Since one of my AR9 carbines in built on a Glock-compatible lower, I thought it might be fun to build up an upper in .40S&W, since the lower would accept the mags without modification.
I picked up an 8.5" Kaw Valley Precision .40S&W barrel from JobBob's Outfitters, along with a New Frontier Amory .40 Bolt Carrier Group. I also swapped out the Spikes ST-9X 7.7oz buffer for a heavier 8.4oz one to counteract the extra umph of the .40. I decided on a regular A2-style flash hider, rather than one of many linear comps. I paired it with a generic carbine-length free-float tube, a set of HK sights, and a Primary Arms red dot.
The final product:
Close-up of the upper:
Hard to see, but the bolt is marked ".40S&W" just to prevent any mix-up.
Here she is ready to rock:
And some testing fodder to see how she runs.
I tried it with 165gr WWB and Federal 185rg. Note that the Federal (right) is a little longer and has a more rounded ogive. That will manifest itself later.
The Federal fed flawlessly, and I used it to sight the red dot in, POA at 25 yards. What surprised me was how easy it was, once sighted-in at 25 yards, to consistently ring the 18" gong at 100 yards. Pretty much POA/POI.
When I switched to 165gr WWB, though, I started to run into hiccups. The shorter/flatter round made of quite the jump into the barrel.
I had some FTF's that wedged into the top of the chamber mouth. It's a pretty good "shuunk" as the bolt slams forward. Hard enough to compress the rounds. Bam, bam, bam, bam, shuunk.
Occasionally you could feel the round sliding against the top of the chamber mouth even on the rounds that fed.
It's really fun to shoot. I like how it runs on the 185gr, and the .40S&W really thumps the falling steel plates on the range. I want to try some other rounds as well, maybe something without a flat profile. I realize .40S&W is the devil's round in this forum, but if you have a Glock-compatible lower, I recommend trying it out for yourself.
Oh, and here's the way it looks in normal 9mm attire.
I picked up an 8.5" Kaw Valley Precision .40S&W barrel from JobBob's Outfitters, along with a New Frontier Amory .40 Bolt Carrier Group. I also swapped out the Spikes ST-9X 7.7oz buffer for a heavier 8.4oz one to counteract the extra umph of the .40. I decided on a regular A2-style flash hider, rather than one of many linear comps. I paired it with a generic carbine-length free-float tube, a set of HK sights, and a Primary Arms red dot.
The final product:
Close-up of the upper:
Hard to see, but the bolt is marked ".40S&W" just to prevent any mix-up.
Here she is ready to rock:
And some testing fodder to see how she runs.
I tried it with 165gr WWB and Federal 185rg. Note that the Federal (right) is a little longer and has a more rounded ogive. That will manifest itself later.
The Federal fed flawlessly, and I used it to sight the red dot in, POA at 25 yards. What surprised me was how easy it was, once sighted-in at 25 yards, to consistently ring the 18" gong at 100 yards. Pretty much POA/POI.
When I switched to 165gr WWB, though, I started to run into hiccups. The shorter/flatter round made of quite the jump into the barrel.
I had some FTF's that wedged into the top of the chamber mouth. It's a pretty good "shuunk" as the bolt slams forward. Hard enough to compress the rounds. Bam, bam, bam, bam, shuunk.
Occasionally you could feel the round sliding against the top of the chamber mouth even on the rounds that fed.
It's really fun to shoot. I like how it runs on the 185gr, and the .40S&W really thumps the falling steel plates on the range. I want to try some other rounds as well, maybe something without a flat profile. I realize .40S&W is the devil's round in this forum, but if you have a Glock-compatible lower, I recommend trying it out for yourself.
Oh, and here's the way it looks in normal 9mm attire.
