CAS 357 Magnum load underperforms - Crimping issue or ??

[JimGnitecki]

Some of you know that recently I have been prepping to get back into CAS after a couple of decades away from it.

I’ve been trying to develop a handload for my 2 .357 Magnum Cimmaron Model P peacemaker replica revolvers with their short 4.75” barrels that I can also use in my 1873 Uberti 1873 replica rifle.

I developed a Trail Boss handload that seemed reasonably good in Ladder Testing, delivering 1.5” to 2” 5-shot groups at 25 yards when I did MY part in aiming and grip, but Trail Boss is now not only unavailable but also discontinued.

Both of my CAS revolvers are new Cimarron Model P Peacemaker replicas that a few days ago, using much of the last of my Trail Boss powder at 4.1g and no-name cast bullets of 142g, 147.5g, and 154g weights, fired 1.5” to 2” groups at 25 yards.

But, I had to switch to whatever powder was actually available to me.

The only other powder available to me in more than token quantity is TiteGroup. I did a Ladder Test on it a couple of days ago, but got very confusing results.

My Ladder Test used:
Federal SP primers (regular, not Magnum because Magnum primers not available to me0
Starline Cases with measured wall thickness average = .0104”
TiteGroup powder at 3.2, 3.4, 3.6, 3.8, 4.0, and 4.2 grains
Hornady no. 10408 “Frontier” 158g SWC swaged bullet

I set the COAL to run 1.580” or above., for good reasons stated later in this post.

Actual performance of these handloads on the range is a bit of a puzzler.

First, only the 4.0g load performed even close to being “normal”, but it still produced rather crappy 5-shot groups at 25 yards. Like 2.5 to 4.5 inches. The other loads were basically total failures which really did not meaningly group. All over the paper targets.

On the one hand, the statistics look fine with the 4.0g of TiteGroup powder that at least has potential were:
Std Dev is just 9.7 fps, which is decent
Extreme spread is 29.

But . . .

The average velocity is only 781 fps, when the Hornady load table shows I should expect more like 880 fps from 4.0g IF I had a 10” test barrel like they used. Still, THAT much lower with my 4.75” barrel?

If I load to 4.2g of TiteGroup, some things improve and some get worse:
The Std Dev is down to 9.2 fps
The extreme spread is basically the same at 28
The average velocity climbs to only 808 fps when the Hornady table suggests it should go past 900 fps IF I had a 10” test barrel. Is a 4.75” barrel length going to produce tHAT much lower a velocity?
And the 5-shot grouping pretty much disappears, with group sizes of about 7.5” at 25 yards!!

I have thought about what changed besides the powder, and that turns out to be both the bullet and the crimp, and how those 2 factors interact. Let me explain:

Case mouth diameter going INTO the crimp die = 0.3805

Case mouth diameter after crimping = .375 (This is also the OD of virgin Starline cases)

Bullet shank diameter going into crimp die = .355 (This is how it comes out of the Redding Competition Pro seating die. Isn’t this a little too small a bullet diameter for .357 Mag?)

Bullet shank diameter, right above case mouth, after crimping = .355 (i.e. unchanged)

The actual bullet diameter fresh out of the factory box runs at ..3578” average

So, my progressive press setup is clearly compressing the bullet by .3578 - .355 = .0028”

This is occurring right in the Redding Bullet Seating die.

Case diameter below the crimp after crimping die = .3750 (i.e. the crimp die does not further compress the case diameter)

Case wall thickness = .0104" average

So, amount of additional crimp applied at the actual crimping die station = .355 already compressed bullet dia + (2 x .0104 case wall thickness) -.375 = .0008” more “crimping” beyond the .0028” done before the crimping die, at the Redding seating die.

i.e. I have a “total crimp” of .0028” done before the crimp station + .0008 applied at the crimp station = .0036”

BUT, the Hornady 158g swaged SWC bullet (no. 10408) has no crimping groove. Its shank is 100% cross-hatched and dry lubricated from the factory. The slightly smaller diameter semi-wadcutter head simply protrudes from the shank.

