Designing .357 Bullet

[detox]

I am trying to design a gas check 160gr bullet for my 686. Bullet in picture is a combination of two RCBS bullets (9mm 147gr. and 158 Cowboy), but with "two crimp grooves" and gas check added. Bullet has same band area as 9mm and nose shape as Cowboy. What do you think? Is there more to designing a bullet than just drawings...what about balance point? Will this boolit be accurate?

[Wayne Smith]

First off, why a gc? Unless you are going to shoot it out of a rifle it is an unnecessary expense. Go to the Mountain Molds website and plug your design in there. You will get a lot of answers.

[Outpost75]

Agree. Myexperience has been that GCs are a waste of expense and effort in revolvers, because in most casez, their diameter is too small to seal the cylindercthroats. Rifles are a different story.

[MtGun44]

GCs are not needed in any pistol cartridge, at least up to the normal magnums like
.44 mag, .357 mag at full power loads.

Bill

[detox]

I here gas checks are needed for maximum accuracy? Thats if you can seat it squarely and without raise sprue cut.

[williamwaco]

These guys are giving you the straight dope.

Listen to them.

[detox]

These guys are giving you the straight dope.

Listen to them.

Plain base it is. Back to drawing board. Other than gas check, does this shorter design look like it may perform good?

[detox]

I have narrowed it down to four versions

[btroj]

Either of the ones with a standard groove.

Why the crimp groove at the base of the nose? Got something that needs that short a nose?

[Larry Gibson]

I disagree. If the revolver has a 6" or longer barrel GC cast bullets come into there own. They are more accurate, they do size "large" up to .360 in but I've not found a need for over .358 or .359 at the largest for revolvers, they allow softer alloys to be used for better terminal performance and they allow true magnum level velocities with all the before mentioned attributes, especially accuracy.

If you want top end performance stick with your GC'd design or just get a 358156. It is a proven design and is very close to your 1st design except it is a SWC.

You can always get a 6 cavity 358-158-SWC or such for medium range or plinking loads and use the GC'd bullet for your top end loads. That's what I do with complete satisfaction.

Stick with your original design.

Larry Gibson

[detox]

The crimp groove at base of nose is a close copy of the RCBS Cowboy with bore ride width of .350". When bullet is crimped here there is alot of excess freebore in cylinder, but bullet shoots verygood. The second crimp groove will extend bullet closer to cylinder forcing cone (less free bore). I want to see which works best in my gun.

The RCBS 147gr 9mm bullet shoots better than my RCBS 150gr SWC Keith bullet.

[detox]

My gun seems to like lighter weight bullets so maybe this shorter Gas Check version? I like a more shallow crimp groove...works brass less. I have also included picture of Lyman's 358156

[btroj]

I like the nose tapering into the body's edition more than I do the swc shoulder.

I think it will shoot well.

[357maximum]

I disagree. If the revolver has a 6" or longer barrel GC cast bullets come into there own. They are more accurate, they do size "large" up to .360 in but I've not found a need for over .358 or .359 at the largest for revolvers, they allow softer alloys to be used for better terminal performance and they allow true magnum level velocities with all the before mentioned attributes, especially accuracy. If you want top end performance stick with your GC'd design or just get a 358156. It is a proven design and is very close to your 1st design except it is a SWC.

You can always get a 6 cavity 358-158-SWC or such for medium range or plinking loads and use the GC'd bullet for your top end loads. That's what I do with complete satisfaction.

Stick with your original design.

Larry Gibson


I have to say that I agree with Larry, :lol: especially the text of his that I turned RED
At upper end revolver and contender speeds the gas check design will almost always take 1/4 inch or mor off my 100 yard groups, plus as Larry has said the proper alloy for hunting can be used.

[MtGun44]

Yep, soft alloys cannot be shot accurately in the .357 mag. . . . . :bigsmyl2:

http://castboolits.gunloads.com/attachment.php?attachmentid=50446&d=1244513448

I do not shoot .357 beyond 6" bbls, so cannot comment on Larry's point about longer barrels. I
have found Larry to be a knowledgeable source, and rarely does our experience differ, but here
I have found no reason whatsoever FOR REVOLVERS 6" BBL AND SHORTER to use GCs. Frankly,
in my experience, HPs with 8 BHN are fine for .38 Spl velocities and are way too soft to do anything
but blow the front half off at .357 velocities, although this is definitely related to HP cavity size and
depth, in addition to alloy hardness.

Bill

[Larry Gibson]

Bill

If that was a 50 yard group I'd sure agree with you;-)

Larry Gibson

[Nrut]

When I first starting shooting big bore handgun silhouette (up to 200m for Rams) back in the 80's everyone that shot cast used GC bullets..
So I just followed their lead..
I can't speak to using PB bullets as I never used them..
I was only interested in silhouette shooting and hunting..

detox, if you are going to use that bullet for hunting you might consider a larger meplat..

[Bigslug]

Now that you've lost the gas check, relocate some lead to the base in order to make the lube groove larger. I like where you're going otherwise, especially the twin crimp grooves.

[detox]

Been doing some reading...this boolit thing is way over my head...a couple of things i have read.

"One method of stabilization is for the center of mass of the bullet to be as far forward as is practical, which is how the Minié ball and the shuttlecock are designed."

"Powder should burn completely before bullet exits bore". I have noticed some unburned Unique flakes (5.4gr load) lately after shooting 158gr Cowboy @ 1000fps from 686 pistol. Also the faster burning Tin Star powder delivers better accuracy from same gun, bullet and fps...no unburned powder residue.

Nose heavy bullet example

[paul h]

I've shot a whole mess of cast handgun bullets with and without gas checks, and with loads that generate over 40,000 psi. As stated, gas checks are not strictly required to achieve steller accuracy in magnum handguns, even at the higher pressures and velocities. I've shot alot of 5 shot 1" groups at 50 yds with my 480 with 310-460 gr cast bullets, plain and gas checked cast from coww, both water quenched and air cooled. In an accurate revolver, it simply isn't that tricky to get top accuracy. That said, gas checks do give you more flexibility in your alloy hardness and your loads.

Personally I'd go with an ogival wadcutter design aka lbt lfn though other manufacturers designs shoot just as accurately. I'd suggest a 0.090" driving in front of the canalure. If you're looking for top velocity, then design the nose of the bullet so that the meplat is 0.030" shy of the front of the cylinder, and decent size single lube groove. If you're looking for top accuracy at mid level loads, I'd keep the 0.090" driving band but shorten up the nose to put more of the bullet in the case. I would not design a bullet that has no driving band in front of the forward crimp groove. You can do a chamber cast to see how long the throat is in your cylinder and make the driving band 0.010" shorter than that length if you really want to dial it in. Here's some .476"" cast bullets that have shot those 1" 50 yd groups, as you can see various nose lengths work just fine.

http://forums.accuratereloading.com/evefiles/photo_albums/3/4/4/344100033/744100033_3339F6808143EE14AD3755B7E8638787.JPG

[detox]

How about "no" crimp groove. Just roll crimp into band where needed. Something like this. Gas check section was added just for heck of it and to help make bullet more nose heavy.

[detox]

Here is the "no gas check" version. No crimp groove needed

[paul h]

I'm partial to crimp grooves, just measure the throats of your cylinder and design the front driving band accordingly.

That said, in a good gun you can come up with 1/2 dozen different but similar designs and they should all shoot superbly. I'd go with a 0.268" meplat, puts you right at 75%