Barrel blocks

[Matt P]

Thinking of using a barrel block for my next build with a delrin sleeve, thoughts for and against will be in 6BR or BRX and be around the 22 pound mark.
Those using blocks how much "crush" is required ??
Thanks
Matt Paroz

 

[Dave Tooley]

Delrin is plastic and has about 11 times the thermal expansion of steel. Proceed at your own risk. Phenolic has worked well as a replacement material.

Dave

 

[jackie schmidt]

Expansion of Sleeves

My Rail Gun's barrel is mounted in a block that I converted to a non metalic sleeve last spring.

I am going back to metal to metal, probably a simple V-Block. The material I used is called Thorplast, a high impact non metalic material produced by Thordon. It's primary purpose is bushings made for high impact loads where lubrication is not feasable.

I had alot of trouble at the Nationals with point of impact moving, sort of in a random pattern, even tho the Gun never moved. I think the barrel is shifting ever so slightly in that sleeve as heat builds.

I can get Micarta, which is Phenolic. But, considering the two shooters who won both yardages at the Nationals use a simple block, the sleeve might be one of those solutions to a problem that does not exist.........jackie

 

[Bob Kingsbury]

Jackie, your opinion

The current wisdom is a v on the lower half and flat on top. Obviously
this works, but I wonder if the flat on top, not being self centering,would
allow a scope mounted to it to shift laterally. I would think that a top
plate with a v would give better stability and allow better holding power
with lower torque on the bolts. Though small, the additional contact
could allow more heat to disipate to the upper plate.

 

[jackie schmidt]

Bob

Many Rail Guns are not quite like a 1000 yard Rifle. My scope mount is attached to the bottom half of the block, not the top.

I think you make a good point. Under the shock of recoil, that top could move ever so slightly, while still applying pressure to keep things in alignment in the V. If the scope is mounted on the top half, and it does shift any at all, the results on the target could be less than desirable.........jackie

 

[Don]

Many Rail Guns are not quite like a 1000 yard Rifle. My scope mount is attached to the bottom half of the block, not the top.

I think you make a good point. Under the shock of recoil, that top could move ever so slightly, while still applying pressure to keep things in alignment in the V. If the scope is mounted on the top half, and it does shift any at all, the results on the target could be less than desirable.........jackie

Jackie, I do not think that happens because you would notice a point of aim shift when looking thru the scope after a shot, the x-hairs would be on a different spot than the same point previous to the shot............Don

 

[Lynn]

Matt
You don't need to tighten the capscrews with all your might just snug them up and your all set.
I bed the top and bottom of my blocks with J-B Weld so the barrel has full contact and doesn't wick away any heat.
Waterboy

 

[Matt P]

Thanks all for your in-fo, looks like the delrin idea might not be the way to go, how long are blocks normally ?? The barrel will be a straight 30" long 1.25" diameter, and are you running the block close to the action or further along towards the middle of the overall weight of action and barrel ???
Thanks again
Matt Paroz

 

[jd12]

I built a barrel block .284 this past winter and have been very happy with the way it shoots. Mine has a round honed hole with .003 press fit.

 

[jd12]

more pics