Optimum Cylinder throat dimension

[wv109323]

I have a S&W model 14-6 that I use for NRA Distinguished Revolver Competition. I am trying to wring out the last bit of accuracy for 50 yard loads.
Since the barrel has five lands I have no way of measuring the bore diameter. The throats of the cylinders are .3565 to .3575. There are two throats that are .3565.
My question is: Should I take the throats out to .358 not knowing the true bore diameter? My sized bullets are .3577 and considering taking the sizing die to a true .358.
I recently Ransom Rested the gun. With 3.6 gnss. Of WST with a RCBS 158 RN bullet I got 2 1/16" CTC at 50 yards. After the 10 shot group in the larger throats I shot 4 rounds( 2 per small throat) through the gun. These four rounds did not enlarge the group and printed within the 2 1/16" group.
Your thoughts on enlarging the throats to .358.

[jcren]

I would guess from that that your barrel is smallish and would only throat the cylinders to match the largest for consistency. Check with Dougguy on here, he is a wizard on revolver throats and has done enough of them to give reliable advice.

[fecmech]

I have no way of measuring the bore diameter.
If you carefully rotate your slug so that you catch the front edge of 1 land and the back edge of one on the opposite side you can measure S&W groove size quite easily. I have done it on a number of S&W pistols.

[Larry Gibson]

I recently Ransom Rested the gun. With 3.6 gnss. Of WST with a RCBS 158 RN bullet I got 2 1/16" CTC at 50 yards. After the 10 shot group in the larger throats I shot 4 rounds( 2 per small throat) through the gun. These four rounds did not enlarge the group and printed within the 2 1/16" group.
I believe the revolver answered your question; it ain't broke so no sense fixing it.

Larry Gibson

[dubber123]

If you carefully rotate your slug so that you catch the front edge of 1 land and the back edge of one on the opposite side you can measure S&W groove size quite easily. I have done it on a number of S&W pistols.


+1 on the measuring, it can be done. I think with a bit of work, you could beat your best groups. I would like to see all throats equal. Check for thread choke too. Contrary to some, it DOES exist, and it DOES make a difference.

[Joni Lynn]

If you are determined to open up the throats I would open them to no more than the dimension of the largest throat.

[9.3X62AL]

Given the limits of my handgun ability, I would leave the throats alone. 2.06" at 50 yards would please me right to the ground in a box-stock wheelgun. I understand The Chase, and wanting to make every element as perfect as possible. Just make certain that The Catch is worth The Chase. IOW, mods might degrade rather than enhance accuracy. It's a bit of a dice roll.