I set the COAL to run 1.580” or above. I control the COAL this way to ensure that all the cartridges are shorter than the recommended SAAMI maximum of 1.590”, regardless of the fact that lead bullet cartridges in a progressive press are going to vary in COAL, and with light CAS loads for a revolver, keeping the COAL under 1.590” for SURE is more important than keeping the case volume from shrinking too much if a bullet is seated deep, since our peak CAS pressures are low.

This 1.580” minimum COAL setting leaves about 1/16” of bullet SHANK protruding above the case mouth. So, crimping into the start of the SWC section of the bullet is not possible. I’d have to run a COAL of at most no longer than 1.580” minus .063” = 1.517” which would be ridiculously short for a .357 Magnum cartridge.

Since Hornady designed this bullet, which they refer to on its box as the “Frontier” bullet, specifically for CAS, and for .38 Special or .357 Mag use, AND Hornady’s own loading table for the bullet specifies a 1.590” COAL, I assume they know what they are doing by not providing a crimping groove. And, a COAL of 1.580" and higher, but always below a max of 1.590" should work fine.

And Redding specifically states that the “crimping” die in their .357 Magnum “Competition Pro die set” (which was designed specifically for progressive presses, and which I am using on a Dillon XL750 progressive) is intended to apply a sort of combination roll crimp & taper crimp.

So, obvious questions:

- Why is the velocity SO MUCH lower compared to Hornady’s 10” barrel length result?

- Why is the 5-shot grouping so poor? (Compared to the actual Trail Boss results with the same revolvers and the same shooter)

- Is it normal for the stations on a Dillon XL750 progressive running Reddings own .357 Magnum Competition Pro seating and crimp dies (Dillon sizing and powder drop dies) to compress a .3578” diameter bullet to .355” before the crimp die?? And then have the crimp die add a .0008 crimp on top of that??

- Isn’t a .355” lead bullet diameter too small for accuracy in a .357 Magnum barrel?

I am thoroughly confused by these results. Can someone shed some light on what might be going on here?

Jim G

 

[Roverguy]

I’m not a huge fan of Tite Group but I use it in 38 spl because it’s available. Having said that, I have no had the problems that you are experiencing.

when I look at the starting loaf for 158 cast semi wad cutter in Hodgdon for 357 mag, it’s 4.5 grs, so you are significantly below their published data. There may be insufficient load density to get best ignition and combustion. I would start there; try 4.5, 4.7 grs and see what results you are getting. You may get better obturation as well.

You will or course also get more recoil and have to use more powder. Neither of which are ideal for CAS. Do you have, or would you get 38 Spl brass? With 38 spl and that bullet, your starting load is 3.2 grs and 3.5 should give you plenty of oomph, certainly enough for CAS.

I would start with the published minimum charge from Hodgdon in 357 brass and see what that tells you. If 4.5-4.7 grs works and you can live with powder usage and recoil, all is well. If it works, but the bite is more than you want shooting 6 or so stages, going 38 spl may be worth exploring.

 

[buck460XVR]

Are you saying your seating and crimp die is swagging the bullet down to .355? If so, that could certainly be the reason for the accuracy issues. Hornady claims that bullet measures .358, which should be appropriate.

 

[P Flados]

Your velocities do look a little low. I ran a Quickload table. Note that Quickload uses breech to muzzle for barrel length. I generally reduce the results by 50 fps or so below the Quickload prediction as an estimate to cover cylinder gap losses. If you bullet is undersized, you could be getting "blow-by" that is an additional velocity loss.

The swaged bullet is probably very soft. Your combination of sizer die and expanding plug are giving you a case ID that is swaging down the bullet more than I would be happy with.

You may want to try either using a commercial cast bullet (harder and less prone to swaging during bullet seating) or getting a bigger expander plug (NOE has a good product).

