Home Forums Hunting & Shooting AR and Tactical Rifles Short cycling AR-15

We all have our standards.

Ok, my gas port is now drilled out to be .096", which, best I can tell, is actually the proper diameter for it to be with a .750" journal.

Actual M193 functions fine so far. Cycles, locks open, the whole nine yards. I've tried the PMC Bronze, and also some Armscor USA, and also some steel case Wolf military classic. All these cheapies will function about half the time, otherwise, the bolt slips over the cartridges or a cartridge starts to nose up and the bolt jams into the side of it. None of them lock back on empty. This is not a problem I have ever had with a carbine/midlength before. I guess that the gas pressure is just so much higher, it'll shuck through anything.

I will probably drill it out larger, but not today. I would like for it to be able to digest whatever ammo I put in it. But at least it is going with good ammo. I wonder if the dreaded "overgassing" is such a big problem with a rifle as it is supposed to be with a carbine, given how much softer the rifle action is to begin with.

Hell, I'm used to a Mini-14, which will slam its way through anything, and chuck the empties fifteen feet away!

It's a nice day today, at like 65 degrees. I don't want it to choke when it's 30.

.093 is the mil spec port for 20"/rifle gas and runs stuff like PMC bronze OK at warm temps.

Rifle gas works fine but you have told us that the gas block is not aligned with the gas port. Middy gas or carbine gas will have the same problems with misaligned block/port.

With a misaligned block/port when you drill the port oversize you are attempting to create the same gas flow of a .093 port in an aligned setup. I would not be afraid of a .096 port in an aligned 20"/RG because the .093 20"/RG is marginal for low powered ammo and really dirty/cold.

To much fuss has been made of overgassed for most situations especially in a forgiving setup like the 20"/RG. There was a time where some companies were sending out Carbine gassed guns that were way overgassed but the pendulum has swung back a bit and now it's more likely to get a AR undergassed for cold or dirty conditions than one overgassed.

My gas block is now clearanced so that the gas port in the barrel is fully within the opening. The port is now .096". It functions fine so far with m193, but still short cycles on the cheap stuff.

Before I go drilling out the gas port hole any more, I'm gonna try something. You can get a spacer (kind of overpriced, but whadda ya gonna do?) from Spike's Tactical whereby you can put this spacer into the rifle buffer tube, and then use a carbine spring and buffer. This way, I can try different buffer weights, since there are a plethora of different carbine buffer weights, and pretty much only one rifle buffer weight. I'll see where that gets me.

Good lord…

I don't believe that the way you clearanced the gas block is giving the same gas flow as a block that lines up.

But I am interested in your experiments with different carbine buffer weights. My testing with buffer weight was counter intuitive. Up to a point increasing buffer UNSPRUNG weight took less gas to run.

Let us know what happens and document as best you can. This stuff is fun.

Thanks

You know I’ve tried to sort out what upper you have and if I’m reading right it’s a front sight and not just a gas block.

So if the FSB is not centered over the gas port and you opened the hole in the FSB then that means there’s a good possibility that you irons will be way off center if they even sight in.

What you should’ve done was send it back to the mfg. but now that you messed with it, I doubt they’ll fix it but they might.

And on top of all the help you’ve received here from John and MM, you want to buy junk from spikes to make it even more of an anomaly.

Good luck.

Dude, I can't help you if you're not paying attention.

Well, that was my concern with opening up the hole in the gas block, but I figured, what the hell. It was only a slight amount, the holes were mostly aligned to begin with, just off a tiny bit. In fact, I had no functional difference before and after working the hole out.

By the way, the hole in the gas block appears to have been just ever so slightly off center to begin with, so while the sight itself is perfectly straight, the hole was just a smidge out of whack.

I will likely end up drilling the gas port hole in the barrel a little larger anyway, as JohnBurns and Montana Marine suggested, but I figured I could give this a try with the buffers. Nothing permanent there, as it's easily swapped back to the way it was before.

Thank you all for your help!

Keep us updated.
This is interesting

I'm going ahead slowly with drilling the gas port ever larger. I know, I could just hammer down with a .105" hole or something, but I'd rather ease up to it.

Drilled to .098". No appreciable difference in performance. Winchester M193 worked perfectly, as it always had, Everything else, still slipping over the magazine some times, and not locking open.

Drilled to .099". Now, all of a sudden, I see some noticeable improvement. I'm only firing a few shots at a time with different ammo to see what it does. With all ammo, ejection was more energetic, and much more like what I would expect it to be. All 3 to 4 o'clock, as before, but at least a foot farther away. And still very consistent. For the first time, I got through five shots of steel Wolf without it jamming or slipping over. Still no bolt hold open. Same with Armscor USA, and something else, maybe, I don't remember. But.. now was the very first time I got through with PMC Bronze, no magazine overrides, no jams, AND the bolt finally locked back when empty! That alone made my little clogged heart pitter patter! M193 operates just the same as before, but with the same improved ejection distance.

I'm not super worried about getting any of that steel case crap to work reliably, I mean, it's not like it's readily available anymore (and probably never will be), but I would really like to be able to reliably shoot the other normal brass case stuff. I'm not always gonna be able to be picky about ammo, so the gun can't be picky either. I think I'd rather get it going this way first, rather than go down with different buffers, and still, if necessary, I could use different buffers to tone it back down if I need to.

I will drill it out again to the next bit size, which, I think, is .101", but I don't feel like taking the thing all apart again right now... it's supper time!

I would be very interested to know what some of the other manufacturers, like PSA, Anderson, whatever, use for their "budget" (that dirty word) 20" rifles that are so horribly "overgassed". Just to see how I'm comparing.

Glad you decided against playing with carbine buffers. But I will say if you want to experiment just take a weight or two out of the rifle buffer. You should replace them with some kind of spacer but leave enough room for them to slide back and forth.

FWIW the rifle buffer weighs 5 oz and a standard carbine buffer weighs 3 oz.

Bitching about being overgassed has become the cool kid thing to do.


If one can't have a perfect gun🤣🤣🤣, I'd rather have one that will beat itself to death overthousands of rounds.


That's better than a POS that doesn't work.

+1

Ok.... I was kind of hoping that one more size up would do it, so, I drilled the gas port today out to .101" (a #38 bit).

Results after firing only a few rounds of each ammo type a few times

PMC Bronze 223: Fires and feeds, locks open
Armscor USA 223: Fires and feeds, but after one failure to lock the bolt open, it now works perfectly fine.
Wolf Military Classic 223 steel: Fires and feeds, and bolt locks open!!!
Winchester m193: Fully functional, bolt lock open, of course, as it always did.

A vast improvement over every other shot slipping over and "click", along with no bolt locks!

All eject very consistently about the 4 o'clock direction, and land 8' to 10' away (the M193 at the farthest distance, but still the exact same direction). Probably 3 feet farther away than originally.

Action feels more "snappy" but not at all "violent" (ever shot a Mini-14? There's a violent action). I don't really notice any difference in feel among the different ammos, but I wasn't really paying attention to that, mostly watching my brass and bolt!

I think I'm gonna stop here. At least for now. And shoot the thing a while. If problems persist, then I might go one more size up, but I think I'm good.


I'm feeling a lot better now.

Good to hear, might just want to confirm in some colder weather just to be safe.

MM

I'll have to wait quite a while before I can do that!