Milspec versus commercial buffer tubes....

[Caveman Jim]

I like the looks of the strike Industries Viper QBC milspec stock for my AR & I bought one used not knowing that I had a commercial receiver extension. Thought mine was Milspec...
So I guess that my original buffer & spring will work if I just swap out the commercial receiver extension to a milspec receiver extension? Or will I have to fork over more $$$$?

As always, thanks in advance for any professional advice.

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[Joe13]

I like the looks of the strike Industries Viper QBC milspec stock for my AR & I bought one used not knowing that I had a commercial receiver extension. Thought mine was Milspec...
So I guess that my original buffer & spring will work if I just swap out the commercial receiver extension to a milspec receiver extension? Or will I have to fork over more $$$$?

As always, thanks in advance for any professional advice.

Same thing happened to me... was given a nice magpul stock from a member here and came to find out I had the wrong tube.

I'll get the parts someday. I'll be interested in the answer to your question as I will have to do the same thing.

 

[Caveman Jim]

I emailed the rep for SI & his reply was;
"Our stocks are all dimensioned for Mil-spec buffer tubes. In order to use them you will need to purchase a Mil-spec diameter buffer tube, which we carry."

So I assume that all the innards will all work in either tube since the ID of both tubes is 1.000.

 

[etrain16]

I like the looks of the strike Industries Viper QBC milspec stock for my AR & I bought one used not knowing that I had a commercial receiver extension. Thought mine was Milspec...
So I guess that my original buffer & spring will work if I just swap out the commercial receiver extension to a milspec receiver extension? Or will I have to fork over more $$$$?

As always, thanks in advance for any professional advice.

I assume you're talking about swapping out the buffer tube itself? If so, it's my understanding that a milspec stock will not fit on a commercial buffer as the commercial buffer is a slightly larger diameter. I've only put milspec buffer tubes on my AR's so I haven't run into that myself. It sounds like you may need to swap out the assembly - I don't know if you can keep the same buffer and spring.

Perhaps a more experienced AR builder can answer that question.

Edit - looks like you posted as I was typing, and you got your answer - same inner dimensions, different outside dimensions. Good to know.

 

[Caveman Jim]

I assume you're talking about swapping out the buffer tube itself? If so, it's my understanding that a milspec stock will not fit on a commercial buffer as the commercial buffer is a slightly larger diameter. I've only put milspec buffer tubes on my AR's so I haven't run into that myself. It sounds like you may need to swap out the assembly - I don't know if you can keep the same buffer and spring.

Perhaps a more experienced AR builder can answer that question.

Yep, I thought I made that clear, maybe not.

All the research I did, the talk was that the tube just needed swapping out. with the ID being the same all I can assume is buffer & spring will work.

 

[Garg]

yes. just the tube

 

[Caveman Jim]

https://search.yahoo.com/yhs/search...dows+7+Home+Premium&type=wncy_nwmeddnld_16_12

See 44 second quote.

 

[Caveman Jim]

yes. just the tube

Thank you Sir!!!!

 

[Ura-Ki]

All the internals will work! The exterior difference may or may not force you to change any thing, but a loose fit may result. the other way round would be too tight to get the stock to slide for and aft!

 

[Caveman Jim]

All the internals will work! The exterior difference may or may not force you to change any thing, but a loose fit may result. the other way round would be too tight to get the stock to slide for and aft!

I found this one site where the guy said the milspec tubes were not extruded like the commercials are that it is milled so the insides may not be very smooth..... just what I read so not a fact till I get the word from a professional....

 

[Caveman Jim]

US Made Mil spec 7075/T6 10 POSITION Buffer Tube w/ EVERLUBE COATING

US Made Mil spec 6 position Rod - 7075/T6 Aluminum

Anyone have any experience with these?

 

[partsed]

Amazon has Mil-Spec buffer tubes.... Why do I know this, because when I bought my rifle the first thing I did (even before getting it) was to order a Mil-Spec buffer tube to replace what I thought would be a commercial tube on the rifle. To my pleasant surprise, the rifle came with a Mil-Spec buffer tube already. So now I have a spare for my next rifle..

 

[Ura-Ki]

I found this one site where the guy said the milspec tubes were not extruded like the commercials are that it is milled so the insides may not be very smooth..... just what I read so not a fact till I get the word from a professional....

I have seen some commercial tubes that were very smooth and uniform, and some that were so bad that the buffer would get hung up. Not a problem I have run into with the Mil Spec stuff!

 

[Member 5605]

Yes

 

[3MTA3]

@Caveman Jim as others have said all you need to do is to replace the buffer tube. Any well made mil spec tube will work just fine, no need for anything fancy.

You will need a lower vice block and a castle nut wrench to make the swap. If your castle nut has been staked you can still remove and reinstall it - just search youtube for vids on this.

When you loosen the castle nut the back plate will also loosen and it holds in the detent and spring for the take down pin. be careful so as not to lose it, or plan ahead and get a spare of each.

The next place to take care is when you unscrew the buffer tube out of the receiver as it holds the buffer retaining pin and spring in place. I use a starter punch to hold the retaining pin captive as I unscrew the tube and again as I install the new one. If you don't hold it captive somehow it will shoot out with a surprising amount of energy.

BTW if you want so swap out your back plate for one with a QD or other mount this is a good time as you remove it as part of the process.

If you make it down my way I have all the tools and Curt's is nearby for lost parts... It's really not a hard job and takes about 10 minutes.

Removing a staked castle nut - note you can restake it after you put it back on. Staking is also shown on the same channel:

This shows back plate and buffer installation:

 

[ORYGUNHolsterCompany]

Milspec vs commercial comes down to manufacturing process. Basically commercial tubes are larger in OD (not ID) because when manufactured the comm tubes aren't machined down as far as the milspec tubes, saves time and money in manufacturing process.
For instance the milspec tube will have the threads protruding out from the OD of the buffer tube, this means that any material that used to be larger than the thread had to be removed (milled, extruded) the commercial side just leaves all the excess material (thus the larger OD) and cuts out the threads to size.

Commercial tube, notice OD is same as threads.


Milspec tube, notice material behind and some of thread is removed smaller OD.


Just like a lightweight 556 barrel vs heavy barrel, same material one is just machined further.

Side note. Easy way to tell if tube is comm or mil without removing any parts, the comm tube will have a radius from the cylinder to the alignment/adjustment bar below. The milspec has a no radius and meets at 90°

 

[Caveman Jim]

@Caveman Jim as others have said all you need to do is to replace the buffer tube. Any well made mil spec tube will work just fine, no need for anything fancy.

You will need a lower vice block and a castle nut wrench to make the swap. If your castle nut has been staked you can still remove and reinstall it - just search youtube for vids on this.

When you loosen the castle nut the back plate will also loosen and it holds in the detent and spring for the take down pin. be careful so as not to lose it, or plan ahead and get a spare of each.

The next place to take care is when you unscrew the buffer tube out of the receiver as it holds the buffer retaining pin and spring in place. I use a starter punch to hold the retaining pin captive as I unscrew the tube and again as I install the new one. If you don't hold it captive somehow it will shoot out with a surprising amount of energy.

BTW if you want so swap out your back plate for one with a QD or other mount this is a good time as you remove it as part of the process.

If you make it down my way I have all the tools and Curt's is nearby for lost parts... It's really not a hard job and takes about 10 minutes.

Removing a staked castle nut - note you can restake it after you put it back on. Staking is also shown on the same channel:

This shows back plate and buffer installation:

Thanks for the info brother, I have all the tools and remember to close the door to the room when I'm working on the AR.....
I changed out the stock buffer backing plate & still two years later I have not found the detent spring!!!!! No kidding....