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Posted: 1/26/2020 9:48:40 PM EDT
I’ve been dealing with this issue for years. I finally am looking into it more heavily. I’ve read many forums about it and have had some ideas. Here is info and what I know:
16 inch, I think, LaRue PredatAR Upgraded buffer and heavy spring. 8oz heavy buffers 8oz buffer JP adjustable gas block Silencerco Harvestor 30 cal suppressor Stove pipes randomly usually it seems more on first cold shot. When I try to troubleshoot it it seems pretty reliable once warm. Anyways it gets stuck on ejection. I shoot various rounds but lately Remington core lokt 180 grain and permanently will be 150 grain core lokt. I just started using the 180 grain core lokts so haven’t had much time to troubleshoot (since the new twice as heavy buffer) Buddy borrowed rifle and shooting 150 grains has jammed twice. I am a couple clicks above where the bolt cycles and locks back. I’m aware larue has a larger than average gas block hole? But adjustable block should fix this Gas rings look ok. Extractor seems ok this is a high quality gun (or so I thought) Call to larue was useless as they cannot guarantee anything suppressed. What are y’alla ideas? Does this can have a Lot of back pressure? I need to do more testing it just never seems to end and I only just got the heavy buffer to slow down the carrier group. It didn’t seem To help on 150 grain, tho I haven’t been able to test / tune for this round Do heavier rounds like 180 have MORE back pressure? As this would possibly be the issue. I wouldn’t think it would matter unless powder charge is changed for the heavier round. Gun is lightly used. Hunting only. Just cleaned it thoroughly. Same issue. No known issue with gas tube or things like that. I turned up gas way high and it seemed to have more issues jamming. Something is wrong with the Timing. Bolt unlocking. Or something else! ejection pin? Don’t think so. Less than a few hundred total Rounds though gun Thx! |
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Try a box or two of fggm or some sort of non lead nosed bullet,I have had stove pipes with lead nosed bullets. I'd also go back to the factory spring and buffer and adjust bolt speed using the gas block. To me you have introduced so many variables you need to start over from factory and adjust from there.
Pete |
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For what it’s worth. I have a 16” tAR and shoot a lot of 150gr corelokt. Those rounds are absolutely devastating. Anyway, I don’t have my tAR suppressed though. (Not to throw too much info I do shoot my OBR with 150gr corelokt suppresses without issue)
As Pete mentioned, I’d go back to the h2 and red spring. Like he said a lot of variables have been introduced since it came from from the LT factory. My understanding has always been when you have an adjustable gas block you shouldn’t need to play with buffer weights. Just tune the gas block to the ammo and suppressor. |
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Does JP’s gas block have the proper screw spacing? This may something you've worked out during your install but I’ll mention it. If the screw spacing has the block oriented a little off it may be restricting flow.
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Did you play with buffer weight/gas block settings or go right to the current combo.
ETA: I looked at the core loct speeds they seem so so, but the 180 at 2620 might be a little steep. The 150 at 2820 is steep. https://images.remington-catalog.com/586d201b19ffc Those rounds if they are factory are probably not meant for the gasser, more than likely meant for a bolt gun. |
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Forgot to ask how does it shoot without the supressor,maybe a tranquillo is needed to tame the beast
Pete |
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I grabbed some data from a buddy, a 175 should be leaving a 18" gasser at about 2450-2500.
Im blaming the ammo |
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Thanks for all the replies!
I only tried heavier buffer to slow the carrier group down and because nothing else has worked. If core lokt ammo isn’t great then what is? It’s too fast? Gun operated fine non suppressed. Suppressor throws everything off. |
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Try some federal gold medal match. Tune the buffer and gas to that.
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I was shooting those gold match and same issue. It’s pretty random.
I like core lokt because it’s at Walmart I have 10+ boxes and want to make it work. They had a sale and we got a bunch. Does this suppressor create a lot of back pressure vs orhers? I’d figure they all about same And 180 vs 150, aren’t pressures similar? Or is 180 less. I’ve read generally powder charges are measured to keep pressure at same safe levels so why does weight matter. Or bullet brand for that matter. |
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One other thing I wanted to try is turn gas up just until cycles and stop. It seems so sensitive and non linear. I’ve been going 2 clicks above where it cycles to be reliable but maybe that’s too much gas already.
