Building a Shorty 9mm M16 upper

Well its been coming along! Tried it out for the first time today. So far we have:
M16 lower.
Colt SMG upper and charging handle.
TROS three lug barrel
CMMG bolt
VM Hy Tech 9mm Uzi Mag feedblock conversion

So still needing a handguard. I think a Samson Star-4 handguard is what I am going to go with. Has the anti-rotation and seems pretty strong. Seems like a lot don't have the anti-rotation or don't offer a short pistol version. Also need to add a Mk9K.

Anyway, had it out for a test spin today! Thought you guys might like to see.

Two words...

DOE upper.

Seriously though...you have a good start there.

For your hanguard. http://yhm.net/mini-keymod-handguard.html

You may know these things, but Ill suggest them just in case.

BTW it's a nice setup IMO, good choices thus far. That forged upper is better than a billet upper, all day, every day. Billet is just a cool looking, but weaker, fancy overpriced option.

May I suggest you get the heaviest 9mm Buffer you can buy. It's a full blowback design and mass is the only thing that will keep it from destroying your M16 lower. It will egg out your FCG bores if you're not careful.

If you have too much rearward bolt travel it can break your bolt catch as well and damage the Lower Receiver as well. You want to minimize bolt travel. The only way to do this is with long 9mm buffers and receiver extension spacers.

Don't use KNS pins, they are soft and will royally screw up your M16 lower when they break and you won't know they are broke because they won't fall out. Regular Pins will walk when they break giving you and indicator that they are broken. If you want upgraded FCG Pins use Colt or Geissele Pins.

Here is my Suggestion:
Pay M60 Joe to replace your steel Bolt weight with a Tungsten one.
Buy a Superior Shooting Solutions AR15 Flat Wire Buffer Spring. They last 500,000 Cycles
Heavybuffers.Com Heavy Buffer or Equivalent Carbine 9mm LONG Buffer. NOT a Colt Buffer

It seems you are looking for a Handguard that is anti-rotation. This is good because a common problem with 9mm AR's is the lack of a Gas Tube hole in the Upper Receiver and gas Tube to engage the teeth on the Barrel Nut. The Gas Tube on a D.I. AR prevents a standard Barrel Nut from shooting loose. Most 9mm AR'S don't and will shoot themselves apart, especially on a M.G.. If your Upper has a Gas Tube hole, get a long solid or roll pin to lock the Barrel Nut to the Upper Receiver so they won't shoot loose. For years Colt has not remedied this issue with 9mm Subguns. If you want to lock your barrel nut and upper as I mentioned and have an undrilled upper you can send it to ADCO and have it drilled for $40.00.

Caeb75 said:

DOE upper.

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To be frank, that looks like a great old school upper. However I think its a bit out of date today. I am looking for something cutting edge.

Joe Blow said:

For your hanguard. http://yhm.net/mini-keymod-handguard.html

Click to expand...

Thanks, good suggestions but I don't really want to go with the KeyMod.

clandestine said:

You may know these things, but Ill suggest them just in case.

BTW it's a nice setup IMO, good choices thus far. That forged upper is better than a billet upper, all day, every day. Billet is just a cool looking, but weaker, fancy overpriced option.

Click to expand...

Thanks, yes I agree, forged is always better. I paid a bit more for a Colt but with FA, staying with Factory spec can be worth the extra.

May I suggest you get the heaviest 9mm Buffer you can buy. It's a full blowback design and mass is the only thing that will keep it from destroying your M16 lower. It will egg out your FCG bores if you're not careful.

Click to expand...

Sorry, did not post about that. I am running Slash's Heavy Buffer XH at 8.5oz. http://heavybuffers.com/xhcar.html

If you have too much rearward bolt travel it can break your bolt catch as well and damage the Lower Receiver as well. You want to minimize bolt travel. The only way to do this is with long 9mm buffers and receiver extension spacers.

Ever tried these: http://heavybuffers.com/9q.html

I could pick up one of these. Its not a bad idea. However with using a Uzi Mag (not Modified), I have no last round BHO, so I don't know if I really have this problem. I was willing to give up last round BHO to use stock Uzi mags. It slows things down a small bit but...

Don't use KNS pins, they are soft and will royally screw up your M16 lower when they break and you won't know they are broke because they won't fall out. Regular Pins will walk when they break giving you and indicator that they are broken. If you want upgraded FCG Pins use Colt or Geissele Pins.

