Buffer tube question

[TrickyNicky]

So recently found out one of my ARs came with a commercial spec buffer tube rather than mil spec. Of course I found out when I ordered and received a mil spec buttstock.

Now rather than return the magpul I figured I'd rather just replace the tube and keep the comm spec as an option for my pistol if I decide to go the SBR route.

My question to you pros is are the springs and everything inside the tube compatable between the mil and comm spec?
There's a kit on amazon I could buy that's all inclusive so I'd defiantly have everything plus it comes with an AR wrench so may go that route as well... Still with X-mas coming up it would be nice to not have to spend more than I really need.

What do you all think?

[scoutfsu]

You need to pay attention to the specs on the receiver extension. All "milspec" tubes are not equal. Generally, a comm spec tube is not the greatest and definitely not the preferred option....stock compatibility being one of the issues.

What amazon kit are you looking at? Do it right the first time so you're not (paying) to do it again.

[TrickyNicky]

Tapco AR mil spec extension tube kit. It's getting good reviews but I was wrong about it coming with a wrench. Seems a bit on the pricey side too at $62.

Oh well I've got some time to figure it out, between Christmas and a certain pistol I'm looking to procure this will either be going on the gift list or just wait.

[mikegideon]

The guts are the same size. You just need the tube.

[Dolomite_supafly]

A milspec tube will accept ANY stock out there. With a commercial stock it might rattle and such but it will work just fine.

As far as durability there is no difference between a commercial and a milspec tube. As a matter of fact a commercial tube has a larger OD while the ID is the same making the wall thickness larger on the commercial tube. The wall thickness on a true milspec tube is .073 while the wall thickness on a commercial is .085. It also has additional strength because there is extra material next to the stock adjustment channel. So the commercial tube is going to be stronger and, IMHO, better than milspec. Also, the commecial tube has more positions than a milspec tube. A true milspec tube only has 4 positions while commercial tubes have 6. Not all things milspec are the best.

Have you tried the stock yet? I have several milspec stocks that work on commercial tubes but are a little tight. This reduces the movement and rattles.

Dolomite

[scoutfsu]

The threads on a comm spec stock are inferior. This is where it matters. Avoid the TAPCO and go with a known quantity. You're looking for a milspec diameter extension and they can have 4-6 positions.

[TrickyNicky]

Yeah I tried the stock and it was a no go. Had I known I would have just ordered the comm spec stock and been perfectly happy but now it just seems to make sense to go with a new tube so I have a backup stock/tube set in case I go SBR with my pistol or just need a backup.

Knowing the inner diameter is the same definitely simplifes things, thanks guys.

[mikegideon]

[quote name='scoutfsu' timestamp='1353772121' post='850037']
The threads on a comm spec stock are inferior. This is where it matters. Avoid the TAPCO and go with a known quantity. You're looking for a milspec diameter extension and they can have 4-6 positions.
[/quote]

Yep, the threads are better. I have both types. My Milspecs are 6 position. When I first started with these things, I couldn't find a Milspec in 6 position. That's why I have a couple of commercial tubes.

[Dolomite_supafly]

I have seen several lowers break before the commercial buffer tube. They crack right at the rear takedown pin.

I have yet to see where the threads on a commercial buffer tube become an issue. Yes they are a bit smaller but I can assure you .015" isn't enough to be a problem with a lower that [u]is[/u] in spec.

Dolomite

[mikegideon]

[quote name='Dolomite_supafly' timestamp='1353775892' post='850061']
I have seen several lowers break before the commercial buffer tube. They crack right at the rear takedown pin.

I have yet to see where the threads on a commercial buffer tube become an issue. Yes they are a bit smaller but I can assure you .015" isn't enough to be a problem with a lower that [u]is[/u] in spec.

Dolomite
[/quote]

Yeah, the tube probably isn't the weakest point. It's mostly a non-issue. Some Magpul stocks won't function properly with commercial tubes. It's not because of weakness, but because of the slanted back. I would have to dig to tell you which ones. I'm not going to change out my commercial tubes, but if I buy new, it will be Milspec.

[Dolomite_supafly]

Milspec will work with every stock out there so that is a big reason to go milspec. Strength is not a consideration, nor is the threads, for me.

Dolomite

[mikegideon]

[quote name='Dolomite_supafly' timestamp='1353777447' post='850068']
Milspec will work with every stock out there so that is a big reason to go milspec. Strength is not a consideration, nor is the threads, for me.

Dolomite
[/quote]

I started using Milspec when I changed from a fixed stock on my .458 SOCOM. That caliber has a reputation for breaking collapsible stocks. The small difference in thread quality may or may not be a factor in that case. That's certainly not a common AR application. It will bruise your shoulder.