Gas Piston AR ?

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Dec 6, 2005
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I'm piecing together a M4gery and got confused about piston lengths. Most pistons systems I've seen come in pistol,carbine, mid-length and full rifle lengths, but I've seen a lot of people putting longer pistons in shorter frames i.e mid-length piston in a carbine. Any reason why ? ? ?
 
Do you have a barrel for your build? If so, what length gas system is it tapped for?

Unless they are getting a different barrel for their piston build, the idea doesn't make sense to me. A carbine length gas system is a carbine length gas system; The same for the other length gas systems. A middy piston is going to be longer that a carbine-length piston, and as far as I can figure, wouldn't work in any other length gas system other than a middy. But what do I know about anything? No much. I just have direct gas impingment systems.

Now, were they possibly talking about a mid-length piston system on a 16" or carbine-length barrel? Folks still refer to the 16" barrel length as a carbine. I have seen carbine, mid-length, and rifle-length gas systems on a 16" 'carbine' barrel.
 
Length of the gas system and length of the barrel are two separate things, although not all combinations will work together.

For example, you can put a carbine length gas system on a 20" barrel (not that you'd want to), or you could put a mid-length gas system on a 16" barrel (great combo). If you try to put too long of a gas system on a barrel, the weapon will be underpowered and short stroke. If you put too short of a gas system on a barrel, your weapon will operate too violently and potentially cause you extraction problems.

Shorter gas systems will generate higher pressures and cycle the action more violently which can wear parts faster and potentially cause extraction issues. The mid-length system was a solution to these problems. It operates a carbine length weapon at lower pressures and should facilitate easier extraction. For more info: http://www.m4carbine.net/showthread.php?t=94

A longer gas system will also generally have a softer recoil impulse than a short one, all things being equal.

How that would translate to a piston gun, I don't really know. I'd imagine there would still be carry-over since a piston that only moves a shorter distance will do so in a more violent nature, but I could be wrong.
 
I'm piecing together a M4gery and got confused about piston lengths. Most pistons systems I've seen come in pistol,carbine, mid-length and full rifle lengths, but I've seen a lot of people putting longer pistons in shorter frames i.e mid-length piston in a carbine. Any reason why ? ? ?

Instead of "piston", do you mean "buffer" ?
 
I was looking into doing a adams arms piston conversion on the upper. I saw a lot people putting mid length conversions on carbine length barrels and carbine length systems on SBRs, just wondering why . . .
 
I'm not an advanced expert on these gas piston dealies, but the dimensions of a CARbine (car/m4/LtWt) are different than a (true) MidLength (ML is not a "Dissapator" or whatever).

The gas tube length and thus the gas port are drilled 2" further out on the MidLength (ML).

The handguard on the ML is also 2" longer. (7" CAR, 9" ML, 11" Rifle. These measurements are close enough for descriptive purposes)

You can't really "convert" a CAR into an ML because of the location of the gas port on the CAR. You run into handguard (HG) fit issues when you try to put a ML HG on a CAR Barrel because the gas block or Front Site Base FSB gets in the way. The "Disappator" is an imagineered cosmetic contraption that looks kind of like a ML.

There are "phantom" Gas Blocks that are very slim profile that may be installed (and even hidden under certain types of longer handguards).

You can remove and replace a standard gas block (GB), but if you have a "post ban" permanently attached flash suppressor, you can't slide it over and off the muzzle. If you have one of these designs (California?) you can destructively remove the GB and replace it with a two piece "clamshell" gas block. As long as you have .750" maximuym diameter, the regular ones will slide off and on. Pinning them back is the magic trick, the A2 FSB is usually sold as a "take off" when removed, not replaced.

The only advantage to using Mid Length tubes and gear on the CAR length set up is exactly what the above referenced M4carbine.net post was going on about. You can manipulate the function of the weapon by increasing the length of the Gas Tube, usually this is done with a "pig tail" or a coil of tubing (instead of a straight Gas Tube) that encircles the barrel, looking much like a CFL bulb.

Gas systems have real world applications in improving combat reliability of m16's. A well maintained properly constructed standard AR will perform perfectly for any LE or civilian use.

Here's the Ferrari version: http://www.lewismachine.net/store.php?cid=11&session=6fe491f1c6ce875e854bbd6c3b4e16f3
 
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