PSA upper on Promag block?

[mikeor70]

I'm considering a 10.5" PSA upper to go on a SBR lower with what I believe is a promag block.  The 16" on it now runs great with PSA mags other than the mags needing a tug to drop.  The PSA uppers I've been looking at all say "to use with PSA 9mm Lowers designed to work with either Colt or Glock style magazines".  Is anyone running this combo?   Compatability/reliability issues?   

 

[Flatland Shooter]

I had a similar question for a forum member earlier this week.  I wanted to buy a PSA 9mm lower and top it off with a regular old AR stripped upper I have laying around.  The note on their website saying you "must" mate their upper with their lower concerned me.

His response was the PSA lower appeared to be mil spec and there should be no problems.  He and a friend had some stripped lowers on order and they were building their own franken-uppers.

Maybe if he sees this he will chime in.

UPS says mine will be  delivered Monday.

[bmiller]

I swapped my PSA upper on to various lowers that I have.  I have 2 lowers that are tight. A Colt competition rifle and a S&W. That upper was close to going, but wouldn't and would require minor fitting. It fit all the others I tried fine.  My psa lower accepted all my uppers. Colt and S&W included. Looking at them, I am not sure what the differences PSA is talking about.  

[Southpaw]

PSA has done a good job tricking people into thinking there's something proprietary about their parts so you buy everything from them. The upper is just a regular slick sided upper and should work with any lower.

[mikeor70]

1 hour ago, Southpaw said:

PSA has done a good job tricking people into thinking there's something proprietary about their parts so you buy everything from them. The upper is just a regular slick sided upper and should work with any lower.

That's what I am starting to believe also.  I just want to make sure there's no compatability issues between the block and bolt before I give them $400.  I'd have no use for a 10.5" upper that won't run on my SBR lower.

[Southpaw]

While I can't speak from personal experience since I don't have that same block or a PSA bolt, everything I've heard is that the PSA bolt is just a normal 9mm bolt with a Glock mag cut so it will work with both Glock and Colt mags. That's why they call it "hybrid", to also further confuse people and make it sound like there's something different about their bolt from all other 9mm bolts.

[bmiller]

My psa pcc came with the gen 1 bolt. It would only work with colt mags. The gaskey facsimile was held on with 1 Allen bolt.  It sheared off in a match. I sent it back and they replaced it with the hybrid bolt: It is cut for glock or colt mags and has 2 bolts holding the gaskey facsimile on.  

[wgj3]

This is some great info! Thanks for sharing your experience.

[mikeor70]

On 9/30/2016 at 10:43 AM, Southpaw said:

While I can't speak from personal experience since I don't have that same block or a PSA bolt, everything I've heard is that the PSA bolt is just a normal 9mm bolt with a Glock mag cut so it will work with both Glock and Colt mags. That's why they call it "hybrid", to also further confuse people and make it sound like there's something different about their bolt from all other 9mm bolts.

Here is what I found out.  I ordered and received a 10.5" PSA upper complete with "hybrid" bolt.  I put it on my SBR lower with Promag block.  The two do not play well together....unless you're interested in malfunction clearing drills.  What appeared to be happening is that the PSA bolt was pushing the ejector out of the way on the back stroke.  Several times, the spent case would stay attached to the bolt face.  Repeated cycling would not eject the spent case.  The brass has a nice scratch alond side the case pretty much confirming the ejector was rubbing the side of the case and not making contact with the head/base of the case.  Of course, I did not have a standard bolt and upper to compare it to at the time, but I did put the two side by side when I got home.  It seems as there is a slight difference in the machining of the lower bolt surface.   When I called PSA, it was almost as if the customer service rep was reading from a script.  When I asked if a standard 9mm bolt would function in their upper, he said that it was "against company policy" to suggest trying that and that their uppers were "designed to work with their lowers" as indicated on their website.  I took that as a green light to try a standard bolt.  So I swapped the "hybrid" bolt with a standard ramped bolt and headed back to the range.  It cycled 3 different 124gr hand loads and some 115gr Remmington like a champ.  No issues as all.  As a side note, I ended up using an AR10 spring and 4.6oz carbine buffer for the least amount of felt recoil.  Comparing the actual uppers side-by-side, there is definitely some differences in geometry.  When mating the PSA upper, with PSA bolt, to my lower, I would have to push both pins in at the same time.  Pinning the front, closing, then pinning the rear was a no-go.  So, it seems as if a Promag block will not jive with a PSA Hybrid bolt.  I can't speak for any other block manufacturers.  I will say that after 20 min wait on hold with PSA, that they did offer a full refund minus return shipping.  So, there's my experience.  Hope it helps.  

 

I can post some side-by-side pics if anyone is interested.