S&W 67 with undersized chamber throats-hollow base wad cutters???

[Wooserco]

I have a last of run stainless Combat Masterpiece in 38 spl. 5 of the cylinder throats are under sized compared to my 60. The 2 inch snubbie will group tighter at 15 yards the the 67. Putting a measured .356 bullet in all cylinder throats, in the 60 all depths are consistent. On the 67, one chamber matches the 60 but the remaining 5 are clearly undersized.

Before sending the gun out for chamber reaming, would a hollow base wad cutter mold from Miha (MP Molds) obturate enough to compensate for the undersized throats?

[MT Gianni]

The question is kind of vague to me. The diameter should not relate to depth as I see it, did you mean that all the holes in the model 60 had the same diameter?
In any case, a hb wadcutter allows the bullets rear end [skirt in a hb] to expand and fill an oversized throat. Yours are undersized. Make sure that your measuring device is accurate, though the difference in between the 67 and 60 is notable.
Before reaming the cylinders, I would shoot several jacketed and see if the accuracy is the same. If so that is your next option.

[Dusty Bannister]

Yes, it is sort of difficult to see what the issue is that needs to be corrected. The model 67 is 38 special, and the mod 60 used to be 38 special and later became available in 357 Mag, I think. It seems odd to me that a .356" bullet would not slide through the cylinder throats. Maybe I am missing a step here. I hope a good micrometer is being used for any measurements. Nothing to suggest actual measurements of the cylinder throats. It is not too unusual for different bullet diameters and loads for different guns. perhaps that may be influenced by the weight, barrel length, and grip style? More information?

[TomAM]

Yes.

Once the boolits pass through the undersized throats, they will be bumped up by pressure to groove diameter to fit the bore.
Machining the throats to proper diameter is the best solution, but try the HBs first. They might do just fine.

[alfadan]

Make absolutely sure there is no leading in the throats.

[rintinglen]

Uniforming the throats will help with accuracy with all bullets or boolits. HB wadcutters in the case you describe may help, but it'll be a wadcutter-only affair. At least, if you want best accuracy.

[Wooserco]

New revolver, no leading. Only 100 rounds tested. Patterns, not groups.

[Wooserco]

Make absolutely sure there is no leading in the throats.

New revolver, no leading. Only 100 rounds tested. Patterns, not groups.

[walnut1704]

Ream them. I mean HBWC might help but who wants to be limited to that? I have reamed all mine.

[Chill Wills]

Now you have me on the way to pin gauge my M-67 no dash.

[LAH]

Now you have me on the way to pin gauge my M-67 no dash.

My Smith 67 has .358 throats & .358 grooves.