Beagling moulds

[kjohn]

Just read a few short blurbs on how to increase the “as poured” diameter of a mould that proves to be a tad small for a particular barrel.

Whether one believes in this method or not, it is food for thought. I am going to dig into this a bit more.

 

[vagrantviking]

I've polished out a couple mostly just to remove burrs and imperfections. Now a days a layer or 2 of powder coating is the easy way to increase diameter a bit.

Aluminum tape on the mating surfaces is another one I've heard about but never tried.

 

[fingers284]

I have done a couple in the past using the "cast a bullet & impregnate with milling/grinding compound...it works but is not an easy chore or quick to do....Vagrants suggestion of powder coating mmmmuuuuchhh easier

 

[oldrodder]

My understanding of "beagling" a mould is the application of aluminum tape to the mating surfaces of the mould to increase the as cast diameter. This results in an "out of round" bullet. I did this with a RCBS mould for a 250 Gr bullet for my M-94 in 38-55. I was able to gain a few thousanths of an inch. Much prefer to powder coat these days.

 

[BigRobb]

I’ve done it lots. Most recently, I wanted 405gr bullets with a diameter of .460 for a lever action. The mould would cast .457 with my alloy. Lee aluminum mould.
-Cast as normal and break the sprue.
-Leave the bullet in the mould.
-Drill a small hole into the bullet through the sprue hole.
-Thread a screw into the hole you just drilled.
-Pull the bullet/screw out and apply a small amount of fine valve lapping compound to the bullet. (Available at most auto parts stores)
-Cordless drill to spin the bullet slowly via the screw with the mould closed obviously.
I got lucky and only had to do it once, but it may take a few tries depending on how brave you are. I’d suggest only spinning bullets cast in their own cavity, but if you’ve got uniformity issues with multi cavity moulds, this might work for you.

 

[Lionel]

I've Beagled a couple molds with the aluminum muffler
tape method. It was quite fiddly with the tiny gaps
between the two cavities, but with a pointy knife tip
and a fair bit of patience I was able to get it right.
I only did one side of the mold and it increased the diameter
by a couple thou without making the boolit out of round.
I checked with a .0001 micrometer.
I think I did one mold with aluminum tape on both halves
of the mold and that one might have come out ever so
slightly out of round. After running through a sizing die
and installing gaschecks, they shot just fine.

 

[kjohn]

Okay. Thanks for the input. I am going to consider this and maybe try it with tape. It will have to wait for the shooting part until warmer weather arrives.