["Follow Me!"]

Not new to reloading but I am new to adjustable gas blocks and their use? Hope this is clear. I believe that I am getting failure to lock back on reloads as I'm hitting max pressure...most failure to lock back on last rounds are do to underpressure loads. My lower charge weight loads lock back on last rounds but us I increase the loads and approach or reach max pressure, even though I'm not seeing signs of pressure my bolt sometimes fails to lock back. I guess my question is: If I start restricting the gas should the bolt start locking back or is it best to reduce loads to where it locks back?

 

[just_me_mongo]

Will you tell us about your rig? Caliber, barrel length, gas system, and what type of ammo?

 

[Strawdawg]

Maybe I read wrong but opening up the gas block to add more pressure to the bolt is the normal course of action for weak loads. Increasing the size of the port may be the solution ASSUMING the gas block is centered on the gas port to begin with. We recently saw a case here where the gas block was pushed all the way to the shoulder instead of usual credit card thickness of gap that puts the gas block centered over the gas port in the barrel. Installing the block correctly fixed the problem as I recall.

 

[Nativeman30]

The purpose of the agb is to tune it to have just enough gas to lock back on the weakest ammo you run. For example an Superlative Arms AGB considers 18 clicks as equal to a non AGB. Currently mine is set as 9 clicks (half open) after firing one round at a time and adjusting the block for more or less gas till it locks back

 

["Follow Me!"]

My rig= 16" arp flutted socom 1/11.25 midlength gas, superlative arms GB, arp superbolt, full auto failzero bolt carrier and carbine buffer spring and buffer.

I've been using this rig since 2014. All reloads. In the beginning I had short stroke issues due to not bumping my shoulders back enough. My shoulders need to be bumped .004 to .005 so I just bump .005 I tried bumping .003 to .004 but would get the occasional short stroke. Bumping .005 off of shortest length shoulder got rid of those issues. I've had this issue with most bullets as I get higher in the powder charges where it starts to not lock back on last round but it does cycle the rounds. I read in here somewhere that and overgased load can act like an under gas? When I have these higher powder charges short stroke the brass kind of limps out of the chamber landing around 4:30. I'm not seeing obvious pressure signs on the brass though. I'm wondering...guess I should just test it for my self that if I start closing the gas block will it eventually allow these higher pressure rounds to cycle properly? Or does this have nothing to do with gass and it's reaching max chamber pressure and needs the powder charge backed off. For example it did today with my 115 gr Gold dot with 28.4 grains AA2200, 2.295" seat, hornady 6.8 Rem spc head stamp 1x fired brass and CCI #41. Thing is it doesn't do it every time. This load worked in the past. That said my GB is set 14 clicks out from closed and. Cycles my 90 gold dot loads and my 120 sst loads?

 

["Follow Me!"]

This problem existed before when I had just a low profile non adjustable GB. It would cycle lower charges of powder with a given bullet but as I increased towards the upper limit it would shortstroke with gas wide open. Sometimes it will do this if I work up a load and find an accurate powder node without pressure. I go and run a seat test and at some point as I go deeper it will sometime show this same problem. It has something to do with pressure. IT'S KIND OF PISSING ME OFF BECAUSE I'll get the load running good it will go away and then all of a sudden it rears its ugly head again. I'VE checked gass block alignment over and over everything checks out and the is no noticeable signs of gass leak around GB?

 

[Nativeman30]

My rig= 16" arp flutted socom 1/11.25 midlength gas, superlative arms GB, arp superbolt, full auto failzero bolt carrier and carbine buffer spring and buffer.

