This article, written by James S. Knowlson, was published in the May/June 2010 #205 issue of the Fouling Shot.
Beagling a mould to cast bigger bullets is a great idea from John Goins, a.k.a. Beagle. You glue alu-minum foil strips to the faces of the mould block to increase the diameter of the bullet. After you squeeze out all the excess glue, and after casting about fifty bullets, you are supposed to get larger bullets. What I got is a bullet only about 0.001 larger in diameter after starting with 0.003 of foil, and vent grooves full of glue. Not exactly the right solution to my problem.
THE PROBLEM:
My 1943 vintage Mannlicher Schoenauer Model 1924 High Velocity Rifle in 7x64mm Brenneke has a groove diameter of 0.288, not the standard 7mm 0.284. It will shoot Sierra 160 grain Game King bullets at 2689 fps to sub-minute groups at 100 yards using the 6X Zeiss scope. Apparently these 0.284 diameter bullets obturate up to the larger groove diameter and shoot very well for an older 7-1/2 pound hunting rifle. On the other hand, a 170 grain #287308 Lyman gas checked cast bullet made from Lyman #2 alloy, sized to 0.285 using NRA lubricant and Hornady gas checks shoot three to four inch pat-terns at 100 yards with 15 grains of Alliant 2400 and same brass and primer as the jacketed load. Reduced loads of IMR 4895 do about the same. A Lyman #287442, gas checked 140-grain bullet sized to 0.287 also performs in a similar manner.
After a local precision machine shop lapped my 0.285 Lyman sizing die out to 0.2882, Veral Smith at LBT made me a 170-grain mould, which drops a 0.2884 bullet. The base of the bullet is 0.260 for the gas check which means that a Hornady 7mm gas check with a 0.251 ID has to be enlarged with a taper punch to about 0.265 to get proper centering without shaving lead. This bullet shoots 1.3 five-shot groups at 100 yards with 15 grains of 2400. One four shot group went 7/8. (I had tried Alliant 2400 from 13 grains up to 15 grains in 0.5-grain increments and 15 grains seemed to close the group size. Going higher in powder was not tried because the rifle has an 8.25 twist that may be too tight for a 15 BHN bullet without land-jumping and stripping the bullet.) This load has not been chronographed yet but should be in the 1600 to 1700 fps range.
MOULD MODIFICATION METHOD:
Because my Lyman #287308 mould is much easier to cast with using a ladle than the LBT mould, I decided to Beagle it up to at least 0.288 in diameter. The alu-minum foil and glue method was not satisfactory after three trials. After researching high-temperature adhe-sives on the Internet I called the local automotive supply shop and they had a J-B Weld high-temperature, two-part epoxy resin good for 500 degrees. I decided that three strips of brass shim with a 0.003 thickness should give me a 0.288 diameter bullet from the Lyman two-cavity mould that unmodified drops a 0.285 bullet with #2 alloy. Brass shim stock has less memory than steel that makes it easier to press flat for a uniform thickness on the mould face and will not compress like aluminum foil.
Beagling a mould to cast bigger bullets is a great idea from John Goins, a.k.a. Beagle. You glue alu-minum foil strips to the faces of the mould block to increase the diameter of the bullet. After you squeeze out all the excess glue, and after casting about fifty bullets, you are supposed to get larger bullets. What I got is a bullet only about 0.001 larger in diameter after starting with 0.003 of foil, and vent grooves full of glue. Not exactly the right solution to my problem.
THE PROBLEM:
My 1943 vintage Mannlicher Schoenauer Model 1924 High Velocity Rifle in 7x64mm Brenneke has a groove diameter of 0.288, not the standard 7mm 0.284. It will shoot Sierra 160 grain Game King bullets at 2689 fps to sub-minute groups at 100 yards using the 6X Zeiss scope. Apparently these 0.284 diameter bullets obturate up to the larger groove diameter and shoot very well for an older 7-1/2 pound hunting rifle. On the other hand, a 170 grain #287308 Lyman gas checked cast bullet made from Lyman #2 alloy, sized to 0.285 using NRA lubricant and Hornady gas checks shoot three to four inch pat-terns at 100 yards with 15 grains of Alliant 2400 and same brass and primer as the jacketed load. Reduced loads of IMR 4895 do about the same. A Lyman #287442, gas checked 140-grain bullet sized to 0.287 also performs in a similar manner.
After a local precision machine shop lapped my 0.285 Lyman sizing die out to 0.2882, Veral Smith at LBT made me a 170-grain mould, which drops a 0.2884 bullet. The base of the bullet is 0.260 for the gas check which means that a Hornady 7mm gas check with a 0.251 ID has to be enlarged with a taper punch to about 0.265 to get proper centering without shaving lead. This bullet shoots 1.3 five-shot groups at 100 yards with 15 grains of 2400. One four shot group went 7/8. (I had tried Alliant 2400 from 13 grains up to 15 grains in 0.5-grain increments and 15 grains seemed to close the group size. Going higher in powder was not tried because the rifle has an 8.25 twist that may be too tight for a 15 BHN bullet without land-jumping and stripping the bullet.) This load has not been chronographed yet but should be in the 1600 to 1700 fps range.
