Powder position sensitivity

[GSWEAR]

Here is something I posted on a couple other forums.

Hi guys!

I was wondering if anyone has done any testing and if so what they found or what their opinions were.

I loaded some test rounds to get a start on a load for SSR in IDPA, they were 38spc and I was using a 160gr RN Bayou Bullet and when I started chronoing I was getting some erratic readings and by the recoil could tell they were accurate.

Since the case volume is moderate and the charges low I thought maybe it had to do with powder position but was kinda surprised to the amount.

All rounds were mixed 38spc brass, 160RN Bayou Bullet loaded on a Dillon 550, I chronoed 6 rounds of each load with the powder flat in the case, powder at the bullet end and powder at the rear of the case.

3.4gr N320

Powder forward: Avg = 444fps SD = 32

Powder flat: Avg = 523fps SD = 19

Powder to the rear: Avg = 600fps SD = 19

3.2 Titegroup

Powder forward: Avg = 548fps SD = 12

Powder flat: Avg = 586fps SD = 16

Powder to the rear: Avg = 649fps SD = 14

2.8 Clays

Powder forward: Avg = 482fps SD = 20

Powder flat: Avg = 551fps SD = 22

Powder to the rear: Avg = 627fps SD = 13

4.0 Trail Boss

Powder forward: Avg = 638fps SD = 8

Powder flat: Avg = 667fps SD = 17

Powder to the rear: Avg = 665fps SD = 7

I have used N320, Clays and Titegroup in 9mm and 45acp in the past with very good results but I may do a little more testing with Trail Boss for light loads in 38spc due to the low case density.

If anyone else has done any testing or has any experiences to share it would be appreciated.

Greg

[Bill Nesbitt]

Yes, I've seen it before. I found it years ago when I was shooting AA#5 in .45 ACP. I still see it using Bullseye and Titegroup in .38 Special.

I try to make the power factor I want, plus a margin higher, with holding the gun level. If I tilt the gun up before each shot I get a little higher velocity.

Chrono at a big match is no place to find you should have spent 50 cents more on powder.