I’ve read larues have bigger gas ports too. Ugh |
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Yes but suppressed? Is there a better gas block out there than JP? View Quote View All Quotes View All Quotes Quoted:
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From my experience 150gr corelokt in a 16” tAR shoot great. Is there a better gas block out there than JP? I’m just saying the barrel, bolt, buffer, buffer spring and so on from the factory will shoot 150gr corelokt. The variable seems to be your suppressor. I would bring the gun back to factory specs as close as you can. Then start changing things one at a time. If I were you I would check the adjustable gas block fit. Then I’d get the factory h2 and red spring back in the tAR. I would start shooting it unsuppressed to see if I can get it reliable. Then add the suppressor and tune it. |
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I’ve inspected ejector pin and extractor all seem perfect. I figured Larue uses high quality components there. I know they make upgraded stuff for all that.
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I was able to tune my PredatAR 7.62 in with an SLR Sentry 7 adjustable gas block. You would want the option with 0.450" set screw spacing.
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I was shooting those gold match and same issue. It’s pretty random. I like core lokt because it’s at Walmart I have 10+ boxes and want to make it work. They had a sale and we got a bunch. Does this suppressor create a lot of back pressure vs orhers? I’d figure they all about same And 180 vs 150, aren’t pressures similar? Or is 180 less. I’ve read generally powder charges are measured to keep pressure at same safe levels so why does weight matter. Or bullet brand for that matter. View Quote I do believe the harvester is heavy on back pressure. If the rifle is doing the same with the FGMM, I would guess the gas is not set up right. Really hard to diag without knowing your MV to start. Did you look at the chart from the link I posted? It shows perspective muzzle velocities. FGMM 168 2650 fps FGMM 175 2600 fps This from an 18" larue gas gun 2500 fps REM CORE 180 2620 fps REM CORE 125 2820 Site did now show this as 150 grn Those are advertised MVs on their websites The stove pipes lead me to believe your bolt velocities are high. Despite having a heavy buffer its still doing it, so that makes me think gas set up or too much pressure(basically MV). How does your brass look when it comes out? |
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You could get someone with an IPhone 6 or up to film it in slow motion. It might allow you to see what the bolt is doing as it cycles. Then you could maybe answer questions like is the bolt going back far enough, does bolt speed seem to fast, is the bolt dragging on the feed lips of the mag.
I really don't have an answer but I would put it back stock, shoot with the suppressor, and film it. Start trouble shooting from there changing one variable at a time. Changing a bunch of things at one time will most always leave you chasing your tail. |
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Quoted: I was just going off experience, and then what I read from the remington website. The muzzle velocities are high. Adding the can, will make it worse. I do believe the harvester is heavy on back pressure. If the rifle is doing the same with the FGMM, I would guess the gas is not set up right. Really hard to diag without knowing your MV to start. Did you look at the chart from the link I posted? It shows perspective muzzle velocities. FGMM 168 2650 fps FGMM 175 2600 fps This from an 18" larue gas gun 2500 fps REM CORE 180 2620 fps REM CORE 125 2820 Site did now show this as 150 grn Those are advertised MVs on their websites The stove pipes lead me to believe your bolt velocities are high. Despite having a heavy buffer its still doing it, so that makes me think gas set up or too much pressure(basically MV). How does your brass look when it comes out? View Quote So after the heavy buffer and with 180 grains it was ejecting near perfect around 1-2 o clock if I remember correctly. But the jams even are so hard to film and capture because it’s very random. It seems when I try to test it can fire perfectly for 5 rounds. Like it only does the stove pipe when it’s cold and randomly. This seems to have been the trend. If I could catch it on slow mo video would be awesome. I need to do some more testing when I get home. I travel for work so diagnoses is a very slow process and busy when home. |
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Generally, would the 180 grain core lokt be more or less pressure back to the bolt?
