Need advice about Rimrock .38/.357 SWCHP bullet

[Forrest r]

Your revolver seems to have low velocities/low performance. This is why I asked about die sets.

Several years ago I decided to thin the herd with the different 38spl/357mag bullet molds I had. Here is a picture of some of them along with 3 others not pictured.

I did a lot of head to head testing over a chronograph and in wetpack looking for the best performing bullets. After testing in 2 1/2", 4" (2x), 6" (3x), 8" & 10" 357mag bbl's these 4 always had the highest velocities. Didn't matter with the 5 different powders tested, they were always to dogs.

What they have in common is the ability to seal the throats of the cylinders and bbl faster with their large bottom drive bands (bullet bases) or long full diameter bodies or a gc. This makes them more efficient makes better use of the pressures exerted on them.

Most reloading dies are designed for the shorter, smaller in diameter jacketed bullets. The expander doesn't actually open the case enough where it counts. Namely near the bullets base.

They will flare the mouth of the case but not anywhere near the depth needed to use cast or coated bullets. A lyman m-die expander next to a lee factory expander. You can clearly see the high water mark on the lee die that was left from the case mouths. The cases need expanded further in the case to keep the cast/lead bullets from being swaged down.

If the bullet gets swaged down it will not only loose pressure from the load blowing by it. It will use more pressure to bump it back up in diameter to seal the cylinders and bbl.

I'm not saying that the rimrock swc is a bad design. It's just odd that a gc'd bullet has the same velocity as the plain based bullet does. Typically when you see this it's telling me that the soft gc bullet is being swaged down when seated and the harder swc isn't.

Just something to think about. A lyman m-die expander next to a factory lee expander. You can clearly see the high water mark left by the top of the case mouths on the expander button on the lee die.

 

[Paul in Nevada]

NOE makes expander plugs for the Lee Universal Expander. Just like Forrest said the idea is to provide a better flare for cast bullets not just in the mouth but into the case.

 

[rhodesengr]

Forrest, great posts. Love the detail.

NOE makes expander plugs for the Lee Universal Expander. Just like Forrest said the idea is to provide a better flare for cast bullets not just in the mouth but into the case.

So the Lyman die expands further down?

How about the RCBS version (which I have) . My sense was that it was different than my Hornady expander. More of a taper than a flare.

 

[Paul in Nevada]

I have only used the NOE plug and then I have an aftermarket powder funnel for the Dillon which does the same thing. Most flaring dies just roll the case mouth outward enough to start the base of the bullet. The case will then yield to a copper jacketed bullet or a very hard BNH cast bullet. But a soft bullet is going to lose the contest and get swaged down. Think about how a rifle die works. As the case enters the die the neck is sized a little smaller than necessary. As the case is withdrawn the neck is sized to the proper spec from within. This also means that no matter how thick the case material is, the neck I.D. is always the same. Not so with a pistol. The standard flare only opens the mouth. If we had a plug shaped flaring tool we could resize the inside of the case as well, providing a better fit for long soft bullets.

 

[John Patrick]

I would think that the gas check would inhibit swaging when both seating a bullet and when crimping. No?

I've used a Lee Factory Crimping Die but it was a long time ago, I don't recall whether there was any swaging possibility. Anyone know?

 

[rhodesengr]

I would think that the gas check would inhibit swaging when both seating a bullet and when crimping. No?

Maybe. It would depend on the stress produced when the bullet is seated. If the g/c is copper, copper is softer than brass and the g/c is not very thick so I could see how it might buckle or dome as it is pressed in. Sadly, we can't see the final state through the brass. The lead might also squeeze outwards. The lead in the HP bullet is very soft and its OD is less than the g/c. So I can see how the lead might bulge outwards if the force is enough.

 

[rhodesengr]

I think this discussis great but efficiency aside, I wanted a 357mag load with that bullet at around 1000fps. So I am pretty happy just loading my 8.0 grains and calling it a day. I have moved on to working on higher speed 357 loads with the Hornady XTP 125gr bullet using Enforcer. I will be testing 17gr tomorrow. I already posted my 16.2gr results.

