Sort out my 300blk

[FUNCTIONAL]

Built a 300blk and just trying to get it operate how I'd expect.

BA Hansen 10.3" 300blk barrel
Standard brownells melonite bcg
Standard carbine spring/buffer
Sico omega 99% of the time

Cycles supers fine. Hornady black subs do not cycle (dirty as hell by the way), PSA aac 220smk subs cycle fine (1050ish fps).

Handloads with 220 seconds (clear/cloudy poly tip, not smk)
8.5gr lil gun 1080fps does not lock back
9.0 lil gun 1095fps does not lock back

Although my handloads are supersonic and I need to drop the load they already aren't locking back. I've got some A1680 I'm going to try but with lil gun being such a common powder in 300blk I'm wondering if something with my setup is off. Are there weaker springs or buffers for 300blk I'm missing?

 

[USK308]

I'm currently sorting out my 300BLK as well (10.5 Rosco Mfg barrel). Similar issues with Hornady 190 Sub-X, 208 A-Max & Fiocchi 220 Range Dynamics Subsonic ammo. I don't have my suppressor yet, but in trying to at least get the rifle working, I have 110gr & 150gr SUPERSONIC ammo working just fine.

The Subs don't lock back with gas wide open AND the 208 A-Max never eject. I've gone through a myriad of buffer & buffer spring configs, to no avail.

Have you measured the actual gas port diameter? If so, what was that measurement? Mine measures 0.0850" (digital calipers). "Might" have to drill out to next size larger using a #43 machinists drill bit, but waiting until my suppressor arrives to further troubleshoot/evaluate.

One suggestion, since the 220SMK subs cycled fine is to acquire some other subsonic ammo in the 190 - 220 grain subsonic range and try that to see what it does. My suspicion is that the Hornady Black 208 A-Max are NOT good since you are the 2nd person I have heard with issues...

 

[biffj]

You may find the 1680 works a lot better than the lil-gun but if not your gas port may need to be opened up. Subs are hard to get working without having issues with the supers. An adjustable gas block with a larger port gives you a lot more leeway with loadings. Also adding a suppressor will improve operation for the subs and is basically the only reason to shoot subs anyway....

Frank

 

[Ape_Factory]

Built a 300blk and just trying to get it operate how I'd expect.

BA Hansen 10.3" 300blk barrel
Standard brownells melonite bcg
Standard carbine spring/buffer
Sico omega 99% of the time

Cycles supers fine. Hornady black subs do not cycle (dirty as hell by the way), PSA aac 220smk subs cycle fine (1050ish fps).

Handloads with 220 seconds (clear/cloudy poly tip, not smk)
8.5gr lil gun 1080fps does not lock back
9.0 lil gun 1095fps does not lock back

Although my handloads are supersonic and I need to drop the load they already aren't locking back. I've got some A1680 I'm going to try but with lil gun being such a common powder in 300blk I'm wondering if something with my setup is off. Are there weaker springs or buffers for 300blk I'm missing?

CFE Black for powder. Dirty, but it'll cycle everything. VV N120 is also a good one and a lot cleaner. But CFE is the king of cycling everything. I never had good luck with the A-Max factory loads either, two different barrels. I also use a lightweight BCG and buffer which helps. Lots of guns seem to have issues with the 190 Sub-X rounds, mostly with smooth feeding and bullet setback. My Sig LT runs them flawlessly but that's an expensive answer.

 

[wvfarrier]

H110 and Lil Gun has worked better for me with both subs and supers. Are you using an adjustible gas block?

 

[mr45acp2u]

What length is the gas system? Pistol or carbine. Sorry, 10.3 should be. Pistol

 

[hlee]

In my 8.5” pistol gas 300 blackout, 125 gr bthps in front of enough 110 to hit ~1900 fps cycle and lock back. As do 208-220 gr bullets in front of enough 1680 to hit ~950-1050 fps. Some varieties of Hornady factory ammo do not lock back in my gun. I don’t buy them…

 

[MO Fugga]

I have same barrel as OP, no suppressor. Rolled up some Berry's 220 with Hodgdon's 8.1gr H110 @ 2.24" recipe. Lee autodisk throws 7.9-8.1 reliably. I'm guessing they won't cycle. Cci 400 primers, very first loadings.