Click to expand...

I have been using stock, what I think are Colt pins so far. I took your advise on that one a while back. I have been thinking about a Geissele trigger but with another guy in our club having issues with them and my not being overly sensitive on the triggers and them not being cheap... I have put it off for now.

Here is my Suggestion:
Pay M60 Joe to replace your steel Bolt weight with a Tungsten one.

Click to expand...

I think I have that covered above.

Buy a Superior Shooting Solutions AR15 Flat Wire Buffer Spring. They last 500,000 Cycles

Click to expand...

I got one but man, they are a major PITA to get in and out! I switch a lot running the Shrike as it has the longer spring. So I moving away from this just because that flat wire makes it hard to quickly remove or install. I might get some of the other Sprinco CS round wire springs instead.

Heavybuffers.Com Heavy Buffer or Equivalent Carbine 9mm LONG Buffer. NOT a Colt Buffer

Click to expand...

Haha, just got this part of the reply. Do you think the longer buffer one is worth it? If so 8.5 or 12oz. I do have to tell you in FA, its maybe just a little bit of rocking with this bolt as is.

It seems you are looking for a Handguard that is anti-rotation. This is good because a common problem with 9mm AR's is the lack of a Gas Tube hole in the Upper Receiver and gas Tube to engage the teeth on the Barrel Nut. The Gas Tube on a D.I. AR prevents a standard Barrel Nut from shooting loose. Most 9mm AR'S don't and will shoot themselves apart, especially on a M.G..

Click to expand...

Yup, you see my concern exactly. I am not looking for that type of quick change barrel!

If your Upper has a Gas Tube hole, get a long solid or roll pin to lock the Barrel Nut to the Upper Receiver so they won't shoot loose. For years Colt has not remedied this issue with 9mm Subguns. If you want to lock your barrel nut and upper as I mentioned and have an undrilled upper you can send it to ADCO and have it drilled for $40.00.

Click to expand...

There is no hole drilled. Will an Anti-Rotation handguard not be enough? I was looking at the Star 4 from Samson... Seems pretty solid but never seen one in person.

You are covered if you have a Slash buffer. If he has a heavier one, it would be better for your lower and on recoil. Especially once you add a can. My 4.5" will run with a 12 ounce and an 8 ounce. I use the 8 ounce on my LWRC shorty Stock since it won't accommodate a 12 ounce.

You are correct about the BHO, it's not a concern with an UZI Mag setup. The only rearward travel to be concerned about at this point is clearance for the non functional 9mm gas key. If a buffer setup is too short, or a buffer tube is too long it can allow the gas key to strike the lower receiver ring on the rearward stroke and can break the upper portion where the buffer tube threads in.

You are spot on about the CSS flat wire springs, they are a PITA to remove An XP Action Spring is a good thing for this setup, so you may have to play around a bit to see what your gun likes.

You should be fine with a good anti rotation handguard. For cautionary sake, I do suggest going on the high value of recommended torque on the barrel nut. 80 Foot Pounds.

I have seen a few M16 owners mess up their lowers with improperly setup 9mm uppers. It's a pricey endeavor to fix when it happens.

You really covered your bases well so theres nothing to worry about, but if I can assist with anything, I'll help however I can. It's a damn cool gun you have.

IMBLITZVT said:

So still needing a handguard. I think a Samson Star-4 handguard is what I am going to go with. Has the anti-rotation and seems pretty strong. Seems like a lot don't have the anti-rotation or don't offer a short pistol version.

Click to expand...

Have you considered SLR for the handguard? If you can talk to them direct they might be able to custom make you to any length you want.

Midwest Industries just came out with the Gen 3 and the updates are really good with respect to anti-rotation and security. Just cut the 7.25" M-Lok version to size, $140.

clandestine said:

You are covered if you have a Slash buffer. If he has a heavier one, it would be better for your lower and on recoil. Especially once you add a can. My 4.5" will run with a 12 ounce and an 8 ounce. I use the 8 ounce on my LWRC shorty Stock since it won't accommodate a 12 ounce.

Click to expand...

Yeah thats what I figured. I am using the same buffer with the Shrike. It seems to be working well. I will probably order the Shrike buffer H3? I think it is, just to try it but I plan to stick to the 8.5oz for the most part.