I have also turned my attention to buckshot rounds for my M2 tactical. Buckshot is a real can of worms it turns out.

 

[John Patrick]

Maybe. It would depend on the stress produced when the bullet is seated. If the g/c is copper, copper is softer than brass and the g/c is not very thick so I could see how it might buckle or dome as it is pressed in. Sadly, we can't see the final state through the brass. The lead might also squeeze outwards. The lead in the HP bullet is very soft and its OD is less than the g/c. So I can see how the lead might bulge outwards if the force is enough.

I think I'll load up a dummy with the SWCHP GC and the pull the bullet to see what it looks like. Going to be awhile, I have a bunch of Berry's HBWCs to load first.

 

[rhodesengr]

I think I'll load up a dummy with the SWCHP GC and the pull the bullet to see what it looks like. Going to be awhile, I have a bunch of Berry's HBWCs to load first.

You could pull the bullet but that might deform it more. Another possible approach if you want to see the actual "as seated" state would be to section the assembly. Just cut the bullet and case in half. Then you can see the actual cross-section. Could be crudely done with a Dremel and cut-off wheel. Actual metallurgical sectioning saws are rather expensive.

 

[John Patrick]

I thought about that and said to myself, "Too much trouble…" But if it's off-season (late fall, winter) I'll have plenty of time and maybe I'll do the gas checked Brinnel 5, a 12, a 15 and maybe an 18, and some coated bullets too.

 

[rhodesengr]

maybe there is a metallurgical lab near you that would do the sectioning for little or nothing just to help out with something cool.

 

[Forrest r]

It's no big deal, simply putting out there that it's good to "read" the signs that your reloads are telling you.

Any time I use 2 drastically different bullets and get the same velocities for the same load. I start taking a hard look to see why. Could be something as simple as the difference in seating depth (case volume). Visual things like nose deformation from the pressure of seating the lead bullet or powder residue on one side of the case are clues.

The other thing to keep in mind is that I used the same alloy to cast 10 of those bullets (1 was a home swaged jacketed bullet) that was a 8/9bhn alloy. A lot easier to pick up on things when everything is cast with the same alloy/same sizing die.

What others are doing with AA#5 in the 357mag's with +/- 158gr cast bullets.
AA #5 in a .357 Mag. with 160 gr. cast

At the end of the day if you're going to use cast/coated bullets it's best to use an expander designed for them. A lot of commercial casters use extremely hard alloys to make there lead/cast bullets with. This keeps them from getting banged up/looks good when you open the box. A side affect of this is there isn't a lot of distortion to the bullet when seating the rock hard bullets.

Lee has come out with a collet crimp die for the different revolver dies. These are not their fcd dies, they are an actual collet crimp die. The same type of crimp that is used on rifle bullets. These things are the cats meow if you want to lower your es/sd's. Consistence ='s accuracy.
357 Magnum Custom Collet Style Crimp Die - Lee Precision

Glad to see people enjoying the 357mags. There not as popular as they used to be. Myself I'm what you consider an antique/outdated.

 

[boatbum101]

Lyman M has been a cast bullet shooters staple for a long time . RCBS Cowboy series dies have a similar type expander & NOE has all types of wonderful useful tools / moulds . With that Rimrock bullet as long as impact velocity is between 900 to 1150fps you're good . Any faster it'll over expand & penetration suffers , too slow just the opposite . Regardless of which case used , 38 or 357 tons of medium burners will give desired speed . To us geezers mid range loads scream Unique , better choices for lower flash now days .

 

[John Patrick]

FWIW, I pulled a couple of Berry's 148gr copper plated HBWCs Saturday.

I measured an out of the box vs two pulled bullets and found no diameter difference, and that held true for the whole length of the bullet except the very top where the crimp was. There was a hard to discern length difference of maybe .003", which I attribute to the crimp pushing some material in the only direction it could go.

The copper plating was intact at the crimp.

Dillon expander set at or close to minimum flare. Redding dies, including the competition taper/crimp die.

The sizing/decap/cap die was set at the minimum for sizing that would still allow decapping.

