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9mm AR's

Let me ask you a question. Actually 2 questions.

The upper receiver you are using, in reference to the ejection port, is the ejection port the same length and placement front to back as a standard upper?

Is the 9mm buffer you're going to use longer than a standard carbine buffer? I know it should be heavier, but I'm asking about the length from front to back.

When you get it together, pull the charging handle all the way back and see if the bolt goes well past the back of the ejection port into the upper receiver and get back to me.
 
John A. said:
Let me ask you a question. Actually 2 questions.

The upper receiver you are using, in reference to the ejection port, is the ejection port the same length and placement front to back as a standard upper?

Is the 9mm buffer you're going to use longer than a standard carbine buffer? I know it should be heavier, but I'm asking about the length from front to back.

When you get it together, pull the charging handle all the way back and see if the bolt goes well past the back of the ejection port into the upper receiver and get back to me.
Click to expand...

Ejection port I'll measure this weekend. Seems exactly the same spot just no dust cover and no shell deflector on the upper receiver.

I'll be running the Blitzkrieg hydrolic buffer which is longer from eyeballing it and I'm running an AR-10 heavy buffer spring
 
Roger that.

If you were using a standard buffer length, I have the numbers to make an extended buffer to keep the bolt from cycling too far rearward. That's why I asked.

FWIW, my 9mm upper is also a slickside. There was no reason to use a standard upper that had the forward assist and stuff, because, well, there are no forward assist 9mm bolts :confused:
 
OK... Build Done:

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Angstadt Arms - Upper, Lower and bolt
Thorsden NY compliant stock and buffer cover
ALG - Advanced Combat Trigger (3.5lbs pull)
ALG - mil spec lower parts kit
Wilson Arms 9mm barrel
Radical Firearms rail 12"
Noveske Ambi short throw safety
Magpul MBUS PRO metal sight set
Primary Arms Adv Micro Red dot
Larue QD mount
Haley Strategic Inforce WML 400 Lumens
Andersen mil spec buffer tube
Blitzkrieg Hydraulic Buffer
Heavy AR-10 Buffer Spring

Total weight is 7.4 lbs Would be sub 7 pounds if I can use a real stock and not this crapper.

Ran it through some drills today about 250 rounds before I had to run back home:


Pros:
No recoil
No muzzle flip
Fairly quick transitions (need to work on it with carbines)
light
good looking
cheap on ammo

Cons:
Bolt hold open is not consistent. Could be the buffer spring needs to be worked in
Noveske Ambi on the trigger finger side gets in the way of my trigger pull and had excessive rubbing on my hand (aka I ripped that part off)
Pricey but I used some really quality parts.

It's a keeper, Fa Sho.

Water Monkey
 
The BHO issue may be the mags or the parts needing to wear in. May also be related to the hydraulic buffer but my money is on the AR10 buffer spring. You'd have to diagnose it like you would any other AR. One piece at a time.

Can you look to see how much of the bolt remains protruding in the ejection port when the charging handle is pulling it all the way rearward? And with an empty mag by hand to see how well it works?

OK, enough tech talk, now I'm going to tell you that it looks like a real shooter. Do you need more convincing why I like pistol cal carbines now? (evil laugh: Bwhahahahaha)
 
John A. said:
The BHO issue may be the mags or the parts needing to wear in. May also be related to the hydraulic buffer but my money is on the AR10 buffer spring. You'd have to diagnose it like you would any other AR. One piece at a time.

Can you look to see how much of the bolt remains protruding in the ejection port when the charging handle is pulling it all the way rearward? And with an empty mag by hand to see how well it works?

OK, enough tech talk, now I'm going to tell you that it looks like a real shooter. Do you need more convincing why I like pistol cal carbines now? (evil laugh: Bwhahahahaha)
Click to expand...

Yeah been working the charging handle on an empty mag. Still won't lock back. Probably the buffer and spring. Angstadt has a buffer and spacer they use but I opted for the hydraulic buffer and heavy spring to kill recoil for my wife. I'll play with options later on down the road. I can live with this for now.
 
If it won't lock back on an empty mag by hand, something isn't right.

Sounds like the buffer/spring is too long.
 
John A. said:
If it won't lock back on an empty mag by hand, something isn't right.

Sounds like the buffer/spring is too long.
Click to expand...

I'm betting that's what it is. I have an extra carbine spring I can swap out to check. Probably do it this weekend.
 
Ok. So I put in a regular carbine spring and still no hold open on an empty mag. Seems it only holds open when I manually press the bolt catch. Looking at what's going on seems the reduced spring provided by Angstadt is still not enough to allow the bolt catch to go high enough when the mag becomes empty. Wondering if I should contact them. Factory Gen 4 glock magazines.
 
