Post by twomoons on Apr 1, 2010 13:02:15 GMT -5
Slugging the Bore
First put on your boxig gloves... No Wait we want to measure the inside diameter of the lands and grooves to see what size bullet to use. For that you need a 5/16" rod, preferably brass or coated steel so there is no chance of scratching the bore. Then for a 357 we want a 375 or 380 round ball and a little grease. Grease the ball and put it in the chamber and TAP it through the bore with a mallet and the rod. This wont hurt the bore at all. Then take the egg shaped slug you have and measure the land and grooves. Typicaly you will get a groove depth, the most important measurment, of somewhere between 356 and 360 for a 357 mag chambering. NOw lets say the bore is 350x 357, If i were looking for a cast bullet for this I would start with a 359 or 2 thou over groove. Depending on how well the chamber is cut youo might even need to go up to 359 to get the accuracy you want. If the bore is oversize.Say 360-361 and you cant chamber a cast bullet that big you will either need to use jacketed slugs or what has worked for me is to use corn meal filler behind the powder charge, drop your load 10% and fill the space between the powder and the base of the bullet with corn meal. Don't pack it in it will pack up nicely when the powder goes bang. What this does is acts like a big cas check to push the bullet down the bore w/o letting gas blow by. By doing this I was able to shoot 315 bullets in a rifle that needed 318 to seal the bore and I was able to shoot this load under 3" at 100 yards. W/O the corn mael groups were over a foot.
Dovehunter, I didn't jump in because I thought Jack had itr about covered, hope this helps.
First put on your boxig gloves... No Wait we want to measure the inside diameter of the lands and grooves to see what size bullet to use. For that you need a 5/16" rod, preferably brass or coated steel so there is no chance of scratching the bore. Then for a 357 we want a 375 or 380 round ball and a little grease. Grease the ball and put it in the chamber and TAP it through the bore with a mallet and the rod. This wont hurt the bore at all. Then take the egg shaped slug you have and measure the land and grooves. Typicaly you will get a groove depth, the most important measurment, of somewhere between 356 and 360 for a 357 mag chambering. NOw lets say the bore is 350x 357, If i were looking for a cast bullet for this I would start with a 359 or 2 thou over groove. Depending on how well the chamber is cut youo might even need to go up to 359 to get the accuracy you want. If the bore is oversize.Say 360-361 and you cant chamber a cast bullet that big you will either need to use jacketed slugs or what has worked for me is to use corn meal filler behind the powder charge, drop your load 10% and fill the space between the powder and the base of the bullet with corn meal. Don't pack it in it will pack up nicely when the powder goes bang. What this does is acts like a big cas check to push the bullet down the bore w/o letting gas blow by. By doing this I was able to shoot 315 bullets in a rifle that needed 318 to seal the bore and I was able to shoot this load under 3" at 100 yards. W/O the corn mael groups were over a foot.
Dovehunter, I didn't jump in because I thought Jack had itr about covered, hope this helps.
