Question about slugging a cylinders and barrels

[oldracer]

Well I am about ready to try casting my own bullets and plan to make some 148gr DEWCs similar to the ones I have been using from Missouri Bullet Co. I bought 6000 a couple years ago and are starting to run out.....Theirs have two large lube grooves and the mold I have is a Lee with multiple small grooves. The diameter of the DEWCs in both cases is supposed to be 0.357 give or take the tolerance of the molds.

Anyways, I slugged both my 357 magnums just out of curiosity and here are the results:

- Model 66 (no dash) cylinder (all 6 holes) slight resistance to existing DEWC. Barrel has 5 lands and very deep and without the V block I can't measure the actual diameter.

- Model 327 TRR8 cylinder (all 8 holes) there was minimal to no resistence to same size DEWC. Barrel has 6 lands and seem to be shallow compared to the Hog Hunter but the resistance of hitting the brass rod to drive the bullet through the barrel felt just about equal.

My question is should the cylinder have a smaller diameter in each bore in the TRR8 or is this the way new allow guns are made. Surprisingly both have nearly the exact same grouping at 10, 20 and 25 yards with the same DEWC loads! Any thoughts are appreciated.

 

[cp1969]

I would imagine the difference is attributable to something called 'manufacturing tolerance.'

 

[Wayne M]

With rare exception cast lead works extremely well at 0.358 and most commercial cast 38 cal bullets use that diameter although a few-very few!-casters will cast any diameter you want. If both guns group well with your MBC bullets just but a caliper on one of those to see what diameter it runs. I know a couple shooters who will drop a jacketed bullet through each charge hole of any Smith they are thinking about buying. Any that drop all the way through and they don't buy the gun. I don't go that far I guess because I've never been unlucky enough to own a S&W which wouldn't shoot.