OK, when you have an empty mag inserted and pull the bolt back by hand, can you look through the ejection port to see if the bolt and the BHO lever is too close clearance or if the BHO just maybe has some grit and burr that may smooth out with some use? The hydraulic buffer may not be allowing the bolt to move back far enough to engage the BHO lever. I can take a picture of mine for reference if you need me to, but just for the sake of discussion, say that my bolt will travel 1/8 of an inch behind the BHO when it's all the way back. This gives the mag spring enough time to push up on the bho before the bolt comes back forward.

Maybe check the lower and a mag without the upper installed when you insert a mag to see if the BHO pushes up or not. That would eliminate anything going on the the lower itself and possible grit/burr on the BHO or the lower that needs worn in.
 
John A. said:
OK, when you have an empty mag inserted and pull the bolt back by hand, can you look through the ejection port to see if the bolt and the BHO lever is too close clearance or if the BHO just maybe has some grit and burr that may smooth out with some use? The hydraulic buffer may not be allowing the bolt to move back far enough to engage the BHO lever. I can take a picture of mine for reference if you need me to, but just for the sake of discussion, say that my bolt will travel 1/8 of an inch behind the BHO when it's all the way back. This gives the mag spring enough time to push up on the bho before the bolt comes back forward.

Maybe check the lower and a mag without the upper installed when you insert a mag to see if the BHO pushes up or not. That would eliminate anything going on the the lower itself and possible grit/burr on the BHO or the lower that needs worn in.
Click to expand...

OK I'll take another look this weekend. Tough to get some "alone" time with a 3yr old running around bossing me around lol.

But the BHO does push up with an empty mag inserted. Just seems not up enough. could be a wear in thing as you mentioned. I'll also just toss in a regular buffer to see if it's the hydraulic buffer.

I racked the charging handle wayyyy back on the empty mag with both springs and it doesn't engage. Only with I press on the lower part of the bolt catch does it engage. Seems like a fraction of an inch it needs to engage.
 
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I had a 9mm M4 for several years, used UZI mags, which I could get by the bucket. Did have to cut a higher retaining slot. Main problem, unless kept super clean was cases getting stuck in the receiver. They would flip around and stay inside. Otherwise, within the limitations of 9mm, a lot of fun. Traded it a while back for another rifle and shed load of cartridges.
 
My MP5 is like that. It's been a lot more problematic than my other 9mm guns.

I have several converted uzi mags.

And the new Tavor 9mm mags already have the notch cut and will hold the bolt open too. I've been meaning to pick up a few of them.
 
I know my quarter circle 10 lower has a weaker spring for the bolt hold open perhaps it could be that. If you took out the bolt catch and cut a few coils off the spring it might help but I would only do that if you exhausted other reasonable options first. I know this can be a huge pita to do so but it might be the reason why its not locking back.
 
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That could help.

I know on my conversion parts, the magwell has a spring loaded arm, which is built into the magblock, and that is actually what raises up the AR bolt hold open lever.

This puts a lot more work on the 9mm mag/follower/spring than the way a traditional AR is set up.
 
Re Stoppages.....We also used to use coins, the old british penny was ideal, in the M16/ M4 mag tube under the spring to vary the strength. The only answer I found to flipping spent cases was keeping the working parts clean and well lubed (best quality teflon based). Also, oddly letting out the depth of the mainspring tube helped. Just a turn or two, so the detent was still captive. I also on a couple of Ar's over the years bevelled the inside of the mouth of the mag tube.
 
I completed this PSA AR-9 about a year ago. Bought lower first which came with a s-load of various Glock and Glock-compatible hi-cap mags as a BF "deal". The upper came later as PSA was perpetually out of stock on them. Still haven't had a chance to bring it to the range and a more complete write-up will be forthcoming as will be "better" pics of the carbine and components. I'd say I have about $600 into it without the mags. That mag only has 25 in it, BTW. This model does not have LRHO (last round hold open) and looking at pics of one that did, I didn't like the spindly mechanism they used for that purpose. The LRHO lowers were never available, anyway.

I just ordered a set of MBUS to put on it and I'll probably turn a spare grip into an A1 style or put a Hogue on it, which I like the feel of.

ar9a.jpg
 
Mmm.

I helped a young man put his first AR together a while back and he had the same handguard on it. It was very light, and a lot more comfortable than larger diameter handguards than I expected.

As for the 9mm, I think you're going to enjoy shooting the snot out of it.
 
Update:

Took the wife out today. Had an awesome time and she loves the rifle. Really a great build for her and she was crushing the target at all ranges from 7-25 yards. BHO was working much better today. Think it just needs to work itself in. Only had 3 instances where the BHO failed to engage.

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Little Video of the day:

 
I think I've been bitten with the bug. I want to build another one. Thinking of a drop in magwell adaptor from Kak industries or Hahn. My buddy was jelly and built one with the Kak adaptor and so far it's been solid. He shoots a lot and is a master RO so if it's held up by the end of the year I'll jump on some black friday deals. If Primary Arms has another stripped lower deals I'll jump on them.

This build will be more budget based than the one I built for my wife.
 
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