BCM Prototype upper?

[Stickman]

Bought one out of curiosity just to see for myself after waiting for two years to get it released. Some original skepticism and concerns aside...

Initial impressions - absolutely great! Perfect machining, finish, anodizing, and dry lube inside.
Overall design, in my opinion is a step or two ahead of a mil-spec upper. For some reason it feels lot more streamlined and compact around a brass deflector and a forward assist.

Haven't assembled it into the complete yet, but barrel extension seems to be ultra tight - much, much, tighter than a standard BCM upper and definitely will require some heat to install.

Area around the port cover door is very thick, so is the area just below a barrel nut threads. Geissele rails with lower anti-rotation tabs (MK13/14) won't fit out of the box and will require tabs to be filled off approximately 1.5-2mm on each side. Rails like Centurion might or might not fit, as the area just above barrel nut (and below the area where BCM MCMR anti-rotational tabs install) also appear slightly thicker than a mil-spec. For the reference see post #129 for BCM rail tabs location: https://www.m4carbine.net/showthread...41#post2783841

If you're not planning to move a handguard around it's probably worthwhile to file tabs to size.

Fit to lower (again try fit for testing) - feels to have less slop than a regular BCM upper (good improvement), but not medium-tight like some Aero uppers. No concerns regarding a fit.

It feels like a solid product. No concerns with aesthetics. After some initial concerns about a rail fitment, I think it's a winning product and see no reason to buy other higher priced mil-spec uppers like a regular BCM, COLT, LMT, DD over this.

Thank you for making a quality post to add in your thoughts and actually having product in hand. When I read your post, I grabbed a Centurion Arms rail and trying fitting it to the BCM improved upper. It is ALMOST close enough to tap it into place. I'm going to heat the rail and see if it will, but my guess is that it will take a couple swipes with a file. If I can find my calipers, I'll pull some measurements.

[Eurodriver]

When will these be shipping? Has BCM had them in stock? I noticed Brownells has them available for “pre-order”

ETA: Clarifying that I’m asking about the upper alone not assembled uppers from BCM.

BCM ain’t got that good good RGP or Centurion CHF goodness

[Stickman]

When will these be shipping? Has BCM had them in stock? I noticed Brownells has them available for “pre-order”

ETA: Clarifying that I’m asking about the upper alone not assembled uppers from BCM.

BCM ain’t got that good good RGP or Centurion CHF goodness

BCM had a bunch for sale and they went quick. If I talk to Paul I'll find out when they are expected back in stock. I know that I want to order a few for builds. Which makes no sense as I'm already sitting on a bunch of uppers, but I feel that need for new cool toys!

[Outlander Systems]

It sure would suck if you told Paul people were asking for 16” Recce URGs with Mk2 uppers...

BCM had a bunch for sale and they went quick. If I talk to Paul I'll find out when they are expected back in stock. I know that I want to order a few for builds. Which makes no sense as I'm already sitting on a bunch of uppers, but I feel that need for new cool toys!

[Eurodriver]

BCM had a bunch for sale and they went quick. If I talk to Paul I'll find out when they are expected back in stock. I know that I want to order a few for builds. Which makes no sense as I'm already sitting on a bunch of uppers, but I feel that need for new cool toys!

Have you talked to Paul

I have everything I need for a badass upper except the upper itself. I’m not usually a fan of new things but BCM uppers are something I trust. It’s crazy you can’t find these *anywhere*.

PS did we just become internet friends?!?

Edit: Got one. Just waiting on the 9” MCMR now. Very excited.

[naturerancher]

Have you talked to Paul

I have everything I need for a badass upper except the upper itself. I’m not usually a fan of new things but BCM uppers are something I trust. It’s crazy you can’t find these *anywhere*.

PS did we just become internet friends?!?

Edit: Got one. Just waiting on the 9” MCMR now. Very excited.

Where did you find one? They are listed for pre-order at Brownells and I can't find them at all on BCM's site any more.

I found out about these one day before they went out of stock in Dec 2019 and have been wanting to try one out.

[Biggy]

I wonder if this machined out cavity in the MK2 upper, is for an anti-rotational insert that mates to a new *hard use* handguard BCM is working on?

[georgeib]

I wonder if this machined out cavity in the MK2 upper, is for an anti-rotational insert that mates to a new handguard BCM is working on?

Sure looks like it...

[MistWolf]

BCM doesn't have the stripped MkII uppers on their website

[jerrysimons]

I wonder if this machined out cavity in the MK2 upper, is for an anti-rotational insert that mates to a new *hard use* handguard BCM is working on?

Possible. My opinion is it is that cut out is like the flutes on the forward assist housing and is there to compensate for the increased weight of the areas they beefed up the dimensions. With the page off the BCM site now I can't double check but I think I remember reading one of the design goals was to increase rigidity and strength for little to no weight increase over a mil-spec profile upper.