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boatbum101
02-19-2016, 01:52 PM
Started off Bullseye target shooting with 38 wadcutter & 45acp where group size ( particularly @ 50 yds. ) was king . Pressure was of no concern due to the mild loads . Now I'm trying to work up loads for 357 & 41 mags . I want reasonable accuracy & in the neighborhood of 1150 - 1200fps to start with . Bullets I'm using are the 358429 & 410459 sized to fit my guns . Assuming that a load is accurate enough & has the velocity I want , what is reasonable in terms of spread & standard deviation ? Case in point a 357 load of 8.5grs SR-4756 & 358429 has a mean vel of 1,253 fps , spread of 31 fps & SD was 8 . 25 shot string & was able to keep all within the 9 ring on a B-8 target @ 25 yds . I suspect that this kind of uniformity is the exception rather than the rule . When working up from a starting load how much of a bump in charge weight to the next load ? For instance if say starting load is 8grs & max is 10grs , would you load 8.0 , then 8.5 next , then 9.0 & so on ? Later down the road loads that show promise I can try different crimp amount & maybe different primers to boot to see if they can be improved ? BTW I'm using WSPM in 357 & plan on using WLP in the 41 .

Outpost75
02-19-2016, 04:24 PM
Working up loads over the chronograph and chasing numbers is a distraction.

If accuracy is the goal shoot 10- or 12-shot groups on paper only, looking for circular normal distribution where the horizontal and vertical variances are equal and you have dense centers. When you think you have a good load, then load not less than 20 rounds and shoot them all one one target, placing a clean center over your original ten, and changing the top target after each group and keeping the composite.

Then repeat the test bracketing the charge 0.2 grain above and below. Then load at least 50 rounds of the best combination, loading different primers in 10-shot series if you want to try that as a refinement.

Any load which shoots under 3 inches at 50 yards for 10-shot groups and under 5 inches for a composite of 30 rounds or more is a good load.

ONLY after you have a good load do you even care what the velocity is, so you can find the sweet spot again when you change powder or primer lots.

In the .357, .41 and .44 Magnums, velocity is more a function of alloy strength. I have found that revolver velocities in the high subsonic range, with a heavy bullet for the caliber give better accuracy because they are not affected by transonic buffeting as range increases. If you require greater energies either go to a larger caliber and heavier bullet, or use a harder alloy strong enough to withstand sufficient velocity that the bullet remains supersonic all the way to the target.

In the .44 Magnum my hunting load is the Accurate 43-230G cast 1:30 tin lead, with 24.5 grains of RL7 which gives 1250 fps in a 7-1/2" revolver, and 1400 fps in a 20" carbine. A proven deer killer to 100 yards and very accurate. A charge of 22 grs. of 4198 also shoots well in both rifle and revolver. Also good are 7.2 grains of Bullseye for 1050 fps in the revolver and 1200 fps in the carbine.

runfiverun
02-19-2016, 04:48 PM
that's a plan and a long term one at that.

jumping in 1/2 gr increments will give you a good idea of what you want, then when you find 2 pretty good ones you can work in-between them and find the sweet spot.
then shoot the large group sizes to 100% confirm the results.

fredj338
02-19-2016, 05:33 PM
I stopped chasing numbers years ago. The proof is always in the shooting. If the load groups well, who really cares about the numbers? I have had some great shooting loads with larger spreads & some single dig loads that wouldn't group nearly as well. For revolvers, I am looking for sub 2" groups at 25yds, open sights. That is my measuring stick, your may be diff. The amount of charge increase depends on powder choice. Medium burners, like Unique up thru PP, 2/10gr increases will show a diff in accuracy. For slower powders, 3/10gr diff works for me. For powders faster than Unique, 1/10gr increments.
With lead bullet, many things can affect accuracy but bullet fit is #1. Particularly cyl throat fit. Too small, it sizes the bullet down, then it bumps as it hits the bore, not good for accuracy.

44man
02-19-2016, 05:40 PM
I work loads with slow powders 1/2 gr at a time but with fast powders I do less at a time but with powders like Unique, 231 and others i see less changes. Then I test alloys and primers for each gun.
I test boolit configurations and shapes. But mostly brass means a whole lot with case tension. I test die makes and have to say what you do to brass and the differences from case to case will be a thorn in your side.
Let us say you are using a slow powder like 296, you should see groups tighten as you increase, then with too much, they will open at the same rate. Go back to the smallest and forget velocity. I really do not see that with fast powders. To see a difference with 1/10 gr means you are a machine rest with eyes of an eagle.
Then toss in lube tests and primers, OH MY!
It can't be told in one post, might take a thousand or more.

44man
02-19-2016, 05:49 PM
My measure for a revolver is less then 1" at 50 meters but have done hundreds of 1/2" at 100. One hole at 50. I am happy with 3/4" at 50, never shoot the big bores at less then 50.
That takes work and thought. It is not easy.

Outpost75
02-19-2016, 06:53 PM
My measure for a revolver is less then 1" at 50 meters but have done hundreds of 1/2" at 100. One hole at 50. I am happy with 3/4" at 50, never shoot the big bores at less then 50.
That takes work and thought. It is not easy.

How many shots are those groups? Would you care to post some pictures, would love to see some.

44man
02-19-2016, 07:20 PM
How many shots are those groups? Would you care to post some pictures, would love to see some.
I have, over and over. Go back a few posts. 5 shots minimum. No tagged chambers, all must shoot.