Psa AR 9mm the punishment begins

[freebullet]

Most all the parts arrived. Here is the lrbho glock mag lower.


Looks like it uses a standard bolt stop & a little proprietary lever for the mag to engage the stop. The mag catch also appears to be proprietary. The spring is weak for the length of the lever. A little fussing has improved it but, I'm not convinced the spring is stiff enough. More later.

 

[freebullet]

Had a fcg minus the pins & a standard carbine stock/buffer on hand. Got a little CMMG lpk minus the fcg from bps for half off with points. If you can follow all that you might have ar-itis, read on.

Got that put together full well knowing the buffer is to light. Here's the upper.
16" mid length. Didn't really choose the parts for this. Set out with a goal of putting together a reliable ar9 blaster as close to free as possible. I'm planning for tinkering & some obvious parts replacements. It will need a heavier/longer buffer weight.

The upper won't chamber my long standard cast load. I've found that any 9mm that won't chamber this round will be ammo picky. I've tested the dummies & fired this round in mass quantity through multiple guns. It's the plain old lee.

I do have some plated loads from eons ago that do chamber for the initial test.


That means I'd have to take the chance on replacing the barrel or I'll have to throat it. I'll work up some cast loaded shorter to get through the function trickery trials. Hope to swing by an indoor range to fire it tomorrow.

 

[Ian]

Load 'em light or from what everyone says you'll be replacing the ejector in short order. Need that heavy buffer.

 

[freebullet]

Well, I'm gonna risk it once but, am about to order this one here I think.

http://www.kawvalleyprecision.com/KVP-Solid-Stainless-Steel-Blowback-Buffer-7-5oz-p/kvp-7.5.htm

 

[freebullet]

The carbine is 3oz. The psa 9 buffer is 5.3 but, it's been unicorn status for a good bit. Most of the research I've done points to a 7-8oz being best but we'll see.

 

[Ian]

Well, I'm stoked, that looks like a fun little toy. Love the Glock magazine concept, not crazy about the angle it sticks out, but it's about the best option there is if you want capacity, affordability, availability, options, and reliability. Hopefully yours is more accurate than my DI-45.

The only thing I have reservations about is the lrho. The the transfer bar is right in the area of maxiumus crudia accumulus and I see that causing some failures to lock back after a bit.

 

[freebullet]

Finished assembly last night. The only mags I have are two gen 4 glock 15rnd the shop had on hand. One slips in nice & drops free. The other not so much.

The lrbho feature doesn't work like, at all on either mag. The other mags/parts will be here today yet but, I used the aimpoint it will wear as a peep sight to go get a baseline.

Umm, thats ugly. The ejection port & muzzle blast seemed like I was sitting at a bench next to a short & ported barrel '06. The felt recoil was low but, violent.

It fed good at first but, as it warmed the rounds would slam into the barrel extention & set back while doing so. Didn't shoot the set back rounds for obvious reasons. The rounds can't be set back by hand. The bolt travels to far back & to fast.

The mag catch is definitely an issue as it allowed 2 separate mag fall outs.

Didn't test the lrbho feature as it didn't work on an empty & the bolt stop would probably break off if it did with its current over travel. It did not cause any issues. New buffer ordered.


Looks like I may need to gently break the edge on the sides slightly to improve feeding without changing the headspace.

Shot to point of aim at 25yd indoors without issue but, it will need to punish me more before we try for groups.

This is truly a ninja weapon at this point but, I'm confident I can turn it around. I'll mess with it some this evening after work.

 

[Ian]

It would be nice if the manufacturers worked some of the bugs out of these parts BEFORE selling them, but that seems to be the way it goes sometimes.

On the feed angle, that's totally off. It has virtually no feed ramp in front of the magazine, and the bolt face will leverage the top of the rim and try to drive the nose down as it strips the round. That lower needed to have a ramp built into it right in front of the mag well, and to have a little "Glock smile generator" carved into the bottom of the chamber entrance to match the ramp and feed lip angle.

 

[freebullet]

The punishment continues as the drum mags don't fit in the mag well. The centerfire systems Korean 15rnd slide in but, really tight. The Korean 33rnd fit & drop free but, didn't engage on the mag catch reliable & fell out empty if shaken a bit.

I sanded the glock mag & the Korean 15's to drop free. Sanded the drum to fit without undue force but, not drop free as I'd like them not hitting the ground.
The glock 15's only held 14 the first few loadings but, once broken in hold 15 fine.
After I fitted the tight ones I decided to remove the mag catch. Wanted to clean things up & measure the spring to find a slightly stiffer unit.


After taking it apart & thoroughly cleaning it all up it now returns as it should. Even the 33rnd Korean mags stay put and they all drop free except the 50drum. It works so well now I doubt I'll change the spring unless it proves necessary.

It's hard to believe psa and there lack of attention to detail. Fellers that don't make things work themselves would be calling with multiple issues already. They sell their complete ar9 for 8-900 which is crazy since I'm in this for 470.

Got a little china crooked riser for the Rd & a flip up rear sight.

I ordered the above linked buffer/ heavier spring jic & a little rail for the underside front end to allow it to share a slide on bipod. I'm glad I looked around as I found all those same parts at Joebob cheaper. Hopefully it shows up quickly, first order from them.

