.30 cal semi-auto with gas cutoff - No good options?

[Esoteria]

I've owned probably two dozen guns of various types in the decade or so I've been shooting, but I've never actually owned a semi-auto rifle besides a .22 LR.

The main reasons are (1) I don't care for the noise and (2) I hate the idea of fetching all the brass for reloading, at least when shooting from the bench.

So I liked the idea of an M1A or similar where I could close off the gas port and shoot light or heavy loads from the bench, manually cycling the action to collect my brass. However, I'm having a hard time finding a good option. Maybe I'm missing something, and I'm hoping you guys can help.

Side note: Yes, I know I could just get a bolt action and a semi-auto separately. I have bolt actions. I want to be able to shoot the same gun in both a slow-fire bench setting and on-the-move.

Requirements (or preferences):

• .308 diameter (7.62x51, 300 BLK, etc) for cheap reloading, especially subsonics. .311" (7.62x39) wouldn't be a deal-breaker, but probably not ideal for what I'm doing. A big part of the goal is to shoot semi-quietly.
• Semi-auto action that can be manually cycled for very light loads or for brass retrieval. Gas setting needs to be feasible in the field, i.e. 30 seconds or less to change from semi-auto to bolt action. I'm fine with using after-market parts to achieve this.
• Action needs to be smooth and accessible for manual cycling. This is purely a personal preference thing. Cycling the action is half the fun for me.
  • I realize that brass may get stuck because I'll have limited mechanical advantage, so that's just a hurdle I'll have to get over, but at least when brass expansion isn't at fault I should have a slick action.
  • An open action like the M1, M1A, Mini-30, etc. is a bonus as it's bench-friendly and just plain cool.
• Price can't be outrageous. $1500 is probably the cap, and if I'm going to get into that territory it should be justified.

Guns I've considered, and why they might not fit the bill:

• M14/M1A - I have read that the gas setting is pretty finicky and you need to match mil-spec ammo pretty carefully to get it to run properly in semi-auto. I have also heard that the brass tends to get stuck badly enough that manually cycling simply isn't viable, and you have to mortar/pogo the gun. If these downsides are not typical, then this gun is probably my front-runner, because I really like the open action.
• Piston AR-15 in 300 BLK or 7.62x39 - The rear charging handle is a problem for me. It's pretty unergonomic for a gun I intend to manually cycle a lot. However, if I can build a 300 BLK / piston / side-charging upper, then this seems like a good choice?
• PTR-91 (.308) or PTR-32 (7.62x39) - These are roller-delayed blowback so I'm worried I'd be denting up my light load brass with partial-extractions. If the load is light enough that the action simply doesn't open then maybe this is a good option?
• FN/FAL and similar - Fluted chamber may or may not cause issues for reloading? Haven't looked into it as much. Concerned about the difficulty of changing gas setting and possibly the smoothness of the action. I'm uneducated on this one.
• M1 Carbine - Can't change gas settings quickly. (Maybe there's an after market modification for this?)
• Mini-30 - I have seen a lot of quality and reliability issues come up related to these, and related to the "action smoothness" preference this was a real turn-off. However, maybe I didn't give it enough of a chance....
• AK Pattern - Gas setting not readily adjustable. Maybe there's a good after-market option?

So what have I missed, or what I have I got wrong about the guns above? The AR-15 seems like the safest bet at the moment, but I'm a little wary of buying a bunch of parts when I'm not an AR guy.

 

[MachIVshooter]

However, I'm having a hard time finding a good option.

That's because you have a very strange desire.

Lucky for you, pretty much any semi auto that isn't .300 blk will become manual action with subsonic loads

PTR-91 (.308) or PTR-32 (7.62x39) -These are roller-delayed blowback so I'm worried I'd be denting up my light load brass with partial-extractions.

That's a potential issue with any semi auto being short stroked by weak ammunition, regardless whether it's delayed blowback, gas operated or recoil operated.

• FN/FAL and similar - Fluted chamber may or may not cause issues for reloading? Haven't looked into it as much. Concerned about the difficulty of changing gas setting and possibly the smoothness of the action. I'm uneducated on this one.

FALs don't have fluted chambers. That's CETME/G3 pattern, and it does damage brass.

Honestly, the FAL is probably your best bet here, with it's widely adjustable gas system and a non-reciprocating LH charging handle with a fixed knob (optional) that is easily manipulated. They are not, however, precision rifles. Nor are any of the others you're considering except the AR pattern, unless you spend well more than your $1,500.

 

[Robert]

FAL. You can run the gas port wide open and the action will not cycle. But honestly, the nut can get caked in carbon and hard to turn. Why not just get a brass catcher and avoid all the unnecessary futzing with the gas system?

 

[Panzerschwein]

Get a PTR-91 and put in the largest rollers you can find to open up the bolt gap as wide as it will go. You will find it won't eject the cases and you can manually extract them.

