M&P 15 compliant model

[Sven]

I bought this (M&P150 RC) several years ago as my first AR and haven't done much with it. It's main features are a non-threaded 16" barrel and a fake, non adjustable stock. I bought an Ace fixed skeletal stock that will suit my needs, but need to replace the buffer tube. Somewhere I read there are commercial and mil-spec tubes with different diameters. Any idea what I have? Any other weird things about my "compliant" AR?

Through an interesting chain of events, I picked up a Wilson AR15 -- nice rifle!!! But now I am thinking I need to get this S&W in good enough shape for more or less home defense. Basically that means well sighted in and maybe a different trigger. If I would have to pull the trigger on someone, I'd sure hate to see the Wilson end up in an evidence locker for who knows how long! Paid $399 for the S&W.

Thanks in advance!

 

[WR Moore]

If your receiver extension/buffer tube is the same diameter from castle nut to end, it's commercial. The mil-spec tube necks down slightly after the threads to save weight.

No idea how your stock is secured, you should be able to remove it even if it is "fixed".

 

[vmtcmt]

IIRC, the ACE stock uses a straight wall rifle buffer tube, and is not included in the kit. It also requires a rifle buffer and spring. I've seen fixed collapsible looking stocks come either way, with rifle buffer and spring, or carbine buffer and spring. Don't mix rifle and carbine buffer components, and don't try to use a carbine buffer and spring in a rifle length tube.

The shorter "E" (Entry) stock uses a proprietary carbine length, but rifle profile buffer tube that does come with the kit.

HTH.

 

[vmtcmt]

OK, you made me look at my compliant M&P-15. It does have a fixed, collapsible looking stock, with a carbine buffer and spring. If you're using an ACE ARFX Stock, (ARFX) Skeleton Stock you will need a rifle length A2 type tube, a rifle buffer, and spring. There is only one diameter rifle tube. The mil spec/commercial only apply to collapsible stock tubes. You will need an AR wrench to remove the castle nut and end plate, as you don't use them with the ACE stock. Be careful not to lose your takedown pin spring and detent.

If you're using the shorter Entry stock, (ARFX-E) Skeleton Stock Entry Length With Buffer Tube (QD Swivel Not Included) you can use the buffer and spring you already have, and use the tube that comes with the kit.

This is by far the easiest method for installing the foam:
AR-15 ACE Skeleton stock Easy installation & removal of cheek weld/pad - YouTube

If you don't have a compressor, hair spray works like a charm. Slippery while wet, sticky when it dries. Just use a lot, and work quickly. Used to use good old cheap Aqua Net to install Grab On foam bike grips back when.

 

[Sven]

Thanks for the replies! The factory stock is pinned in place, but into a blind hole, so I'd have to drill. At least now I know what I have and can proceed. Thanks.

 

[vmtcmt]

Thanks for the replies! The factory stock is pinned in place, but into a blind hole, so I'd have to drill. At least now I know what I have and can proceed. Thanks.

If you're planning on using the ACE stock, don't bother. You can't use that buffer tube anyway. The ACE stock will not fit over the track or channel that has the position detent holes.

You're going to need a new buffer tube, no matter what. If you're switching to an ACE ARFX, you need an A2 tube, rifle buffer and spring. If you have an ACE ARFX-E, you use the tube that came with the ACE stock, and your buffer and spring.

 

[TopBreak.38-S&W]

I'm familiar to the issues withe the buffer tube..
The inner dimension og the tube is the same AS a carabine lenght tube..
But it's like a rifle tube outside..
I hava the same rifle and ordered a Magpul fixed carabine stock and a carabine buffer tube..
But..inn my country the minimum legal oal length is 84 cm and i fear the rifle will be to short..
I'll see what i choose to do..
The rifle looked good with the MOE OD-green handguard tough and the original stock is stabile and functions well enough..

 

[mscampbell2734]

I'm familiar to the issues withe the buffer tube..
The inner dimension og the tube is the same AS a carabine lenght tube..
But it's like a rifle tube outside..
I hava the same rifle and ordered a Magpul fixed carabine stock and a carabine buffer tube..
But..inn my country the minimum legal oal length is 84 cm and i fear the rifle will be to short..
I'll see what i choose to do..
The rifle looked good with the MOE OD-green handguard tough and the original stock is stabile and functions well enough..

Hello

If you end up too short there are a couple of fixes, one easy and one harder.

The easy fix will give you about 17mm. Magpul offers a thicker butt pad and it's an easy swap.

The harder fix is to use BOTH of the included spaces and drill a hole through the square section on the BOTTOM of the tube for the retainer screw. This will give you about 45mm