JimGnitecki
Member
- Joined
- Mar 28, 2010
- Messages
- 1,258
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
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