BCM Prototype upper?

[26 Inf]

I’ve read through a lot of this thread and I don’t get what this upper is. So what is it?

The first thing you might notice is that the forward assist is moved forward - this especially helps lefties run the changing handle.

The next thing is that they have beefed up the left forward side of the upper, nominally opposite the ejection port. This is reportedly to minimize the flex in the upper because of the ejection port.

I'm not sure how much that flex actually impacts practical accuracy. I'm ssuthere are shooters and rifles that might benefit, I have enough MOA rifles that I don't see much utility in replacing existing receivers.

Hopefully, once they get going with them, I'll be able to buy blems for new builds, and will happily do so.

ETA: how does sure there turn into: ssuthere?

[Wake27]

The first thing you might notice is that the forward assist is moved forward - this especially helps lefties run the changing handle.

The next thing is that they have beefed up the left forward side of the upper, nominally opposite the ejection port. This is reportedly to minimize the flex in the upper because of the ejection port.

I'm not sure how much that flex actually impacts practical accuracy. I'm ssuthere are shooters and rifles that might benefit, I have enough MOA rifles that I don't see much utility in replacing existing receivers.

Hopefully, once they get going with them, I'll be able to buy blems for new builds, and will happily do so.

ETA: how does sure there turn into: ssuthere?

Isn't the extra material supposed to also help in case of a kaboom too?

[Biggy]

Theoretically, I believe a more rigid upper receiver should both enhance accuracy and extend bolt life to some degree. To what degree that is, all things being equal, I don’t know. Added protection in case of a kaboom would is a good thing. Moving the FA location forward some is probably also a good thing. I believe when they went to the flat top receivers they lost some of the rigidity they had with the intregal carry handle receivers. I doubt BCM would have went to all the trouble and expense, if these receivers didn’t provide significant enough benefits over the standard receivers.

[lysander]

Isn't the extra material supposed to also help in case of a kaboom too?

If you really what to help in the case of an over pressure event, the best thing is to drill a hole somewhere to vent to pressure off, rather that attempt to contain it. And the hole should be somewhere the directs the gas away from the shooter.

[opngrnd]

If you really what to help in the case of an over pressure event, the best thing is to drill a hole somewhere to vent to pressure off, rather that attempt to contain it. And the hole should be somewhere the directs the gas away from the shooter.

The magazine well and ejection port, to a degree, act as such. Wouldn't a more rigid upper receiver help?

[IKnowNotEverything]

I believe the Vltor MUR is the best receiver currently in production, though they have some quirks. I seem to remember Iraqgunz had a kaboom and had nothing but praise for how well it contained everything.

This looks like a nice improvement over traditional units, and would allow offset irons and the LMT ambi lower to function correctly while having a similar effect on rigidity. +1 for innovation. I plan to use one on an upcoming precision build.

[opngrnd]

If they go slightly undersized on the barrel extension as on their BCM4 upper receivers, I can see myself becoming a bit more interested.

[Biggy]

[QUOTE=taekwondopreacher;2783807]If they go slightly undersized on the barrel extension as on their BCM4 upper receivers, I can see myself becoming a bit more interested.[/QUOTE

I have absolutely no reason to think they won’t. I am in for three of them as soon as they are available.

[Robb Jensen]

They’re pretty nice I’m using one on my 2gun rifle.

[jerrysimons]

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I believe the Vltor MUR is the best receiver currently in production, though they have some quirks. I seem to remember Iraqgunz had a kaboom and had nothing but praise for how well it contained everything.

This looks like a nice improvement over traditional units, and would allow offset irons and the LMT ambi lower to function correctly while having a similar effect on rigidity. +1 for innovation. I plan to use one on an upcoming precision build.

The pics of the forward assist I have seen one these pre production versions would not be compatible with LMT MARS-L or LWRC IC ambi lowers. The forward assist housing looks to interfere with the right side paddle.