Rclark said:
Once you have reamed the throats, they still must be cleaned up
I've reamed all of mine, and none needed 'cleaning up' . They don't need to be as 'smooth' as you think.
You got lucky and I will tell you why. Ruger makes cylinders from long rods that come in on rail cars from the steel mills, they are drawn and heat treated specifically for Ruger. This stuff is TOUGH, it is granular, and does not like to be machined. It is inconsistent and VERY unpredictable in it's "finish" qualities. The outsides of the cylinders are ground to their finish, but the insides are reamed with HSS cutters.
After reaming well over a thousand Ruger cylinders I can tell you this with certainty, I don't care who's name is on your reamer, how new or how sharp it is, you will run into cylinders that are harder than woodpecker lips, you WILL experience tear-out in the throats, and they will leave some very unsightly tool marks that even following with an ACRO lap or a Sunnen hone you will NOT get all of them out, they simply pull out and tear too deeply to polish/hone out without going way oversize with the intended diameter of the throat.
After putting the Sunnen hone in the tooling here I am able to buy reamers of smaller diameter that will leave enough meat in the throat so that I can then hone it to size and polish out all or nearly all of the tear-out. This is how I like to deliver the finished work to a customer. Anyone who simply reams the throat and then sends the cylinder out as "finished" is just shortcutting the job.
There is also the variations in hardness from cylinder to cylinder and within the same cylinder throats "as reamed" will be a different size if the metallurgical makeup changes from one side of the cylinder to the other which I have seen more than once. Some cyllinders cut like butter, these will have throats that finish smoother and at a larger diameter than cylinders that are harder and difficult to cut smoothly. Other cylinders are so hard that a new Manson reamer will actually "squawk" while turning and will require two hands to turn the handle. This is where honing to final diameter will win over the "as reamed" throat all day, every day. I try to send cylinders out with throats within .0002" of each other. This is not possible with the reamer alone due to inconsistencies in the hardness and metallurgical properties of the cylinders themselves.
Some of the customers have more machining in their background than many of the 'smiths and for one of these guys to open a box and hold the cylinder up to the light and look into the throats and see a collection of radial scratches and toolmarks like what Ruger sends out as a "forcing cone" more times than not, is quite insulting. I currently do not have this issue with the work that I turn out because I believe in doing the best work you can possibly do. Your work speaks for itself. It speaks volumes about the kind of craftsman you are.
Accuracy will improve from reaming the throats evenly and to the proper diameter, it will likely not improve any over the polished throat vs. the as-reamed throat with the inherent tool marks, and once filled in with lube and powder residue, will be as accurate as the finely polished throat. However, the as-reamed throats are only likely to be all the same size *IF* the hardness of the cylinder is consistent all the way around. This is not always the case. LOTS of variation in the metallurgical properties of these cylinders, and both blued steel and stainless exhibit the same inconsistencies. This is where honing to final diameter ensures +/- .0002" sizing from throat to throat, and accuracy WILL improve with the hone finished throat over the as-reamed throat if the final diameters are more even after honing to finished diameter.
You can buy the reamer and the pilots, but without precision finishing tools, you are stuck with whatever tool marks and whatever finished diameter and whatever variations from throat to throat that the reamer leaves you with. There really isn't a financial savings to be had over sending cylinders out to have them professionally done, I do this work at a very attractive price, less than half of the cost of the reamer + the pilots for one cylinder. I have detailed the differences in finished product with the reamer vs. the precision honed finish. It is the customer's choice what degree of precision they desire.
