could swap out, but that's not really the build I was going for.
|
|
|
|
|
Posted: 2/26/2024 12:32:03 AM EDT
[#30]
Actually, it runs fine suppressed. I'll put one on it.
|
|
|
|
|
Posted: 2/27/2024 9:24:02 PM EDT
[#31]
Decided to do something different with the handguards, so replacing the gas tube with a Colt carbine gas tube.
|
|
|
|
|
Posted: 2/27/2024 9:24:12 PM EDT
[#32]
Decided to do something different with the handguards, so replacing the gas tube with a Colt carbine gas tube.
|
|
|
|
|
Posted: 3/3/2024 7:06:20 AM EDT
[#33]
did adco do anything besides confirm gas port size ?
that thing should run like a raped ape without needing a lightweight carrier or spring or anything special good call on the colt gas tube to try have you tried other ammo than the hornady 75gr ? |
|
|
|
|
Posted: 3/3/2024 10:52:30 AM EDT
[#34]
Steve ran through all the components to make sure everything was sized correctly, in good repair and assembled correctly.
I can run some IMI Razor, BH Mk262 or Aussie 69gr BTHP but that's about all I have for alternatives (can't run steel core at the range I go to). |
|
|
|
|
Posted: 3/6/2024 4:36:08 PM EDT
[#35]
New Colt gas tube, H buffer, BH Mk262: no FTFs or FTEs. 1 of 5 mags failed to lock back. Got the irons sighted in. Calling it good until I get a suppressor on it.
Thanks for the help all. |
|
|
|
|
Posted: 3/7/2024 2:08:34 AM EDT
[#36]
awesome
 |
|
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
