Light .38 Loads

So I loaded my first .38 light loads. I used 4.0 grains of Winchester 231. I chronographed the resulting velocities.

#1 639
#2 641
#3 687 - variation probably due to 0.2 grain inaccuracy of scale?
#4 491 - Variation probably due to position of powder in the gun?

Anyone have any ideas on why shots #3 and #4 varied? (more specifically #4)

I was using a ProChrono Digital Chronograph with the Digital Link app. It's accuracy is within 1%.
 
More results after the first 4:

5. 592
6. 713
7. 706
8. 644
9. 470
10. 718
11. 452

Shots #9, #10, and #11 were a test to see why the variations were so large.
Shot #9 I tilted the gun forward before firing, #10 I tilted it back, #11 I tilted it forward again. That's good enough proof for me that the powder position in the cartridge has a lot to do with velocity in light loads.
 
That's good enough proof for me that the powder position in the cartridge has a lot to do with velocity in light loads.
Click to expand...

Yeah, you gotta do a tilt-back before each shot. Although, I found the amount of variance was still a bit of an eye-opener - even for this long-time low-power 38 Special chronographer.

I'm not particularly surprised though. Most of my 38 target load chronographing is done with heavier bullets; and more specifically, wadcutter type rounds that sit much deeper in the case. So your experience is somewhat apples n oranges from what I do so much of.

Funny thing is, I have spent so much time chronographing that I do the tilt-back on second-nature - I do it without even thinking about it. I do give a little laugh at myself when I automatically tilt-back high-power rounds that are full of powder :p.

That said, load up your 125's and have fun with them. But moving forward, for your application, you might want to consider moving to a heavier bullet. The extra mass keeps the propellant igniting more consistently. Not to mention that they sit deeper in the case, reducing internal space. Both characteristics bode well for your application.
 
Plated 125s

Using Xtreme 125 plated bullets. Tried 231 but did not like the inconsistency. 4.0 grains of Bullseye was more consistent. This load is from Alliants site using 125 gold dot load data reduced 10%. Used in 4" 686 and 2 inch 37. You could go lower but no Alliant data to base that on. So I don't.

Good luck,

Tom
 
If using light loads remains a concern in the future, a dewc leaves little room in the case and allows for good ignition for smaller charges, and a quick burning powder allows lighter, low pressure loads. Don't bother with plated bullets, a plain cast and lubed bullet is good for low velocity rounds. Think it over as you use up what you have. Still, an ordinary lead semi wad cutter 158 grain bullet with starter charges will serve you well. A heavy gun gives little more than a bump in recoil, and it will add no wear to heavy steel.

Love that gun as you would your pet.
 
I had some magnum primers on hand (was using standard before), so I figured those would help ignite all the powder more consistently. I chrono'd 4 shots:

Magnum Primers
#1 306 tilted forward
#2 780 tilted back
#3 589 tilted forward
#4 646 tilted back

So that definitely didn't help with consistency. Thanks for the suggestion about seating bullets deeper and using heavier ones. I cant use heavier ones because I already have too many 125gr FNs, but I'm thinking the combo of seating the 125s deeper and maybe also crimping will help burn the powder more consistently?

Also, had my first squib round. I had the gun pointed almost straight down at a 2x4 and pulled the trigger. I heard a small pop, and saw no bullet hole in the board. When I opened the cylinder I saw a bunch of unburned powder in the barrel flush with the face of the forcing cone and when I cleaned it out I could see the base of the bullet. It was probably only 1//4" past the forcing cone and not hard to get out, But it was a good learning experience. The 4.0gr is not enough on its own. I need to do some other things to make the powder more likely to burn. Like crimping and seating deeper.
 
A round that is that sensitive to position cannot be used again, you have to abandon that load entirely. The problem that you had was that the powder was flat on the bottom of the case, the flash of the primer only touched the very bottom, and that's not good, since it also compressed the powder and kept it from being scattered throughout the case and igniting fully.

There are just so many factors involved in getting a good ignition and burn for the charge. Part of the problem with this one is that with only partial ignition, it fizzled out, there wasn't enough heat and pressure to get the covered, suffocated part of the charge ignited.

Just keep trying and learning, you're doing good.
 
Welp the crimp and seating deeper method worked as far as I can tell. From the old OAL of 1.475" I seated it to 1.435" and medium crimped it. Results:

#1 678 No tilt
#2 696 tilted forward
#3 601 tilted back
#4 751 tilted forward

Much more consistent. But most importantly when I fired the gun pointed straight down at a 90 degree angle, the bullet actually left the barrel. I'm gonna experiment some more but I'd call this a success for now.
 
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