Question on AR15 stock swap

[bdturner]

I want to change out a buttstock on my Colt match target competition rifle. It has a 20" barrel. The stock I want to use is a Magpul CTR compact type restrictive. Will I be able to use the factory Colt buffer and spring? Or will I need to swap the spring and buffer too.

[NSO_w/_SIG]

All you need to do is make sure that when you order the stock you get the mil-spec version and not the commercial and you'll be good to go.

[bdturner]

Thanks it is a mil spec.

[NSO_w/_SIG]

Actually what type of stock and reciever extension is your colt currently set-up with?

If it is the A2 style stock which I think is what comes on that model you'll need a different extension, buffer and spring I believe if you want to go with a colapsable style carbine stock.

This is what you'll need to get if you want to switch out a "rifle" stock for a "carbine"
http://www.bravocompanyusa.com/Stock-Hardware-Mounting-Kit-Mil-Spec-p/stock%20hardware%20kit.htm

Sorry I was mistaken at first of what stock that model came with.

[Powderman]

Be careful....

and be well aware that each type of buffer is specific to the rifle you use. This is because of the location and dimensions of the gas port, and the amount of gas that must come back to the bolt carrier group for proper function.

You can NOT simply put a carbine type stock on an AR15 with a 20 inch barrel for this reason. Ensure that whatever stock you choose takes the full length stock and buffer if you have the 20" barrel; likewise with the 16 inch barrel.

[NSO_w/_SIG]

Actually lots of people are finding they run fine.

http://www.ar15.com/forums/topic.html?b=3&f=118&t=457042&page=1

Candian Military and even some of our troops are being issued these now I hear.

http://www.coltcanada.com/c7-page.htm

and here is a thread with a picture of teh exact set-up the OP wanted.
http://www.ar15.com/forums/topic.html?b=3&f=118&t=444658&page=5

[Powderman]

Point taken...

but the problem is that the gas ports might be in different locations, or might be of different dimensions. You see, the amount of gas going back is crucial--just enough to cycle the weapon, not too much, which would break buffer tube and buttstock eventually, and not too little, which would not cycle the firearm.

Also, you might note that while the Canadian C7 is a bit different in the stock, the C7 is a piston driven rifle, not a direct gas impingement system like ours are.

The picture on the AR15 site shows a stock with the same buffer tube dimensions as the standard stock.

[Shawn Dodson]

It'll be unbalanced - barrel heavy.

[NSO_w/_SIG]

Not saying I like it, just saying it is done without cycling problems, I agree it'll be unbalanced.

In that first thread there are lots of rifles set up on carbine extensions. It was only recently that I realized that people are doing this but there are many examples over there where people run these set-ups in DI weapons with no cycling issues.

And here is the quote from the Candian Colt site.

• Direct Gas System. The unique direct gas system eliminates the operating rod and keeps all of the firing forces in line with the bore for maximum accuracy and reliability.

[Bartholomew Roberts]

Also, you might note that while the Canadian C7 is a bit different in the stock, the C7 is a piston driven rifle, not a direct gas impingement system like ours are.

That is incorrect. The C7 is a direct impingement rifle (http://www.coltcanada.com/c7-page.ht) just like the M16 according to Colt-Canada who manufactures it:

"• Direct Gas System. The unique direct gas system eliminates the operating rod and keeps all of the firing forces in line with the bore for maximum accuracy and reliability."

Considering the wide range of carbine sized buffers available (standard, H, H2, H3, 9mm, Endyne, MGI Hydraulic), a shooter should have no problem tweaking his rifle to run reliably with a carbine stock even in the odd event that there was an issue with the 20" gas port.

[BusGunner007]

I've put the carbine stock / rifle-length bbl. combination together and not had ANY problems.

I spoke with a gunsmith yesterday about this combination.
Yes, he IS intimately familiar with all things 'AR', competition, LE, Military, etc.
He showed me a set-up he'd just completed for a customer. It had a Magpul carbine stock with a 20" bbl. ... :D

It works. :)