therifleman556
Well-Known Member
Can I ask what's meant by scatter node and how it's identified?
1. 69.5 3159fps
2. 70 3218fps
3. 70.5 3249fps
4. 71 3277fps
5. 71.5 3279fps
6. 72 3319fps
7. 72.5 3340fps
8. 73 3348fps
9. 73.5 3343fps
10. 74 3367fps
1. 72.6 Error
2. 72.8 3377fps
3. 73 3408fps
4. 73.2 3438fps
Why are shots 3 and 4 so much faster than the shot 8 (73 gr.) from the previous session? Are you cleaning the barrel between sessions? Is it a factory barrel? Are you annealing the brass or maybe changed brass?
I use 140 Berger Hunting VLD's in front of 76 grains of RL-33 which yields 3281 FPS from my Extreme Weather Model 70 264. I used .030 back of the lands.
Is it possible the reason for the change in velocity is you may have been touching the lands? Not sure what your reloading practice is, but with a 0.005" jump maybe you were touching and got higher pressure/velocity. Maybe increase your jump, shoot them again to find the velocity of the node then fine tune with shooting groups at different seating depths.Didn't clean the barrel. Barrels a Pac-Nor 1-8" polygonal twist. Brass was full length resized and that is all, not the same brass I used the other day, but from the same lot, Nosler brass. Not annealing.
idcwby
I haven't used RL33 either. If the brass you used on todays test was new never fired brass and the brass used on the previous test was once fired or something The powder could have been a little more compacted and raise pressures some.
A primer change can cause speed increases. Especially going from a standard to a magnum primer.
i looked at a few other posts with RL33 and 140 gr. bullets. You load seems to be running faster than most. Here's an old quote:
How long is the barrel?
I would try a few rounds at about 72.5 Gr. and see how stable the speeds are and what the SD and ES numbers are.
Is it possible the reason for the change in velocity is you may have been touching the lands? Not sure what your reloading practice is, but with a 0.005" jump maybe you were touching and got higher pressure/velocity. Maybe increase your jump, shoot them again to find the velocity of the node then fine tune with shooting groups at different seating depths.
I've only used rl33 for one ladder and seating depth test on subsequent day. I saw the same thing. I won't go back.