• Custom 6mm BR Norma with Sleeved Barrel

    Submitted by Greg Idso

    Last summer I happened to pick up a stainless steel barrel at a very cheap price. It was a rather unusual looking piece being it had been fluted in a radial pattern. It was also different in the fact it had started life as a 22" medium sporter contour .243 Winchester caliber and was now a 20" 6mm BR Norma. I got it home and screwed it onto a receiver, then headed to the local Cabala's to get ammo components. There I managed to find a set of Redding dies, but the Norma brass was not so easy to find and was going to have to be ordered. An EBay store had the best price at the time so a quick Buy in now had some brass on the way.

    The brass and dies finally meet each other a few days later and I chose 31 grains of Hodgdon Varget to propell the 70 grain Nosler Ballistic Tips. (31 grains to 34 grains of Varget was the suggested load in my 2002 Hodgdon manual) Seldom have I had full power loads shoot well, and this being a new barrel to me I also had to learn the pressure signs for it. A minimum load was as good a starting point as any.

    A couple weeks later I am ready to finally try the 6mm BR that everyone brags about. The first shot surprises my a little as I did not expect the same amount of recoil out of that little case as I would get from a 6mm Rem. The second shot does not look good, and the following three yield a 4"@100 yard 5-shot group. Not to good.

    Even on one of my bad days I can do better if the gun is up to the challenge, so something must be wrong. I checked the normal things: scope mount, bases, action screws and barrel nut...nothing was loose. I then tried replacing the scope with a new Burris 3x9 I had just purchased a couple days earlier. Next group is still at four inches.

    Barrel w/o SleeveOk lets look at the barrel. I was shining a light down the bore and looking in the receiver when I noticed something that was totally new to me. The barrel was flexing with the weight of my hand as I was holding the light to the muzzle. I could bend the barrel. When I returned home I got out the calipers and did some measuring. Bore was 0.243" and the outside of the barrel where it was turned down was 0.50. Ok math was not my favorite subject but I did learn a little. 0.500 - 0.243 = 0.257" Divide by 2 and arrive at a wall thickness of 0.1285". It's now easy to understand why one finger can flex the barrel.

    The flute cuts started at 8" from the chamber. Cutting it to revolver length was a waste. Tent stake? There had to be something to do with it other then waste a good receiver on a pretty odd looking wall hanger. The previous owner had mentioned putting a sleeve on it, so I thought I'd give that a shot.

    However, I then needed to figure out how to secure the sleeve to the barrel. Epoxy may work if all the air pockets could be eliminated, but I don't recall any epoxies that are that thin and the volume needed would be hard to estimate. Then I started thinking about threading the muzzle end of the barrel to accept a nut that would put the barrel under tension in relation to the sleeve. If this works a brake could always be added as well to help dampen the recoil.

    With that in mind I made a trip into town with my funny looking barrel. I walked through the door of the local gun shop and as expected took a good ribbing for what is in my hands before I even got to say HI! Some days I wonder if it is a good thing to get in good with a gun shop. After explaining my latest idea of sleeving the barrel, the smith agrees that he could do that for me. The sales weasel behind the counter, being the kind if friend that would be sitting in jail beside my, continues to heckle the idea. The smith being a lot smarter and the guy we would call to bail us out then throws me a curve. He will do it if I find the tubing. Well now that was not how it was supposed to go! Where do you find short lengths of tubing? I did not want a 10 foot length, but the local steel yard would have them if I was left with no other option. I did not want to think of the cost this idea was approaching.

    Next stop was the hardware store to get bolts for another project. A glance at the odds and ends of metal rod, angle iron and other things reveled a piece of alum tubing that looked close to the right size to slip onto the barrel. Five dollars to take a chance. If I lost this lottery at least I would have more then a piece of paper. When I got it out side and gave it a try it slipped over all but the last 3 flutes. Things were looking up. The caliper showed that the outside of the alum tubing was very close to the diameter of the barrel if I got those first 3 ribs turned down so it could slide up to the unturned portion of the barrel.. Back at the gun shop I happily hand the project back to my friend.

    Assembled ViewOne week later the smith calls to let me know the barrel is ready to pick up. The cost a surprising $40.00 sure helps to stay on the good side of my significant other. The nut was cross drilled for a T handle to make for a way to install and remove the nut. Handy idea, glad he thought of that so I am not using a pipe wrench. If there is a next one I will suggest wrench flats to eliminate the flame ports out the side. The holes can be filled with set screws if they become a problem. Now that it is done the sales weasel is wondering when we can try it out.

    At home once again I reinstall the barrel onto the same action, grab the stock and see I have some work to do. The barrel is no longer a sportier; in fact it will no longer fit a heavy factory channel any more. Guess it is time to do what any good home cobbler would do. Get out the Dremal and go to work on an old wood stock. A large pile of saw dust in the living room floor later (you have to be comfortable and watch TV, right?) the job is done and a few dollars will slip from end to end of the barrel. It's free floated! Well maybe the job is not done. Some one has to vacuum up my mess. Some days I wonder about teaching my girls about cleaning up after them selves. They decided to use it against me today.

    Next stop is the range with the same load from the first test. When I arrived at the range the weather was nice with a calm wind in the valley and temps in the 50s. I wanted a target with a before and after so the sleeve was removed and 3 rounds were fired. The group measured .409. Under something sure changed. What happened to 4"s from the last try? Only idea comes to mind is the end of the barrel was threaded so the mass and harmonic vibrations changed. Well it will be interesting to see what the sleeve will do now that it shoots well with out it. Did I waste my time and energy? The sleeve is put back on for the next group. The next 3 shots measured 0.60"...we lost some ground. This is not going at all as planed. A little tweak on the tension nut and the next 2 shots went 0.255. Now this is looking up and headed in the right direction so lets try another tweak. Time to try a 5 shot group. 3 shots were looking great through the scope. One nice small hole. Next shot was right in there with the rest. The gun is cutting a one hole so far. Number 5 I knew was a flyer as soon as the trigger was pulled. The ending group with out the flyer came in at 0.214. .601 If some one needs to add in the stray bullet. As I was out of test ammo that ended the day.

    Playing with the tension may lower the group some more if the world is in a good mood. The next problem is going to be heat. With the main barrel encased in the sleeve and nothing but air inside to transfer the heat I am wondering how many shots it will be before the point of impact changes. The thin metal between the flutes has got to heat fast and while aluminum is a good conductor it is not in full contact with the barrel for good heat transfer. Some day maybe I will find out what the effects of filling the air space with some liquid or running some hoses pumping liquid through has on the accuracy.

    Additional Photos:

    Sleeve Material Sleeve Installed
    Tension Nut Installing Nut
    Nut Installed Barrel to Sleeve Joint






    Comments 1 Comment
    1. HoytFlinger's Avatar
      HoytFlinger -
      I know this article is ancient, but I would throw that barrel away. Looks like a pipe bomb to me.