Minimum velocity(pressure) for RL7

[stubblejumper]

New to the board...what a wealth of information!

I've recently switched to RL7 from the "factory" powders and have a question regarding minimum required pressure for consistent ignition and how that relates to velocity.

I started at 60 grains of RL7 with 300 XTP's and mmp short sabots and the load chronied at 2250fps. With 300 mz expanders and the supplied sabots it was 1980 fps. Obviously lower pressure on the second load

I see that most here load higher than 60 grains but with similar velocity that I am getting at 60. I'm not sure if I can safely go to 65 as some have suggested(or if my shoulder would like it) or if I can use velocity as an accurate indication of pressure.

As I cannot directly measure pressure, is there a range of velocity for RL7 with 300 grain bullets that I could use as a guideline for minimum and maximum pressure?

From the difference in recoil felt and the velocities measured above it would seem that I cannot just use X number of grains of powder as a minimum because pressure seemed to change substantially with different bullet/sabots.

As a side note I did not see these large differences with the same bullets and the factory recommended powders. Because they are faster burning??

Thanks for allowing me to post here. Great board!

[edge]

In a 50 caliber Quickload would estimate 60 grains should yield 2307 fps @ 36 Kpsi.

Powley would estimate the pressure a bit higher.

With 65 grains QL would estimate 2420 fps and 39 Kpsi.

and finally 70 grains @ 2530 fps and 43Kpsi.


IF, I wrote IF you use a chronograph and your velocities are lower than predicted then most likely the pressures are too!

None of those pressures scare me, but I personally would NOT proceed without a chrony.

edge.

[stubblejumper]

Thanks Edge.... if you see this could you please give me an approximate velocity of a 300 grain bullet that would result from around the 30,000 psi minimum Ive seen suggested?

[edge]

I don't know that 30Kpsi will be consistent, but 52 grains of RL-7 would be in the ballpark @ 2100 fps....estimated by QL.

edge.