 

[BobB257]

Great post. Really like the RimRock product line. Kept me from going way down the casting rabbit hole. Just not enough time with work and family. But I could read about all the details that good reloaders find till the cows come home. The 357 chamber is so versatile and even more so if you have a press and some carefully chosen dies. My girls like to plink with the powder puff wad cutter loads I make in 38 cases. I like my more stout FBI loads in the 357 cases similar to what was worked up here. The RimRock product has been consistent for me for over 12 years.

 

[SuperMan]

Nice work rhode.. I don't think you have anything to worry about...

What you are doing is basically duplicating the original .38-44 rounds... They were 158 grain bullet at 1125 from a 5" gun. The rounds were made for LE from the early 1930s to mid-1940s. The round was discontinued in 1946 as the .357 Magnum had basically taken over the LE revolver market.

The .38-44 ammo was made for the S&W Outdoorsman and Heavy Duty. It could also be run in the Colt Army Special, Police Positive, New Service, Officers Model and SAA... Buffalo Bore basically duplicates that ammo today with their Outdoorsman and +P HP load.

Good video of what the HP load will do...it is what I carry in my .38s...inclusing a 649-2 snubbie...

[ame]https://www.youtube.com/watch?v=GTJYsc6PdEM[/ame]

...and here are the 158 solids...

[ame]https://www.youtube.com/watch?v=LXF5HOQz5WY[/ame]


I use a slightly different home cast 357156 from both Lyman and MP molds... The MP mold has a HP... Run with 6.0 grains of Unique about equals the BB loads...all loads from .38 Special cases...

Take care...Bob

 

[boatbum101]

Discontinued IMR SR4756 really used to shine in these type loads

 

[rhodesengr]

great posts guys. Thanks.
having basically settled on the load, I am now looking at the different dies. I made my first batch with the Hornady dies. It was a few weeks back but I don't recall having any problems other than needing more expansion for the g/c bullet. Sunday, I made another batch using my RCBS dies. I got through the run but I think there was an issue with the RCBS expander.

The g/c OD is .360. I had to go pretty deep with the expander to get the bullet in. I had used those dies before with Hornady XTP bullets that have a nice smooth jacket with .357OD. The RCBS expander worked well on those.

With enough flair to get the g/c into the case, the case mouth was hitting the mouth of the seat/crimp die. They went in with a little force but I saw some brass shavings collecting around the case holder.

I am going to try my Hornady dies again and I also now have Lee dies to try but seems like that .360OD on the g/c is a bit of a problem.

Any tips about this issue with the g/c and the expander die?

 

[BobB257]

My older Lyman Carbide set has an expander that seems to handle the gas check without issue. If I get a minute I will get it out and measure the stem so you have a reference. No idea if Lyman has changed the design.
I would guess some of the "Cowboy" marketed dies likely have an expander set to optimize for a lead bullet.

 

[rhodesengr]

Good video of what the HP load will do...it is what I carry in my .38s...inclusing a 649-2 snubbie...

...and here are the 158 solids...
Take care...Bob

Great videos. The terminal ballistics is the part missing from what I can do. Seems like the 158 g/c bullet is really great for its intended purpose. The hard cats ones, not much expansion and lost of penetration. I guess they have their use.

He was getting more like 1100fps from the commercial ammo. I was getting that too before dropping down to 8gr. I might go back up a bit.

 

[SuperMan]

Discontinued IMR SR4756 really used to shine in these type loads

...sad day when that powder was discontinued...it made "Specials" really SPECIAL...

 

[sniper]

I would not try to push a soft bullet like the Rimrock bullets to 1100 fps. They are only rated @5 BHN. You usually want at least a 12 BHN or better for that kind of pressure and they need to fit the barrel well too.

I load that bullet with either W231 or better yet HS-6 but Power Pistol should do fine.

The bullet has a gas check, which minimizes leading.

 

[1sailor]

I was just at the Rim Rock site looking at those bullets. They sure are spendy for a cast bullet. A lot more than I've ever paid for JHP's or JSP's. Gas checks aren't that expensive.

