In the process of buying a 1916 Spanish Mauser Civil Guard short rifle, one fo the ones rebarreled to "7.62". Now, I know that these guns were made before Nato standardized the 7.62x51 Nato round, and used some strange Spanish 7.62 CETME round, which is loaded to lower pressure than the nato round.
Here's what I've found out. Standard factory .308 win usually run about 56000 psi, and 7.62x51 usually around 52k? The cetme round is supposed to run about 47-48k. I've looked in the alliant, accurate, hodgdon and IMR manuals. IMR is the only one that lists pressures, and the extreme low end loads run about 48000psi pressures.
Here's my question: How does one work up a below max load? I've been told that this may be unsafe, as going below max with your powder charge can actually INCREASE pressure? Not sure how this works... Is there some kind of calculator that has different calibres, powders, bullets, barrel lengths, etc, that you can plug in a load and it will give you approximate data?
I'm going to want to load 150gr bullets, maybe even 125s (they're listed in the .308 sections, though most manufacturers list them as 30-30 bullets?). Also, depending on the gun (don't have it yet), I've read that the bore may not be .308, but maybe .310-.312, so i might have to use .303 bullets or cast my own? I have access to a casting setup, and have read that with a high tin/antimony hard alloy you can push 2500fps without having to use gas checks?
Also, maybe more for the gunsmithing forum, but i found an article regarding multiple different tests of these rifles. Apparently they're proofed to more than double the "safe" operating pressure. The article I read showed that dozens of these rifles have been tested to destruction and survived pressures of over 90k psi before having a catastrophis failure. Also, many have said they shoot factory .308 rounds without any problems, though other say this may cause the lugs to press back into the "soft" reciever, and can result in gradually increasing headspace over time.
Any ideas?
Here's what I've found out. Standard factory .308 win usually run about 56000 psi, and 7.62x51 usually around 52k? The cetme round is supposed to run about 47-48k. I've looked in the alliant, accurate, hodgdon and IMR manuals. IMR is the only one that lists pressures, and the extreme low end loads run about 48000psi pressures.
Here's my question: How does one work up a below max load? I've been told that this may be unsafe, as going below max with your powder charge can actually INCREASE pressure? Not sure how this works... Is there some kind of calculator that has different calibres, powders, bullets, barrel lengths, etc, that you can plug in a load and it will give you approximate data?
I'm going to want to load 150gr bullets, maybe even 125s (they're listed in the .308 sections, though most manufacturers list them as 30-30 bullets?). Also, depending on the gun (don't have it yet), I've read that the bore may not be .308, but maybe .310-.312, so i might have to use .303 bullets or cast my own? I have access to a casting setup, and have read that with a high tin/antimony hard alloy you can push 2500fps without having to use gas checks?
Also, maybe more for the gunsmithing forum, but i found an article regarding multiple different tests of these rifles. Apparently they're proofed to more than double the "safe" operating pressure. The article I read showed that dozens of these rifles have been tested to destruction and survived pressures of over 90k psi before having a catastrophis failure. Also, many have said they shoot factory .308 rounds without any problems, though other say this may cause the lugs to press back into the "soft" reciever, and can result in gradually increasing headspace over time.
Any ideas?
Last edited:
