So, it looks like my extension tube/“buffer tube” on my PX9 is a little larger in diameter than a standard AR stock (I have done the Form 1 stuff for SBR, so I am thinking of going to adjustable stock). Is it possible to replace the AR-9 tube w a mil spec AR 15 stock on this firearm?
Yes
I used a standard AR 6 position buffer tube on my AR9 build
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Is the bsck slanted instead of straight? If so you have a commercial tube and it is a bigger diameter.
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What/where back slanting? (sorry! not trying to be dense, just not sure 
)
Thank you for any direction!!!
And… if commercial, is it replaceable or is there a commercial stock available?
The part of the tube closest to your shoulder. Commercial stocks are harder to find these days. Just go with a milspec tube.
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ok, now makes sense! thank you for that!! I will check and see.
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On my PX9 lower I switched out the KAK Shockwave buffer tube with blade brace for
Mil-spec buffer tube and adjustable pistol brace.
Before:
After:
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commercial tubes and stocks were developed during the weapons ban under Clinton. that became repealed in the bush II administration. they were made so that we could have AR’s and stuff for them during the AWB cause it made the guns less scary if we had to make an entire lineup of accessories for the gun only slightly bigger and with an angled back to the tube . LOL. what a crock.
So long story short, Commercial = Crap
Mil-Spec = Standard now a days.
another part that they did was BCG’s.
Full Auto BCG’s = MIl spec = Standard today. always have been standard in M16’s.
a commercial/ non-full auto bcg is easy to visualie as well The Channel on the bottom of the bcg is much longer on the commercial bcg versus what it is on the full auto bcg.
see this :
while this may not apply for your 9mm application, it does for any standard ar-15
Thanks and i know its more info than you needed probably but it never hurts sto review things too.
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So, on the PX9, is it a simple swap out, commercial (or whatever it is) for a mil-spec buffer tube? I’ve looked and haven’t been able to find info on this. Thanks all for any advice!!
Unscrew one, screw in the other.
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“commercial tubes and stocks were developed…”
Sorry, but this is complete Fanboy FUD make up in the forums.
Both buffer tubes are made using aluminum alloy extrusions.
Mil-Spec tubes are threaded using a thread rolling machine in a separate operation. Colt chose this method because they had a lot of depreciated machinery still in use in their factory in the 1980’s.
This is a thread rolling machine:
It only does one thing and occupies floor space and uses up labor.
Rolled threads end up larger that the diameter of the original piece because the material is deformed into shape and the displace material can only move into the die.
Commercial tubes are made in modern CNC machines that can finish the blank, cut the channel and holes for the adjustable stock and cut the receiver end threads in one operation. Because cutting a thread on a lathe removes material, your blank has to be the o.d. of the thread needed. It is a cheaper, more efficient manufacturing process.
That is it. The tubes are different because of the technology used to produce the thread. The rest is marketing hokum and justification for higher prices due to a more cumbersome manufacturing process.
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Rolled threads are a little stronger as well.
well thanks for the education on how they were made… but still it goes back to the ban does it not for the reason they were sold.they also have an angled back as compared to the mil spec tubes that have a flat end on them.
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That only applies to steel parts. The rolling process induces phase changes in steel that increase fatigue resistance.
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Colt had the M4 under patent and, as far as I know, was the sole supplier of carbines during the ban period. The TDP was theirs and theirs alone. Colt only sold the large pin FCG full size H-Bar to the civilian market. Carbines were banned and Law Enforcement sales had an LE serial prefix. .
Competitors like Bushmaster and Olympic were pretty much low volume operations at that time.
If I had to guess, the demand for a low price ARs after the ban by Walmart/Bass Pro/Academy is what drove the “commercial” buffer production with new makers like DPMS building new manufacturing facilities.
The angle back is to tell them apart by visual inspection.
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Thank you for clarifying. That was too broad of a statement on my part.
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Great info. Thanks.