Lyman #4 offers the following for 38 special
Lyman 358665 158gr. Flat Tip/TC bullet
Titegroup 2.9 @ 12,800 cup to 3.3 @ 16,100 cup
COAL 1.445”
Lyman 358311 160gr. RN bullet
Titegroup 3.2 @ 11,100 cup to 3.6 @ 16,200 cup
COAL 1.550”
SAAMI max pressure - 17,000 cup
Lyman lists a redding #52 wadcutter 148gr..titegroup 2.9 - 3.4
150gr Lyman 358091 titegroup 3.1-3.5 and notes it as most accurate load.. That 358091 is a plain flat base dimple tip FULL wadcutter. 13.6-16k cup
Guess Lyman has no idea what they are doing publishing their own data on their own bullet... Right?
No idea. I just crunch the numbers. Seating depths make large differences, which is what I was trying to get across.
Cognitive Dissident
I would use the crimp groove and back the powder charge down. Keep in mind that load data are based on the bullet they use. If your bullet is different, you need to back down and test it yourself.
I tested one and got 799fps with 3.2 of titegroup with data showing 815 in their test gun. There is a lot of empty space in the case.
The big question is, what is the difference in the boolits when you measure from the crimp groove to the base?
I believe you're greatly over thinking the issue. IF I crimp at all, I always seat to crimp in the groove for any revolver reloads. Revolver cartridges usually have a much larger powder space and they always have a LOT more "freebore" than autoloader cartridges so they are much less twitchy than autoloader ammo.Going by hodgdons online data for Tightgroup, I find I must seat bullets .100 deeper to get the case mouth to the crimp groove. That's a lot less space in the case.
Off the top of my head, I don't remember the modest peak pressures for .38 Spec. OR the high pressure 9/10MM rounds but the difference between them is quite high so modest differences in book OAL figures hardly matters for revolver (or .45 ACP) reloads. "Experts" rightly warn us about pressure vs. seating depth of the small, high pressure autoloader cartridges that just don't apply to larger, much lower pressure cartridges.
In fact, in some 55 years of reloading everything that goes BOOM! I've never paid any attention to book seating depth for anything EXCEPT the 9/10MM rounds. I have never seen a hint of excessive pressure from any book powder charge for revolver reloads. That has included a lot of .357 loads in .38 S. cases with cast bullets seated to the factory crimp groove.
I don't believe it's an issue but do it if it makes you more comfortable. But, at 3.4 gr. you're already a bit more than 10% below the maximum book charge. At 3.2 gr. you'll be some 20%+ below max and you might need a range rod to hammer out any bullets that get stuck in the bore!Data says 3.2-3.8grs with a coal 1.475. Thoughts? Will I increase pressure too much by seating to groove? I had charged the cases with 3.4gr but I may dump and go 3.2.
Birdman, I last looked at NV's Yucca Flat in Feb. of 1962. For a Florida blue-suit boy a long way from home, it was kinda fun to work there for a few earth shaking months but I haven't missed it!
Thank you for your service.
Last edited by 1hole; 09-27-2022 at 01:51 PM.
People have been using 158 grain cast bullet data and seating into the crimp groove for decades and decades and decades. If someone tells you it's going to be pushing the envelope for .38 Special they might not be up to speed on what's been going on in reloading for like the last 100 years.
Deleted Post
Last edited by gwpercle; 09-28-2022 at 06:35 PM.
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Oh, I'm "up to speed on it" alright because I've measured the psi.
If you have a load, particularly a top end load, and use another bullet, even if the same weight, that seats deeper into the 38 SPL case the psi will be higher. As I've posed a .001 deeper seating can mean 8,000 psi difference. With a top end 38 SPL load that would push the psi up to 25,000+ psi. With a top end +P 38 SPL load it could be 28,000+ psi. That is low end 357 magnum factory psi level.
The question is; by switching bullets of 158 gr and seating to the crimp groove is the bullet seated lower in the case than the load was developed for? There is a plethora of damaged/blown 38 SPL revolvers out there. I've seen enough of them. So, who's to say they weren't damaged due to excessive psi from deep seated bullets? Older RD and SWC 38 SPL bullets had close to the same seating depth to the crimp groove. Many newer, especially custom or individually designed, cast bullets can have much shorter or longer lengths to be seated inside the case. Probably why most all manuals and reloading data sites tell us if we change any components, to drop back the load and work back up. Sound advice.
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
What pressure signs do you look for when working up a load in .38 Special?
Fortunately lead bullet loads tend to develop much less pressures than jacketed bullet loads..when comparing equal weights and same profiles... Note.. Equal weight and profile lead bullets are usually shorter than jacketed due to lead vs copper weight . this all works towards making lead less pressure than jacketed loads of the same weight and profile. Lastly..most lead bullets have less bearing surface than a jacketed counterpart... Again..lowering pressure... And let's face it.. Lead slides easier down a barrel than copper anyway. This all work together in favor of lower pressure lead shooting.
Good question.
I've always believed that reloads for handgun ammo might well blow a barrel off before showing any of the common incipient signs of excess pressure for a rifle. Even hot loads for most magnum revolver reloads are designed for lower pressures than modest rifle ammo.
I have my own pressure rules for MY max rifle loads but for handguns I follow the loading book maker's recommendations. The effective down range differences between book max and loading at the ragged edge of a KABOOM is too small to make much difference in use and lighter loads don't pound my handguns to an early death.
We're not going to get any "pressure signs" at 38 SPL pressure levels. If you do then you are probably above 357 Magnum pressure levels.
However, this is where the chronograph comes in handy. If you're using a different bullet than the manual, then drop back and work up to the same velocity level as the manual load. Not necessarily precisely accurate pressure wise but if all the other components, particularly the powder, then you'll still be within safe pressures.
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
I remember reading in a load manual (Lyman or Western) that if you do see pressure signs, you are probably WAAAYYY over pressure. That statement may be more true for .38 Special and .45 Colt than it is for .357 Mag and .44 Mag.
That was the myth for many, many years. I believed it too because it sounds reasonable. Problem is, it doesn't work out that way in reality. I've spent a lot of time, effort and expense trying to determine, by actually measuring the pressures, that cast/lead bullets give less pressure with the same loads as does jacketed bullets of the same weight, seating depth and bearing surface. I've done this with numerous handgun and rifle cartridges. Best I have come up with as to which will give the greater pressure for a given load is; it depends. What exactly it "depends on" I haven't found a concrete answer for. Thus, based on actual pressure testing that theory is not provable.
If you have any empirical data based on the actual measurement of pressures demonstrating such, I would certainly appreciate seeing it.
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |