Boolit Design for S&W Model 60

[Daekar]

Hey Folks,

I recently picked up a S&W M60 in 357mag (3"), and I am now in search of the ideal boolit design for it. In my experimenting, it seems to be fine with the Lee 358-158 RF when powdercoated, but I'm interested in a NLG design and like the idea of a custom that keeps the large meplat. For giggles I used the Accurate 36-158V as a starting place, removed the lube groove, cut 0.050" off the bottom so slightly less is seated in the case (about the same as some 125gr SWC) and moved that length to the front drive band above the crimp groove - it is now a Keith-approved 0.100". According to my measurements, the maximum length a boolit can extend beyond the case mouth before interfering with cylinder movement is 0.375", so I believe the front-heavy design will fit OK.

I'm kind of operating in a vacuum in terms of design philosophy and accepted procedure, though. Is this line of thinking how folks usually go about it?

[35remington]

Velocity variations are high enough that designing a more shallowly seated bullet of a given weight is not something I favor. Case space is the downside of the 38.

[Daekar]

Velocity variations are high enough that designing a more shallowly seated bullet of a given weight is not something I favor. Case space is the downside of the 38.

So, this might be a silly question, but what does the seated length have to do with velocity?

[rintinglen]

Most 38 loads take up very little of the space in the case. It has been repeatedly shown that allowing the powder to shift from front to rear can cause variations in velocity in the order 8-15%. The more empty space a boolit allows, the more likely the wide variation when a small charge "sloshes" around in there. The most accurate 38 Special cartridges have bullets that seat fairly deep.

[35remington]

The above response in terms of explanation said it as well as I could have. To give specifics, a 158 of standard seating depth experiences velocities of from 710 to 820 fps when standard charges are used as an example. This with powder forward versus rearward.

Something to consider. Powder shifting is the normal occurrence, such as when drawing from a holster versus some other manipulation. As long as enough band is outside the case to center the round in the throats that is plenty. Lots of weight forward is fine for something like the Auto Rim 45 case. 38 not so much.

[Daekar]

Most 38 loads take up very little of the space in the case. It has been repeatedly shown that allowing the powder to shift from front to rear can cause variations in velocity in the order 8-15%. The more empty space a boolit allows, the more likely the wide variation when a small charge "sloshes" around in there. The most accurate 38 Special cartridges have bullets that seat fairly deep.

Ah, I see. I assume the same would apply to my 357 cases for this gun too. I believe that will be less of an issue if one uses large, fluffy powder like Trail Boss, yes? That's been my primary powder in this gun so far.

[tazman]

Ah, I see. I assume the same would apply to my 357 cases for this gun too. I believe that will be less of an issue if one uses large, fluffy powder like Trail Boss, yes? That's been my primary powder in this gun so far.

Anything you can do to decrease the empty space in a 38 special case(and still be safe) will give more consistent velocity results. Fluffy powders is a good way to achieve that.
Now, a practical question. What is your intended usage for the revolver?
If you will be shooting paper at longer distances, then anything you do to improve consistency is a plus.
If you are looking for practice ammunition for close range defensive work, it doesn't matter much at all. Accuracy at 7 yards is nearly unaffected by velocity variances due to powder shift. The only concern about velocity at that range, is penetration and expansion.

If you are interested in a large meplat, you might look at something like a Lyman 358432. It is a wadcutter, designed to have much of the boolit outside the case. They are extremely accurate in all my revolvers, including my model 60. They also offer a nearly full meplat.
The only drawback I have found is, they are a bit more difficult to do a fast reload with compared to a boolit with a more rounded nose. I carry my revolvers with full power wadcutters in the cylinder with something like what you are using in the speedloaders for backup.
JHP style bullets can be unreliable in expansion from shorter barreled revolvers. Wadcutters don't suffer from that.

[35remington]

Chaining yourself to a single powder seems to run at cross purposes to a custom bullet design. The downside to Trail Boss is it leaves velocity on the table.

If low velocity plinking loads are desired a wadcutter of deep seating depth is most often the best choice as it addresses the inconsistencies that result from shallow seating depth without chaining yourself to a single powder. If pressures are low even a more filled case sees some level of increased inconsistency...the 32 Long being an example of this despite its smaller case.

