C
Corn
Guest
Dear All,
Hello everybody, I’m new here in this forum but I’ve been shooting and reloading for several years already. I have a problem in reloading when in it comes to velocity consistency in hand loads. This might be bit long story but I try to tell accurately my reloading process. Gun that I’m using is AR15 with match grade LW st/st barrel.
Extreme velocity spread does differ a lot. One reload batch might be 80 fps and another 35fps. Standard deviation is hardly ever under 26 fps which my understanding should be 10 or less. Well, from my calculations 26 fps velocity extreme spread is only ~0.6 inch in vertical dimension @ 300 yards. So it only matters in theory, but I’m bit perfectionist and I’m bothered by the velocity spread.
Recently I bought tuning fork lab scale which is accurate to 0.015grain. I’ve tested to measure every load up to that accuracy but it didn’t make any differences. Well again my calculations show that the powder I use, 0.015 grain of it is in speed wise 2.6 fps. So it’s not the amount of powder that is the variable here. Anyhow that tuning fork scale is much much more convenient, accurate and faster when it comes to dynamical weighing than those using loadcell so money well spent (I guess).
Here’s how my reloading process goes. I select same manufacturer cases, mostly S&B and with same manufacturing year head stamp. Resize with Forster Benchrest FL die. Push shoulders back by 0.004”. Before I was using RCBS but changed to Forster as it claims to have free floating expander button and that it supports neck while expanding. I don’t have the equipment to measure the neck run out so can’t comment if this is true. Anyway, this shouldn’t affect the velocity spread nor does it? After resizing I trim the cases to length, ream the primer pocket with K&M primer pocket correction tool to set all with same depth. Uniform flash hole with Lyman flash hole uniformer. Chamfer case mouth by K&M tapered reamer. That’s about the case preparation.
I do the reloading by Dillon RL550B and next goes the primers and mostly I use CCI 400, gunpowder measured by hand, bullet seated with Forster micrometer seater die. Bullets that I use are Nosler CC 52 grain and Sierra Match King 69 grain.
I have tried to scale the brass but it didn’t do any differences to the velocity spread. I’m not turning the case necks so is there any other variable that I’m missing which could cause the velocity spread? I’ve read that these shouldn’t be crimped but came into my mind that could auto loader hit some of the bullets deeper to the case and this cause spread? This comes also to the not uniform case tension, so how could one be sure of that?
Ok, I’m happy with the grouping that I get currently with it which is ~0.7MOA up to 300 yards which is the maximum distance at the gun range I use. But like I said I’m bit perfectionist and try to improve wherever possible and this velocity spread bothers me.
Sorry for the long first post. Hope you could point me to right direction. Any help greatly appreciated.
Hello everybody, I’m new here in this forum but I’ve been shooting and reloading for several years already. I have a problem in reloading when in it comes to velocity consistency in hand loads. This might be bit long story but I try to tell accurately my reloading process. Gun that I’m using is AR15 with match grade LW st/st barrel.
Extreme velocity spread does differ a lot. One reload batch might be 80 fps and another 35fps. Standard deviation is hardly ever under 26 fps which my understanding should be 10 or less. Well, from my calculations 26 fps velocity extreme spread is only ~0.6 inch in vertical dimension @ 300 yards. So it only matters in theory, but I’m bit perfectionist and I’m bothered by the velocity spread.
Recently I bought tuning fork lab scale which is accurate to 0.015grain. I’ve tested to measure every load up to that accuracy but it didn’t make any differences. Well again my calculations show that the powder I use, 0.015 grain of it is in speed wise 2.6 fps. So it’s not the amount of powder that is the variable here. Anyhow that tuning fork scale is much much more convenient, accurate and faster when it comes to dynamical weighing than those using loadcell so money well spent (I guess).
Here’s how my reloading process goes. I select same manufacturer cases, mostly S&B and with same manufacturing year head stamp. Resize with Forster Benchrest FL die. Push shoulders back by 0.004”. Before I was using RCBS but changed to Forster as it claims to have free floating expander button and that it supports neck while expanding. I don’t have the equipment to measure the neck run out so can’t comment if this is true. Anyway, this shouldn’t affect the velocity spread nor does it? After resizing I trim the cases to length, ream the primer pocket with K&M primer pocket correction tool to set all with same depth. Uniform flash hole with Lyman flash hole uniformer. Chamfer case mouth by K&M tapered reamer. That’s about the case preparation.
I do the reloading by Dillon RL550B and next goes the primers and mostly I use CCI 400, gunpowder measured by hand, bullet seated with Forster micrometer seater die. Bullets that I use are Nosler CC 52 grain and Sierra Match King 69 grain.
I have tried to scale the brass but it didn’t do any differences to the velocity spread. I’m not turning the case necks so is there any other variable that I’m missing which could cause the velocity spread? I’ve read that these shouldn’t be crimped but came into my mind that could auto loader hit some of the bullets deeper to the case and this cause spread? This comes also to the not uniform case tension, so how could one be sure of that?
Ok, I’m happy with the grouping that I get currently with it which is ~0.7MOA up to 300 yards which is the maximum distance at the gun range I use. But like I said I’m bit perfectionist and try to improve wherever possible and this velocity spread bothers me.
Sorry for the long first post. Hope you could point me to right direction. Any help greatly appreciated.
