Bore measurement ?

[tommag]

I slugged my Ruger security six and the cylinder measured from .358-.3587.
The bore measured .356 using the "twist the slug in calipers"method for 5-groove bbls. described by Double D. Does this sound like a Ruger bore for measurement?
If the measurement is correct, would I be better off with a .357 or .358 die?

Thanks. Tom

[felix]

Hard boolits, use 359 for full velocity with slow powder. Softer boolits, WW, use 358 with fast or medium speed powder. ... felix

[44man]

I would do what Felix says. It is hard to measure 5 grooves and I don't trust your readings. I wrap thin shim stock around the slug and measure, then subtract the thickness of the shim. (Both sides.) Close but still not perfect.

[slughammer]

Since you measured the cylinder throats, take the bore slugs and stick them in the throats. As long as they are smaller than the throats, you are in a good starting position. Only concern is if your slugs were sized by a bore constriction where the barrel screws into the frame.

When I do a bore slug, I start the slug in the muzzle and then make an index mark up near 12:00. Then after I run through the whole bore, I can take the slug and run it through again and again to feel where the restrictions are.

[DonH]

Unless the is a large discrepancy between barrel groove dia. and throat dia. or you are loading hotter than Hades, size to fit the throat.
Lyman 429421 heat treated to bhn25, sized .431 to fit throat over 25.0 W296 shot VERY well from my Bisley Blackhawk. IIRC, this .0015 over groove dia. at the breech end of the barrel.

[Bass Ackward]

I slugged my Ruger security six and the cylinder measured from .358-.3587.
The bore measured .356 using the "twist the slug in calipers"method for 5-groove bbls. described by Double D. Does this sound like a Ruger bore for measurement?
If the measurement is correct, would I be better off with a .357 or .358 die?

Thanks. Tom


Tom,

I think you will need both over time. Different bullet designs will benefit from different diameters. And the .357 die will size .358 with lino anyway if it has wide bands. So it will depend on your hardness what diameter you get too.

But don't worry what diameter your gun wants, it will tell you quite clearly.