Cartridge          : .357 Magnum (SAAMI)
Bullet             : .358, 158, Hornady SWC 10408
Cartridge O.A.L. L6: 1.580 inch = 40.13 mm
Barrel Length      : 6.5 inch = 165.1 mm
Powder             : Hodgdon TiteGroup

CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms
-25.0   26     3.00    750     197   10175   1684    100.0    1.118
-20.0   28     3.20    781     214   11349   1779    100.0    1.067
-15.0   29     3.40    811     231   12584   1874    100.0    1.017
-10.0   31     3.60    840     248   13879   1969    100.0    0.970
-05.0   33     3.80    868     265   15235   2063    100.0    0.928
+00.0   34     4.00    896     281   16651   2157    100.0    0.890
+05.0   36     4.20    922     298   18127   2251    100.0    0.856
+10.0   38     4.40    948     315   19663   2344    100.0    0.824
+15.0   40     4.60    973     332   21259   2437    100.0    0.795
+20.0   41     4.80    998     349   22916   2530    100.0    0.769
+25.0   43     5.00   1022     367   24635   2622    100.0    0.744

 

[Hooda Thunkit]

I agree that the bullet diameter is too small. Are you getting any barrel leading?

 

[JimGnitecki]

I’m not a huge fan of Tite Group but I use it in 38 spl because it’s available. Having said that, I have no had the problems that you are experiencing.

when I look at the starting loaf for 158 cast semi wad cutter in Hodgdon for 357 mag, it’s 4.5 grs, so you are significantly below their published data. There may be insufficient load density to get best ignition and combustion. I would start there; try 4.5, 4.7 grs and see what results you are getting. You may get better obturation as well.

You will or course also get more recoil and have to use more powder. Neither of which are ideal for CAS. Do you have, or would you get 38 Spl brass? With 38 spl and that bullet, your starting load is 3.2 grs and 3.5 should give you plenty of oomph, certainly enough for CAS.

I would start with the published minimum charge from Hodgdon in 357 brass and see what that tells you. If 4.5-4.7 grs works and you can live with powder usage and recoil, all is well. If it works, but the bite is more than you want shooting 6 or so stages, going 38 spl may be worth exploring.

I have 700 .357 cases and NO .38 Special cases, so would be reluctant to change to .38 Special cases. I also want to keep the .357 Mag length for better 1873 rifle operation (I want to use the same load for CAS rifle as for CAS handguns).

The Hodgdon load table is based on, as you said, cast bullets.I could make a bullet change, but I bought a lot of the Hornady 158g swaged because I have had such great performance from Hornady products with other firearms that use the Hornady HAP 9mm pistol bullet and the Hornady 6.5 Creedmoor bullet. VERY impressive results with both (0.3 MOA with the rifle and 1" 5-shot groups with the 9mm handgun at 25 yards!).

I hear your comment about insufficient load density, but look at those standard deviations (9.X !). That suggests the powder load is perhaps appropriate?

More recoil would not bother me. I have a husky build that seems impervious to even 115g 1375 fps 9mm loads, so a higher powder charge would not bother me. It takes the "sharpness" of a FULL .357 Mag load for me to notice and not like. So, more recoil than now would be fine, PROVIDED that it would not cause the soft swaged bullet to lead the barrel excessively. I do not appear to be getting much leading. After the range session, there were no gray streaks, and the barrel still looked shiny. Just MPro5 cleaner and just 2 patches made the 3rd patch already come out clean. Hornady probably had a reason for stopping the load table for the bullet with TiteGroup at 4.1g. I may need to just try a stronger load. With the 32.g to 4.0g loads, the spent primers looked like this:



and with 4.2g, no visible difference:



So, I think going higher in powder load would be safe.

But the loaded bullet diameter from the Redding SEATING die bothers me. .355 seems to me too small a finished diameter for a 357 Mag bore. I realize that the land diameter in a .357 Magnum barrel is .346, so there's plenty of rifling engagement between a .355" diameter bullet and the .346" barrel land diameter, but still . . .
SAAMI specs call for a LEAD bullet to be .3590" with a .356" minimum diameter, not .355".

Jim G

 

[Docendo Discimus]

I would back off your bullet seating die a few turns and reset the stem for correct AOL. I would try only crimping at the crimp die. It sounds like you may be double crimping.

 

[JimGnitecki]

Are you saying your seating and crimp die is swagging the bullet down to .355? If so, that could certainly be the reason for the accuracy issues. Hornady claims that bullet measures .358, which should be appropriate.

