Cylinder Bore Dimensions for 460 XVR

[memtb]

I’ve searched the internet and have called S&W. S&W consider it proprietary information and will not divulge! So, I’m coming you you guys.

Can someone supply me with the specifications, and tolerances (+ or -) for bore (not throat) ID for a S&W 460 XVR.

With my less than perfect tools, expanding ball for bore ID measurements, and I am not a trained machinist.....my cylinder measurements are pretty close in measurements.

While attempting to develop a good load....I’m experiencing a couple of cylinder chambers (bores) that continually give very difficult extraction, while others offer easy extraction. Yet, all chambers appear to be very similar, and throats appear very similar. I have polished all cylinder bores to a nice slick (mirror) finish. Any ideas to explain the difficult extraction issue? Thanks for humoring me! memtb

[cwtebay]

Yes, S&W has not had the best machining in the past 25 +/- years. I have had less than stellar experiences with any of their products since the '90's.
A revolver in 460 had better have incredibly tight tolerances with the punch packed in that cartridge!!!
I believe that I would contact said company and request that they examine it very closely.
I will refer you to Chuck Hawkes for further ranting!

p.s. I do actually have several Smith and Wesson revolvers that I truly enjoy!!! (They were all made prior to 1880).

Sent from my Pixel 5 using Tapatalk

[Mal Paso]

Here is the SAAMI info.

My experience with 44 Mag in a 629 is when I got sticky brass I was over pressure and expanding the cylinder. I would have S&W check it out too.

If you think S&W couldn't make a mistake on a cylinder, the last new S&W revolver I ordered arrived with no grooves in the barrel.

[DougGuy]

I would think it is time to start weighing every charge, in case a tad bit of inconsistency in loading is pushing up pressure randomly, just so you can rule this variable out, then if the same chambers are sticky, and they are smooth, might be time to back down off the load a bit. Although it is not out of the question that you may have chambers tighter than the others, sounds like that might only be part of the problem.

[memtb]

All loads are weighed charges.

Applying a fairly significant crimp, while hoping to extend case life.....a compromise (?) But, am getting no bullet movement from recoil

Some of the cases fall freely, while some of same load stick pretty tightly.....always same chambers (bores)

Using WW 296.....continually reduced load until I got erratic ignition! Same extraction situation with same chambers when using AA 1680

Mal Paso, Thanks for the spec’s. I couldn’t find them!

Doug, I know that you correct throat issues.....do you also clean-up any cylinder irregularities? With my primitive tools, I show minor dimensional changes along the bore length, as well as slight diameter changes at one spot (egg shape). These may be real or may be my lack of precision tools and my inexperience.

Thanks for everyones help! This has been pretty frustrating! memtb

[gwpercle]

All brass the same maker ?
Gary

[memtb]

All brass the same maker ?
Gary


Gary, yes same brass, Hornady, with same number of firings per case. Just loaded some with Starline brass. I don’t think that it will help, but.....stranger things have happened.

And by the way......I grew-up about 20 miles north of Baton Rouge! I’ve got 2 grandsons playing baseball for Zachary HS! memtb

[redneck1]

If your reducing w296 until you get erratic ignition you are making a big mistake .
296 does not play well with reduced loads !

[memtb]

If your reducing w296 until you get erratic ignition you are making a big mistake .
296 does not play well with reduced loads !

Yes I know....but it appeared that I was still experiencing “High” pressure issues! So....I reduced in very small increments. With the last 0.5 grain decrease, I experienced the erratic burns! memtb

[redneck1]

I'm going to suggest you find a different powder to use . 296 is a fairly safe powder to work loads up from a starting load to the ragged edge
Well safer then most powders if you use some common sense and a chrony

Down loading on the other hand .... , well the fact that you did it until you had inconsistent ignition is pretty telling that you don't understand the proper use of 296
Do realise that at the point of inconsistent ignition your also well below the point of possibly having very bad things happen .

[Mal Paso]

Are the sticky cylinders next to each other? If it's not machining it might be temper.

Speer doesn't give pressures but they say they limited max loads to 55,000 PSI and they list 36 grains of 296 as max load. I'm guessing that doesn't fill the cartridge and 296 likes a full cartridge. I think that's why 296 gets erratic fast with small reductions. AA#9 is the fastest powder they list both burn rate and velocity at 1784 fps/8.375" barrel.