 

[Jgault]

CFE Black for powder. Dirty, but it'll cycle everything. VV N120 is also a good one and a lot cleaner. But CFE is the king of cycling everything. I never had good luck with the A-Max factory loads either, two different barrels. I also use a lightweight BCG and buffer which helps. Lots of guns seem to have issues with the 190 Sub-X rounds, mostly with smooth feeding and bullet setback. My Sig LT runs them flawlessly but that's an expensive answer.

Cfe black is the perfect for subs albeit I don’t load them anymore, lil gun is a terrible powder for subs but great for super sonic, I personally use enforcer but lil gun is my second choice, but that is for achieving maximum velocity and with lil gun I would normally have to use a magnum primer.

 

[91Eunozs]

Went through a similar issue with my very first 300BLK build, turned out to be a slightly undersized gas port.

That one was a carbine length gas system on a 16” barrel though, so kind of apples to oranges, but if it’ll cycle supers fine, and some subs, but not all subs, my first guess is the gas system is under sized. 300 BLK subs run very little powder of course and it’s a fine line with buffer, spring, and even BCG weight to get it right; everything has to be perfect if you run a minimally sized gas port.

Do you have a set of pin gauges? If not, invest in a cheap set or try to borrow a set and see what you’re working with on gas port diameter before you run down the rabbit hole of checking every possible combination of spring and buffer weight to see if you can get it to cycle properly.

Ask me how I know! LoL

Also, I typically prefer Accurate 1680 for subs, but 100% success with Hodgden H110 for both supers and subs.

Edit: I typically run 9-10 grains of powder for my 300BLK subs, think the lowest I’ve ever run is 8.5. Curious how y’all are getting yours to cycle at 8gr or less.

 

[Ape_Factory]

I did run H110 for subs and it worked decently but found CFE Black was more accurate for subs. For supers H110 rules. I've never found anything that's as accurate or produces more velocity in several 300 blackout rifles and even with monolithic bullets.

Lil Gun is also LOUD, temp unstable too, and not as good as CFE. I'd try the Vihtavouri N120 powder as well. It seems to work as well as CFE Black but is cleaner by a mile or four. But try CFE Black first and I think you'll find your cycling problems will be gone.

 

[Steel+Killer]

Also check for a misaligned gas block. I had that happen before if the gas block is canted slightly left or right the holes may not line up correctly and cause a under gas situation.

 

[FUNCTIONAL]

Going to try the a1680 and see how she goes. If no dice I am going to look for n120 or some h110. I'm really trying to find a powder that burns clean for this but if I must in the end cfe blk it will be.

It's a pistol length gas system. No idea on port size, I was hoping to not screw with that before I tested accuracy for the 1moa guarantee (huge reason I bought this ba barrel). I'm fairly positive alignment is good with the gas block, I'm anal about alignment. Gas block is non adjustable but if I end up having to enlarge it I'll end up switching to a adjustable.

I may play with deconstructing a buffer and removing all of the weights and see if the light buffer helps. This is primarily going to be a subs and suppressed setup so I don't mind tailoring it to that.

 

[biffj]

If you're expecting a 1 moa or better result with the subs you're smokin crack. There are so many things that will affect your accuracy that perfection is required on all of them. Neck tension, powder charge, position and place in the firing order and so on. All of those will affect the velocity and surprisingly by a greater amount than you may think. You need to get them all perfect just to stay even. On top of that you have the same issues every cartridge/gun combo has. You need to find the right bullet, powder, cartridge case and primer combo. It is possible of course but trying to figure out which bit has messed up is nearly impossible so blaming it all on the barrel becomes a problem the maker can easily push off on any of those other things. I suppose if they're giving you the guarantee with one particular type of factory ammo you might have a chance to blame the barrel maker but you wouldn't be looking for loading info and such if that was the case.

Buffers and springs can affect things but seldom to a great extent. With a gas operated rifle running 9gr or less of powder the problem normally comes down to insufficient pressure and volume of gas to operate.

In the end, especially with the blackout, most have found that the cartridge isn't what it was hyped up to be and have gone on to others. Remington messed with the chamber spec that made the whisper such a versatile round and accuracy for the subs suffered. Accuracy for the supers did too but not as much....

