Here's the facts: Rem 700 SPS Varmint - 26"
7mm-08 - 150gr SMK, 39.5gr RE-15, Hornady Case, Fed. 210M.
The load from the Sierra book states that this is max load and velocity ~2700fps. I have exceeded the 2.780 max OAL by .032" Length to Ogive is 2.282" being .015 before lands. OAL is 2.812.
The 20 shot average velocity is 2512fps with very low ES/SD numbers and great accuracy but there is about a 150fps difference in velocities. I am assuming no fault with the chronograph as it has performed very well in the past.
Is this seating depth enough to cause pressure to drop enough to effect velocity this much?
Lot to lot powder differences?
I am not a velocity freak but I want the most I can get safely without sacrificing accuracy. There are no pressure signs on cases or primers and I am thinking about very cautiously going over the published data watching for pressure. My thought is that Sierra safely achieved the stated velocities with that powder and that exact bullet so why should it be unsafe for me to do so? I am no physics major or ballistician, but velocity is a function of pressure assuming consistent friction and other factors that have shown themselves in the chrono data(SD/ES).
I'm not asking anyone to condone this and I will not post any data should I choose to exceed the listed maximums, but has anyone done what I am thinking about?
7mm-08 - 150gr SMK, 39.5gr RE-15, Hornady Case, Fed. 210M.
The load from the Sierra book states that this is max load and velocity ~2700fps. I have exceeded the 2.780 max OAL by .032" Length to Ogive is 2.282" being .015 before lands. OAL is 2.812.
The 20 shot average velocity is 2512fps with very low ES/SD numbers and great accuracy but there is about a 150fps difference in velocities. I am assuming no fault with the chronograph as it has performed very well in the past.
Is this seating depth enough to cause pressure to drop enough to effect velocity this much?
Lot to lot powder differences?
I am not a velocity freak but I want the most I can get safely without sacrificing accuracy. There are no pressure signs on cases or primers and I am thinking about very cautiously going over the published data watching for pressure. My thought is that Sierra safely achieved the stated velocities with that powder and that exact bullet so why should it be unsafe for me to do so? I am no physics major or ballistician, but velocity is a function of pressure assuming consistent friction and other factors that have shown themselves in the chrono data(SD/ES).
I'm not asking anyone to condone this and I will not post any data should I choose to exceed the listed maximums, but has anyone done what I am thinking about?