I think I've fixed LRBHO on my Poverty Pony PSA AR9 with a Multical lower and Endomag PMag conversion.
The problem was two fold. First, the milspec bolt catch did not move up high enough to actually catch the G4 PSA AR9 bolt. Removing a little material from the catch solved that. The catch only moved up 1.5 mm when depressed manually. After a little Dremel work (actually the cheap Harbor Freight rotary tool), I was able to get the bolt catch to move up an additional 2mm. This solved the problem of not even being able to lock the bolt manually. Prior to this, I might have been able to lock the bolt back manually, but as soon as you set the rifle down, or looked at it cross eyed, or the wind blew, the bolt would release to battery.
I thought I won the battle there until I slapped an empty mag in, and cycled it. Still wouldn't lock back. The design of the Endomag allows a little too much play to fully engage the bolt catch. A 1/4" slice of brass sheet took care of that.
I've attached pics, they might be hard to follow, since the site makes uploading pics in any reasonable order difficult.
First pic shows you the trainwreck my bench is right now.
Sixth pic shows factory lift of bolt catch at 5mm on this ruler. Actually 9mm, due to the 4mm space before the beginning of the scale.
Second and seventh pic shows the increased lift of the bolt catch after modifying the bolt catch. A little over 2mm gain.
Third pic shows the fabbed brass piece to correct the mag follower issue. Same with fourth and fifth.
I've cycled it a ton of times by hand, and it works every time. The only downside is the 30th round does not feed. LRBHO occurs at round 29. I tried changing the length of the brass piece, but can't find the sweet spot so far. There's either one round left, or it doesn't work. I'll continue to work it until I get it though. For now I can live with it.
The problem was two fold. First, the milspec bolt catch did not move up high enough to actually catch the G4 PSA AR9 bolt. Removing a little material from the catch solved that. The catch only moved up 1.5 mm when depressed manually. After a little Dremel work (actually the cheap Harbor Freight rotary tool), I was able to get the bolt catch to move up an additional 2mm. This solved the problem of not even being able to lock the bolt manually. Prior to this, I might have been able to lock the bolt back manually, but as soon as you set the rifle down, or looked at it cross eyed, or the wind blew, the bolt would release to battery.
I thought I won the battle there until I slapped an empty mag in, and cycled it. Still wouldn't lock back. The design of the Endomag allows a little too much play to fully engage the bolt catch. A 1/4" slice of brass sheet took care of that.
I've attached pics, they might be hard to follow, since the site makes uploading pics in any reasonable order difficult.
First pic shows you the trainwreck my bench is right now.
Sixth pic shows factory lift of bolt catch at 5mm on this ruler. Actually 9mm, due to the 4mm space before the beginning of the scale.
Second and seventh pic shows the increased lift of the bolt catch after modifying the bolt catch. A little over 2mm gain.
Third pic shows the fabbed brass piece to correct the mag follower issue. Same with fourth and fifth.
I've cycled it a ton of times by hand, and it works every time. The only downside is the 30th round does not feed. LRBHO occurs at round 29. I tried changing the length of the brass piece, but can't find the sweet spot so far. There's either one round left, or it doesn't work. I'll continue to work it until I get it though. For now I can live with it.
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