I've been using this rig since 2014. All reloads. In the beginning I had short stroke issues due to not bumping my shoulders back enough. My shoulders need to be bumped .004 to .005 so I just bump .005 I tried bumping .003 to .004 but would get the occasional short stroke. Bumping .005 off of shortest length shoulder got rid of those issues. I've had this issue with most bullets as I get higher in the powder charges where it starts to not lock back on last round but it does cycle the rounds. I read in here somewhere that and overgased load can act like an under gas? When I have these higher powder charges short stroke the brass kind of limps out of the chamber landing around 4:30. I'm not seeing obvious pressure signs on the brass though. I'm wondering...guess I should just test it for my self that if I start closing the gas block will it eventually allow these higher pressure rounds to cycle properly? Or does this have nothing to do with gass and it's reaching max chamber pressure and needs the powder charge backed off. For example it did today with my 115 gr Gold dot with 28.4 grains AA2200, 2.295" seat, hornady 6.8 Rem spc head stamp 1x fired brass and CCI #41. Thing is it doesn't do it every time. This load worked in the past. That said my GB is set 14 clicks out from closed and. Cycles my 90 gold dot loads and my 120 sst loads?

I run full power loads with my 16" bison barrel and a Superlative AGB. My recommendation is to start over with your AGB, if you are only going to run your hand loads. Close your AGB all the way, then back it out 7 clicks. Load one round and fire. If it locks back decrease the gas and repeat. If it doesn't open the gas and repeat. Keep increasing or decresing your gas till it either locks back or stops locking back. Once you get to that point open it 2 more clicks for reliability. You could do the same woth factory ammo. If you plan on shooting it.

 

["Follow Me!"]

These aren't weak loads is my point?

 

[Nativeman30]

These aren't weak loads is my point?

No clue then. I have not had any issues with a Superlative AGB (I have 4). I did have to the gas port for my SFAR. What weight buffer and whose spring are you running.

 

["Follow Me!"]

Standard weight buffer and stardard carbine spring. Been so long can't remember what brands. This problem existed with standard gas block too so even with gas wide open. The pisser is that its random.

I don't think I've had this issue with my 120sst loads at all both with H322 and AA2200. Both are loaded to 2.295" H322 is 27.7 grains and AA2200 is 27.4 grains hornady brass.

That said I have had this issue with bullets under 120 grains and with AA2200 and reloader 7. I'm thinking about getting a Tubb speedlock systems flat wire spring because reading reviews and their description it addresses these issues.

I've lived with it all these years because it cycles fine picking up next round it just randomly doesn't lock back on last round. Sometimes it locks on the face of the bolt carrier and most of the time it locks back properly and sometimes it doesn't lock back at all? Like I said its done it with 2 different gas blocks both wide open and tuned like Superlative suggests. Hasn't screwed me on a hunt so I live with it. It does gnaw on me though.

 

[Nativeman30]

Standard weight buffer and stardard carbine spring. Been so long can't remember what brands. This problem existed with standard gas block too so even with gas wide open. The pisser is that its random.

I don't think I've had this issue with my 120sst loads at all both with H322 and AA2200. Both are loaded to 2.295" H322 is 27.7 grains and AA2200 is 27.4 grains hornady brass.

That said I have had this issue with bullets under 120 grains and with AA2200 and reloader 7. I'm thinking about getting a Tubb speedlock systems flat wire spring because reading reviews and their description it addresses these issues.

I've lived with it all these years because it cycles fine picking up next round it just randomly doesn't lock back on last round. Sometimes it locks on the face of the bolt carrier and most of the time it locks back properly and sometimes it doesn't lock back at all? Like I said its done it with 2 different gas blocks both wide open and tuned like Superlative suggests. Hasn't screwed me on a hunt so I live with it. It does naw on me though.

I would change the bolt catch spring then. I had one that was weak on my 10mm sbr. The recoil would bounce the bolt catch up sometimes causing it to lock back with a round still in the mag. This sounds like something similar. I dont think you have a gas issue at all.

 

["Follow Me!"]

I would change the bolt catch spring then. I had one that was weak on my 10mm sbr. The recoil would bounce the bolt catch up sometimes causing it to lock back with a round still in the mag. This sounds like something similar. I dont think you have a gas issue at all.

You know I have a spare spring I will try that. I'm going to laugh if it was that simple.

 

[Xman]

I have had two issues that caused a bolt not to lock back. One was high chamber pressure. The other was too much fore/aft play inside the magazine (Nativeman's post reminded me of that).

