IMR SR 4759 Reduced Load Powder Loads?

[Slowshot]

I have had difficulty finding data on loading with IMR 4759. I have tried it with my Ruger No 1 220 Swift but have found only one suggested load (from Chuck Hawks). That load is 13.5 grains of IMR SR 4759 with a 55 grain bullet, giving 2000 fps. It works OK, but as always, I want to fine tune the load for accuracy.

What I do not find is any kind of a chart giving minimum and maximum loads with that powder. For all I know 13.5 grains may be the max, or the min. with the 55 grain bullet.

I like the idea of reduced loads for 100 yard practice and for teaching my grandchildren to not be afraid of a centerfire rifle. I certainly don't need to worry about burning out my barrel at 2000 fps.

[GP100man]

This is where a chronograph & payin close attention to load development comes into play .

measureing fps , case deminsions before & after firing !!!

REAL HANDLOADING instead of RELOADING

My Lyman castbullet hand book gives from 12.4 to 19,2 grs for a 54gr. cast bullet , I`d reduce 10% if using jacketed & pay attention.

[Slowshot]

I have been handloading for some time, keeping careful records for accuracy load development. I do not own or use a chronograph, but simply use test target five shot groups as a measure of how I am doing. With this data gathering technique I have found my most accurate load in my 220 Swift Ruger is 37.5 gr. of IMR 4064 with a Berger 55 gr. bullet.

I started with 50 cartridges I loaded to the minimum load suggested in my Lyman manual. This ammo was tested starting with a clean bore. I fired the 50 into a series of 5-shot groups, with a cleaning pause at 25. I then loading another 50 and repeated the test at increasing loads until an obvious sweet spot was found. By staying within the guidlines in the Lyman manual, I feel confident that I have a reasonable safety factor.

I enjoy this process. It works fine for me.

All I need are min.-max load suggestions. I will calculate figuring jacketed bullets, using your guidlines.

Thanks.

[SL1]

from Speer Manual #10:

Speer 40 grain spire point:
     grains    fps
     12.5     1973
     11.5     1826
     10.5     1662

Speer 45 grain spitzer:
     grains     fps
     12.5     1938
     11.5     1790
     10.5     1631

Speer 50 grain spitzer:
     grains     fps
     13.0     1977
     12.0     1830
     11.0     1669

Speer 55 grain spitzer:
     grains     fps
     13.5     2000
     12.5     1864
     11.5     1709

Speer 70 grain semi-spitzer:
     grains     fps
     14.0     1906
     13.0     1774
     12.0     1642

Speer's manual says these loads are all less than 53,000 CUP. From the pattern of the charge weights, it appears that they were adjusted to provide about 2000 fps for the highest charge weight, without regard to pressure, except perhaps for the top load for the 70 grain bullet, which has a conspicuously lower top velocity.

Unfortunately, QuickLOAD does not have a powder file for SR-4759, and the old Powley correlation doesn't address that powder, either. So I don't have the tool to "fit" this data and try to estimate pressures.

Also, be aware that QuickLOAD does not have the file because the author does not think that the powder has been consistent enough in its lot numbers over the years for the program to give reliable data. So, I'd work-UP to the top load for the heavier bullets, rather than down. I'd still start in the middle and work-DOWN for the lighter bullets if I wanted to go really slow.

Also, you should look at the Hhodgdon website for "youth" loads using H-4895, which is unusually stable-buring over a very wide pressure range and can be used for loads between these SR-4759 loads and normal power loads.

SL1

[jlbpa]

From a NRA reloading handbook. isbn 0-935998-34-9
55 grain speer semi pointed full jacket 11.5 dup 4759 1709 fps cci 200 primer
55 grain speer semi pointed full jacket 13.5 dup 4759 2000 fps cci 200 primer

[Slowshot]

I have been working my way up 1/2 grain at a time. I started at 13.5 grains and have tried 14 and 14.5 so far. Using inexpensive bulk pack 55 grain bullets, I have achieved acceptable results at 14.5 grains of the IMR 4759. Nothing spectacular but OK.

One interesting change that has occured already is an improvement in powder burning. At 13.5 gr. I found a bit of unburned powder in each brass case after firing. At 14.5 gr. the problem went away. The change to complete powder burning is probably responsible for the improved consistancy.

Based on the 12.4-19.2 range for cast bullets, with the 10% suggested reduction for jacketed bullets, the heaviest load I might try is 17.0 gr. I expect to find a sweet spot before that is reached, so I doubt I will ever go that high.

I'll try to bertter keep in touch and let you all know how it works out.