[memtb]

Are the sticky cylinders next to each other? If it's not machining it might be temper.

Speer doesn't give pressures but they say they limited max loads to 55,000 PSI and they list 36 grains of 296 as max load. I'm guessing that doesn't fill the cartridge and 296 likes a full cartridge. I think that's why 296 gets erratic fast with small reductions. AA#9 is the fastest powder they list both burn rate and velocity at 1784 fps/8.375" barrel.


Yes sir, the offending chambers are adjacent to each other. I knew that I was “pushing the envelope” with the powder reductions....but, was trying to determine the cause of my extraction issues! What is unusual (I think) was that the previous reductions when reducing toward a recommended starting load.....I observed very small velocity losses. Almost non existent!

You are quite correct concerning the case fill, a lot more “free space” than I like to see.....even with this long bullet! As primarily (over many years) a rifle shooter.....I like full cases! Not really practical/achievable with a 8” barrel! :-)

I really hope that it’s not a cylinder “tempering” issue. Hoping some something that is easily correctible!

IMR4227 shows good performance in this cartridge combination I’m working with......but, I don’t have any. I’ve never heard any negatives about 4227 as with 296. I’d like to make 296 work, as I have some, I was satisfied with velocities and getting awesome accuracy (at least for me) @ 100 yards. I just can’t get past this extraction issue! [smilie=b:

If I could get mv’s anywhere above 1400 with good accuracy using my desired bullet.....I’d be quite happy!

[sparkyv]

I tried measuring them last night with calipers. Definatly not the way to do it, and I don't have a pin gauge set.

[DougGuy]

I could take a look at the cylinder and pin it out, sounds like a worn reamer cut two of your charge holes. Problem with using something to hone those, is the Sunnen hone does not do tapered bores at all, and the flex hones won't just hit the high spots, they want to polish everywhere which only carries the irregularities farther as you go. The proper thing to do would be to put a finishing reamer in there and see if it would clean up some of the ridges or woop te doos as we would call them riding dirt bikes, small smooth ridges. The finishing reamer will only cut if there are spots that are smaller in diameter than the reamer so you can get like an A or B or C finisher, which are slightly different sizes, but in 460 there may be only one and it may or may not true up charge holes.

Have you spoken to S&W about this problem?

I have had to buy finishers to save someone's cylinder before, and it worked well, just pretty costly on the shooter's part and even more so with that caliber.

Can you feel the tightness if you take a piece of fired brass from another chamber and push it in the tight ones?

I had to "relieve" a certain brand of two shot derringer 410 barrel to accept 460 brass for shot shells, I used a worn and resharpened 45 Colt reamer with the rim flutes ground off to do it with and it would then plunk 460 brass very smoothly. It was the only solution that didn't involve spending a LOT of money on a finishing reamer and waiting weeks and weeks for delivery. Just thought I'd throw this out there.

[memtb]

Thanks again Doug.

I have not talked to S&W, as from what I hear I would be disappointed in their work and their turn around time.

I do not think the charge holes are tapered, at least according to S&W.....which means perhaps the Sunnen hone may work.

I (after the fact) tried the fired brass in the charge holes. All brass had resistance about 1/4” inch from being fully chambered in “every” charge hole. The two chambers that I marked as having the greatest resistance.....were tighter with “all” cases. Perhaps the Hornady brass doesn’t “spring-back” as much as it should....but, these two specific charge holes exhibit much greater resistance than the other (3) three charge holes!

I may be going out of town for a while.....you may be getting my cylinder to work on while I’m not at home to miss it! If I decide to send it, I’ll contact you!

I hope to go out today and shoot some loads using my new Starline cases.....maybe they will respond differently. But, I don’t expect miracles! memtb

[Mal Paso]

Speer mentioned when testing the similar pressure Casull loads, that stiffer brass extracted easier. Winchester took 5,000 psi more than Starline for the same deflection. This was published in 2007 and brass may have changed but harder brass should help. Speer also says DA guys are going to have a bigger problem than the SA guys who only extract one at a time.

[memtb]

Mal Paso, Thanks! Still in a “holding pattern”.....didn’t get the opportunity to shoot yet! memtb