For defensive use I personally don’t want my ammunition greatly varying depending upon how the gun is held or drawn either. If I desire say 820 fps from my snubby I’d like to consistently get as near to that as I can and not something else greatly different but that is how I roll.

As Taz mentioned what you want influences what the resultant design should look like and accomplish. The velocity variation of shallowly seated bullets bothers me so I choose not to accentuate it with my projectile choices.

[Daekar]

Chaining yourself to a single powder seems to run at cross purposes to a custom bullet design. The downside to Trail Boss is it leaves velocity on the table.

If low velocity plinking loads are desired a wadcutter of deep seating depth is most often the best choice as it addresses the inconsistencies that result from shallow seating depth without chaining yourself to a single powder. If pressures are low even a more filled case sees some level of increased inconsistency...the 32 Long being an example of this despite its smaller case.

For defensive use I personally don’t want my ammunition greatly varying depending upon how the gun is held or drawn either. If I desire say 820 fps from my snubby I’d like to consistently get as near to that as I can and not something else greatly different but that is how I roll.

As Taz mentioned what you want influences what the resultant design should look like and accomplish. The velocity variation of shallowly seated bullets bothers me so I choose not to accentuate it with my projectile choices.

I think I see what you're saying. I was thinking about freeing up space so I could use closer to 5.0gr of Trail Boss with a 158gr bullet (tested as safe in that gun with long-seated bullets) but the general consensus is that a custom boolit design shouldn't be based on something so specific. This makes me wonder if the best solution is a boolit without a crimp groove - you could have the weight you want with the nose profile you want without committing to a specific overall length. I wouldn't hesitate to try that in my single-shots, but I was under the impression that crimp grooves were strongly recommended in a revolver so I didn't pursue it.

My intended use is general purpose. This will be primarily used for steel targets, but it must serve as a carry gun as well. Honestly, I am not convinced that huge amounts of power are required for an effective civilian carry gun, so I'm relying on the large meplat plus the boolit weight to do the damage and my main concern is accuracy and control - doesn't matter what kind of power you're making if you can't hit anything, and accuracy makes the gun more useful in every scenario. I'd like to avoid falling below 800fps though, and the standard load of TB (4.2gr under a 158gr) was hovering around 750fps in my gun. I have some Green Dot which will work, and some Lil'Gun, but the former doesn't have a lot of data out there and the latter doesn't seem to play nice except under heavy boolits and full-house loads. Plus I have more TB than any other powder for pistols... and no idea when I'll be able to get my hands on other powder.

[35remington]

It’s sort of an interesting demand for your bullet. Such a design has a higher performance envelope and limiting yourself to velocities a 38 can exceed would make you wonder why you would bother with a 357.

Usually a bullet seated out is intended to maximize velocity by freeing up case space for a bulky slow powder. For what you want to do I’d load a wadcutter in the chambers and carry a speedload with a more rounded ogive bullet. If only slow to medium speeds are contemplated I’d definitely address the excess case space in some way. What you’ve got is a 426 that you want to run at 120 horsepower, so you have to address the excess displacement.

I fully get the idea of running it at a controllable speed. I am of that thought pattern myself.

[onelight]

Unless you want to you don't have to stick with one powder . You can always change when you find something else you want to try. Use what you have and when available try some of the other recommendations .
And the nice thing about a WC bullet is it is not dependent on velocity to perform like a HP .

[Daekar]

It’s sort of an interesting demand for your bullet. Such a design has a higher performance envelope and limiting yourself to velocities a 38 can exceed would make you wonder why you would bother with a 357.

Usually a bullet seated out is intended to maximize velocity by freeing up case space for a bulky slow powder. For what you want to do I’d load a wadcutter in the chambers and carry a speedload with a more rounded ogive bullet. If only slow to medium speeds are contemplated I’d definitely address the excess case space in some way. What you’ve got is a 426 that you want to run at 120 horsepower, so you have to address the excess displacement.

I fully get the idea of running it at a controllable speed. I am of that thought pattern myself.

So I actually standardized on 357mag this year and sold a number of guns... I had too many I didn't shoot, and my skill wasn't where I wanted it to be with any of them since my trigger time was spread too thin. I still have a 223 and a few military bolt guns, but I basically shoot only 357 and 22LR on a routine basis. My supply concerns are simpler by far, and I never have to chase brass again because I got rid of all my centerfire autoloaders. Plus I was able to buy 1000pcs of 357 brass... I don't think I will need to buy more for years.

That's a long way to explain why I am running a 426 at 120hp. If it makes you feel better about it, I also have a T/C Encore pistol that was specifically purchased to shoot hot handloads. MGM made a great barrel for me with a nice tight chamber.

[Daekar]

So... based on the advice in this thread I've thrown together another design, this one perhaps better suited to letting me use up more of the case capacity for better consistency with Green Dot while still keeping the power in an easy band. I don't really want to go to a pure wadcutter because I want to be able to use the same loads in the gun as the speedloaders, and even SWCs give me fits in the speedloaders. Does this seem a bit more on-track?

Thanks for helping me think through the different ways and reasons you might choose to change different pieces of a boolit. Any other wisdom or constructive feedback will be absorbed and assimilated.

[35remington]

That is close to an ogival wadcutter or stubby WFN which has a long history. I know lube grooves don’t thrill you but it is a way to make a given bullet weight longer. And deeper seated in the case for the same weight and crimp groove location. I do think the crimp groove should be present as you may want to speed them up and avoid bullet pull from recoil.

If you don’t contemplate lobbing those at longer ranges that would have some advantage over the first iteration, but in the best of instances a 357 case will leave considerable airspace when loaded mildly with a bullet that is other than something like a 160 grain wadcutter. If you try Titegroup and load those to about 850-900 fps that is about the best you will do in terms of variation at those lower speeds. At lower pressures/velocities even Titegroup has issues with consistency.

The truth of the matter is the 357 is a sort of “black powder” design in terms of excess capacity for lighter loadings.

[Catshooter]

This is a timely thread for me as I've recently un-expectedly acquired a .357 Model 60 myself. I've never owned a 2" .357 before so I've been looking at data to choose a boolit and powder combo.

I've tentatively settled on Lyman's 358430 which out of my alloy drops at 195 grains. Deep seater too it looks like. I'm not a fan of the round nose so I've been entertaining thoughts of altering the mould to give me some meplat.

The fluffiest (is that a word?) powder I have would be 2400 which I really don't think of as fluffy but with enough of it will take up some case room. Not easy to find loads for it. Lyman's 49th & 50th manuals don't show it at all. Figures.

Fun stuff.


Cat

[tazman]

35remington has it figured out.
I do like the looks of this design and yes, the crimp groove is necessary. I have found I get a better, more consistent powder burn with a good crimp in my revolvers.
That design should feed from a speedloader as well as anything other than a round nose. It will also give you most of the benefits that a full wadcutter will. It should be a good compromise.

[charlie b]

I would first ask why you are trying to design your own bullet? There are plenty out there to choose from and most are proven to perform well at a variety of velocities from .357 cases.

I just use different molds for different purposes, just like powder charges.

For carrying in the field I use full power magnum loads with 140gn or heavier bullets, usually SWC or RF. For range shooting I download powder and/or bullet, maybe a 125 or 105gn SWC.

For target shooting (many decades ago) a WC was the ticket. Load was determined by the pistol. Some liked a hotter load than others.

[Daekar]

I would first ask why you are trying to design your own bullet? There are plenty out there to choose from and most are proven to perform well at a variety of velocities from .357 cases.

I just use different molds for different purposes, just like powder charges.

For carrying in the field I use full power magnum loads with 140gn or heavier bullets, usually SWC or RF. For range shooting I download powder and/or bullet, maybe a 125 or 105gn SWC.

For target shooting (many decades ago) a WC was the ticket. Load was determined by the pistol. Some liked a hotter load than others.

Partially just because I can, and partially because the selection of NLG boolits out there is still lacking and I would love to see another one available for others to work with. I don't see why I should settle for something that isn't exactly what I want if it's an option...

Of course existing classic designs should be considered for use and as a source of knowledge too.

[JoeJames]

In my early Model 60-4 3” in 38 Special for some reason it really liked semi-wadcutters better than wadcutters. Kind of surprised me.

[charlie b]

I figured it was the NLG thing. I want my molds to have lube grooves even though I powder coat everything these days. If by some chance I was without the ability to powder coat I could still lube and shoot them.