Yes, that is exactly what the Redding seating die and crimping die are doing, and that is my current biggest concern when I analyze the dimensions I am getting. I know the dimensions I am measuring are accurate as they can be, since I am using a Mitutoyo digital caliper. However, I also realize that even a Mitutoyo cannot in theory be more accurate than to the nearest .001" at best. Yes, it displays to a 4th decimal digit, BUT that 4th digit can only be a "0" or a "5".

Jim G

 

[fxvr5]

Jim, where are you getting your data? My Hornady manual (#11) uses a 8" Colt barrel. The HODGDON manual uses a 10" barrel.

Your shorter barrel will produce MUCH less velocity than a 10" barrel. The usual rule of thumb is that you lose ~ 50 fps per inch.

 

[Palladan44]

Taper crimp only enough so the cartridges drop in the cylinders, and no more. Over crimping can be a double-whammy....
Excessive crimping does swage down the bullet, and the brass springs back a little bit where the bullet stays swaged down, thus destroying neck tension causing possible ignition anomalies, and the smaller bullet/ bore fit further diminishing accuracy.

There could be other issues as well. I can be fully responsible for very poor groupings depending on the day.

 

[fxvr5]

Swaged bullets are soft and can be more easily swaged down during seating than a cast bullet.

BTW, while brand loyalty is admirable, your gun(s) might simply not like the Hornady bullet.

 

[Jim Watson]

Is a 4.75” barrel length going to produce tHAT much lower a velocity?

Yes. You have half the barrel length with a hole in it (the cylinder gap.) Full charge .357 used to be listed at 1510 fps... from an 8.375" barrel. About 1250 now from a 4" vented test barrel or real revolver.

Bullet shank diameter going into crimp die = .355

That just ain't right. I think you need to try a different seating die. If you were here, I would lend you one.
Have you pulled a bullet to see and measure the body?

 

[lordpaxman]

The Hodgdon load table is based on, as you said, cast bullets.I could make a bullet change, but I bought a lot of the Hornady 158g swaged because I have had such great performance from Hornady products with other firearms that use the Hornady HAP 9mm pistol bullet and the Hornady 6.5 Creedmoor bullet. VERY impressive results with both (0.3 MOA with the rifle and 1" 5-shot groups with the 9mm handgun at 25 yards!).

I’m getting a bit confused, most likely as usual, but did you develop and see an acceptable group with the Hornady 158 swaged and trailboss? If you’re thinking a swaged bullet will perform like a cast or jacketed, it may not.
Do you targets indicate any tumbling, odd shaped holes? If the bullet isn’t engaging the lands enough, it won’t stabilize well. Sounds like that may be part of the issue. Are there any other bullets available to you?

 

[Palladan44]

Is that brass you have the shortened Leverloution 357 brass that is like a full 1/32" shorter than normal 357 brass?

 

[JimGnitecki]

Ok, I did some more measuring. The problemS might be occurring a lot earlier than I thought:

1. The brand new Hornady cases come out of their factory paclaging at .3712" average OD and the brand new Starline cases come out of their factory packaging at about .3734" average OD. So, they are "too small" a diameter right from the get go.

2. The fired Starline cases coming out of the revolver before resizing are .376"

3. The Dillon sizing die resizes a fired case back down to .373"

So, whether I load a cartridge that has a brand new case, or a resized case, my case going INTO the Redding seating die is going to have only a .373" OD, which, subtracting 2x the .0104" wall thickness, leaves a .3522" ID, which is far smaller than the .3578" virgin bullet being seated into it. What APPEARS to be happening is that the case is being stretched a bit out to .375"OD and the bullet is being swaged down to .355" ! That's too small a diameter to meet the SAAMI bullet diameter spec of .359 -.003" + 0" which calls for a .356" minimum for a lead unjacketed bullet.

When I push a cartridge firmly into a wood surface, I can reduce the COAL by about .003". This proves that despite the compression of the bullet diameter and the stretching of the case diameter, the bullet is still not being "firmly enough" held by the case to prevent movement under just hand pressure, which is not anywhere close to cartridge peak pressure!

