45 acp handloads velocity variation and s.d.

View previous topic View next topic Go down

45 acp handloads velocity variation and s.d.

Post by ShooterSteve on Tue Feb 26, 2013 7:13 pm

After a 10 year break, I have decided to get back into Bullseye Shooting. I use to shoot Star 185 swaged HP's with 3.8 gr. of BE. While I still have about 1,000 of those, I have since acquired an 8lb container of HP-38. This past weekend I hit the outdoor range to set the zeroes on my red dots. I also wanted to get an idea of what velocity my lot of HP-38 produced on a 200 gr. SWC. I had some Lyman 460 200 gr. SWC's that I cast years ago. I was trying to find something around 775fps. I loaded test rounds with 4.8 - 5.0 - 5.2 grains. Velocity, extreme spread and std. dev. were:

4.8gr. 744 fps spread 63 sd 16.5,
5.0gr. 804 fps spread 44 sd 18.2
5.2gr. 825 fps spread 59 sd 21.5

I was surprised at how wide the low/high velocity spread was and s.d. I used Speer brass all with .100" flash holes (most of my older mixed brass has .080") Win LP primers, 1.175" O.A.L. (about .030" full diameter of lead above case mouth) and taper crimped at .470". It was 33 degrees F. and windy. Since weather conditions were less than ideal, I did not spend the time to shoot a lot of groups for accuracy, just zero the dots and get an idea what this Lot of HP-38 does with .45 ACP.

I know the group size on paper is most important but my question to others that chronograph .45 ACP handloads, what do you normally see for velocity variation and standard deviation? Is there something I can do to reduce the variation?

Thanks,

Steve

ShooterSteve

Posts : 21
Join date : 2013-02-26

Back to top Go down

Re: 45 acp handloads velocity variation and s.d.

Post by DavidR on Wed Feb 27, 2013 11:52 am

HP38 is the same powder as Winchester 231,you can find lots of bullse type load info if looked up under it. 231/hp38 should do well at 4.8-50. temps were a little cold when you tested, better test would be 45 or above, as for speer big hole brass, i stopped using it because of sparatic results and went back to using all pre lead free primer brass myself.

DavidR
Admin

Posts : 2856
Join date : 2011-06-10
Age : 62
Location : NRA:Expert, Georgia

Back to top Go down

Re: 45 acp handloads velocity variation and s.d.

Post by Al on Wed Feb 27, 2013 12:34 pm

Steve,
Don't get caught up in over analyzing SD & ES, remember we're only shooting 50 yards max.

I used to look for the same until I aquired a ransom rest. My best groups also had some of the worst extreme spread. While this may not be the same for everyone, it was enough for me. We shoot paper (doesn't move, doesn't charge) at a relative short range. We need tight groups, not low ES & SD. They may exist together, but don't need to.

Now for my 1000 yard shooting, it's a whole different story.

FWIW

Al

Posts : 300
Join date : 2011-06-10
Age : 61
Location : Bismarck, ND

Back to top Go down

Re: 45 acp handloads velocity variation and s.d.

Post by noylj on Sat Mar 02, 2013 9:49 pm

>I know the group size on paper is most important

I have yet to read any report that there is a correlation between SD and group size at distances under 600 yards.
I you run an external ballistics calculation of the bullet drop at 50 yards for each of your velocities, you will find that the rounds impact almost exactly in the same spot.
Chronographs have never been "needed," just fun to know the numbers. If you are trying to shoot action pistol and need to meet a power factor, chronographing become more of a need since accuracy is not at the heart of the sport.
If one goes back in various magazines since they started reporting chrono data for their handloads, you'll quickly see that the small SD loads are very very seldom the most accurate.

noylj

Posts : 225
Join date : 2012-03-09
Age : 67
Location : SW USA

Back to top Go down

Re: 45 acp handloads velocity variation and s.d.

Post by BE Mike on Sun Mar 03, 2013 10:14 am

I agree that machine rest tests at 50 yard are the only thing that matters for a bullseye pistol shooter. The chronograph is handy when using a new powder and trying for a specific velocity. This can be good for target or hunting/ defense pistol loads.

BE Mike

Posts : 1145
Join date : 2011-07-29
Location : Indiana

Back to top Go down

Re: 45 acp handloads velocity variation and s.d.

Post by ShooterSteve on Tue Mar 12, 2013 4:23 pm

Thank you all for your input. I no longer have a Ransom Rest but tried some 50 yard rested groups. They ranged from 2.9" to 5.2" for 10 shots. I also tried some loads I still have from 10 yr ago that back then averaged 2.75" from a Ransom Rest. These were 3.8 gr. BE, 185 gr. Star swaged HP, Win primer, mixed brass. My current bench rest groups for these loads were 2.6" and 4.5" for two 10- shot groups at 50 yds. I don't think I can shoot consistent enough from the bench to be confident which powder charge does the best. Steve

ShooterSteve

Posts : 21
Join date : 2013-02-26

Back to top Go down

Re: 45 acp handloads velocity variation and s.d.

Post by Sponsored content Today at 6:10 pm


Sponsored content


Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum