Position sensitvity in low pressure revolver loads

[applefish123]

I'm trying to reload some low pressure 38 Long Colt to keep under <12,000 PSI for and original 1892 revolver.

I was using 3.8-4.0 gr of unique with a 125 gr .358" bullet, in order to use a slower powder to keep pressures low. Quickload tells me 3.8gr should give around 10,000 PSI, and 4.0 gr gets around 11,000 PSI (maximum)
As it turns out, even with 4.0 gr of Unique I'm getting >100 fps ES, which I discovered to be because of position sensitvity.

If the barrel is tipped down before each shot, I get velocities around 570-625 fps.
If the barrel is tipped up before each shot, I get velocities around 800-900 fps.

Any tips on a powder that is LESS position sensitive than Unique?
I'm thinking of going something faster like bullseye or red dot, and aiming for around ~750-800 fps

 

[Docendo Discimus]

You could try W231/HP38. It gives good results in my experience.

 

[Walkalong]

WST, Competition, Clays.

Tightgroup advertises bein position insensitive, but it was average for me as far as velocity loss, still burned and shot well.

I tested a boatload of powders in light .38 Spl & .357 Mag loads.

 

[mcb]

Silly suggestion. You could go to 38 Short Colt cases and reduce the usable volume. Pressure would go up slightly to get the same velocity but you can tweak that as need to get the desired velocity and approximate pressure.

 

[N555]

Need something more fluffy like trailboss, herco, ect.
Yeah unique doesn't like a lot of dead space inside the round.

 

[jmorris]

What powders can you get your hands on?

If you have a lot of unique and otherwise like it, a wad holding the powder in the same place would fix your problem.

You can get them for .38

https://www.trackofthewolf.com/List/Item.aspx/1163/4/WAD-360-B

 

[applefish123]

WST, Competition, Clays.

Tightgroup advertises bein position insensitive, but it was average for me as far as velocity loss, still burned and shot well.
I tested a boatload of powders in light .38 Spl & .357 Mag loads.

What pressures are these running? I have good luck with Unique above 14-15,000 psi, so it's never been a problem in light 38 special loads even with the giant case capacity.

Are faster powders better for position sensitvity in this case, or should I try slower powders for more case fill, knowing they will probably have incomplete combustion.

Silly suggestion. You could go to 38 Short Colt cases and reduce the usable volume. Pressure would go up slightly to get the same velocity but you can tweak that as need to get the desired velocity and approximate pressure.

The main goal is to the avoid overpressure, so while I could seat the bullets deeper to achieve the same effect, the pressure rises very quickly to levels I'm not comfortable running through a 130 year old gun. I've tried different seating depths but at this point the conclusion is a different powder is necessary to solve the position sensitvity issue, while remaining at safe pressures.

What powders can you get your hands on?
If you have a lot of unique and otherwise like it, a wad holding the powder in the same place would fix your problem.

I've thought about using dacron/cotton balls/tissue like what 45-70 shooters use, but that's too much of a pain for pistol, so I would rather switch powders if I can avoid that.
Plus fiber wads takes up useable case capacity and affect internal ballistics in a way I don't want to experiment with ina 130 year old gun.

 

[jmorris]

I've thought about using dacron/cotton balls/tissue like what 45-70 shooters use, but that's too much of a pain for pistol, so I would rather switch powders if I can avoid that.
Plus fiber wads takes up useable case capacity and affect internal ballistics in a way I don't want to experiment with ina 130 year old gun.

Sounds reasonable to me, what suitable powders are available for you to purchase?

 

[Crunchy Frog]

I’m a cowboy action shooter. We have a lot of experience with light loads in .38 Special cases. Fast burning powders seem to do well. As was stated, Titegroup is advertised as not being position sensitive but I find it to be snappy.

I used a lot of Clays in the beginning; I like it except in cold weather. I mostly use Red Dot these days. Shooters World Clean Shot is another popular powder.

I have never done experiments with powder position.

I don’t use fillers except with some black powder substitutes.

 

[Thomasss]

Your loads seem high and you don't mention what kind of 125 grn. bullet you use. I would recommend you check out Hodgdon's cowboy loads for your 38 Long Colt at their web site. I saw some low pressure loads using 13 - 15 grains of 777 reduced pressure down to 6000. And there are other recipes using conventual powders too.