NordicG3K,

I've been thinking about your "rule-breaking" 10mm Oly-style-Upper-but-mid-magwell setup, and I was wondering about a new application, namely using the caliber 7.62x25.

Originally, when setting my 7.62x25 AR idea in motion, I was planning to go with a RRA (Colt-Style) design, since the magazines I've chosen (PPS-43) need the mid-magwell design, owing to the curved mag.  However, your 10mm AR has shone light in a new direction: using the mid-magwell Colt-style setup with (an originally designed to be front-magwell) Oly Arms upper.

IIRC, the 7.62x25 cartridge is even longer than the 10mm, so logically, that would make the non-issue of the cartridge "jump" even less of a non-issue with the longer case (or is that *more* of a non-issue? :))

What do you guys think?

Reason I'd prefer the Oly design is threefold: 1) You can get different weight bolt carriers with Oly, and I think I'll need a heavier one for the 7.62x25 cartridge, 2) this uppper will go on an Oly lower, so there will be parity in manufacturers, and 3) none of that hammer bounce problem that comes with the Colt-style uppers).

Corvus, sounds like an interesting idea!  About the only thing that jumps to mind that you'll have to consider is how much a standard Colt 9mm magblock can be opened up (front to back).  Using the modified Uzi mags I had to open up the magwell just about as far as it could go.  The magwell body is aluminum, but the feed ramp is steel and has a peg-style base that sits in a hole in the magwell body.  If I were to cut any deeper in the front I would have cut into the hole that held the peg-base of the feedramp.  You might be able to remove more material from the back edge of the magwell opening, but if I remember correctly there wasn't a lot left to remove there either.  Maybe someone has a Colt 9mm magblock they can lend you just to take some measurements. Good luck with your project and keep us informed!

[url=http://www.bren-ten.com][img]http://image1ex.villagephotos.com/1214950.jpg[/img][/url]

[b][i][red]10mm-aholic:[/red][/i][/b] S&W 1006, S&W 610, Colt Delta Gold Cup, T/C Contender, Olympic Arms CAR-97/10mm, Bren Ten SM, Bren Ten SFL, Ruger Buckeye, Glock 20, iAi Javelina, Bren Ten MP, Paraordnance P16.40 LTD 10mm Conversion, S&W 1086 & S&W 1076

Which company's one-piece magwell did you use?  Maybe there is a difference between the various one-piece magwells that I can take advantage of.

Thanx!

I used an actual Colt made one-piece magblock.  In addition to those made by other manufacturers you could also look at one of the older Colt two-piece units.  I'm not sure exactly how they fit in the magwell, but it may give you some other alternatives to work with.

[url=http://www.bren-ten.com][img]http://image1ex.villagephotos.com/1214950.jpg[/img][/url]

[b][i][red]10mm-aholic:[/red][/i][/b] S&W 1006, S&W 610, Colt Delta Gold Cup, T/C Contender, Olympic Arms CAR-97/10mm, Bren Ten SM, Bren Ten SFL, Ruger Buckeye, Glock 20, iAi Javelina, Bren Ten MP, Paraordnance P16.40 LTD 10mm Conversion, S&W 1086 & S&W 1076