S&W 610 & Custom Keith Design

[BLTsandwedge]

I'm just about ready to put in an order to Mountain Moulds for a standard Keith design in 10MM. This would drop at .402" (correct for cylinder throats and groove measurement) and weigh 200g using straight WW.

The reason I'm going with a custom mould is because there are very few 10MM bullet designs available. There are plenty of weight choices, but not much in design other than a truncated cone or something close. The question- has anyone else gone down this road? Advice is greatly appreciated- the goal is to get the S&W 610 6" to shoot as well as my K-38. And that's a lofty goal.

Many thanks,

Tom

[Dframe]

I presently don't own a 10mm mould but would certainly be interested in how yours performs. I also own a 610. I doubt I'll ever get it to shoot as well as my 44 specials but certainly worth trying.

[MtGun44]

I think you will do well with a Keith design. Make sure the 'as cast' will be throat diam +.002
or .003, so you can size it to throat +.001. IME dead on to +.001 seems to work best.

OTOH, some guns still do real well with throat -.001, but IMO, why would one CHOOSE
to have the boolit sloppy in the throat? Also, since some throats are oval a bit or hard
to measure really correctly to .001, I prefer to add an extra .001 to be certain of a slight
interference. Sizing the boolit .001 is totally negligable, but guarentees no slop.

But then there are guns like my Colt 1917. . . . . won't chamber a boolit that is throat
diameter. :sad:

A 610 is kinda a rare beast, isn't it? I have only seen a few.

Bill

[subsonic]

In your shoes, i would measure the gun, correct any dimensions that are out of whack and go from there. I dont know if you can find any dies that will roll crimp, but id look. 2 problems you'll encounter will be crushing the boolit undersize when you taper crimp and boolits designed to have the front driving band in the case to ease chambering in autos.

Try a 180 to 200 gr (or even heavier) wfn style boolit with a strong front driving band. Since i'm betting you won't be able to roll crimp, and a roll crimp will effect headspacing if you're not using moon clips, work to acheive good neck tension by using an expander that is at least .003" smaller than the boolit you end up using and taper crimp lightly enough that a boolit is not crushed undersize when pulled. Try a max charge of AA9 with a NON-magnum primer.

[Mal Paso]

I'm just about ready to put in an order to Mountain Moulds for a standard Keith design in 10MM. This would drop at .402" (correct for cylinder throats and groove measurement) and weigh 200g using straight WW.

The reason I'm going with a custom mould is because there are very few 10MM bullet designs available. There are plenty of weight choices, but not much in design other than a truncated cone or something close. The question- has anyone else gone down this road? Advice is greatly appreciated- the goal is to get the S&W 610 6" to shoot as well as my K-38. And that's a lofty goal.

Many thanks,

Tom

Very cool! How long is the chamber and how close to the throat could that front drive band be? Or maybe just in the throat?

[bowfin]

I have a similar problem as I have a .401 Herter's Powermag revolver coming home to live.

I have contacted Accurate Arms to see if they can cut a 220 grain .41 design to .403" diameter.

[roysha]

The Grandson has a 610 in which we have tried 3 different bullets, Lee TC, Lyman SWC and NEI RF (actually cast this one for my 38-40). If you are using the clips, the SWC is a pain to insert into the cylinder. Accuracy was acceptable but not good enough to put up with the loading hassle.

The 38-40 bullet was ok but not near as accurate as the TC bullet.

9.3 grains of Bluedot pushes the TC bullet along quite nicely with excellent accuracy. This bullet is cast straight WW, sized .401 and lubed with a 2 to 1 mix of NRA ALOX and some CH lube I bought in the late 80s/early 90s. The CH lube is (was) HARD and very touchy about temp so I diluted it with NRA and it works great.

We taper crimp because there is no crimp groove and when we tried to roll crimp we got an occasional wrinkled case.

He always uses moon clips but with the taper crimp he could shoot without them if he had to. We tested that very early in the load development.

[ReloaderFred]

My S&W 610 really likes my SAECO 200 grain FP mold. The bullets drop at 206 Grains with my alloy and I load them over Winchester 571/HS-7 powder and standard primers. It will shoot a ragged hole @ 25 yards from a sandbag rest. I've found that the heavier bullets shoot more accurately through all my 10mm pistols.

Hope this helps.

Fred

[Glen]

Yes, I had Mountain Molds make such a mould. For details, see:

http://www.lasc.us/Fryxellmountainmolds.htm

Sized .400" and seated so that the driving band are all inside the case, they shoot just fine in the S&W 610. I designed this bullet for the Herters .401 Powermag, so I put in a crimp groove. For the S&W 610 you won't need to do that, so leave out the crimp groove and taper crimp.

[Lloyd Smale]

a little secret ill share with you 610 shooters is the lyman 150 swc. Its only available in there 2 cav blocks which sucks but its been a great bullet for target shooting. A bit light for real serious work but in my 610 and 646 and my buddys two 610s and one 646 its the most accurate bullet weve found. to be that good in that many guns shows me theres something to it. If you want something that feeds a bit better with clips try the 180 rcbs round flat mold.

[Paulinski]

I have S&W 610 on order so this is interesting thread for me.

So far I have NOE 200gr mould to try but I would like a Keith style boolit as well.

[BLTsandwedge]

Good information all- many thanks. MtGun44- I like the advice of going .403. My 610 throats and groove run .401 and .400 respectively- that extra .001 can come in handy as I'll size to
402". Re the 610 being a rarity- dunno. I believe S&W did discontinue the model. The versatility (.40 and 10MM) is an attractive feature.

I'm a fan of roll crimping- Lyman's seat die can do that. However, as I can't answer Mal Paso's question yet, I may have to take Glen's advice- do away with the crimp groove and fine-tune a taper crimp if the COAL roll crimped to a crimp groove proves too long. We shall see. The nominal COAL is 1.250" and the Mountain Mould Keith in question has an OAL of .712".

The revolver shoots well right now. "Well" isn't good enough. I need this 610 to be exceptional. It'll take 3 or 4 months to bring the project through testing. I'll bring this thread back to life and post my findings.

Thanks gents,

Tom