Modern Sporter - Build Discussions

[tbough]

You cannot use a Magpul BEV block, the geometry of the front of the upper interferes, as the front takedown pin is quite a bit lower than would exist on an ar15

The Bev block might work if you drive out the pin holding the center part in, then adjust the distance between the "bolt head" and the front takedown pin hole. It's then locked up firmly as designed except that the rifle bolt won't engage in the back of the Bev block.

[ATRS Shaun]

The Bev block might work if you drive out the pin holding the center part in, then adjust the distance between the "bolt head" and the front takedown pin hole. It's then locked up firmly as designed except that the rifle bolt won't engage in the back of the Bev block.

If you modify the BEV block then yes, I expect it could be made to work, you'll still be able to get the bolt carrier to engage on the back of the BEV block as that's still in line with the bore.

I'll see if I can snag a picture later... If anybody wants a BEV block to screw around with I've got one that I'll sell for forty bucks cash (no box). I opted to pick up a reaction rod for at home rather than trying to modify the BEV.

[jiffx2781]

...

[greg olmstead]

What about just drilling a hole further down on the bev block to match the front pin on the ms

[JIP911]

I thought RR's transfer all the torque to the index pin when cranking down the barrel nut? Would a panther claw work with your upper or same issue as the Bev block?

[greg olmstead]

I thought RR's transfer all the torque to the index pin when cranking down the barrel nut? Would a panther claw work with your upper or same issue as the Bev block?

The only torque transferred would be how much resistance there is on the threads between them and the barrel nut.

Using good grease on the threads will eliminate most of it. Most of the index pin failures associated with the reaction rod are due to faulty index pins or improper use of the tools.

A reaction rod keeps all the stress out of the upper eliminating flex on the upper. Think about it. How would aluminum be stronger than the hardened stainless steel of the index pin?

I'd rather have to replace an index pin that shears vs an upper that flexed and cracked.

[griffin86]

I thought RR's transfer all the torque to the index pin when cranking down the barrel nut? Would a panther claw work with your upper or same issue as the Bev block?

As long as you keep it under 80 ft lbs you will be fine, I’ve never needed more than 45 ft lbs though.

[propliner]

Using proper grease, especially on the rear side of barrel nut will reduce most of the torsion on the upper and pin.

[Brianma65]

I’ve been using 35 ft lbs , as to manufacturers spec.

[KePet]

Why do people always try to complicate things.

A reaction rod can be bought CHEAP from Brownells or TNA.

Not trying to complicate things. It’s just that some of us already own BEV blocks. If possible, why not use a tool that you already own. I’m not above buying a reaction rod - probably the cheapest part that I’ll be buying for this build - I just didn’t realize when I made the comment that a BEV block wouldn’t work.