High chamber pressure can actually hold the brass case against the chamber's sidewall delaying the bolt from opening. When the chamber pressure reduces enough for the case to extract, there isn't enough gas left to cycle the bolt. You can tell this is occurring by looking at the brass which will have a cloudy appearance right after it comes out of the chamber. It is easy to spot if the brass is new or recently polished. Sometimes altering the timing with an AGB or buffer spring will help. Otherwise, you have to reduce your load.

If there is too much fore/aft play inside the magazine, high recoil can cause the follower to shift forward enough that it doesn't activate the bolt lock. I resolved this issue by disassembling the magazine an placing soft velco on the front of the follower. I've had to do this with several magazines that allowed me to load out to 2.3" COALs.

 

[stooxie]

I don't know if this has been mentioned yet but I've had a bolt fail to lock back because it was just cycling too damn fast. There's no magic, the mag follower has to have enough time to push the bolt stop up. Reducing your gas block flow as your pressure increases could help.

Is your brass flying forward? 1 o'clock?

-Stooxie

 

["Follow Me!"]

I don't know if this has been mentioned yet but I've had a bolt fail to lock back because it was just cycling too damn fast. There's no magic, the mag follower has to have enough time to push the bolt stop up. Reducing your gas block flow as your pressure increases could help.

Is your brass flying forward? 1 o'clock?

-Stooxie

With the Gas wide open it ejects around 3:30 to 4:00.

 

["Follow Me!"]

I have had two issues that caused a bolt not to lock back. One was high chamber pressure. The other was too much fore/aft play inside the magazine (Nativeman's post reminded me of that).

High chamber pressure can actually hold the brass case against the chamber's sidewall delaying the bolt from opening. When the chamber pressure reduces enough for the case to extract, there isn't enough gas left to cycle the bolt. You can tell this is occurring by looking at the brass which will have a cloudy appearance right after it comes out of the chamber. It is easy to spot if the brass is new or recently polished. Sometimes altering the timing with an AGB or buffer spring will help. Otherwise, you have to reduce your load.

If there is too much fore/aft play inside the magazine, high recoil can cause the follower to shift forward enough that it doesn't activate the bolt lock. I resolved this issue by disassembling the magazine an placing soft velco on the front of the follower. I've had to do this with several magazines that allowed me to load out to 2.3" COALs.

I will check my followers. The brass comes out nice and clean...so do you put the velcro on the front of the follower or the mag wall? I use to have a bad lever on the gun but it magnified the problem. I removed it and now it only occasionally does it. That said it cycles the rounds no problem.

 

[stooxie]

With the Gas wide open it ejects around 3:30 to 4:00.

And that's with your max pressure loads? An adjustable gas block should usually be cranked down a good bunch of notches to get brass flying that softly with max pressure (or powerful commercial) loads. Wide open with max pressure loads should be shooting forward. At least that's been my experience.

-Stooxie

 

["Follow Me!"]

And that's with your max pressure loads? An adjustable gas block should usually be cranked down a good bunch of notches to get brass flying that softly with max pressure (or powerful commercial) loads. Wide open with max pressure loads should be shooting forward. At least that's been my experience.

-Stooxie

Yeah I don't know? I've never had brass go ahead of 3 0 clock it's always run from 3 to 4? I've run my loads from 8 clicks out from closed to wide open it cycles locks back but always between 3 to 4? Just sometimes it doesn't lock back I've fried my brain over it.

 

[Strawdawg]

Cleaned the bcg well and installed new gas rings?

 

["Follow Me!"]

Cleaned the bcg well and installed new gas rings?

Yup done that no change. Sometimes i wonder if I need to open the port but I really don't want to that and the one reason why I don't is it will run with weaker loads so I don't think it's a gas issue? I'm getting ready to put a Tubbs flat wire buffer spring in it. And upon inspection when I press on the lower half of the bolt catch it doesn't seem to have the same resistance as my other ARs so that might be it. So I'm going to replace the whole bolt catch assembly. Also I haven't checked yet but I'm going to check my mag followers for too much movement and if they are loose I'll try the velcro mod.