.358 cylinder throats bad for jacketed bullet accuracy?

[3gunnah]

This kind of goes along with Seanc's question. I am using my 627-3 V comp 357 mag with short Colts and Berrys plated bullets for USPSA matches. I am getting good results but would like to use cast lead and coated bullets for practice and cost savings. I have run into some erratic velocity issues using tite group and 170 grain coated bullets. After talking with my bullet caster and checking my cylinder throats they appear to be around.356. I was contemplating having them reamed to .358 and was wondering what you guys thought about the possibility of loss of accuracy using jacketed and plated bullets. thanks

[Toolguy]

First you need to make sure you have an accurate measurement. A caliper can't be relied on for that. You need to be using gage pins or a small hole gage with micrometer. From my experience it seems pretty unlikely that the throats are actually .356.

Secondly, I wouldn't go over .357 even if you're using .358 lead. A jacketed .357 bullet probably won't be as accurate out of .358 throats.

Edited July 17, 2015 by Toolguy

[AzShooter]

You can open the throats by using a good drill press a piece of brass with a slot cut in it and some 600 grit sandpaper. Use your pin gage to make sure you get the right size. If you open them all up to the same size your groups will be tighter.

Remember to go slow you can't put metal back on.

Use bullets .001 over your throat for best accuracy.

[toothguy]

I have never been able to shoot consistently good groups with plated bullets, and lead is not worth the mess. I really like the polymer coated Bayou bullets because they shoot clean, accurate and are reasonably priced. Before you do anything to your cylinder try some.