S.D. as guide for working up reloads
#1
Spike
Thread Starter
Join Date: Jul 2013
Posts: 3
S.D. as guide for working up reloads
Pressures in the 7x57 'family' and 30-06 'family' vary from 270 Winchester levels to 257 R levels, maybe more.
Is it feasible/wise to use the S.D. of a cartridge in one of these family's in the other cartridges of that family since case capacity will be virtually the same?
examples -
270 Winchester cartridge for lower pressure 35 Whelen?
244 Rem for 257 R?
Is it feasible/wise to use the S.D. of a cartridge in one of these family's in the other cartridges of that family since case capacity will be virtually the same?
examples -
270 Winchester cartridge for lower pressure 35 Whelen?
244 Rem for 257 R?
#2
IMO there is alot more to safe reloads than SD. The Model / make /year of construction of your gun all play into reloading.Measuring your cartridges expansion and using a chronograph would be safer than using SD . I dont load anything faster than the new reloading books say to.
#3
Spike
Thread Starter
Join Date: Jul 2013
Posts: 3
Well, thanks for your interest.
Type of firearm not really relevant to my question. Expansion check fine if you are working up max loads, I'm not. Chronograph good for seeing how fast you're going, I'm not interested yet. Current reloading books always play it safe in the listed cartridges.
Maybe this isn't best place to put my question - which is a little theoretical but also practical. If a 270 Win load is in the book, it is safe for rifles designed for that cartridge, but can I apply that load to an equally strong 35 Whelen? I think I can, if I work up slowly, but ...
Oh, just we're together, "S.D." is "sectional density".
Type of firearm not really relevant to my question. Expansion check fine if you are working up max loads, I'm not. Chronograph good for seeing how fast you're going, I'm not interested yet. Current reloading books always play it safe in the listed cartridges.
Maybe this isn't best place to put my question - which is a little theoretical but also practical. If a 270 Win load is in the book, it is safe for rifles designed for that cartridge, but can I apply that load to an equally strong 35 Whelen? I think I can, if I work up slowly, but ...
Oh, just we're together, "S.D." is "sectional density".
Last edited by Catchem; 07-21-2013 at 05:57 PM. Reason: define S.D.
#4
I really don't know the answer to your question. But on one hand, all the cartridges you mentioned have reloading data available. And on the other hand, I would not use the data for a .270 to load a . 35 Whelen. It is my thought that the differences in bullet weight alone (+40%) would be cause for excessive pressures.
I suggest that if you want to use lighter loads out of your rifle then use the lightest bullets available for the task you want and use the starting loads listed in the manuals you have
I suggest that if you want to use lighter loads out of your rifle then use the lightest bullets available for the task you want and use the starting loads listed in the manuals you have
#5
Nontypical Buck
Join Date: Aug 2008
Location: Rapid City, South Dakota
Posts: 3,732
IMR 4895 was the common powder.
The 150g .277 bullet and the 250g .358 bullet have the same SD of 0.279.
The .270 load with the 150g bullet, was 44.5g which produced 50,600 cup.
The 35 Whelen load with the 250g bullet was 53.5g @ 50,300 cup.
It seems to me, you can safely work up from a 270 load to the 35 Whelen load. However, it will take so long you will miss hunting season. Another problem i foresee, is if you are using a popular/common 270 powder, the 35 Whelen case will fill up and overflow, before you reach a suitable charge.
Going from 244 to 257 could be doable, and should be safe, but i didn't research any loads for these caliber.
#8
Spike
Thread Starter
Join Date: Jul 2013
Posts: 3
My interest is limited to seeing how high SAFE reloads for the 257 R and 7x57 Mauser can be made. Both have low SAAMI specs, and both safely could be shot faster.
257R +P = 58,000
7x57 = 51,000
6 MM Rem= 65,000
It seems to me at first glance that a bullet with a given S.D./velocity/pressure relationship in 6 mm Rem in a reloading manual would be shot at the same velocity/pressure in the other 2 as long as the S.D. and type of powder was held constant. By using a chronograph and going up slowly performance of the calibers would be improved safely(?).
I realize that theory and practice don't always match up.
#9
Thanks to all for your feedback.
My interest is limited to seeing how high SAFE reloads for the 257 R and 7x57 Mauser can be made. Both have low SAAMI specs, and both safely could be shot faster.
257R +P = 58,000
7x57 = 51,000
6 MM Rem= 65,000
It seems to me at first glance that a bullet with a given S.D./velocity/pressure relationship in 6 mm Rem in a reloading manual would be shot at the same velocity/pressure in the other 2 as long as the S.D. and type of powder was held constant. By using a chronograph and going up slowly performance of the calibers would be improved safely(?).
I realize that theory and practice don't always match up.
My interest is limited to seeing how high SAFE reloads for the 257 R and 7x57 Mauser can be made. Both have low SAAMI specs, and both safely could be shot faster.
257R +P = 58,000
7x57 = 51,000
6 MM Rem= 65,000
It seems to me at first glance that a bullet with a given S.D./velocity/pressure relationship in 6 mm Rem in a reloading manual would be shot at the same velocity/pressure in the other 2 as long as the S.D. and type of powder was held constant. By using a chronograph and going up slowly performance of the calibers would be improved safely(?).
I realize that theory and practice don't always match up.
I have a 257 Roberts AI I recently built and am in the same boat of having to slowly build up a load watching for signs of pressure.
Just remember...speed doesn't always equate to accuracy....I build accurate loads watching for signs of pressure.