 

[ercnjasmine]

Yugo 59/66 has an easily accessible gas cut off valve, open mechanism, inexpensive, and I assume cheap to reload. Put tech sights on it and it's decently accurate

 

[LocoGringo]

Why not a .308 AR with an adjustable gas block? Then it would just be a matter of remembering the settings to go back and forth from fully functioning and reliable to "off". I haven't researched it, but there may even be one out there with a "side-charging" function to aid in cycling.

I'm not affiliated with them, but my father recently bought a .308 AR from Live Free Armory. He ordered at a time when they were swamped with orders just before the election so, unfortunately, some rifles went out the door assembled or machined poorly (not sure which) such that match ammo wasn't getting ejected properly. My dad called them and they took care of it without hesitating. Anyway, it consistently shoots solid 1 MOA 5-shot groups with various brands of match ammo and cost less than your $1500 limit. Replace their standard gas block with an adjustable from SLR Rifleworks, Syrac Gen II, Seekins Precision or Superlative Arms and you're set with pretty much exactly what you want.

 

[Vern Humphrey]

• M14/M1A - I have read that the gas setting is pretty finicky and you need to match mil-spec ammo pretty carefully to get it to run properly in semi-auto. I have also heard that the brass tends to get stuck badly enough that manually cycling simply isn't viable, and you have to mortar/pogo the gun. If these downsides are not typical, then this gun is probably my front-runner, because I really like the open action..

Nope. The M14/M1A gas system is self-adjusting. The piston is hollow (think of a water glass pointing forward) and gas enters the piston through a port. As the piston moves back, the hole in the piston is no longer aligned with the hole in the gas cylinder and the gas flow is cut off. This means if you have high pressure, the piston moves rapidly, cutting off the flow of gas. If you have low pressure, the piston moves slowly, allowing more gas into the piston.

This, coupled with the short stroke action, makes the M14/M1A very forgiving in terms of gas pressure and ammo quality.

 

[NWcityguy2]

The answer is fairly simple. Get an AR with an exposed, clamp on gas block. When you want to go single shot, just loosen the gas block with an allen key, rotate it a few degrees, and then re-tighten it. Now your AR is single shot. When you want to go back to semi-auto, reallign the gas block. This will work equally well with the AR10 and the AR15.

Edit: Just don't burn your hand, gas blocks can get hot.

 

[FL-NC]

Get a FAL and shoot it in the grenade launching mode. Can also be done with the M1A.

 

[Esoteria]

Thanks for all the input so far, guys. Sounds like I got some stuff wrong or there's just not as much consensus about what happens in these scenarios as I thought.

The M1A is the top contender if feasible for the reasons I outlined originally, so I'm happy to hear it may be back in the running. I'm still worried about the stuck brass thing, though. Does anyone have personal experience firing the M1A with the gas block cut off, either heavy or light loads (as in subsonic 175s or 220s or around that muzzle energy)? Vern, you say it's pretty forgiving -- maybe that means with light loads it wouldn't cycle but might "unstick" the brass at least with the gas still on, which would be ideal. For accurate shooting I'd still like to send 145's down range at full power without my brass ending up in the woods though, so I still like the idea of gas adjustment.

The FAL was worth looking into but it was never a top contender, but purely based on personal aesthetic preference. Cooldill mentioned changing the rollers on a PTR-91 -- that won't work for me because I want to switch back and forth easily in the field, but it did bring up the question: If I shoot subsonic 220s out of a PTR-32, which would be about 1/3 the usual muzzle energy of a 7.62x39, could I expect zero ejection? It won't solve the full-power problem, but 7.62x39 may be cheap enough that I'm willing to put up with losing 25% of my brass by flinging it everywhere. I guess if that wouldn't work then the PTR-91 should certainly not cycle in the same scenario, given that it's like 1/6th the energy, right?

For the record, I realize this is a bit of a weird quest I'm on, but I don't feel like it's totally ridiculous -- lots of people want to run their suppressed .30s subsonic without cycling the action, right? For minimal noise? I basically have the same requirement. I have seen this done on the FAL, which sadly is my least favorite design of the guns mentioned.

 

[Tommygunn]

If you want to turn off the gas system and use a semiauto as a repeater, the M1A has a gas cutoff. Well, mine does. Don't they all? I didn't think mine was a nonstandard model.......

 

[Esoteria]

Regarding the M1A, it seems getting a model with the scout rail may cost something like $250 more than the standard model, based on current pricing. Anyone have an opinion on the barrel-mounted rail or aftermarket options?

 

[Vern Humphrey]

If you want to turn off the gas system and use a semiauto as a repeater, the M1A has a gas cutoff. Well, mine does. Don't they all? I didn't think mine was a nonstandard model.......

Yep. The gas cutoff was to make it possible to launch rifle grenades without damaging the rifle.