I drink LMT koolaid, but I’m not big on the changing barrels thing. But it does work and is a cool feature if you like that. I have enjoyed shooting Colt-LMT-Vltor Monolithic uppers, they were all very good. But I still dig my 11.5 with RISII. All quality builds. LMT makes the 10.5 and 12.5. I would cut one down, seems like a waist of money and asking for trouble.
Buy the barrel you want, then build the gun around it.
LMT only makes the 12.5 for piston setups. I really don’t understand why LMT makes a 10.5 and a 14.5 but nothing inbetween for DI setups. This is why I’m on the fence when it comes to picking up a lmt mrp. It’s too much work and risky to cut a 14.5 inch barrel down imo.
What’s too risky? There are plenty of competent shops that can do the work and generally their thread and crown results are better then factory.
I own two Noveske rifles with VIS and they are heavy suckers. That’s all I am going to say.
I was trying to consider weight, even if I dont need it to follow the new lightest AR possible trend.
Two options Im looking at,
keymod 12" VIS is 22.4 oz (or the slimline which might weigh less)
http://www.vltor.com/product/vis-km-polylithic-upper-with-keymod/
MUR with 13" geissele is (10oz + 12.8 w/ nut) = approx 22.7 oz
I’ve got a couple of LMT MRP Uppers and they are nice overall.
But, they require LMT specific barrels. You might be able to have a standard barrel modified to work with the MRP system but that takes time & $$$.
The Vltor VIS, Mega Arms, and the Aero Precision COP uppers can use standard barrels. So while they aren’t as “quick change” capable as the LMT MRP, the ability to use any AR15 barrel makes up for that in part.
And it isn’t very hard to change out a barrel on a Daniel Defense RIS II or similarly equipped upper either.
I like my MRPs but if starting over, I’d rather have the Mega Arms or the Vltor for their use of standard barrels.