Also, I haven’t tried this but I do have a different 30 cal suppressor called the “Texas suppressor” I could try to see if it jams as much. But my preferred is the harvester as it’s very light nice can. |
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I was able to tune my PredatAR 7.62 in with an SLR Sentry 7 adjustable gas block. You would want the option with 0.450" set screw spacing. Mine was ejecting brass between 12:00 and 2:00 and stovepiping one out of every 4-5 rounds when shooting suppressed, so at first I ordered/installed the following: XH Carbine Buffer (8.5 oz) AR10 Rifle Buffer Spring (#EA1095) It then consistently threw brass to a pile at 2:00 with no stovepipes, but with the suppressor removed it ejected between 3:00-5:00, and would not consistently feed the next round from the mag (175gr FGMM). Rather than chase buffer/spring weights, I installed the SLR gas block and didn’t look back. |
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Quoted: With a Sandman-S. Mine was ejecting brass between 12:00 and 2:00 and stovepiping one out of every 4-5 rounds when shooting suppressed, so at first I ordered/installed the following: XH Carbine Buffer (8.5 oz) AR10 Rifle Buffer Spring (#EA1095) It then consistently threw brass to a pile at 2:00 with no stovepipes, but with the suppressor removed it ejected between 3:00-5:00, and would not consistently feed the next round from the mag (175gr FGMM). Rather than chase buffer/spring weights, I installed the SLR gas block and didn’t look back. View Quote Of course the heavy buffer guy said they were not. Even with heavy buffer and gas turned way up, the rounds jammed even more so the heavy buffer alone wasn’t enough thus far. |
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How does SLR block compare to the JP adjustable block? Aren’t they similar and perform same function? Sometimes I wonder if gas blocks are consistent on how much gas they allow each shot. Of course the heavy buffer guy said they were not. Even with heavy buffer and gas turned way up, the rounds jammed even more so the heavy buffer alone wasn’t enough thus far. View Quote View All Quotes View All Quotes Quoted:
How does SLR block compare to the JP adjustable block? Aren’t they similar and perform same function? Sometimes I wonder if gas blocks are consistent on how much gas they allow each shot. Of course the heavy buffer guy said they were not. Even with heavy buffer and gas turned way up, the rounds jammed even more so the heavy buffer alone wasn’t enough thus far. Quoted:
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I was able to tune my PredatAR 7.62 in with an SLR Sentry 7 adjustable gas block. You would want the option with 0.450" set screw spacing. The Sentry 6 is 0.625” diameter - it fits LT 5.56 tAR barrels. Both models are available with 0.450” set screw spacing. |
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I may try it as mine has sideways screw and get tired of removing hand guard to adjust it.
It’s low profile to sit under the hand guard? |
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I went ahead and got one to rule out any JP installation or operation issues. I will install and tune with the SLR. It’s also has recess screws from bottom whereas the JP just had clamp force. Finally the rear facing gas screw vs sideways. If I understand it correctly.
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Quoted: Muzzle velocity or back pressure? So after the heavy buffer and with 180 grains it was ejecting near perfect around 1-2 o clock if I remember correctly. But the jams even are so hard to film and capture because it’s very random. It seems when I try to test it can fire perfectly for 5 rounds. Like it only does the stove pipe when it’s cold and randomly. This seems to have been the trend. If I could catch it on slow mo video would be awesome. I need to do some more testing when I get home. I travel for work so diagnoses is a very slow process and busy when home. View Quote Perfect ejection is 4:30, 1-2 is a hard eject and the round is hitting the deflector hard and going forward. The new gas block might make it easier to adjust properly. |
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Adjustment screw faces the front of the rifle. Not the receiver end.
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Excellent, front facing means I can adjust the gas without removing the handguard!