MOULD MODIFICATION METHOD:
Because my Lyman #287308 mould is much easier to cast with using a ladle than the LBT mould, I decided to Beagle it up to at least 0.288 in diameter. The alu-minum foil and glue method was not satisfactory after three trials. After researching high-temperature adhe-sives on the Internet I called the local automotive supply shop and they had a J-B Weld high-temperature, two-part epoxy resin good for 500 degrees. I decided that three strips of brass shim with a 0.003 thickness should give me a 0.288 diameter bullet from the Lyman two-cavity mould that unmodified drops a 0.285 bullet with #2 alloy. Brass shim stock has less memory than steel that makes it easier to press flat for a uniform thickness on the mould face and will not compress like aluminum foil.
. As shown on pictures of the mould block, I cut three strips of shim with a pair of sharp surgical scissors to minimize bending of the shim stock. After cleaning the surface of the mould block with 99% isopropyl alcohol, I glued the shims to the bottom and sides of the alignment-hole side of the block with a very fine line of J-B epoxy down the center of the shim well away from the edges to prevent the epoxy from squeezing out onto the block. These shims were positioned carefully with tweezers to assure that the epoxy was not smeared.
The block was positioned on a well-leveled table to minimize gravity shifting because of the lubricity of the epoxy, and a small granite surface plate lightly coated with 3-in-1 oil was lowered straight down onto the mould block. On top of the surface plate a 4.25 pound map weight was positioned carefully to minimize shifting to aid in pressing the shims flat. The care taken with these two operations are important to prevent shifting of the shims. You cannot remove the surface plate for inspection with-out shifting the shims due to the oil coating. (I did have a slight shift of about a 0.010 towards the cavity on the outboard side but the overhang was pared back careful-ly with a bench knife after the adhesive cured.) Again, the critical operation is putting the surface plate over the shims without causing a shift. A possible solution would be to use a 2-inch square, half-inch thick piece of plate glass to see if any shift occurred and then add the addi-tional weight to flatten the shims.
After a 24-hour cure the weights were removed. The surface plate was removed with a light tap from a wood-en mould sprue-plate mallet to break the small amount of adhesive stuck to the surface plate. The increase in block thickness with the shims was measured with a Starrett dial caliper and found to be 0.003 plus an esti-mated 0.0002.
After a 24-hour cure the weights were removed. The surface plate was removed with a light tap from a wood-en mould sprue-plate mallet to break the small amount of adhesive stuck to the surface plate. The increase in block thickness with the shims was measured with a Starrett dial caliper and found to be 0.003 plus an esti-mated 0.0002.
BULLETS:
I doped the mould with Frankford Arsenal Drop Out and cast 20 bullets that miked at 0.2885 to 0.290; 0.0015 out of round. After sizing they were a uniform 0.2880 diameter. The weights for the first ten averaged 166.8 grains with a standard deviation (SD) of 1.4, the second ten were 171.2 grains with a SD of 1.4. One problem I noted was that the mould had to be squeezed firmly or the bullets had whiskers and fins.
I doped the mould with Frankford Arsenal Drop Out and cast 20 bullets that miked at 0.2885 to 0.290; 0.0015 out of round. After sizing they were a uniform 0.2880 diameter. The weights for the first ten averaged 166.8 grains with a standard deviation (SD) of 1.4, the second ten were 171.2 grains with a SD of 1.4. One problem I noted was that the mould had to be squeezed firmly or the bullets had whiskers and fins.
After casting 70 additional bullets the whiskering had ceased and the bullets showed only a fine mould seam line as shown on the two right bullets in the photograph.
Weights stabilized at about 165.5 grains. In the photo-graph, the bullet on the left shows some whiskering in the lubrication grooves. What I found is that if the whiskering can be removed with the thumbnail and the result is uni-form on opposite sides, the bullet will shoot well as long as the weight is +/- 0.4 grains of the other bullets in a batch. In other words, a batch of bullets with a range of 171.0 to 171.4 grains ready to load would shoot well.
So the bottom line is accuracy. Im now getting five shot groups of slightly over one-inch at 100 yards in gusty 3 to 5 MPH winds. With further testing I should be able to get less than one-inch groups but probably not down to the 0.6 that I get with Sierra jacketed bullets. Beagling is a great idea and beats spending twenty or so tedious hours to lap 0.003 out of a mould with questionable results.
Beagling is an easy way to modify an undersized mould and save pulling your hair out try-ing to get your rifle to shoot cast bullets properly. Total time to prep the mould was less than an hour.
Weights stabilized at about 165.5 grains. In the photo-graph, the bullet on the left shows some whiskering in the lubrication grooves. What I found is that if the whiskering can be removed with the thumbnail and the result is uni-form on opposite sides, the bullet will shoot well as long as the weight is +/- 0.4 grains of the other bullets in a batch. In other words, a batch of bullets with a range of 171.0 to 171.4 grains ready to load would shoot well.
So the bottom line is accuracy. Im now getting five shot groups of slightly over one-inch at 100 yards in gusty 3 to 5 MPH winds. With further testing I should be able to get less than one-inch groups but probably not down to the 0.6 that I get with Sierra jacketed bullets. Beagling is a great idea and beats spending twenty or so tedious hours to lap 0.003 out of a mould with questionable results.
Beagling is an easy way to modify an undersized mould and save pulling your hair out try-ing to get your rifle to shoot cast bullets properly. Total time to prep the mould was less than an hour.