Barrel Blocks??

L

Leeroy

Machinest / Gunsmith
G'day Gents..

I've had a few customers ask me about barrel blocks recently.. Not having built a rifle with one as yet i was thinking on how best to clamp the barrel in the block..
My first thought would be that most barrels are not totally straight and parallel (within in a the 0.001 i would think required). So barrels would need to be turned (or ground) to a nominal size prior to being fitted into the block..
Making the hole in the block is easy enough either by drilling and reaming or by 3D CNC machining so no problems there..
My next thought would be, what effect would clamping the barrel (sufficiently to grip and hold it under recoil) have on the bore dia.. I have read about guys fitting blocks and then being able to "feel" the block with a tight patch, which in not ideal. I have also head of guys fitting plastic (delrin) sleeves between the barrel and block to spread out the load and take up any slack or difference in dia.. However making a thin walled delrin sleeve 9" long with less than 0.001 tolerance would be quite tricky indeed! What about making delrin rings 1" wide that fit in pockets in the block, with each ring located central to each clamp bolt? Much easier to make 6, 1" wide delrin rings than to make one long delrin sleve..
What about machining a shoulder on the barrel to sit up against the block face to transmit the recoil forces, therefor reducing the clamping pressure required to hold the barrel?

My next thought would be to glue the block onto the barrel and then either glue the block into the stock or pillar bed it in as we do for actions..

Thoughts?

Cheers
Leeroy
 
leeroy

Or how about making the hole in the block a couple of thou bigger & bedding the barrel to the block? You can control the clamping pressure by how much shim you put between the blocks while doing the bedding job. No stress. Not too much squeeze. Usually the blocks are long enough, so that there is enough surface contact, that you won't need a ton of pressure clamping the barrel......depending on the caliber.
 
Barrel Blocks

I`ve made and used several designs.....all made of aluminum.....never caused any problems and enhanced accuracy.
 
" barrel block "

Leeroy -

Howdy !

I called Bruce Bear up one time, and picked his brains about " barrel blocks ".

Afterwards, for my 6mm wildcat bolt gun, I ordered a Broughton SS 6mm 1-8 w/ Palma taper; and specified a 4" long straight-section at the breech end.
I utilized plumbing repair clamp plates doubled-up, 4a carriage bolts, 2 bottom torque plates taken from "U"-bolts' and 4ea locking nuts.... to make my " barrel clamp ".

I started w/ the back of the clamp plates butt-up against the recoil lug. I tuned-out verticle by advancing the plates forward in .125" increments, shooting 5-shot groups at each new setting.
As it turned out, verticle went away once the clamp plates were .5" ahead of the recoil lug. In hind sight, I did not need the extend length of straight barrel section @ the breech end .

For me, my loads, my gun, my shooting needs.... the clamp set-up works great ! And, it cost me < $10.00. ( See pics )


For my Marlin M-336 XLR .35Rem, I made a mould..... and poured a combo " barrel block/ bi-pod mount block " in-place; using " casting resin ".
This barrel block configuration locks the magazine tube to the barrel, and positions the bi-pod legs right beneath the point where the mag tube mates to the barrel.
This set-up helped make the XLR hyper-accurate (see pics ). The poured method does not induce stress to the barrel ( no "squeezing ", per se ).

Lots of can/things will work !


With regards,
.357Mag
 
" barrel blocks "

Leeroy -

Here's one of my better groups, shot w/ the 6mm wildcat using; the " barrel clamp ".


The double pic set, shows my best Marlin M_336 XLR .35 Rem group ( shot using the poured " barrel block " ). You'll note that 2ea shots went outside the group... a result of my not doping the wind correctly ( I misread the windflag ). I'm still striving for .250' for 5-shots @ 100, w/ this rifle.



With regards,
.357Mag
 
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