Bump fire on MA compliant AR (M&P 15)?

[VetteGirlMA]

So I tried taking my Karma AR bump fire stock and attaching it to my M&P sport. What I have discovered is that the pin end of the bump fire stock is larger in diameter than the hole that is in the rifle. Does this mean I am SOL and not able to use a bump fire on my rifle? I have the little pin and spring that is inside of the stock out, and I can tell from a manual test fit that it isn't going to fit. I was wondering what every else has done. Once I commit to using this stock like drilling out the tapped hole, that means the bump fire is going to be on there pretty much forever. Thanks in advance for any advice.

 

[warwickben]

So I tried taking my Karma AR bump fire stock and attaching it to my M&P sport. What I have discovered is that the pin end of the bump fire stock is larger in diameter than the hole that is in the rifle. Does this mean I am SOL and not able to use a bump fire on my rifle? I have the little pin and spring that is inside of the stock out, and I can tell from a manual test fit that it isn't going to fit. I was wondering what every else has done. Once I commit to using this stock like drilling out the tapped hole, that means the bump fire is going to be on there pretty much forever. Thanks in advance for any advice.

Get a new buffer tube . The stock mp pined stocks are not normal ones.


I assume the bump fire , it's made for a mill spec buffer tube .

If you want to be able to use a normal stock also buy a magpul moe stock (short money) 20-40$. You can swap the detent and spring out so you can make it "pinned" since you'll need tools etc to adjust of remove . Vs drilling and pinning it .

Or don't give a shit and leave the new stock adjustable .

 

[icyclefar]

Sounds like your going to want to buy a new buffer tube that fits the stock properly and swap them out.

Thats assuming you want the stock to lock in the non-bump fire position. If you don't care about the lock out, then the pin is irrelevant.

 

[VetteGirlMA]

Well for now I put the rifle back to stock until I figure out what to do. I was going to take a ride to a gun store this weekend anyways, so maybe I can ask someone.

 

[warwickben]

Well for now I put the rifle back to stock until I figure out what to do. I was going to take a ride to a gun store this weekend anyways, so maybe I can ask someone.

Do you want to leave the bump fire on the gun ?
Just buy a carbine buffer extension .

Do you want to be able to take it off and put a normal stock on now and then ? With out having to remove the buffer tube ever time to put the stock one on ?
then buy a carbine stock also. Since the m&p use there own special buffer extension .
There is a easy hack to make it fixed vs drilling and pinning to be ma compliant .


http://www.amazon.com/gp/aw/d/B00ML...-2&pi=SX200_QL40&keywords=carbine+buffer+tube

 

[JClark]

Is there a good way to get the staked buffer tube off or just muscle it?

 

[VetteGirlMA]

The only single change the bump stock people would need to do is make a MA specific pin a little smaller in size and I would be able to swap back and forth between my MA pinned stock and the bump fire without having to change anything on the rifle. It would be nice if they made a pin (the side with the screwdriver slot) slightly smaller in diameter.

 

[warwickben]

The only single change the bump stock people would need to do is make a MA specific pin a little smaller in size and I would be able to swap back and forth between my MA pinned stock and the bump fire without having to change anything on the rifle. It would be nice if they made a pin (the side with the screwdriver slot) slightly smaller in diameter.

Take a photo of the pin and explain what needs to be smaller . I might be able to make a few.

 

[VetteGirlMA]

Take a photo of the pin and explain what needs to be smaller . I might be able to make a few.

The end of the pin is .275 inches (the caliper was resting so I could take the picture but it reads .275" diameter)



The hole in the buffer tube is a threaded hole which uses an allen cap screw and a tiny little roll pin to hold the stock in place. That hole is about .200" in diameter.



As I can see the threaded end of the pin fits easily into the hole in the buffer tube:


Pin in stock engaged:



Pin in stock disengaged (bump fire mode):




I already got a response email back from bump fire systems who told me that the buffer tube needs to be replaced. I think that's a nutty solution. If a smaller pin existed I could revert back to the S&W stock and leave the rifle in as purchased condition instead of taking everything apart just to switch the stocks around. Anyways, sigh

 

[warwickben]

The end of the pin is .275 inches (the caliper was resting so I could take the picture but it reads .275" diameter)

View attachment 159113

The hole in the buffer tube is a threaded hole which uses an allen cap screw and a tiny little roll pin to hold the stock in place. That hole is about .200" in diameter.

View attachment 159114

As I can see the threaded end of the pin fits easily into the hole in the buffer tube:
View attachment 159115

Pin in stock engaged:

View attachment 159116

Pin in stock disengaged (bump fire mode):

View attachment 159117


I already got a response email back from bump fire systems who told me that the buffer tube needs to be replaced. I think that's a nutty solution. If a smaller pin existed I could revert back to the S&W stock and leave the rifle in as purchased condition instead of taking everything apart just to switch the stocks around. Anyways, sigh

Normaly the pin for the bump fire stock rides in the channel .

It prevents it from just falling off .

The s&w buffer extension tube is its own animal made for commie states .
With out the locking pin on the bump fire stock will it slide on the s&w stock ?

If it will you can measure the threads of the stock pin and I can cross reference it for you.
Depending on the size you can swap the bump fire locking mech for a thumb screw . Won't be a quick change . And the stock can slide off.
But the there is a catch the grip might not be in the right place.

Other option is just to get a new buffer extension and a carbine stock .

You can push the Rollin pin out and switch out the spring and detent for a block so you can't squeeze the lever to adjust it to be mass legal . But say your friend comes to the range and wants to try you gun and the person is bigger or smaller you can adjust the length fairly easily.

 

[VetteGirlMA]

Wow so that's a completely different animal then. Interesting, the S&W isn't standard, they leave off some extra machining on the buffer tube. Sounds like my only option is a new tube or a different rifle.

 

[bostonhockey]

Is there a good way to get the staked buffer tube off or just muscle it?

I am having the same issue, I have an A1 stock and new buffer tube I want to install on my sport II but even with a castle nut wrench I can't get the staked buffer tube to even budge..anyone have any tips?

 

[bostonhockey]

Wow so that's a completely different animal then. Interesting, the S&W isn't standard, they leave off some extra machining on the buffer tube. Sounds like my only option is a new tube or a different rifle.

I don't really understand why they didn't go with standard either, seems like alot of people would want to change out the fully extended pinned stock without having to get a new buffer tube

 

[Canndo]

You need a new tube for sure. The stock tube is a Mongoloid bastard child of S&W's own design.

 

[icyclefar]

I am having the same issue, I have an A1 stock and new buffer tube I want to install on my sport II but even with a castle nut wrench I can't get the staked buffer tube to even budge..anyone have any tips?

Shoot it off


Sent from my iPhone using Tapatalk

 

[bostonhockey]

Shoot it off


Sent from my iPhone using Tapatalk

Luckily that wasn't needed, I was just able to get it off by punching out more of the staking and trying again with it in a vise. success.