Pointers for homemade barrel vise blocks

[Z-Michigan]

I want to swap out the A2 flash hiders on a couple of my AR-15s. I originally bought an upper receiver block for this purpose, but before using it I did some more research and found that holding onto the receiver is not recommended for changing muzzle devices, in part because some builders torque a flash hider to the same level as the barrel itself.

So, I believe the best way to proceed is to clamp the barrel itself near the muzzle. I've looked into commercial barrel vises and don't like most of them. My concerns are (1) cost, as I'll only be using this a few times, and (2) commercial ones are often metal and I don't want to mar or crush the barrel.

So, I'm thinking about making some vise blocks out of wood to hold the barrel in place inside a conventional vise, without marring it and hopefully without crushing it. Barrel OD will be .75" typically, and I was thinking of taking two flat blocks of 1" wood, drilling a hole where they meet (while clamped together) so that each one has a channel that can fit around the barrel, finishing that surface with varnish to make it stickier, and using that.

Here are my questions:
1) Any reason this wouldn't work?

2) Should I use hardwood or softwood? This ties in with...

3) If I make wooden vise blocks like described, is there any chance I would still crush the barrel? I definitely do not want to harm accuracy of the rifles, and I've read that using aluminum blocks can potentially change the bore shape where the barrel has been clamped, which is bad.

4) Will I be better off with the channel as a semicircle or a right-angle "V"?

 

[Mac's Precision]

Let me put your mind at ease. You aren't going to crush your barrel. I use a commercially made barrel vise and it applies 10,000 pounds of pressure to the blocks. It has enough pressure to literally crush the blocks if I want to. The blocks will give before the barrel will crush. I normally apply pressure till I hear the wood starting to crush and then add some more.

Now...as to hard or soft wood. Use Oak or Maple. I use Maple as the grain structure is tighter and it doesn't have such a chance of splitting. Drill your hole across the grain. If you drill with the grain it will split. You want the grain running perpendicular to the bore.

You want to drill a round hole about 1/32 smaller than barrel outside diameter. Now go to the nearest bowling lane and buy a bag of rosin used on bowlers fingers. Dust the blocks with rosin before applying them to the barrel. Put your blocks in the vise and crank it up for all your worth. You want it tight. Very tight. Marks on the barrel come from slipping. The rosin and a TIGHT fixture will prevent slipping.

When I remove receivers from barrels I encounter some that are VERY tight or installed with loctite. It takes a strong barrel press...Hard blocks...lots of hydraulic pressure....a very substantial action wrench and sometimes a cheater pipe to get them loose. A weak block set and loose clamping pressure with no rosin is a recipe for scuffed finishes.

Cheers
Mac.

 

[dfariswheel]

You can also make good barrel blocks by using epoxy glue to make a perfect fit on the barrel.
To do this, you coat the barrel with wax or another good release agent and cast one block at a time.

Start out with two blocks of wood clamped in a vise or one block of wood.
Drill a hole slightly larger than the barrel diameter through the blocks, then either separate the two or cut the one piece in half.

Wax the barrel well, then put epoxy glue in one of the blocks, clamp to the barrel and allow to harden. Remove that block and do the other block, then after curing for 24 hours, clean the blocks out with paint thinner to remove the release agent.
Apply rosin and you're ready.
Note that this only works for most barrels if you use a real hydraulic gunsmith's barrel vise.
Most gun barrels are too tight to use any size of shop vise, including the 100 pound monster vises. Even they simply can't grip tight enough for most barrels. Try to remove most gun barrels with a shop vise and the barrel will spin in the blocks, stripping the finish.

Flash hiders and muzzle attachments are usually not that tight, however, note that many rifles built during the assault weapon ban had muzzle attachments that are either blind pinned, welded, or brazed on and WILL NOT screw off. Make sure you don't have one of those.

AR rifles have at least three tension washer types.
Type one is a standard split tension washer.
Type two is a "peel" washer that is layers of washers put together. You peel off washers to allow aligning the A2 type flash hider.
Type three is the "crush" washer. These you simply turn the barrel attachment until tight, then force it farther until the hider aligns properly.
These crush washers are ONE TIME use only. If you break tension by removing the hider, you need a new washer.

 

[Z-Michigan]

Many thanks to both of you for the very helpful replies. It looks like I'm on the right track.

No plans to replace any barrels for now.

Thanks for the heads-up on pinned devices. I only have one AWB-era gun and I'm just going to shoot it til the barrel wears out. The rest have either peel or crush washers. I have several brand new crush washers ready to go for the new devices.

I am not familiar with a "standard split tension washer" - where would I see one of these? Do you mean the same sort of design that I would get at the hardware store?

While I have your attention - how exactly do you get a peel washer to peel? Why doesn't someone just sell ultrathin washers in stacks instead of forcing you to dismantle a single washer made up of the same ultrathin (0.002" I believe) washers?

 

[Fleet]

I am not familiar with a "standard split tension washer" - where would I see one of these? Do you mean the same sort of design that I would get at the hardware store?

Yup, a split ring lock washer just like from the hardware store.

While I have your attention - how exactly do you get a peel washer to peel? Why doesn't someone just sell ultrathin washers in stacks instead of forcing you to dismantle a single washer made up of the same ultrathin (0.002" I believe) washers?

It's just like getting the backing off of double stick tape, only harder.