View Full Version : unlimited builds

g n brezinski
10-29-2016, 12:06 AM
i see that a lot of guns use a barrel clamp that has bolts to hold the clamp on the barrel.i thought that this clamping type put a strain on the barrel and made it shoot bad groups.i was going buy a article by sinclare that he states a compression is put on the inside of the barrel that is not good for small groups.
gary b

10-29-2016, 10:23 AM
The majority of rail guns today utilize a v block or a round channel with a Delrin sleeve. The Delrin helps to isolate any resonant vibrations created in a traditional metal to metal fit, commonly seen in the v block. I have seen several methods for utilizing Delrin, solid Delrin sleeve, split Delrin sleeve and a 3 piece Delrin sleeve spaced evenly in the block. The guys using these Delrin sleeves rail guns shoot extremely well. As far as fastening the v block there are typically 8-10 bolts that are torqued down and while conventional wisdom would leave one to believe that torquing imparts a strains equally across the barrel, with a 1.350 diameter barrel I don't think that occurs.

jackie schmidt
10-30-2016, 11:09 AM
At the Nationals, I saw Rail Guns with some type of non metallic sleeve isolating the barrel shoot vey well, and some with just a standard V-Block, shoot very well.

I also saw Rail Guns with some type of non metallic sleeve isolating the barrel shoot poorly, and I also saw some with just a standard V-Block shoot poorly.

This I know or a fact. Whether you are using a Sleeve, , or just a V-Block, you CAN close the ID of a barrel with too much torque on the bolts.

I proved this to myself by taking a barrel blank and finding the deltronic Pin that would just slip in, and then seeing at what point I could tighten the ten 5/16 clamping bolts so that it would no longer slip in.

It makes no difference whether you have a non metallic sleeve isolating the barrel, or a V-Block. At some point just north of 100 inch pounds of torque, the ID of the 1.450 diameter barrel collapsed enough to where you could physically measure the closure with Deltronic Pins.

Will this affect the accuracy potential of the barrel. I have proven to myself, at the range, that the answer is yes.

I torque mine to about 50 inch pounds.

10-31-2016, 12:42 AM

Interesting and valuable information.

In your experiment, did the collapsed barrel spring back when torque was released? Or was the deformation permanent?


jackie schmidt
10-31-2016, 05:28 PM

Interesting and valuable information.

In your experiment, did the collapsed barrel spring back when torque was released? Or was the deformation permanent?


When I released the tightness of the bolts, the Deltronic Pin would slip in as before.

Since I have Deltronic Pins in .0001 increments, I could probably do a video showing this. I have the 4 inch long piece of 1.450 unlimited barrel.

g n brezinski
11-01-2016, 08:18 PM
so i gather as long as the bolts are tightened a specifice amount you are safe.
what do others torque the barrels at andhow is this done.
gary b
I see in some 1000 yard guns they glue the barrel in a sleeve.but I like the idea that I can unclamp the barrel and switch out the barrel or the barreled action buy unbolting the clamps.

11-04-2016, 10:03 AM
Build a rail gun that shoots well and forget about the "easy" barrel change. The concept you mention sounds good...but it ain't. The easiest barrel change I've ever seen was where the action was bedded to the rail and all you had to do was screw out the barrel and screw in another. That rail shot VERY well (as good as any)...but the barrel never was changed. Just sayin' !!

Keith Gantt was the owner of that gun and when he bought it I was thinking he wouldn't like it because it was a Remington action, right bolt, right port and because the action was encased it I thought it would be somewhat difficult to load. I was wrong on all accounts because Keith learned to shoot it as fast as any and won quite frequently. The only thing that was aggravating about that rail was the rolling case it came in....took up half a Caravan just to haul it around.

Kirk Ethridge
02-05-2017, 11:50 AM
I built a couple of unlimited rifles with solid machined aluminum stocks (6 inch wide forend) quite a number of yrs ago. Seems like the guy building the stocks was out of Montana or Wyoming. (He quit building them in favor of a more profitable part contract.) They were barrel block bedded with the action floating behind the block and barrel in front. I bedded the barrel in the clamping area. One of them was a 300-338 lapua magnum. I sold it to a "cropduster" in Miss. It was set up for Randy Robinette's 180 grain flat base 30 cal bullets, which i'm quite sure earned someone a 1000 yd shooter of the year award (the bullets, not my gun) .. The guy who bought mine shot at Hawks Ridge, N.C. & called me saying if he was really happy with the rig,... It had a heavy Lilja barrel that was tapered in front of the block... Seems like they weighed around 70lbs. Correct me if i'm wrong, but i think quite a few heavy guns are set up this way (barrel block bedded) in the 1000 yd group/score game? and rail gun's too... I hope someone is still shooting that rig...

I built another heavy gun with a 2 inch straight barrel as a 6ppc. but i never did beat the traditional rails as i hoped to be able to adjust for switchy conditions., even though i had little success i enjoyed shooting the rifle.,,, I liked my Bob Dodd rail even better for my short range (100-300) unlimited gun,. It was barrel block bedded too, seems like it had 8 or more screws on the barrel block & over tightening the screws was the only thing that hurt accuracy I might be wrong but seems like Bob said no more than 25 lbs on the torque wrench??. It didn't take much torque to have it right. . I don't ever remember seeing a tensioned or "cooled" rail in the southeast. (It's been over 10 yrs now since i competed however). I don't see how a gun could out shoot that rail with the correct "driver"...I never did do well adjusting the load for best grouping over the day... I had a top 2 round going down at Winds of the Manatee one year until i shot the wrong relay!! (my bench only had me shooting & not reading my shooter number cost me that "wood") i didn't have to move it between relays) . It was a fun gun to shoot for sure & i never felt "outgunned".

Rail guns are really a lot more fun to shoot than you might think before owning one. They are a hoot!