Coal to the crimp groove vs powder charge 38spl

[brokeasajoke]

I've asked this else where but have gotten little response so I thought I'd try here. Loading 38spl with a cast coated bullet and load data calls for a coal of 1.475 at 3.2-3.8gr of titegroup for a cast LSWC 158gr. In order to reach the crimp groove I must seat to approximately 1.375 for this particular cast bullet. The bullet itself is a total of .635 long. I understand there is a lot of air space in a 38spl case but pressure sign may be too little too late as I understand besides sticky extraction in a revolver. My 38 is a late 90s model 64 I believe and a gp100 357 7 shot. Start low work up? Go with book coal and crimp on driving band? Thanks.

Sorry for the side ways image.

 

[RegionRat]

You will want to work up no matter what, but all loads with Titegroup in the 38 class will have space in the case accounted for in the load data.
To start, use cast data or specific data for cast coated. The Hodgdon site range is from 3.2 to 3.8 for cast, and 3.5 to 3.9 for jacketed, so cast coated or plated is expected to be roughly in between. There is some effect from over all length, but the effect of specific bullets and guns runs just as much.

 

[brokeasajoke]

So you are saying start at 3.2 seated to the groove or start even less? There is lots of space in there but it's moving the bullet a full .100". When we say work up I'm I looking at velocity or a specific sign in revolver?

 

[RegionRat]

You could seat that bullet to either the crimp groove if it has one, or where you are happy with function.

If you are low on experience, try to get data from your bullet source. Many times they will give a recommended COAL and once in a while even some load data.

Your velocity or target performance determines the best charge. With a modern 38, the span of pressure from Special, to +P to +P+ is large, and the differences in barrels and guns in general is large. If you keep it within the velocity of a 38 Special, you will have lots of safety margin.

That said, you have to be diligent with pistol powders. If you get sloppy with powder charges, don't expect good results. Plinking ammo with SPCL pressure is one level of safety margin, but if you load +P+ or full up 357 Magnums, then make sure your charges are disciplined.

Use a chronograph if you are intending to keep these at regular 38 Special pressure. The pressure and velocity of hotter loads means you won't see pressure signs till you get much higher than you want.

Here is the +P version with a jackted bullet for comparison. You can see it takes up to 4.3 grains to get up to 19300 CUP from a baseline at 3.9 grains giving 15900 CUP. That is a 0.4 grain increase, and still leaves room in the case.

A S&W 64 is rated for +P loads and was considered a M&P rig, so you will have plenty of safety margin to seat where the bullet was designed as long as you work up using a chronograph, while keeping with 38 Special pressure.

 

[brokeasajoke]

3.2gr titegroup seated to groove chronographed 799.2 in my Smith 64 with a 4" bbl. and ejected just fine but it was only one. Hodgdon is showing 815 fps in their data for 3.2gr. base of bullet to top of crimp groove is .356. case depth roughly measured with a caliper is .983 or so.

 

[RegionRat]

The difference in barrels, cylinder gaps, forcing cones, etc. etc. etc...

The good news is that 38 SPCL with these revolvers is forgiving. I still recommend a chronograph to have at least one more perspective when you can't measure the actual pressure.

ETA: you may want to add at least a few samples per step just to get a view towards the average. No need to go crazy over filling out the stats till you settle on your selection.

ETA2: another way to get perspective and experience, is to test factory defensive rounds that use bullets that you can also buy and practice loading to match. If you attempt to go higher in pressure, it is best to have a mentor along to make sure you don't go too far. Use something rated for 357 Magnum pressures to have safety margin, not something lightweight or antique.

 

[brokeasajoke]

I have a 357. I'm not interested in hot rodding the 38. I cast these bullet and coated them. These are just some plinkers.