Benchrest quality "fun" CB rifle...

[Idaho Sharpshooter]

I bought two brand new 700 Short actions here last month. I am going to turn one into a "just for fun" benchrest rifle in 308 Win. Bullet and alloy testing, and all that sort of thing.

Several years ago, a gentleman showed up at a Cast Bullet Assn Match with a rather unique free floating unlimited class rifle.

It was very accurate, and he shot it very well. Like in the .3moa range at 100/200yds.

He had purchased a Lilja barrel no taper barrel that was an inch and three eighths of an inch OD, 26" long. Zero taper.

He got a tool steel strip that was three-quarters of an inch thick, by an inch and three eighths wide, and three feet long. He was a very good machinist to hear him talk.

He said he had bored the strip, about one quarter of an inch from one end, and centered. Went down an inch from the bottom of the hole, and bent the strip ninety-degrees.

He has this strip, honed to just fit between the barrel and receiver, like a factory Remington lug. Looked like a sideways "L".

He relates how he measured the length from the bend to the end, and parted it halfway.

He bought a blank like the old Unlimited Stocks of laminated maple (?) with the 3" wide fore end and inletted the "L" section into it lengthwise.

Then, he told me, he inletted the other half of the strip into the bottom, taking care to match them two halves for length. Drilled a couple holes in each one close to the ends, countersunk them, and screwed them together like bread on a fat sandwich.

His concept was to completely isolate the barreled action from the wood and any accuracy degradation due to harmonic vibration.

Similar in many aspects to the newer barrel bedding blocks, but much simpler to construct.

The nice thing, with a barrel vise and bedding wrench, he could change barrels in a couple minutes.

Any of you machinists got any thoughts on this?

Or the rest of you...

thanks,

Rich

[nekshot]

I think I got what he did but I wonder if a sleeve over barrel with o rings would accomplish the same thing in a differant way. I have found every sleeve project I have done shoots far better than expected.

[jmorris]

Something like this is on my to do list.

http://www.benchrest.com/magnummetal/

[357Mag]

Idaho Shooter -

Howdy !


I went the barrel clamp / floating receiver approach for my accuracy bolt rifle.

"V"-blocks contact a notional " round " rifle action in 2 straight/parallel lines.
My thought was: the same result could be attained, using a section of channel.

What I did was: secured a 36" length of aluminum "I"-beam ......... a cut-off piece of structural center-section from
an outdoor vinyl deck rail system ( CERTAINTEED ).

I oriented the "I" beam to serve as an "H" beam. The aluminum beam was not quite wide enough between its upper channel's inner side walls.... to clear my Wichita WBR1375's 1.375" diam receiver. I made a small relief to the upper inside corners of the channel side walls, so that they'd just clear the action; a running length of some 8" or so.

I cut a slot for the barrelled action's recoil lug, and another slot in the floor of the "H"-beam's web; to accomodate the trigger

I used sections of composite 5/4 deck board to fashion a fore end and buttstock. A small strip of deck board is used as a removable cheeek rest, to facillitate rifle cleaning from the breech.

A used a galvanized conduit hanger re-shaped into an " L " and a large button head screw, to give me a rudimentary trigger guard; attached to the front of the buttstock. A small area of the uper fwd buttstock was cut-away, to allow clearance for the trigger.

The barrel is clamped to the "H"-beam, using 2ea doubled-up " plumbing clamps", along w/ 4ea carriage bolts, 2ea doubled-up clamp plates borrowed form "U"-bolts; and 4ea lock nuts.

In-use, the barrel clamp secures the straight section of the barrel to the beam's upper inside channel.
The barrel clamp can be re-positioned to allow tuning-out of unwanted " verticle " in the groups.

I ended up having to move the clamp a total of 1/2" fwd of my initial starting point, which was when the aft clamp' edge was in contact w/ the front of the rifle action.

I'm so happy with how the "beam" stock works, I doubt I'll ever return to a traditional-style rifle stock; for my precision rifle work !


With regards,
357Mag

[Idaho Sharpshooter]

Thanks guys. I looked at Railguns. The one shown here is $2500. I have also looked at the barrel bedding block system. That issue is the need to disassemble the blocks to switch barrels.
The Railgun set up is the best, but when I spoke with Scott Hunter (owner) he said it would be easier to buy an extra set of blocks, and just switch the action from one barrel/block system to another.

I am trying to be cheap...

[357Mag]

Idahosharpshooer -

Here's some pics of the " beam " stock I mentioned, above.


With regards,
357Mag

[Idaho Sharpshooter]

357,

Woo-Hoo!! that is one very neat rig. You should make me a deal on this one, and build yourself a new and improved model with all the changes you probably have floating around in your head since this one was completed...

[357Mag]

Idaho -

Howdy !

Thanx for the remarks !

In truthfullness, it's likely the "H" beam shown wouldn't be a good fit for your rifle. My action is a Wichita WBR1375.

My questions on fit to your action would be things like... spacing of recoil lug cut-out to trigger cut-out.
Spacing between small bolt handle relief on RT upper side rail and recoil lug. Things like that.