Quoted: MV and pressure are relative, I am just pairing them together. I think you have a couple things happening at once, gas adjustment and maybe some slightly hot ammo. I might go buy a box and shoot it so I can tell(in larue rifle). Perfect ejection is 4:30, 1-2 is a hard eject and the round is hitting the deflector hard and going forward. The new gas block might make it easier to adjust properly. View Quote I will do some more experimentation in the coming weeks, and install the SLR, and report back here my results. Higher muzzle velocity is higher pressure? From what I read I thought they try to keep barrel pressure similar, so heavier loads need less powder because acceleration is slower and pressure would get too high. Or something like that. I was previously shooting the federal gold match 168, same behavior, random jams/stove pipe. It has plagued me for a long time but I'm thankful for the advice and discussion and hope to solve it eventually. |
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I got the SLR block installed. Couple things:
1. I stepped up clicks from zero 180 grain core lokt. Once it cycled at 3-4 clicks I immediately stopped did not open more. It ejected at 3pm. 150s ejected at 1 pm. I shot several sets with no jams. The heavy spring and buffer is still installed. 2. Time will tell what happens. Before it would cycle during testing and randomly not eject but also it was a lot dirtier lol. 3. I hadn’t tried with the JP leaving it on the click that makes it cycle and NO more. 4. This all tells me the gun is fundamentally over gassed with this suppressor. Even with the heavy bolt perhaps. I cannot turn it down more to change ejection pattern at all at this point. Do they make a lower volume less jumps per click in volume gas block? |
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So nothing is making a difference with the coreloct ammo?
This was all suppressed? What receiver extension do you have on this rifle? |
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Receiver extension? It’s all original LaRue factory regarding that.
This is so frustrating about ready to sell it. It functioned perfectly over 10 or so rounds this afternoon. So we are coyote calling and it jams first shot. Like always it does it when hunting or maybe when it’s cold not when I test it. Madness! It was dark and friend was in hurry unjam it didn’t see what kind of jam it was. Seemed could have been a short stroke as case was severely bent in middle and it was jammed like that when retrieved from ground. I could try another click out on gas . Who knows. Yes all suppressed. |
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Moved on to a hog. Shot twice perfectly no issue. It’s warmed up now lol
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Isn’t there a company that makes gas tubes with reduced holes in them? Seems like I read about it in the FBI clone thread.
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Interesting. I’ll have to look into. Not sure what’s wrong with this gun lol
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I'd say put the stock spring and buffer in with no can, and get it running properly.
Do not use the coreloct, switch to federal gold medal match and get it tuned up. Once it's running right, change the ammo to coreloct, if it goes wild off the charts again you will see it even with the can off. You will know it's hot or not. Without a chrono we don't know what the speed is in your gun with the coreloct. Switch one thing at a time. |
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I'd say put the stock spring and buffer in with no can, and get it running properly. Do not use the coreloct, switch to federal gold medal match and get it tuned up. Once it's running right, change the ammo to coreloct, if it goes wild off the charts again you will see it even with the can off. You will know it's hot or not. Without a chrono we don't know what the speed is in your gun with the coreloct. Switch one thing at a time. View Quote I will go shoot some 150gr corelokt out of my 16” tAr on the magnetospeed if I can this week. I’ll post. |
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Adding: 4 o'clock ejection Clean brass And no ejector swipes on the brass https://i.imgur.com/pJseYo1.jpg https://i.imgur.com/JkOLySN.jpg View Quote |
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Do y’all think a tranquillo suppressor would solve the issues? In theory the adjustable block does same exact thing doesn’t it.
If I knew it would I wouldn’t have issue ordering one. |
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I was using a Sandman-S when I was able to tune my 7.62 tAR with the SLR block.
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Like I detailed before it went from no ejection to 3 o clock in one click of the SLR. 3 or 4 turns out.
Maybe it needs less even. It jammed again after I did this. The smaller gas port gas tube sounds like an interesting solution. |
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Quoted: And this is suppressed? Im beginning to think too many issues with the mid length system. I’ve read many other forums of people replacing the upper or BCG etc. I’m tired of the rabbit trail but the adjustable block should resolve and it doesn’t seem to. View Quote |
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Like I detailed before it went from no ejection to 3 o clock in one click of the SLR. 3 or 4 turns out. Maybe it needs less even. It jammed again after I did this. The smaller gas port gas tube sounds like an interesting solution. View Quote |
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But it did run fine before unsuppressed. That doesn’t solve anything. It’s already been done. But was a while ago.
Another problem. Even suppressed it runs fine when I test it. Problem is when gun sits up and first round fired often in colder weather. Not that cold, just Texas cold. So it’s very hard to troubleshoot. That’s when the jam will occur just that first round it seems. |
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