 

[John Patrick]

great posts guys. Thanks.
having basically settled on the load, I am now looking at the different dies. I made my first batch with the Hornady dies. It was a few weeks back but I don't recall having any problems other than needing more expansion for the g/c bullet. Sunday, I made another batch using my RCBS dies. I got through the run but I think there was an issue with the RCBS expander.

The g/c OD is .360. I had to go pretty deep with the expander to get the bullet in. I had used those dies before with Hornady XTP bullets that have a nice smooth jacket with .357OD. The RCBS expander worked well on those.

With enough flair to get the g/c into the case, the case mouth was hitting the mouth of the seat/crimp die. They went in with a little force but I saw some brass shavings collecting around the case holder.

I am going to try my Hornady dies again and I also now have Lee dies to try but seems like that .360OD on the g/c is a bit of a problem.

Any tips about this issue with the g/c and the expander die?

I loaded some with Lee dies just a bit of flare from the expander.

The flair was minimally set for a Bear Creek 158gr Hi Tec coated SWC.

That setting worked with the Rim Rocks but took a bit of attention to set the bullet reasonably straight before seating the bullet.

The crimp was a heavy crimp which looked like the Buffalo Bore crimp I was trying to imitate. Crimp with the Lee FCD.

When I pulled the Rim Rock the gas check stayed in the case. It looked flat as far as I could tell.

I didn't measure the Rim Rock but I measured a couple of pulled Bear Creek SWCs done with the same die settings and there was no difference in diameter between pulled bullets and out of the box bullets.

No damage to the Hi Tec coating either.

I loaded six live rounds of each and my first impression was the Bear Creeks shot very accurately while the Rim Rocks did not. I'm going to change powders and work up a 2400 load.

When I go into "production" I'll load Bear Creeks then add a bit more flair and load the Rim Rocks.

FWIW, I don't think the Reading Profile Crimp Die I use for my wadcutter load would be a great choice for the Rim Rock gas checked bullets.

Photo of my 357 dummies with a Buffalo Bore 38spl +P SWCHP-GC below.

 

[BillBro]

Ramshot TrueBlue may be a powder choice you should consider here. Im launching 158gr SWCHP's from Matts bullets, 20:1, no gc at 1220fps with 8.5gr of TrueBlue with ZERO leading from a 5"627. ES=24 and SD=8. This is in 357 not 38 though. I had to load that load a secind time to confirm the stats and got almost identical specs.
Im really glad that TrueBlue is showing such promise, in several calibers I load, since I bought 10lbs of it.
The Western manual shows 1176fps at 8.8gr with a LC SWC, which are harder than the 20:1 Matt casts all of his hollowpoints with which is why I dipped down a little below Westerns recommended start charge.

Maybe TB would be a powder you could give a try. It always seems to be available too. I think Hodgdon has it, Midsouth has it, Natchez has it......
It always gives very low numbers, except velocity, often down in the low single digits. Itd amazing in my 44mags and Specials.

Just a thought.

 

[John Patrick]

Ramshot TrueBlue may be a powder choice you should consider here. Im launching 158gr SWCHP's from Matts bullets, 20:1, no gc at 1220fps with 8.5gr of TrueBlue with ZERO leading from a 5"627. ES=24 and SD=8. This is in 357 not 38 though. I had to load that load a secind time to confirm the stats and got almost identical specs.
Im really glad that TrueBlue is showing such promise, in several calibers I load, since I bought 10lbs of it.
The Western manual shows 1176fps at 8.8gr with a LC SWC, which are harder than the 20:1 Matt casts all of his hollowpoints with which is why I dipped down a little below Westerns recommended start charge.

Maybe TB would be a powder you could give a try. It always seems to be available too. I think Hodgdon has it, Midsouth has it, Natchez has it......
It always gives very low numbers, except velocity, often down in the low single digits. Itd amazing in my 44mags and Specials.

Just a thought.

I have some True Blue and was thinking about trying it to duplicate Buffalo Bore's performance in 357 cases.

The Western starting load is right about the velocity range I'm looking for.

Was the TB clean burning?

 

[38SPL HV]

I've had success using N340 with 150 - 170 gr cast in 357 Magnum. Tighter ESs and lower SDs compared to AA5 and True Blue and very good accuracy in my hands and very clean burning.