Tweet
Got to finally start developing my 6.5 Grendel load yesterday. 20" SS Shilen barrel.
Using Barnes 100gr TTSX and Accurate 2200 (want a load I can use for hunting and possibly for matches). Still need to fine tune seating depth and maybe I'll do another iteration or so of testing but today was a pretty drastic improvement on yesterday, and so far this is my most sucessful endeavor into precision reloading. So many different theories about nodes and "what's important". OCW, Ladder tests, etc. I first went for 10 loads .3 grains apart between the minimum and maximum loads based on the 6.5 grendel reloading for hunting book. That was yesterday. Here are the results of that. Yeah I should have skipped the bottom half, but I suppose I learned something as a result.
From yesterday (target pictures weren't anything to write home about, mostly shooting for velocity data) but if you look at group 10, that was the worst group, despite good numbers. According to Dan Newberry that is the "scatter group" and going up 1% in charge weight should bring me to the accuracy node (the point at which the 18k FPS shockwave is back at the chamber, farthest away from the muzzle as the projectile is leaving). Also related to optimal barrel time.
So after some research, I decided to take the *worst* group which had the best velocity standard deviation, and use that as the basis for increasing the charge. That gave me 27.1gr. (This is safe in MY chamber, and I worked up from the bottom of the load data assessing for signs of pressure. You cannot assume that this is safe for your chamber, and I'm not responsible for what happens if you try this.) I started at 26.9 to give myself some room to move up and because this was just over the highest load I tested previously
From yesterday (target pictures weren't anything to write home about, mostly shooting for velocity data) but if you look at group 10, that was the worst group, despite good numbers. According to Dan Newberry that is the "scatter group" and going up 1% in charge weight should bring me to the accuracy node (the point at which the 18k FPS shockwave is back at the chamber, farthest away from the muzzle as the projectile is leaving). Also related to optimal barrel time.
New data from today. All 50 rounds had half the standard deviation and 1/10th the extreme spread of yesterday, and the ES was half of the best ES group yesterday. Looks like I'll be using 27.1
Best group minus the flyer, pretty sure I pulled that though (it was the third shot so at least 4 "consecutive" shots (was shooting round-robin, so 4 other shots between each of these). I think not bad for 3-10mph wind (not a huge effect at 100 yards but still). I am pretty sure I rushed it and my cheek weld wasn't the same because my neck was uncomfortable so I pulled (instead of squeezing) the trigger... Still, for a 6/7 shot group, I'm pretty happy. Third shot in the group was the flyer. This set also had the lowest velocity SD. Exactly 1% higher charge than my "scatter" group from yesterday.*
.64 group if you ignore the my mess up
I think this hits or approaches both the velocity node and the OCW node in terms of consistency across differing pressures.
Obviously would love input on improving the load (I haven't messed with seating depth at all). It may get better when I resize the brass (these were Hornady factory prepped, I looked them over and chamfered the mouths but didn't weigh them or anything. I did weigh the bullets.)
Using Barnes 100gr TTSX and Accurate 2200 (want a load I can use for hunting and possibly for matches). Still need to fine tune seating depth and maybe I'll do another iteration or so of testing but today was a pretty drastic improvement on yesterday, and so far this is my most sucessful endeavor into precision reloading. So many different theories about nodes and "what's important". OCW, Ladder tests, etc. I first went for 10 loads .3 grains apart between the minimum and maximum loads based on the 6.5 grendel reloading for hunting book. That was yesterday. Here are the results of that. Yeah I should have skipped the bottom half, but I suppose I learned something as a result.
From yesterday (target pictures weren't anything to write home about, mostly shooting for velocity data) but if you look at group 10, that was the worst group, despite good numbers. According to Dan Newberry that is the "scatter group" and going up 1% in charge weight should bring me to the accuracy node (the point at which the 18k FPS shockwave is back at the chamber, farthest away from the muzzle as the projectile is leaving). Also related to optimal barrel time.
So after some research, I decided to take the *worst* group which had the best velocity standard deviation, and use that as the basis for increasing the charge. That gave me 27.1gr. (This is safe in MY chamber, and I worked up from the bottom of the load data assessing for signs of pressure. You cannot assume that this is safe for your chamber, and I'm not responsible for what happens if you try this.) I started at 26.9 to give myself some room to move up and because this was just over the highest load I tested previously
From yesterday (target pictures weren't anything to write home about, mostly shooting for velocity data) but if you look at group 10, that was the worst group, despite good numbers. According to Dan Newberry that is the "scatter group" and going up 1% in charge weight should bring me to the accuracy node (the point at which the 18k FPS shockwave is back at the chamber, farthest away from the muzzle as the projectile is leaving). Also related to optimal barrel time.
New data from today. All 50 rounds had half the standard deviation and 1/10th the extreme spread of yesterday, and the ES was half of the best ES group yesterday. Looks like I'll be using 27.1
Best group minus the flyer, pretty sure I pulled that though (it was the third shot so at least 4 "consecutive" shots (was shooting round-robin, so 4 other shots between each of these). I think not bad for 3-10mph wind (not a huge effect at 100 yards but still). I am pretty sure I rushed it and my cheek weld wasn't the same because my neck was uncomfortable so I pulled (instead of squeezing) the trigger... Still, for a 6/7 shot group, I'm pretty happy. Third shot in the group was the flyer. This set also had the lowest velocity SD. Exactly 1% higher charge than my "scatter" group from yesterday.*
.64 group if you ignore the my mess up
I think this hits or approaches both the velocity node and the OCW node in terms of consistency across differing pressures.
Obviously would love input on improving the load (I haven't messed with seating depth at all). It may get better when I resize the brass (these were Hornady factory prepped, I looked them over and chamfered the mouths but didn't weigh them or anything. I did weigh the bullets.)
Comment