The swaged bullet is evidently soft enough to let this occur.

So, do I have BOTH (a) too small a resized case diameter coming out of the Dillon sizing die which is swaging the bullet down to too small a diameter, and (b) too small a resulting final bullet diameter to achieve the anticipated but unachieved muzzle velocity?

If so, the first problem is not insufficient powder charge, but rather a Dillon sizing die that needs to be RAISED a bit so that it does not resize the case "too" much.

The second problem appears to be that brand new virgin cases (whether Hornady OR Starline), withOUT being resized by the Dillon die, are already too small a diameter, and they swage the soft bullet down to a diameter too small for either good sealing in the bore AND any decent accuracy.

Am I seeing this correctly or not?

It seems odd that virgin .357 Magnum brass comes delivered at too small a diameter. Is the Hornady bullet simply TOO soft for use with virgin brass?

Jim G

 

[JimGnitecki]

I’m getting a bit confused, most likely as usual, but did you develop and see an acceptable group with the Hornady 158 swaged and trailboss? If you’re thinking a swaged bullet will perform like a cast or jacketed, it may not.
Do you targets indicate any tumbling, odd shaped holes? If the bullet isn’t engaging the lands enough, it won’t stabilize well. Sounds like that may be part of the issue. Are there any other bullets available to you?

No, the Trail Boss loads were all done with my previous bullets which I ran out of. They were CAST 142g, 147.5g, and 152g lead bullets as I recall. They all performed reasonably well although not exceptionally.

So, no, the 158g swaged Hornady bullet has only been loaded and fired with TiteGroup powder, but the exact same die setup which worked for the cast bullets and Trail Boss powder, except I adjusted the Redding seating die to maintain the 1.580" minimum COAL.

The holes in the target paper show no signs of tumbling.

The Hornady 158g swaged bullets are the ones I can get the most reliable supply of. Others are going to be hit and miss, which is not helpful when you need a LOT of bullets, and CAS certainly needs a lot of bullets.

You and I are seeing the same issue: the finsihed cartridges, with the present setup, are producing final bullet ODs that appear to be too small for both accuracy and proper peak pressure achievement.

Jim G

 

[JimGnitecki]

I would back off your bullet seating die a few turns and reset the stem for correct AOL. I would try only crimping at the crimp die. It sounds like you may be double crimping.

I THINK you are correct. IF the Dillon die can be raised enough to prevent the over-compression of the case OD without leaving the base of the cases just above the rim too large, this should work. I have measured the average FIRED case OD just above the rim, and it is a very consistent .3755" on the Mitutoyo caliper. That fired diameter fits easily and fully into the .357 Magnum cartridge gauge. So, yes, raising the Dillon resizing die so that the base area of the case is not resized at all will not be a problem.

BUT, will the Dillon die STILL resize the MOUTH of the case too much? i.e. is the Dillon die "tapered' internally or not? If not, it will STILL resize every case to be too small won't it?

Jim G

 

[jmorris]

So, obvious questions:

- Why is the velocity SO MUCH lower compared to Hornady’s 10” barrel length result?

100 fps loss with a barrel that’s less than half the length they used in their testing, I’d be happy that’s all it lost.

- Why is the 5-shot grouping so poor? (Compared to the actual Trail Boss results with the same revolvers and the same shooter)

- Is it normal for the stations on a Dillon XL750 progressive running Reddings own .357 Magnum Competition Pro seating and crimp dies (Dillon sizing and powder drop dies) to compress a .3578” diameter bullet to .355” before the crimp die?? And then have the crimp die add a .0008 crimp on top of that??

- Isn’t a .355” lead bullet diameter too small for accuracy in a .357 Magnum barrel?

Were you not using the same setup with your TB loads that shoot 1.5-2” groups? Same revolver, same shooter, same everything else, except powder and charge weight? If so bullet size wouldn’t be causing the problem you are having now because you already shot 1.5-2” groups with the same setup and components. You just changed powders and charge, correct?

Or are there more changes that we don’t know about adding variables we are not considering?

If you have added other variables, I would suggest going backwards and eliminate them so you actually have an apples to apples comparison between just the powders.

