Cylinder Throat Dimensions for Jacketed Bullets

[Idahoan]

I have read a lot about bullet fit and cylinder throat dimensions for cast bullets but almost nothing about jacketed bullets. My question is regarding a S&W 686 Plus that has all 7 chamber throats measuring at .3565" using the Brownells pilots for the Manson reamer. I plan to shoot mostly jacketed bullets at medium to low velocity for each bullet weight and some plated bullets.

I have access to a Manson throating reamer that will cut to .358". I have not slugged my barrel but I have use a Range Rod and it has a slight thread choke of about .0005" at the frame. The gun does shoot pretty well at around (5 shots) 1.2" at 25 yards with a scope from sandbags with the barrel resting on a bag. Plated bullets shoot about 2.5" at the same distance. Will it hurt any performance or accuracy to open up the throats to .358". I am probably overthinking this which why I need a sanity check from more experienced shooters in this forum.

[reddogs]

I had a couple cylinder throat's opened to .3585 for lead.But what little jacketed hst and golden saber's i have shot it improved if anything.I don't know if it is all throat's are the same,larger or both.I also don't get the accuracy you are getting already but close.

[shocker]

Interestingly, SAAMI calls out 355 groove diameter for 357/38 barrels. Before I reamed throats I'd slug the barrel.
Shooting 1" at 25 yds says to me, don't do anything. Jacketed bullets don't suffer from base melting like an undersized cast bullet would.

[1&done]

I think your accuracy finding with plated makes sense. I have heard of people say that plated pullets are just as accurate as jacketed. I have heard people say that they are less accurate. Never heard anyone say that they are more accurate.

[series guy]

I personally have found tighter throats to be more accurate.

[Idahoan]

Thanks to all for the feedback. I think I will leave well enough alone and not mess with the reamer.