38 special seating depth and pressures.

[bgavin]

My understanding of the charge process is, there is a linear operating range of Min and Max charge pressure values.
Under charged or over charged becomes a bomb or detonation device.

The published load tables are concerned with a specific powder charge relative to a specific case capacity below the seated bullet.
Change the bullet seating depth, and the case capacity changes.
This directly affects the effect of the charge.

Published data never includes the bullet length or seating depth.
My emails to the powder tech support folks come back as "your bullet is close enough if the same weight and type."
This does not sit well with me... especially with high energy powders like Clays where a small change has a large impact.

I use Quickload and the published Lyman bullet dimensions to calculate the actual case volume filled by the powder.
I then measure the seated depth of the bullet I want to use and plug it into Quickload.
I use the standard case trim dimension and let the cartridge OAL float as it will.

Marlin 1894 are known to be finicky about feeding 38SP cartridge lengths.
There are modifications that cowboy shooters make to the carrier to fine tune this.

[Larry Gibson]

Larry, could you test 5.5 grains of blue dot, and /or 7.1 grains of 2400 both with any standard primer at 1.640"? Those should be a +p load at 1.540"
If you cant test all the way out to 1.64" 1.6" will work.
Sorry for slow responses, 2 young kids severely limits reloading time.
Thank you for your interest in this, its not something i have seen discused or tested.

I will endeavor to persevere..........Will load a dummy round and see how far out I can seat it to fit in the Contender test barrel.

[Ateam]

I am not sure I see the problem here. A load in .38 brass loaded with .357 data (INCLUDING COAL) will produce nearly identical velocities and pressure signs as one in 357 brass. I load a 200g gc lee boolit in 38 cases to 357 lengths and it is A. safe, and B. will never be able to fit in a 38. I do it because I have a lot of 38 brass and the crimp groove is just right to make coal. Either way you end up with identical case volumes. I would not increase the COAL on a start or reduced load, that would be asking for a S.E.E. (been talking about that a lot lately around here....)

[Larry Gibson]

The RCBS 35-200-FN loaded in 38 SPL to oal of 1.64" chambers fine in the Contender test barrel and is max length in my Ruger Security Six. I'll load some of the requested loads and test them.

Attachment 249723Attachment 249724

[BrutalAB]

The RCBS 35-200-FN loaded in 38 SPL to oal of 1.64" chambers fine in the Contender test barrel and is max length in my Ruger Security Six. I'll load some of the requested loads and test them.

Attachment 249723Attachment 249724

Sweet, thank you for doing this!
Found data published by western for #9 with a 230 grain boolit 6.2 grains to 6.7. Would be willing to bet that the lighter boolit combined with the added case volume* from seating long would be more than enough to drop pressures down to standard. Their published psi is 19961 at max.
* no clue how much is gained here cause that bullet is basically a really long wadcutter, it is the penn thunderhead.

I am not sure I see the problem here. A load in .38 brass loaded with .357 data (INCLUDING COAL) will produce nearly identical velocities and pressure signs as one in 357 brass. I load a 200g gc lee boolit in 38 cases to 357 lengths and it is A. safe, and B. will never be able to fit in a 38. I do it because I have a lot of 38 brass and the crimp groove is just right to make coal. Either way you end up with identical case volumes. I would not increase the COAL on a start or reduced load, that would be asking for a S.E.E. (been talking about that a lot lately around here....)

I agree with you on the equal pressures and velocity. However, I have loaded a dummy round to 1.64" and it chambered in dad's 38. If it didnt chamber i wouldnt worry about this at all and would be doing exactly this.
I was surprised and disapointed as well.

[Ateam]

Wow, I would never have guessed you could chamber a .357 length cartridge in a .38. Thanks for making me aware of this, I will be sure to label my boxes better just in case someone got a hold of one.

[Jack Stanley]

So if you load these "special" . 38 loads longer than will chamber in the revolvers , would that fix your fears ? I doubt pressure is going to be a problem .

Jack

[BrutalAB]

Got an update on this. I played around with dads revolver and my rifles with different lengths. (It had been years since we did this last.)


1.64 has just a little sticking out of the 38 cylinder, enough that it doesnt want to close but not enough that if one was determined could make it work.
Somewhere around 1.61 would chamber and rotate with relative ease, even though there was a hair sticking out. I did not play around in this length much as my goal isnt to make marginally functioning ammo for this 38.

My rifle will cycle lengths all the way up to 1.75, its around 90% reliable and smooth at that length.


