Seating depth determination

[MOA]

I've acquired a new mold that was designed for the 38 super. (see image). The alloy I'm using gives it a weight of 147.5 to 147.7 which seems to be in the realm of 9mm possibilities. Since there is no data I've been able to locate giving this length cast boolit in a 9mm case I thought I'd run this but y'all out there.
My issue is how deep to seat without getting into trouble of dangerous pressures due to seating depth.
I'm planning on using data for a 147 cast out of Lyman (Blue colored) cast boolit book using universal or bullseye, typically in the 3 grain range. My boolit fits the weight criteria of the load but since the profile length of my boolit is longer than the mold used in the book my seating depth would need to be less and overall length longer. Should I make my seating depth just deep enough to chamber and run through the magazine? Only info I've found is on other forums from those shooting minors an majors. Depths mentioned in those forums centered from 1.135 to 1.165. Some thoughts or experience on this issue would be welcome. Additional info: this boolit is designed to cast a 160 grain boolit.

https://i.postimg.cc/fTpXqDKG/20220410-130707-1.jpg (https://postimg.cc/N5855hZD)

https://i.postimg.cc/FHC2BZ2G/20220425-161131-1.jpg (https://postimg.cc/xXHxkKjb)

[Winger Ed.]

With cast, you'll have to work pretty hard to get into much trouble.
If it fits the magazine, goes through the feeding cycle, chambers OK, you're good.

As I recall, the Navy's SEAL Team Six originally had the 147 developed so it'd hit hard, and could be suppressed well.
Winning the Bianchi Cup, and the accuracy it required--- wasn't a big consideration.

[mehavey]

What is the length of the bullet . . .
and what is the OAL that fits, feeds, & plunks ?

[MOA]

The length of this cast is .668
If I had a length of the cast that the lyman mold number 356637 produced I could calculate the empty space inside the case.

[44MAG#1]

.673 inches. Sized and lubed. Now you have it.

[MOA]

.673 inches. Sized and lubed. Now you have it.

Thank you very much 44MAG#1

A .005 difference. Guess I'll increase the book OAL by .005 and that should be a good start. Maybe a bit further if the magazine and chambering work. Although I'm still not sure how a flat nosed 147 grain is longer than a 160 grain round nose.

[44MAG#1]

Thank you very much 44MAG#1

A .005 difference. Guess I'll increase the book OAL by .005 and that should be a good start. Maybe a bit further if the magazine and chambering work. Although I'm still not sure how a flat nosed 147 grain is longer than a 160 grain round nose.

I will condense it down. The nose on the Lyman is more slender down to the FP and the base is tapered. Your bullet is fatter on the ogive where the Lyman isn't as fat.

[44MAG#1]

Plus the Hornady 147 grain XTP is .655 inches length.

[Willie T]

If you have a chronograph this is what I would do:
Seat one just short of the ogive and make sure it plunks in the barrel. Then using published data for a cast 147 round nose, start my work up at the starting charge, work up till it started to shoot, looking for signs of pressure along the way. Chronograph each charge weight. Pressure makes velocity and you can cautiously monitor what neighborhood you are in. That is not precise, so don’t push the maximum. You are most likely going to have a longer bearing surface which will manifest in making more pressure with less powder. I would be especially cautious if using a really fast powder and a heavy for caliber bullet. Slower powders are generally more forgiving. If you need to adjust OAL to see if longer shoots better, your adjustments are longer, so pressure will fall as long as you don’t jam it in the lands. Short cases are sensitive to seating depth. Starting low and working up and then out is a sensible approach.
Good luck working it out.
Willie

[megasupermagnum]

Load a dummy as long as the magazine will allow reliably. Plunk test. Shorten if needed. Then just pick out some 147 gr load data which is common, and work up to that. If you really want to get fancy, just measure your OAL of your cartridge that plunks, minus your case length (about .75"), and that's your nose length. Take your nose length, and subtract it from your bullet OAL, and that's your seating depth. A quick search and math shows a 147 XTP has a seating depth from Hodgdon of .305" assuming 44mag#1's XTP quote is correct. To match with your .670" bullet, you would want an OAL of 1.115", however, I think it is likely your ideal length will end up longer than this.

Also, if you have WSF powder, there is data for a 147 FMJ on Hodgdon.

[reddog81]

What kind of alloy did you use to get from a 160 grain mold to 147 grain bullet? If the mold was cut for pure lead and you used linotype that be close.

Seat as far out so the rounds fit in the magazine, feed from magazine into chamber , and fit inside chamber without problems going into battery.

3 grains of Bullseye should work. That load works for 158 grain RN 358311 bullet. If the bullet is supposed to be the size of a 160 grain bullet you should use load data for 158/160 grain bullets. Not 147 grain bullets. How much space inside the case the bullet fills is more important than small variations in weight.

[MOA]

What kind of alloy did you use to get from a 160 grain mold to 147 grain bullet? If the mold was cut for pure lead and you used linotype that be close.

Seat as far out so the rounds fit in the magazine, feed from magazine into chamber , and fit inside chamber without problems going into battery.

3 grains of Bullseye should work. That load works for 158 grain RN 358311 bullet. If the bullet is supposed to be the size of a 160 grain bullet you should use load data for 158/160 grain bullets. Not 147 grain bullets. How much space inside the case the bullet fills is more important than small variations in weight.

My alloy is a mixture of wheel weight and Roto metal hardball alloy. BHN is 30.
I've loaded a few that work in the magazine and go plunk. I'm planning on these being shot in a Sig Arms model 2009 Sig Pro. I've pulled the barrel for the plunk test for improved visual check on cartridge chamber fit. All boolits sized at .358. The OAL of these cartridges is 1.145
The power is Universal at 3.0 grains.
The mold was a Magma engineering mold 38S-160-RN for the 38 super.

reddod81...thats the crux of the problem....finding published 9mm load data with a 160 grain boolit. Heaviest I've found is 147 grain.

[JonB_in_Glencoe]

Load a dummy as long as the magazine will allow reliably. Plunk test. Shorten if needed. Then just pick out some 147 gr load data which is common, and work up to that. If you really want to get fancy, just measure your OAL of your cartridge that plunks, minus your case length (about .75"), and that's your nose length. Take your nose length, and subtract it from your bullet OAL, and that's your seating depth. A quick search and math shows a 147 XTP has a seating depth from Hodgdon of .305" assuming 44mag#1's XTP quote is correct. To match with your .670" bullet, you would want an OAL of 1.115", however, I think it is likely your ideal length will end up longer than this.

Also, if you have WSF powder, there is data for a 147 FMJ on Hodgdon.

This is pretty close to how I did this similar thing with my 38 Super.

To the OP, I'm assuming you are talking a 1911.
First, I find MAX COAL that will chamber, then find MAX COAL that works in the Mag...using that info to find the best length to cycle in the action...using dummy rounds.

Then I load starting loads, assuming case capacity is reasonably close to published data...doesn't need to be exact.
Generally, I work up loads using how far the gun throws the empties, but also taking into consideration any signs that indicate higher pressure than I want. A chrono is a great tool as well. Obviously, I am also watching for adequate accuracy, if I don't get it, then it's time to change powder.

[Doughty]

My Lyman #45 shows a starting load of 3.0 Bullseye for the Lyman 358311 (158 grn) and a max of 3.5. I loaded 3.2 under the Lee .358 bevel based truncated cone 158 (160 my alloy / my mold). 1.033 OAL. I didn't chronograph them, but they shot nicely in a Glock 19.