I imagine this has been beat to death before, but I really can't find a decent answer searching the archives.

My issue is that I have a Bushmaster BAR-10 A2, which has been long discontinued, and I would love to make it into a flat top. Problem is that nobody makes a totally interchangeable upper receiver for it, so that option is essentially out. I know RRA makes one that is similar, but that would entail complete new upper internals as well, and would leave me with a paperweight of a complete A2 upper receiver that would be useless to me as well as worthless on the EE.

I know 'smiths in the 80's rolled their own flat tops, just wondering if anyone has any experience with this...if it is really feasible, or if I'm just a moron.

Can you explain to we non-Bushmaster folks what is so unique about that upper?  Basically, ANY standard upper (flat, A2, whatever) should work with ANY standard barrel.

It can and has been done.
Given the way you asked the question I am guessing it is not feasible for you to do.
Have you contacted Bushmaster to see if they might have any flat top uppers?

.308 models use longer uppers and lowers for the longer .308 cartridge, that do not interchange with "standard" AR-15 uppers and lowers.

It looks like the DPMS pattern.
So you say that one of the plentiful DPMS 308AR flat top receivers would not work ?

I see also that Bushmaster did produce some flat top versions, maybe they have some old stock that they would sell ?
The smiths "rolling their own" may have been cutting down the carry handles before BM made the flat tops available ?

He's talking about a gun that was manufactured back in 2003-2004.  It is NOT compatible with the DPMS receivers.  Those are the current Bushmaster .308's, which are an entirely different animal.  When I say entirely, I mean receivers, bolt carrier, bolt, barrel extension, magazines, & small parts.  It was actually a Rock River Arms design that they chose to license to Bushmaster, and is discontinued.

Bushmaster BAR-10A2 Version


Rock River Arms eventually re-designed it after reviewing the problems Bushmaster encountered, and went with a standard-type charge handle, but it is much longer than any other AR10 or DPMS handle (those are compatible with each other)

LAR-8



The new Bushmaster is on the market because of the alliance with the Freedom Group and Cerberus, so they can source DPMS parts, but use 4150 CMV Bushmaster barrels and lowers with standard trigger guard options, unlike the DPMS fixed trigger guard.

Bushmaster MOE Carbine



DPMS 308 Carbine

So it's a bassturd design best kept (or sold off) as is ?

Thanks for the excellent clarification. Yes, the rifle really isn't compatible with anything in production, short of swapping out the upper entirely. Bushmaster hasn't produced the rifle for some time, and I seriously doubt they have uppers lying around for their forgotten bastard child.

I know a few months back there was a guy trying to sell a BAR 10 upper on the EE, but he spray-bombed it and was asking what I thought to be a little much for an upper that would only function on a few older bushmaster rifles...in retrospect, perhaps I should have just refinished that one, but I still would end up with a worthless upper.

I guess the question moreso would be, has anyone here chopped off an A2 carry handle and fitted a rail blank to a upper? And if so, do you have any tips/sugguestions? I have plenty of tools at my disposal, and would like to think if it's possible I could do it myself...

I didn't pick up on the "10" reference in the model number.  That, of course, changes things...

So...knowing it can be done...has anyone here done it? Any tips?