If you have changed dies/components so the bullets are now being swaged smaller than they were when you tested TB, the blame might not be on TG but your other changes.

 

[JimGnitecki]

100 fps loss with a barrel that’s less than half the length they used in their testing, I’d be happy that’s all it lost.



Were not using the same setup with your TB loads that shoot 1.5-2” groups?

Or are there more changes that we don’t know about adding variables we are not considering?

If you have added other variables, I would suggest going backwards and eliminate them so you actually have an apples to apples comparison between just the powders.

If you have changed dies/components so the bullets are now being swaged smaller than they were when you tested TB, the blame might not be on TG but your other changes.

The physical XL750 machine and dieset setup used for the TiteGroup loads is identical to that used for the Trail Boss. What HAVE changed are both the powder (out of availability necessity) and the bullet (also out of necessity - ran out of the old supply of CAST bullets in slightly lower weights (142, 147.5 and 152g versus the 158g SWAGED Hornady).

I agree that the likely issue here is not the powder change, but rather the unfortunate combination of too small an OD on BOTH the resized cases and the virgin cases, coupled with the soft swaged bullet being soft enough to be reswaged down in the seating and crimping dies that worked fine on the harder CAST bullets. But see my last couple of postings this morning.

This might not be easy to solve.

Jim G

 

[jmorris]

I agree that the likely issue here is not the powder change, but rather the unfortunate combination of too small an OD on BOTH the resized cases and the virgin cases…

If you only changed bullets and powder, how could there be a problem with the same brass you shot 1.5-2” groups with?

Really hard bullets with TB testing and really soft new ones?

If it’s the same brass, and dies/expander, the brass wasn’t too small for the bullets you used before.

Did you use all of your TB? Might be worth loading a few just to ensure your baseline is still good, even if you don’t have enough left to play the game with.

 

[JimGnitecki]

Heck, I just measured all my fired cases from the 4.0g TiteGroup load, and realized that my fired case OD is consistently no saller than .3765" and no alrger than .3775" on my Mitutoyo caliper. AND, they all fit into my .357 Magnum cartridge gauage just fine without resizing at all. This sort of implies that if I do NOT resize my cases at ALL, they would not overcompress the bullet diameter which si what apepars to be causing my problems.

Is this crazy or what?

Jim G

 

[JimGnitecki]

If you only changed bullets and powder, how could there be a problem with the same brass you shot 1.5-2” groups with?

Really hard bullets with TB testing and really soft new ones?

Yes, that is exactly what these measurements imply! The cast bullets were evidently hard enough to stretch the case mouths versus the cases over compressing the bullets.

Jim G

 

[jmorris]

Yes, that is exactly what these measurements imply! The cast bullets were evidently hard enough to stretch the case mouths versus the cases over compressing the bullets.

That makes it an easier problem. You need to find another bullet, that works like before.

Or change things you were otherwise happy with before you changed projectiles.

 

[fxvr5]

I agree that the likely issue here is not the powder change, but rather the unfortunate combination of too small an OD on BOTH the resized cases and the virgin cases,

The issue is when loading soft bullets like swaged bullets which are soft. In many cases, it's not a problem. BUT, IF loaders want to remedy this, they obtain an oversized expander die, the oversize part is the portion that goes down into the case. It expands the brass to a larger ID. An example is the Lyman M die. For handgun rounds, it might not go deep enough for the full length of some bullets. But you could check to see if Lyman has something for 38/357.

I'm not real savvy on this topic but you could check with the people at photo escape and see what they might have to offer.

http://www.photoescapeinc.com/products/index.html

The folks on the Bullseye forum have to deal with this sometimes and might be helpful. You could post your issue on the Ammunition section.

https://www.bullseyeforum.net/

 

[Jim Watson]

How about a bigger expander? Even the one made for wadcutters:
https://uniquetek.com/product/T1735

Same thing as at photoescape, looks like same picture.

You might need the one optimized for the Zero bullet
https://uniquetek.com/product/T1772

They say to use a Lee Carbide Factory Crimp die which seems to be at risk of squeezing down a soft bullet.