Frank

 

[FUNCTIONAL]

If you're expecting a 1 moa or better result with the subs you're smokin crack. There are so many things that will affect your accuracy that perfection is required on all of them. Neck tension, powder charge, position and place in the firing order and so on. All of those will affect the velocity and surprisingly by a greater amount than you may think. You need to get them all perfect just to stay even. On top of that you have the same issues every cartridge/gun combo has. You need to find the right bullet, powder, cartridge case and primer combo. It is possible of course but trying to figure out which bit has messed up is nearly impossible so blaming it all on the barrel becomes a problem the maker can easily push off on any of those other things. I suppose if they're giving you the guarantee with one particular type of factory ammo you might have a chance to blame the barrel maker but you wouldn't be looking for loading info and such if that was the case.

Buffers and springs can affect things but seldom to a great extent. With a gas operated rifle running 9gr or less of powder the problem normally comes down to insufficient pressure and volume of gas to operate.

In the end, especially with the blackout, most have found that the cartridge isn't what it was hyped up to be and have gone on to others. Remington messed with the chamber spec that made the whisper such a versatile round and accuracy for the subs suffered. Accuracy for the supers did too but not as much....

Frank

I don't think it's far fetched to expect 1moa out of the right combo at 100yrds. I fully don't expect it to happen for everything, just quality components. As for the barrel I never said anything negative, it's a nice barrel, cleans up well. I just don't want to go modifying it just yet until I get the cycling sorted. If I can't and gas port size is the last option so be it, I'll drill it. As is the barrel is very accurate with the AAC 220smk ammo. I was able to print pinky nail size groups at 50yrds (not 3rd, 5-10rd). So while I don't expect to be sending this barrel back I just don't want to mess with it if I don't have to.

As far as caliber selection it's hard to find a lightweight platform that will shoot subs and be able to take down a deer. Deer management in an equestrian center. Needs to be quiet and farthest shot id be taking is 50ish yards. I also had everything for this except a barrel so it was an easy choice. Just trying to get it to cycle and lock is all.

 

[Ape_Factory]

Understand fully if you don't want to spend more money. I've found really good success with the Rubber City titanium BCG which is a lighter than a standard BCG but not race gun light. Add a POF roller cam pin and you can get an Odin Works adjustable buffer or the Unrivaled dead blow comp buffer. Very flat shooting and helps reduce felt recoil by a good bit.

I can get sub-MOA with subsonic hand loads at 50 yards no problem and pretty damn close at 100 if I slap a big, ridiculous-looking scope on top. I did a lot of development work and I load for practical accuracy so I do take a lot of steps to equalize cases, charges, etc...but I'm able to bulk load on a Dillon too.

 

[roostercogburn98]

If you're expecting a 1 moa or better result with

Over how many rounds

 

[91Eunozs]

If you're expecting a 1 moa or better result with the subs you're smokin crack. There are so many things that will affect your accuracy that perfection is required on all of them. Neck tension, powder charge, position and place in the firing order and so on. All of those will affect the velocity and surprisingly by a greater amount than you may think. You need to get them all perfect just to stay even. On top of that you have the same issues every cartridge/gun combo has. You need to find the right bullet, powder, cartridge case and primer combo. It is possible of course but trying to figure out which bit has messed up is nearly impossible so blaming it all on the barrel becomes a problem the maker can easily push off on any of those other things. I suppose if they're giving you the guarantee with one particular type of factory ammo you might have a chance to blame the barrel maker but you wouldn't be looking for loading info and such if that was the case.

Buffers and springs can affect things but seldom to a great extent. With a gas operated rifle running 9gr or less of powder the problem normally comes down to insufficient pressure and volume of gas to operate.

In the end, especially with the blackout, most have found that the cartridge isn't what it was hyped up to be and have gone on to others. Remington messed with the chamber spec that made the whisper such a versatile round and accuracy for the subs suffered. Accuracy for the supers did too but not as much....

Frank

this. 100%

I still love the round though, and shoot more of it than all my other calibers combined because it’s so easy to tune for my needs, and shooting subs suppressed is a hoot. Almost all of my shooting is well within 150 yards or so, and this round just flat works for 99% of my needs. And “minute of pig” is accurate enough for my needs.

That said, if I was starting from scratch today, I’d probably go 300 HAMR vs 300 BLK.

And I also have no illusions about how effective it is on game; again, for 99% of my shooting it works great, those 110gr Barnes black tips are awesome inside 100 yards, but if I’m specifically going out on a hunt for feral pig eradication or venison, I’m grabbing one of my 6.8s. Maybe even a .308 depending on where I’m gonna be shooting.

 

[FUNCTIONAL]

Circling back to this for anyone ever searching.

