I know that my rifle is a overgassed a good bit & have been looking at reliable solutions to this. I came across the les baer carbine length gas tube, the description states the vent hole size is OPTIMIZED for carbine length gas systems. I cant find any reviews on it to see if it reduces the gas flow at all or if its wide open to ensure reliability. They also offer an extended m4 model but I cant find the details, its 2 inches longer but it doesnt state if it fits over the standard carbine length gas port in the barrel or if the port in the barrel has to be brought out 2inches to match the length of the tube. Most people use the easy fix of a heavier buffer but that doesnt change the volume of gas going back into the upper. Im looking at getting the slr SA7 gas block & will be replacing my tube with it. But for $$ s sake I may be able to get away with a heavier buffer & such a gas tube as the les baer, if I can find out what they mean by carbine optimized vent hole.

Contact Les Baer directly. The are a bunch of straight shooters about their products. If it won't work for you they will say so.

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JOSHUA 1:9

Isn't the buffer spring another way of dealing with this?

Installing a stronger buffer spring, heavier buffer, full auto bolt carrier group, are ways to mitigate the effect of overgassing but it doesn't address the root cause of the issue. Mr. Skywalker wants to address the issue closer to the root of the problem.

Don't quote me on this because I am not 100% certain. Gas pressure is dependent on two immediate factors: the diameter of the gas port drilled into the barrel and the position of the gas port on the barrel. Bigger hole = bigger gas impulse. The closer the gas port on the barrel to the upper receiver, the higher the pressure and heat of the gas used to cycle the action. The farther down the gas port is on the barrel, the lower the pressure and heat of the gas used to cycle the action.

From my rudimentary understanding, the gas port on the barrel of the S&W rifle is intentionally a bit wider in diameter than mil-spec. Because civilians do not use a consistent, single source, of ammunition as the military, S&W has to make the M&P rifle compatible with a wider variety of common commercial off the shelf consumer .223 Remington ammunition. Adding to the issue is that .223 generates less pressure (power) than 5.56 NATO.

Outside of swapping the barrel with one that has a confirmed mil-spec gas port tapped into the barrel, there are only a few ways I can think of to regulate the gas pressure at the barrel.

1. Install a gas block with a narrower gas port than the gas port on the barrel. Never heard of such a thing. I don't know if these exist.

2. Install a narrower diameter gas tube. I have no idea if such a thing exists. I thought they were all standard.

3. Install an adjustable gas block with a built in regulator. An example:

AR-15/M16 ADJUSTABLE GAS BLOCKS | Brownells

If I were to attempt the same thing as Mr. Skywalker, I would choose the third option. I'd install an adjustable gas block, and tune it to a single brand & spec of ammo. The rifle will then run 100% with a single brand of ammo. Case ejection will be 3:00 - 4:30 position.

The upside is that instead of being locked into just one gas pressure, the adjustable gas block allows for tuning when switching ammo.

The downsides:

1. Changing brands/spec of ammo would require testing and retuning of the adjustable gas block. Be prepared to expend a few rounds in the tuning process.

2. You'd be limited in handguard length choice. If an aftermarket free float handguard extends over the adjustable gas tube, then easy access to the adjustment is gone.

These are just my musings... who knows if I'm right.

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-John

Thanks for the responses. I m leaning toward the SLR sa7 adjustable gas block. Its easily adjusted without having push a detent in, uses a leaf spring to keep tension on the adjustment screw & has a low enough profile to fit under my samson 12.3 inch evolution. Since its easy to adjust it shouldnt give me problems at the range. Also putting a heavier buffer & new spring will not change the amount of gas going back into the receiver.1 benefit that sounds great to me is an adjustable gas block can keep your rifle cleaner since it will not be dumping extra gas/carbon back into the upper. I was looking for a cheap way to address the overgas issue but can see its definitely more beneficial to correct it at the source. Right now im getting consistent 130-200 ejection & the extractor is shredding the lips on cases leaving brass shavings all over the place. Not to mention taking the anodized coating off my deflector from brass hitting it so hard. Will a factory gas block wear out? If so, whats the lifespan of a taper pin mounted standard fsb