Think I may go ahead & get a throating reamer on order. I'm already thinking of an hbar barreled, free floated, & scoped varmint ar9. Better make this one work first.

 

[KHornet]

Great pics. Am not a fan of AR's, but sure do like the technology that
they have produced. In 9mm with large cap mags would sure be a
most excellent house to house street sweeper! Look forward to seeing
it in action.
Paul

 

[Ian]

Hooboy I'm glad you're going through all this instead of me! Heck, you're just getting started. I've been fussing with my DI-45 for a couple of years now, but at least I got most of the reliability and function issues worked out.

 

[Will]

I just wish they had one in 45 acp I'd be in for sure.

 

[Ian]

Quarter Circle 10 offers a large frame Glock lower, five in stock right now. I wouldn't personally mess with a blowback .45 ACP, shooting one to me is like bouncing yourself off a brick wall with a pogo stick. DI is the way to go unless your carbine weights 11 lbs like a Thompson, but I wouldn't again go the way I went with a DI AR upper, I'd try out RMW Extreme instead.

 

[freebullet]

Yeah, Ian your about to declare defeat thread wasn't inspiring just before this build. Different animal though so what the heck. Taking the issues in context & working them out will hopefully work out.

I spoke with Dave & placed an order for the Manson 35 pistol throat reamer. The 45 throat reamer we used was top notch and worked very well on several guns. The off brand reamer I tried on the last psa barrel was not as nice of product. They are of course out of stock as, is brownells. Said it should ship in about 4 weeks.

I'm considering making a feed ramp to mount in there. Looks like there is room. I'm not sure why psa thought a partial feed funnel? would work, then again maybe that's part of the punishment.

 

[Ian]

It looks to me like the PSA lower has the Glock magazine presenting the cartridges at a steeper angle than in a Glock 17. It's kinda typical to need a steep feed angle for .45 ACP ARs because of sheer cartridge diameter and how far the case has to lift in a short time in order to strip and make it into the chamber at bolt speed, but for a 9mm that looks like merely an excuse to neglect engineering a feed ramp.

I'm not sure that reverse-engineering a Glock feed ramp is going to fix it with that magazine angle being what it is, but it also appears in the photo showing the cartridge stuck between the feed lips and barrel "ramp" that there's a pretty large gap in which a shallow ramp (just a tad more steep than feed lip angle) could be installed to help guide the nose up over the chamber lip while a) still not being too steep to bind the cartridge in the feed lips and b) still being just low enough to clear the bottom of the bolt.

You could probably fab a steel feed ramp with a tang on the bottom and pin it into a hole drilled in the lower in front of the magazine, or possibly mill out a notch in the front top of the mag well and install a bent piece of flat steel with a countersunk machine screw.

 

[Tom]

I think you'll be happy with Joebobs service. They usually ship my stuff before I order it. At least it seems like it.
They shipped me a wrong item once, and I had the right one three days after emailing them.

 

[RKJ]

I'm glad I saw this as I have a PSA 5.56 chambered 16" upper on a Anderson Lower and can't get it to load any cast reloads. Factory shoots ok from what I've tried but even jacketed reloads are a coin flip. I've ensued the shoulder is pushed back far enough, the OAL of the loaded case (as well as the empty) are the correct length, but still no joy in Mudville. I'm thinking I'll have to have it cleaned up by a smith, which pretty much defeats the whole reason of building one, but I got it to be able to shoot fast & furious and to use it in an if needed scenario. The way it is now, it's pretty much useless to me. Just venting, sorry for hijacking the thread. Your AR looks mighty nice, and is sounds like you know how to fix it and are getting it worked out.

 

[freebullet]

No progress on the feed ramp. Still thinking over how to attach it. I have a couple ideas on shape I'm sure would work but, attaching it is a somewhat permanent mod. I'd like to make a solid doable solution before buggering things hurriedly.

The buffer/stuff from Joebob is supposed to arrive tomorrow. That's really fast. They did charge my card twice but, I'm assuming for a couple days it could just be a precharge authorization that could fall off in a day or two. If not I'll give them a call.

Tonight I pulled the lrbho lever, cleaned out the chanel, & bent the lip the mag raises.




I bent the little lever down a bit and cleaned it up. Now appears to be working pretty well. Will have to test on range.

If I can get a feed ramp made & the buffer shows up we might be able to test it out this weekend.

 

[Ian]

Well, you already have a pin clear through the receiver there holding the lrho activation lever in place, so one possibility would be to cut a slot in the front of the mag well passing through that same pin hole and use that to hold a block in place via a tab. Or, just drill something like a 1/4" hole straight down through the front part of the mag well to intersect that pin hole and use the same pin to secure a peg on the bottom of some sort of ramp block. If you fabbed a ramp out of aluminum, you could also drill it and epoxy or pin a peg into it also rather than try to machine a peg on the bottom of a block.

 

[freebullet]

I was thinking of using a piece of aluminum & attaching it to the upper since it's a cheap easily replaced milspec part.
I'm not sure about mounting it to the proprietary lower & having the upper try to close over it and still have a close fit.