I’ve got a VLTOR MUR (part of an ongoing build), and I just picked up a Brownell’s action block set. To my dismay, it seems not to fit around the MUR. I guess I should have realized that the extra thick walls would alter the external dimensions, but I just never thought about it. It doesn’t matter too much, in the short term, as I bought this to do a few things with some of my forged uppers, but I’ll need another solution for working with this MUR. Is there another solution other than the DPMS white block with pins? Those seem scarce. What have the rest of you done? Any info would be appreciated.
and I think the dpms tool works also not for sure.
OK, I’m a bit of an idiot! After posting this, I go look at GotM4’s tool sticky and learn a little more. The question remains though. Are there other options?
the action blocks don’t fit VIS, Mur, or AR10 uppers, so go buy a small white cutting board, cut it in half, put the upper in sideways using the cutting board to buffer your upper rail against the vise jaws and the cutting board bottom should brase against the underside (you can also use wood) then do your install, your just doing it sideways.
The DPMS Upper receiver block does in fact work. I’ve used it without any problems on my VLtor MUR upper.
Brownells has them is stock:
I know you said other alternatives other than DPMS, but in my opinion it’s a great tool
i’ve always used softwood blocks. i’ll see if i can dig up pictures and edit. MURs are especially not-going-to-break. i checked dimensions constantly back when i first started building, but after so many builds and never any warping/cracking/crushing/etc, i don’t even check anymore. just squish it from top to bottom. i cut doug-fir to fit tight between the takedown lugs, the strongest points on the underside.
here’s one i found of a sundevil getting a vtac, which i torqued to about 70ftlbs. if i find a better pic i’ll edit.
Use barrel blocks like the military manual specifies instead?
i only use barrel blocks for FSB, crush washers and perming MDs… cant remember why i dont use them for barrel nuts, but i had a great reason once upon a time.
ETA: i remember: using barrel blocks for barrel nuts that need the shit torqued out of them can fuck up the index pin slot in the receiver- puts all the stress of the turning on that slot.
I think you have that backwards, using the action block to tighten a barrel nut allows the barrel to twist while tightening thus placing pressure on the index pin slot. This is why uppers that are assembled using a receiver block can require so many clicks to the left on the rear sight to zero. Ask me how I know. 
i guess, in the end, if you want to REALLY do it right, you use both.
my methods have worked for me… we all have our own experiences, though.
bkb0000 is dead on, especially about the part of not using bbl blocks for bbl nuts. This puts a hell of a stress on the alignment pin and slot in the upper receiver. At least that’s how I see it.
Here is my preferred method. Complete with VLTOR MUR upper in the pic as well.
I do NOT SOLELY use this upper receiver block however. I use it IN CONJUNCTION WITH a wood block on the TOP of the upper receiver.
IOW’s, rotate the pictured assembly 90 degrees, and throw a wood block in between the vise jaw and the flat top of the upper receiver.
Voila… Strong, simple, and safe. (doesn’t mar up the finish on your refeiver like that stupid Brownells clamping block either). Best method out there IMO…
Thanks everybody. Helpful information here.
The problem with barrel blocks is that the barrel and upper receiver have a tendency to rotate when tightening the barrel nut.
i generally have to incorporate some other component with my shop-made blocks. stagger them, and roll the FSB behind the stagger for crush washers, or behind the receiver for un-tapped set-screw or clamp blocks. most of the load is still on the barrel, just gives it enough help to not rotate
I have one of these. Had problems with the DD Lite Rail barrel nut and “bolt ring”. Had to grind down the DPMS block a bit on one end.