But yeah... the basic concept oughta be workable for round actions.

I don't believe I actually had to run w/ a recoil lug; at all. The Palma tapered barrel shown is chambered in a 6mm wildcat, of my own design. Gun wt is around 16.75lb ( scoped ) , if I recall right. My point: recoil forces aren't so much that they would defeat the clamping action of barrel clamp. I'm running w/ 24 in lb torque on the nylon-insert lock nuts.

Aluminum beam's side walls & " web " are thicker than aluminum channel one usually enounters @ hardware stores.
If a guy could stand it, a steel "I" beam would likely be easier to find. I know a " High Power " shooter from VA, that fashions his stocks entirely out of steel, then paints them as desired. I've wondered about use of "U"-bolts as the barrel clamp, as an alternative to using the " plumbers clamp ".
Clamping forces on the barrel might be too localized, then ? Hmm....

I've also looked other building materiels that might work for the basic stock. There's a composite door frame piece I've seen, which holds some interest.

Also thought about " casting " the whole stock, using ( casting ) resin. I used the stuff to cast a combo
barrel block / bi-pod mount on my Marlin M-336 XLR .35 Rem. The block works superbly, securing the magazine tube to the barrel in a more rigid set-up. The rifle shoots great !


With regards,
357Mag

[Idaho Sharpshooter]

357,

do you think a wooden unlimited stock would work with a plate underneath and those U-bolts clamping it to the plate? I am open to suggestions from any and all.

I really want a railgun, but 70+ pounds is a bit much for this old man to lug around a couple times a week for testing. My plan would come in about thirty, much easier on a 66 year old chassis(mine).

I could set the spacing on the clamps about 6-8 inches apart.

Rich

[jmorris]

70+ pounds is a bit much for this old man to lug around a couple times a week for testing. My plan would come in about thirty, much easier on a 66 year old chassis(mine).


If you look at the photos in the link I posted above you will notice the "rifle" sits on top of the base plate that contains all of the adjustment parts.

28 lb base with a 32 lb rifle, moved one at a time.

[357Mag]

Idaho -

Howdy !

As regards the use of "U"-bolts for barrel clamping action... whichever way they might be oriented:

I still wonder about how localized the clamping forces might be, right @ the juncture of each "U"-bolt and the barrel.
"V"- blocks and such lay out the contact point on the barrel in extended parallel lines, that are parallel also to the bore axis.
"U"- bolts ( or similar type of clamp ) would position clamping forces radially about the outside of the barrel. Not to say that it wouldn't work,
or that it would hurt the barrel or obtainable accuracy. I guess we experiment in-order to know. So yeh..... I think your idea could work.

I mocked-up a barrel clamping arrangement that used multiple saddle-type clamps, much akin to scope mounts.
Imagine a 1" diam barrel clamped in-place using something similar to scope mounting rings.

I've given thought to using " eye bolts "...... chill the barrel, and heat the eye bolts. Pass the barrel through the close-fit eye of the bolts, spacing the bolts as desired. The barrel then warms to complete a secure union of eye bolts-to-barrel. Tight enough initial clearances so that the barrel won't become loose during use in really cold weather.

Of late, I've thought about using cable clamps similar to those seen on telephone pole " guy wires ". These are sometimes two mating plates w/ internal channels
to fit the cable, and secured w/ 2 parallel rows of bolts/nuts...... a lot like barrel blocks seen on LR rifles.

I've also thought about perhaps knurling the outside straight section of the barrel, and " casting " the barrel inside a poured " barrel block ".
I poured a barrel clamp/fwd bi-pod mount for my Marlin M-336 XLR .35 Rem, and it works superbly ! I used casting resin, but imagine any good epoxy resin available in sufficient qty would work.


With regards,
357Mag

[Idaho Sharpshooter]

I contacted magnum Metal on the phone and talked about a rail gun. $2500 is a bit rich for my blood, but you could never wear it out shooting cast bullets. A guy could spend his lifetime testing designs, powders, alloys, and lubes; not to mention PC. I also sent a followup Email to him and the URL. If I ever get a response...
Of course, that gives me a little more time to assess my financial future.

[jmorris]

Oh, I thought this was a DIY project, yeah I am not interested enough to buy one but thought it would be a neat project to build myself.

[Idaho Sharpshooter]

Yes, it is. I am trying to figure out how to get my idea to work other than going to a barrel bedding block. The rail gun would be in addition to this one, somewhere down the road aways...

[357Mag]

Idaho -

Here's some group pics, shot w/ the " beam stock " rifle pictured previously; above.

I'm not a great shot by any means. I managed to shoot my personal best ever 5-shot 100yd group w/ this rifle. The set-up can/does work.


With regards,
357Mag

[lar45]

159370
I was testing 45-45-10 before I started selling it.
This was at the end of 100 rounds without cleaning in my 30-06 Mauser Hunting Rifle.
The range was 85yds, that's as far as I can get shooting from the porch of the shop.