Messed with a1680 and got a load that worked but it is incredibly dirty. 11.5gr under a 220gr was giving me 1150ish so I dropped it and picked up some h110 that had a better burn percentage at the charge weights.

Below are the results with a 1-4 steiner p4xi at 50yrds. Got a few good loads here so going to load up some more and test at 100. Factory hornady black 208 gave me 5" groups at 100 so I think I'll be in the 2ish moa range with one of the good loads.

Having said all of that...I did open the gas port from .083 to .095 to get it to function 100% with subsonic loads. For reference the hornady black 208 wouldn't even cycle enough to pick up the next round. This is with a standard bcg and carbine buffer/spring. After enlarging it cycles fine and loacks back after last round. Even with the handloads it locked and cycled with all of the ones below.

 

[USK308]

Circling back to this for anyone ever searching.

Messed with a1680 and got a load that worked but it is incredibly dirty. 11.5gr under a 220gr was giving me 1150ish so I dropped it and picked up some h110 that had a better burn percentage at the charge weights.

Below are the results with a 1-4 steiner p4xi at 50yrds. Got a few good loads here so going to load up some more and test at 100. Factory hornady black 208 gave me 5" groups at 100 so I think I'll be in the 2ish moa range with one of the good loads.

Having said all of that...I did open the gas port from .083 to .095 to get it to function 100% with subsonic loads. For reference the hornady black 208 wouldn't even cycle enough to pick up the next round. This is with a standard bcg and carbine buffer/spring. After enlarging it cycles fine and loacks back after last round. Even with the handloads it locked and cycled with all of the ones below.

View attachment 8410378

Good to see you have figured out a good load!

I have found that the Hornady 208gr A-Max subs won't cycle on my rifle at all (10.5" 300BLK Rosco Mfg Bloodline Barrel, OCL Hydrogen L 7.62 suppressor and JP H2 buffer). Gas port from Mfr @ 0.0850") and the SupArms AGB wide open. I even took the time to compare each box for Lot# and tried four different lot #'s...to no avail. My gut tells me that Hornady changed the powder and the performance IS NOT what at the original specification.

My rifle will run like a mad man with S&B 200gr subs, Winchester SuperSuppressed 200gr OpenTip subs or Fiocchi Range Dynamics 220gr subs.

I will use the remaining boxes of Hornady 208gr A-Max that I have as range plinkers. lol

 

[biffj]

Use care with the H110 load. That powder doesn't like unfilled space. While it doesn't give trouble all the time I've seen some unexplained issues often enough that I dumped that powder many years ago. If you can fill the case nearly full it is an excellent powder. A friend uses it in his 500 Leinbaugh and his 458 Leinbaugh but for subs I'd find something else. You can find info on the various loading boards if you look for H110 excess pressure issues.

Yes, the 1680 is a bit dirty but its very consistent, cycles the actions when other powders don't without turning gas ports into huge openings and we've run it for a long time without cleaning to see if it causes any trouble with all the various subs we load. It has never been a problem except to guys that can't stand a bit of scum on their rifles. 300BO, 338 BR, 510 whisper all love it, its accurate, reliable and used to be available. Not so sure now.


Frank

 

[JR1200W3]

Having said all of that...I did open the gas port from .083 to .095 to get it to function 100% with subsonic loads. For reference the hornady black 208 wouldn't even cycle enough to pick up the next round. This is with a standard bcg and carbine buffer/spring. After enlarging it cycles fine and loacks back after last round. Even with the handloads it locked and cycled with all of the ones below.

I have the unpopular opinion that the idea of 300BO being capable of a dual munition in one small PDW like SBR is a bit of a misnomer because of exactly what you have experienced. I experienced the same thing with a DD 300PDW. It only cycle subs with one powder(H110) and I had to drill out the gas port to get there. It would almost cycle my favorite bolt gun sub load with certain suppressors that were obviously really high back pressure cans, but I would still get malfunctions. I would get a couple of rounds through with an Ultra 7 but not an Ultra 5. Opening up the gas port and switching to H110 makes it not sensitive to different suppressors. However now that the gas port is opened up it's way over gassed for supers. The gun came with a different spring for supers but as it sits now I'd have to change the buffer as well and it still won't completely negate the excess gas. A bootleg Adjustable BCG might fix it, but then here I am reconfiguring the gun for supers vs subs so it's not like the gun can just swap ammo with a mag change and run the way you would want it to. I've pretty much tuned and relegated that gun to subs and built a 14.5" 300BO for supers. Used a 1:12" barrel and JP Lo Mass BCG and SCS and tuned it for fast supers. 110gr at 2450 - 2500. I mounted a 1-10x LPVO and zeroed at 100. The PDW just gets a red dot with a 50yd zero and a 6" hold over at 100.