You are correct about the BHO, it's not a concern with an UZI Mag setup. The only rearward travel to be concerned about at this point is clearance for the non functional 9mm gas key. If a buffer setup is too short, or a buffer tube is too long it can allow the gas key to strike the lower receiver ring on the rearward stroke and can break the upper portion where the buffer tube threads in.

Click to expand...

I will check the gas key as I did not think to check that but I think I am ok there.

You are spot on about the CSS flat wire springs, they are a PITA to remove An XP Action Spring is a good thing for this setup, so you may have to play around a bit to see what your gun likes.

Click to expand...

I think I got a wolf spring with the buffer, I will dig that out and try it. Yeah the flat wire are fine if you don't have to change. But like yesterday I changed out springs like 5 times...

You should be fine with a good anti rotation handguard. For cautionary sake, I do suggest going on the high value of recommended torque on the barrel nut. 80 Foot Pounds.

Click to expand...

Yeah thats what I was thinking. I put 60ft-lbs on it to test it. However when its finally done, I will come close to maxing it out.

I have seen a few M16 owners mess up their lowers with improperly setup 9mm uppers. It's a pricey endeavor to fix when it happens.

Click to expand...

Yes I am going to take precautions. However I bought this as a shooter. If it get damaged, it will get repaired and its not the end of the world. Its not a Colt upper, so if damaged, I will use the opportunity to bring it close to Mil-Spec. The rear pin that holds the upper is a bit to low anyway...

You really covered your bases well so theres nothing to worry about, but if I can assist with anything, I'll help however I can. It's a damn cool gun you have.

Click to expand...

Cool, thanks! You are welcome to a few rounds if you make it out there with us!

rayrevolver said:

Have you considered SLR for the handguard? If you can talk to them direct they might be able to custom make you to any length you want.

Midwest Industries just came out with the Gen 3 and the updates are really good with respect to anti-rotation and security. Just cut the 7.25" M-Lok version to size, $140.

Click to expand...

I did look at them but I did not see anything short.

Don't really want to cut as I don't wish to re-anodize and don't want to paint. I also don't want the M-Lok.

I might drop them a line if you think they would do custom.

Sorry for the thread-jack,but is what you posted for ALL 9mm builds or just for FA?

clandestine said:

You may know these things, but Ill suggest them just in case.

BTW it's a nice setup IMO, good choices thus far. That forged upper is better than a billet upper, all day, every day. Billet is just a cool looking, but weaker, fancy overpriced option.

May I suggest you get the heaviest 9mm Buffer you can buy. It's a full blowback design and mass is the only thing that will keep it from destroying your M16 lower. It will egg out your FCG bores if you're not careful.

If you have too much rearward bolt travel it can break your bolt catch as well and damage the Lower Receiver as well. You want to minimize bolt travel. The only way to do this is with long 9mm buffers and receiver extension spacers.

Don't use KNS pins, they are soft and will royally screw up your M16 lower when they break and you won't know they are broke because they won't fall out. Regular Pins will walk when they break giving you and indicator that they are broken. If you want upgraded FCG Pins use Colt or Geissele Pins.

Here is my Suggestion:
Pay M60 Joe to replace your steel Bolt weight with a Tungsten one.
Buy a Superior Shooting Solutions AR15 Flat Wire Buffer Spring. They last 500,000 Cycles
Heavybuffers.Com Heavy Buffer or Equivalent Carbine 9mm LONG Buffer. NOT a Colt Buffer

It seems you are looking for a Handguard that is anti-rotation. This is good because a common problem with 9mm AR's is the lack of a Gas Tube hole in the Upper Receiver and gas Tube to engage the teeth on the Barrel Nut. The Gas Tube on a D.I. AR prevents a standard Barrel Nut from shooting loose. Most 9mm AR'S don't and will shoot themselves apart, especially on a M.G.. If your Upper has a Gas Tube hole, get a long solid or roll pin to lock the Barrel Nut to the Upper Receiver so they won't shoot loose. For years Colt has not remedied this issue with 9mm Subguns. If you want to lock your barrel nut and upper as I mentioned and have an undrilled upper you can send it to ADCO and have it drilled for $40.00.

Click to expand...

SRD said:

Sorry for the thread-jack,but is what you posted for ALL 9mm builds or just for FA?

Click to expand...

All 9mm ARs.

The damage from improper setup is just WAY more costly on a Registered M16 Receiver than a regular Title 1 AR15 Receiver.

Thanks.