1.66" brings me up to 100% cycling through the rifle.

1.66" also has enough boolit sticking out of the 38 that i am comfortable that one could not make it close.
1.66" also prevents it from functioning properly in my taurus 357 revolver, 1.64 is the absolute longest it will rotate, i think i found where i came up with 1.64" as my standard loading length.

For those that are curious, dads 38 is a smith and wesson model 36, my rifle is a henry, brass 20 inch.

Larry, if you still want to do this testing to satisfy curiosity, thats great, but i think i found the solution that will work for me.

[Green Frog]

I know you have mentioned that you have picked your bullet, but the other comment about your ample supply of 38 Spl brass reminded me of an old Skeeter article. He too had more Spl brass than Mag, so he simply took his Ideal 357156 bullets and seated them out one groove less deeply, getting 357 length in 38 Spl brass. As has been hinted, it’s the size of the “combustion chamber” that determines pressure here. It might be worth your time to find those old Skeeter articles about his love for the 38/357.

One caution though... I would be very cautious sorting the brass I used. 38 Spl brass tends to be so ubiquitous and hang around so long, I’ve sometimes found brass that has been compromised for strength (once with a “Kaboom!”) Make sure you use good brass if you are going to be pushing the pressures up. Just a word to the wise.

[Larry Gibson]

Larry, if you still want to do this testing to satisfy curiosity, thats great, but i think i found the solution that will work for me.

I have the test loads ready to test, just have had several things "get in the way" of getting to the range to test. Hopefully can get them tested in the next few days.

[JBinMN]

I know you have mentioned that you have picked your bullet, but the other comment about your ample supply of 38 Spl brass reminded me of an old Skeeter article. He too had more Spl brass than Mag, so he simply took his Ideal 357156 bullets and seated them out one groove less deeply, getting 357 length in 38 Spl brass. As has been hinted, it’s the size of the “combustion chamber” that determines pressure here. It might be worth your time to find those old Skeeter articles about his love for the 38/357.

One caution though... I would be very cautious sorting the brass I used. 38 Spl brass tends to be so ubiquitous and hang around so long, I’ve sometimes found brass that has been compromised for strength (once with a “Kaboom!”) Make sure you use good brass if you are going to be pushing the pressures up. Just a word to the wise.

BrutalAB,

A list & links to some of S.Skeltons writings: http://www.darkcanyon.net/skeeter_skelton.htm

Below is a quote & source link that is likely what Green Frog was talking about:

For heavy duty .38 Special and .357 Magnum loading the 358156 gas check shoots much cleaner than any plain base bullet. It is possibly the most accurate cast bullet I have used, and is an excellent game getter. The HP version offers spectacular expansion, and the solid gives the utmost in combined penetration and shock in its category, being particularly satisfactory for taking small table game without unwanted meat damage.



The 358156 has two crimping grooves. The upper is used when loading .357 cases and standard velocity .38 Special loads. When seated out to the lower crimp groove in .38 Special cases, more powder space is gained, and a very powerful load of 13.5 gr. of 2400 may be used in these cases, giving around 1150 fps. I emphasize that these heavy .38 Special cartridges should only be fired from .357 Magnum revolvers or from .45 frame .38 Special sixguns such as the Colt SA, Colt New Service, or S&W .38-44. While I have fired this round from K-frame Smith & Wessons and Colt Officers’ Models on occasion with no visible ill effects, these lighter revolvers were not designed for such heavy loads, and I definitely do not recommend the practice. Since I commonly carry this round for everyday use in my .357 guns, I have taken more game with it than any other individual handload, up to and including antelope, turkey, and javelina.



Some loading manuals list the 358156 HP bullet with as much as 16 gr. of 2400 in .357 cases, a top load which gives about 1600 fps velocity. Although well below the acceptable factory pressure level, this load is a bit hot, and I prefer 15 gr. of 2400 for better accuracy, less recoil, and longer case life.

Source: http://www.darkcanyon.net/Handgun%20Loads.htm (<<From the list of articles mentioned & linked above)

[BrutalAB]

Thank you green frog and jb, i will be reading that during breaks at work for the next few days. the principals at play are the same and should be quite useful.