 

[FUNCTIONAL]

@USK308 yea the Hornady black 208 is the most anemic subsonic loading I've tried to date. I'm not sure the powder they use but I really want to know if that same bullet runs better out of a longer barrel. Oddly enough the AAC 220gr subsonic loads PSA manufactures shot really really well and cycled just fine even at my smaller .083 gas port. WIth the price they sell them at its likely going to be what I pick up for factory subsonic offering if I dont need a specific bullet head.

@biffj I did a big of googling. I swear I can google one day and see only recommendations and it works great and then today no one recommends it for subs. The internet is a mystery. I did at least get a reason why and it was to keep a 80% case fill with the powder or it could cause pressure spikes from burning at both ends of the powder stack. Running my load through Quick Load and I'm at about 65% case fill with H110 and about 80% with A1680 give or take. I may end up using this H110 and Lil Gun for supers and just sticking with the A1680. I can get it locally all day for about $34 per # which makes it the cheapest around here unless I order online. Im not a clean freak but if I could keep it cleaner with just powder choice I would. My 10.5 556 looks like you tossed mud in the action. I buy melonite treated bcgs for a reason, quick wipe and its done and they hardly ever get sluggish.

@JR1200W3 I dont know anyone who owns a 300blk and this is my first build in that caliber. I really couldnt agree with you more in short barrel 300blk. With all of these loadings it ejected perfectly at about 4 O'clock suppressed with an Sico Omega. When I switched to supers the brass was 1 maybe 2 O'clock, it was a bit hard to tell with how my support setup was but they were hauling out of there. I drilled the gas port because I wanted to use everything standard so if anything ever broke I could easily swap it with a part already on hand from my 556 rifles. Like you I dont want to be reconfiguring every time I want to switch ammo. I built this with the intent to run subs 90% of the time so I dont mind but its certainly not a gun you can switch and have ideal conditions for both. The tuning window for each is just so narrow. If I need to rip supers I'm taking a 556 with a good bullet head.

 

[biffj]

And therein lies the problem with many of these ideas. A Piper Cub is an excellent airplane for landing on football field sized places but it is crap for long distance travel. An F15 will get there in a hurry but needs a lot of runway.
The reality is that there is no one size fits all with anything. The blackout has been marketed as an omni-round but it isn't. It will do both subs and supers but its not really efficient at either one if you try to do both. If you optimize for subs you can get excellent accuracy and cycling but at the expense of running supers less than well. Same goes the other way round. It does do both better than a lot of others but still isn't perfect.

Frank

 

[FUNCTIONAL]

And therein lies the problem with many of these ideas. A Piper Cub is an excellent airplane for landing on football field sized places but it is crap for long distance travel. An F15 will get there in a hurry but needs a lot of runway.
The reality is that there is no one size fits all with anything. The blackout has been marketed as an omni-round but it isn't. It will do both subs and supers but its not really efficient at either one if you try to do both. If you optimize for subs you can get excellent accuracy and cycling but at the expense of running supers less than well. Same goes the other way round. It does do both better than a lot of others but still isn't perfect.

Frank

I haven't dug too far into looking but a gas block with a "suppressed" and "normal" mode with each position being adjustable would solve the issue. You could tune the suppressed setting for subs and normal setting for supers and at the flip of the gas block switch (like the Noveske type) you could run either. That would probably be about as close to perfect as you could get.

Other than that it seems we are on the same thought page.

 

[JR1200W3]

I haven't dug too far into looking but a gas block with a "suppressed" and "normal" mode with each position being adjustable would solve the issue. You could tune the suppressed setting for subs and normal setting for supers and at the flip of the gas block switch (like the Noveske type) you could run either. That would probably be about as close to perfect as you could get.

Other than that it seems we are on the same thought page.

Agreed. The Rifle speed has blocks might be the ticket if you don't mind a sizable gap between the handguard and suppressor. You would still have the problem of two different zeros and over spinning supers or failing to stabilize 200 + grain'rs

 

[msgriff]

I haven't dug too far into looking but a gas block with a "suppressed" and "normal" mode with each position being adjustable would solve the issue. You could tune the suppressed setting for subs and normal setting for supers and at the flip of the gas block switch (like the Noveske type) you could run either. That would probably be about as close to perfect as you could get.

Other than that it seems we are on the same thought page.

If you go down the road for "tool-less" AGBs, here are the ones that I know of. They each have their limitations/pros and cons.
Noveske Switchblock (not designed for the 300BO)
RifleSpeed
Seekins Lever
Strike CAGB

There was also the MicroMOA Govnah and Baby Govnah. Out of production, but Griffin Armament now owns the rights and is said to revive them.

 

[JR1200W3]

If you go down the road for "tool-less" AGBs, here are the ones that I know of. They each have their limitations/pros and cons.
Noveske Switchblock (not designed for the 300BO)
RifleSpeed
Seekins Lever
Strike CAGB

There was also the MicroMOA Govnah and Baby Govnah. Out of production, but Griffin Armament now owns the rights and is said to revive them.

My question on the lever-switch gas blocks is how does one tailor the amount of gas for that particular dwell/ charge weight/ bullet weight/ buffer setup? You just get what you get. Perhaps the operating window would be wide enough in either setting to work, who knows.

 

[FUNCTIONAL]

@JR1200W3 that was my issue also. You could go with a switch gas block but as far as I know none allow you to tune each setting like would be needed.

Edit to your first post: I have a 1/7 and didn't over spin a 125 at 2100fps. If you over spin them you'll know lol. I've had 55s come apart and either look like dust or a shotgun spray. The 2 zeros are right. For me I run a lvpo with capped turrets. Wouldn't be hard to mark each point on the turret to quickly switch.

 

[JR1200W3]

@JR1200W3 that was my issue also. You could go with a switch gas block but as far as I know none allow you to tune each setting like would be needed.

Edit to your first post: I have a 1/7 and didn't over spin a 125 at 2100fps. If you over spin them you'll know lol. I've had 55s come apart and either look like dust or a shotgun spray. The 2 zeros are right. For me I run a lvpo with capped turrets. Wouldn't be hard to mark each point on the turret to quickly switch.

I was referring to 1:5 vs 1:7. I have a 1:7" bolt gun barrel and I get some semi-oblong looking holes from high BC 220gr bullets.

 

[FUNCTIONAL]

I was referring to 1:5 vs 1:7. I have a 1:7" bolt gun barrel and I get some semi-oblong looking holes from high BC 220gr bullets.

Ahhh yea I could see a 1/5 doing it

 

[msgriff]

My question on the lever-switch gas blocks is how does one tailor the amount of gas for that particular dwell/ charge weight/ bullet weight/ buffer setup? You just get what you get. Perhaps the operating window would be wide enough in either setting to work, who knows.

You disconnect the lever from the adjustment screw shaft, then tune like a conventional AGB using your highest port pressure/dwell conditions (i.e. suppressed) until you get LRBHO. Reconnect the lever pointed towards the left side of the weapon. Flip the lever towards to right side of the weapon when running your lowest port pressure/dwell conditions (i.e. unsuppressed). Whether that ~180° throw of the lever is enough for all applications or conditions would be part of the limitations, and you don't have to flip the lever all the way if not needed.

 

[JR1200W3]

You disconnect the lever from the adjustment screw shaft, then tune like a conventional AGB using your highest port pressure/dwell conditions (i.e. suppressed) until you get LRBHO. Reconnect the lever pointed towards the left side of the weapon. Flip the lever towards to right side of the weapon when running your lowest port pressure/dwell conditions (i.e. unsuppressed). Whether that ~180° throw of the lever is enough for all applications or conditions would be part of the limitations, and you don't have to flip the lever all the way if not needed.

Lol, I just got schooled....

 

[FUNCTIONAL]

You disconnect the lever from the adjustment screw shaft, then tune like a conventional AGB using your highest port pressure/dwell conditions (i.e. suppressed) until you get LRBHO. Reconnect the lever pointed towards the left side of the weapon. Flip the lever towards to right side of the weapon when running your lowest port pressure/dwell conditions (i.e. unsuppressed). Whether that ~180° throw of the lever is enough for all applications or conditions would be part of the limitations, and you don't have to flip the lever all the way if not needed.

I like the Riflespeed one. With how far back the GB is in the rail I dont think any of the others would work unless I milled a slot to access the switch. Even with the Riflespeed to be ideal I'd probably need like an 11.5" barrel to have a little sticking out of the rail before I hit the back of the suppressor. Still....definitely a solution!