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Post by nolongcolt on Dec 15, 2020 0:07:54 GMT -5
Anyone know if Smith is still using ECM rifling in their revolvers? I have a new 29-10 that looks for all the world like cut rifling and the one Smith 629 I had a few years ago didn't look like cut rifling at all.
I know that ECM is supposed to be fine and I don't doubt that, with one trip to the range for this new 29 it shows great promise, nice gun, just curious about the method of rifling.
TIA
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Post by matt56 on Dec 15, 2020 7:57:37 GMT -5
Yes I can see ecm rifling in my two 629-6s, one is as new as 2017. My 629-4 from the mid 90s are standard cut.
It’s easy to see if you have 2 barrels to compare. The lands are more rounded with ecm. Regular cut the lands are sharp and square. You can really tell at crown.
It’s possible the 29 barrel was leftover, there are no changes in the barrel that would stop them from using old stock on a new production gun
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Post by nolongcolt on Dec 15, 2020 13:36:47 GMT -5
 Looks like cut rifling to me, what do you think? Thanks! |
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Post by x101airborne on Dec 15, 2020 17:36:24 GMT -5
My humble, uneducated opinion, with those chatter marks; cut rifling.
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Post by nolongcolt on Dec 15, 2020 18:23:03 GMT -5
And to matt's point, the sharpness and lack of round edges of the rifling. I don't have an ECM gun to compare to but have seen them and unless my memory is bad, possible, this is quite different and looks conventional.
Makes me wonder though about another point matt56 made, about using up whatever barrels are on hand. This is a 6.5" bbl, and the first they have made of these for some time I believe, 6" being the previous standard for some years.
Makes me wonder if all of this latest -10 run are cut rifling.
Anyone else have one to compare?
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Post by matt56 on Dec 15, 2020 21:28:34 GMT -5
All my 29s are dash 6 or earlier with cut rifling. Nothing to compare them too.
My 657-5, 610-3, 629-6s and basically any gun after the 2000s are ecm rifled.
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Post by nolongcolt on Dec 15, 2020 22:17:33 GMT -5
What do you make of the pic I posted above?
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Post by cas on Dec 15, 2020 22:56:39 GMT -5
Oh that's not chatter marks, that's to get extra gription on them bullets!  |
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Post by Lee Martin on Dec 15, 2020 23:01:31 GMT -5
It's cut rifling. The marks are likely due to the cutting broach not fitting the bore perfectly. Worn out tooling and pulling the hook at the wrong speed will leave marks like that too. If it shoots, who cares. But my guess is it'll foul quick. -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by bradshaw on Dec 15, 2020 23:12:09 GMT -5
Looks like cut rifling to me, what do you think? Thanks! ***** Lands appear to be cut with a broach. “Cut” rifling generally refers to grooves cut one at a time with a “hook.” The hook or cut is much too slow for production rifling. Lateral scoring as shown in photo may appear on LANDS or GOOVES. It does not automatically kill accuracy. Dimensional irregularity----loose or tight spots----kill accuracy. (A lousy forrcing cone also kills accuracy.) Chatter marks cause bullet abrasion; stripping off bits of jacket or lead, with consequent fall-off in accuracy. As I recall, some ER Shaw barrels with this kind of roughness shot pretty well in IHMSA. Wes Ugalde used quite a few Shaw barrels. I was appalled at one XP-100 Ugalde showed me, which had a rough Shaw barrel. I watched it shoot very well in Nevada. If the barrel shows this kind of roughness but shoots well, stroke it with JB Bore Paste on a flannel patch. How rifling is made is less important that uniformity of BORE before rifling. And then, uniformity of grooves. David Bradshaw |
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Post by nolongcolt on Dec 15, 2020 23:14:21 GMT -5
Thanks Lee. I only shoot jacketed these days as the closest range is indoors only, no lead. Seems to shoot fine thusly, so I am happy.
Look closely with a macro lense and I think a lot of guns will exhibit such machine marks. I was also holding a flashlight to it to enhance it.
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Post by nolongcolt on Dec 15, 2020 23:19:19 GMT -5
Thanks David and everyone for the replies. This is a brand new gun with one range trip but that seemed to show much promise. At any rate I think we can safely say it isn't ECM rifling, LOL.
Which I still find curious considering that seems to be their main method for some time now. This 29-10 is part of the current Classic line so maybe they use a more classic method to rifle it?
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Post by Lee Martin on Dec 15, 2020 23:23:11 GMT -5
David - I have a bad habit of saying cut to imply broached. They definitely didn't single point cut the grooves. Way slow for production. The broach, with its progressive cutting blades (aka hooks), hit all the grooves simultaneously. The broach was either ill-fit to the bore, the cutters were worn, or they broached at the wrong speed. Perhaps all three were at play. -Lee www.singleactions.com "Chasing perfection five shots at a time" |
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Post by bradshaw on Dec 16, 2020 0:33:43 GMT -5
David - I have a bad habit of saying cut to imply broached. They definitely didn't single point cut the grooves. Way slow for production. The broach, with its progressive cutting blades (aka hooks), hit all the grooves simultaneously. The broach was either ill-fit to the bore, the cutters were worn, or they broached at the wrong speed. Perhaps all three were at play. -Lee www.singleactions.com "Chasing perfection five shots at a time" ***** Lee.... seems we answered at the same time. My distinction of CUT vs BROACH aims to clarify jargon for readers. “Broach” means to cut all grooves in one pass. My guess ascribes chattering to speeded-up production, which of course invites tooling wear, etc. nolongcolt.... in my view, a classic Smith & Wesson was made before they dubbed em “classic.” The old S&W’s were gun drilled, reamed or honed, with grooves cut by pulling a broach from breech end to muzzle, with barrel submerged in cutting fluid. EDM (Electron Discharge Machining) and ECM (Electro Chemical Machining) must introduce challenges particular to the process. One which might be to maintain uniform groove depth. If Ronnie Wells reads this, he may throw in. David Bradshaw |
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Post by RDW on Dec 16, 2020 11:21:41 GMT -5
This is the result of a Dull Broaching Tool Gentlemen. I leave a smidge in there so i can Do my last pull with a fresh cut tool because of this problem. Lack of oil as well as a harmonic that can set up at the end of the pull will compound the problem.
There is always a sweet spot in speed or feed rate when broaching and especially single cut. it takes a little trial and error to get it right.
My first 475 barrel was a Standard Ruger Redhawk that i screwed up a month earlier trying to get the chatter marks out of a 44 to 454 rebore. I had just got an old rifling machine and was learning the hard way how to use it.
There are a many a trick that of course no one was available to help me along. I happened on to a gentleman who had worked for Douglas at one time and he straightened me right out.
Young and impatient, i trudged along and got it down. Copper jackets, no problem, Lead and high speed this chattered groove will grab some lead on the way out.
Is it all the way thru the barrel or just the end?
R
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