[redhawk0]

A concern for Larry....I actually have only one concern...You're using a a different boolit then BrutalAB but you are seating it using the same COAL. The critical factor for pressure here may be slightly different. The determining factor would be the amount of case volume not COAL with a different boolit. More accurate pressure measurements would be to seat the boolit in the case the same dept...but that may change the COAL dimension.

just a thought....have you considered this?

redhawk

[BrutalAB]

A concern for Larry....I actually have only one concern...You're using a a different boolit then BrutalAB but you are seating it using the same COAL. The critical factor for pressure here may be slightly different. The determining factor would be the amount of case volume not COAL with a different boolit. More accurate pressure measurements would be to seat the boolit in the case the same dept...but that may change the COAL dimension.

just a thought....have you considered this?

redhawk

I am using the lee clone of the rcbs 35 200 fn. Or do you think there will be enough difference between manufactures that it will cause issues?

[redhawk0]

I am using the lee clone of the rcbs 35 200 fn. Or do you think there will be enough difference between manufactures that it will cause issues?

My apologies then...I though you were using a SWC design...my error...I must have missed that along the way....the pressure/function tests that Larry performs should be accurate.

redhawk

[BrutalAB]

Its good, always better to have multiple eyes on things incase one overlooks simple things.
Its worth pointing out to anyone that may stumble on this years later that the boolits are similar/same. I know this is the type of thread i was reading when i was beginning to learn how to reload.

[Larry Gibson]

Pressure tested the 5.1 gr Blue Dot and 7.1 gr 2400 loads under the RCBS 35-200-FN today. Both gave very low pressure and velocity from the 7/8" Contender barrel. Accuracy for both loads (10 shot test each) was right at 2" at 50 yards......about as good as I can do with the 1.5X scope on the Contender.

Cartridge; 38 SPL (R-P)
Primer; WSP
Powder; Blue Dot (Alliant) 5.1 gr
Bullet; RCBS 35-200-FN, COWWs +2% tin AC'd, Sized .358 lubed with 2500+
Cartridge OAL; 1.64"
Velocity (muzzle); 798 fps, ES 59 fps & SD 42 FPS
PSI (M43); 11,500


Cartridge; 38 SPL (R-P)
Primer; WSP
Powder; 2400 (Alliant) 7.1 gr
Bullet; RCBS 35-200-FN, COWWs +2% tin AC'd, Sized .358 lubed with 2500+
Cartridge OAL; 1.64"
Velocity (muzzle); 785 fps, ES 73 fps & SD 33 FPS
PSI (M43); 10,700

[WheelgunConvert]

So what do you wish to accomplish ?

Do you want a 38 Special cartridge that will function in your rifle and be standard pressure ?
Can you elaborate on WHY your rifle will not feed & function with 38 Special cartridges. Is it the length of the cartridge with that 200 grain bullet? Is it the profile of that bullet? Is it the rifle itself?

While the subject matter experts have answered the posted question, the above does deserve attention. Creating a work around for a known problem can be hazardous to your well being.

[BrutalAB]

Pressure tested the 5.1 gr Blue Dot and 7.1 gr 2400 loads under the RCBS 35-200-FN today. Both gave very low pressure and velocity from the 7/8" Contender barrel. Accuracy for both loads (10 shot test each) was right at 2" at 50 yards......about as good as I can do with the 1.5X scope on the Contender.

Cartridge; 38 SPL (R-P)
Primer; WSP
Powder; Blue Dot (Alliant) 5.1 gr
Bullet; RCBS 35-200-FN, COWWs +2% tin AC'd, Sized .358 lubed with 2500+
Cartridge OAL; 1.64"
Velocity (muzzle); 798 fps, ES 59 fps & SD 42 FPS
PSI (M43); 11,500


Cartridge; 38 SPL (R-P)
Primer; WSP
Powder; 2400 (Alliant) 7.1 gr
Bullet; RCBS 35-200-FN, COWWs +2% tin AC'd, Sized .358 lubed with 2500+
Cartridge OAL; 1.64"
Velocity (muzzle); 785 fps, ES 73 fps & SD 33 FPS
PSI (M43); 10,700

Wow. I would have never have guessed that the pressure drop would be so dramatic. I was expecting somewhere in the neighborhood of 2-3k psi reduction, my load sources had these listed at 17 and 19k so we are looking at a very massive reduction from 0.1"

Velocity published was almost 900 to put it in perspective.

Its very nice to be able to add this to my knowledge base.
From this i now think that my standard 357 mag loads are probably a bit underpressured.
but they work for me, accomplish everything i want them to, so why change?

Once again, thank you for testing and sharing your results.

While the subject matter experts have answered the posted question, the above does deserve attention. Creating a work around for a known problem can be hazardous to your well being.

I completly agree with you on the dangers of experimenting. Id like to think i went about this in a relatively safe way.