When building an ar pistol how can i have no buffer tube like the sig 556 pistols.?

*Edited loads of info for simplicity.

OK dude:

1. you cannot get around the buffer tube without a piston driven platform concerning an AR.

2.There is no piston system available that would fit those weird AR-57 conversion uppers because of the horizontal PS90 5.7x28 magazine sits inline with where the piston would need to be to blowback the bolt carrier group...No one that has answered your question has yet to understand that you are talking about an AR 5.7x28 conversion kit, and that the magazine sits atop the upper reciever's fore end.

3.Why the not buy a FN-PS90? It was designed as FN's answer to what the worlds best PDW should be. It is also chambered in 5.7x28, which is why I can only assume you bought or are thinking of buying a 5.7x28 conversion kit for an AR.

The only rationale I can think of is that you don't want to deal with a 16 inch barrel, or don't like the looks of the PS90, or both. In which case my original recommendation stands: The Sig 556 pistol.

Ar Pistol Without Buffer Tube

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RE:

When building an ar pistol how can i have no buffer tube like the sig 556 pistols.?

looking to build an ar-57 pdw but don't want a big buffer tube out the back

Wrong you can have an Ar with no tube rifle or postal. Check out rock river. Its a upper receiver piston design. I know so. There are many new uppers that Dont require a buffer tube but most make it so you need to have the lower that they make. And for you dummies that Dont know what an ar57 is its an Ar upper that holds the 5.7 round like the fn pistol. But ejects out the mag well of a at15 lower. Like wow. A whole new concept. So why would I want a single use p90 when ibcan swap so much with an ar1 5 lower.

You can't, because the AR is direct impingement. It requires that tube sticking out of the back. The SIG 556 is piston driven, so it doesn't require it (gas tube is above the barrel).

You would need a new rifle system, the AR-15 cannot function without that buffer tube, thats why you dont see it with side-folding stocks.

You would have to use a long stroke gas piston assembly instead of a DI setup.

However I do not think that anyone makes a long stroke kit short enough for a pistol conversion. Unless you don't mind your "pistol" having a 16" barrel(which I don't think is legal anyhow)

It can be done, just not easily.

And yes there ARE side folder AR-15's, para ordinance makes one.