CMV
Member
So the rounds I worked up in a 20" HBAR 1:9 AR-15 were striking targets at the same POI at 50 yds and 100 yds as XM193. That's what I was going for - I don't want have to change sights or add clicks going back & forth between my loads & M193.
So today I decided to try them in the other rifle with a 16" M4 profile 1:9. I expected the velocity to be lower, but assumed I'd get the same POI results. My loads are striking a lot lower than M193 at 50 yds & 100 yds.
So that has me thinking I might be off altogether. If I were going out to 250 yds or 400 yds, would I be seeing the same thing out of the 20" barrel? I'm assuming same POI at 50 & 100 yds means I'm going to be fairly close through the entire effective range.
Anyway, it didn't occur to me to take both rifles while working up the load and measure both at every step along the way. I figured I'd go with the 20" to get closer to book fps and once it was good, it would "just work" in the 16" but with a velocity penalty for the shorter barrel.
Maybe what I want to do is impossible w/o exceeding max load by 6.25% and making carbon copy M193?
Or is there a way I can make rounds that will give me the same POI as M193 at various ranges in both rifles?
As of right now:
Load is 25.0gr H335, 55gr Hornady FMJBT, LC brass, CCI #41.
20":
M193 - 3270 fps
Mine - 3034 fps, 17.4 std dev, 50 yds = same POI, 100 yds = same POI
16":
M193 - 3022 fps
Mine - 2834 fps, 28.1 std dev, 50 yds = .9" low, 100 yds = 2.9" low
Since I shoot both rifles interchangeably, I want the same load to work in both. I don't want to have my ammo segregated into "stash", "load for 20", & "load for 16" lots. If this is possible while staying within published .223 data, what method for working up the load would be best?
So today I decided to try them in the other rifle with a 16" M4 profile 1:9. I expected the velocity to be lower, but assumed I'd get the same POI results. My loads are striking a lot lower than M193 at 50 yds & 100 yds.
So that has me thinking I might be off altogether. If I were going out to 250 yds or 400 yds, would I be seeing the same thing out of the 20" barrel? I'm assuming same POI at 50 & 100 yds means I'm going to be fairly close through the entire effective range.
Anyway, it didn't occur to me to take both rifles while working up the load and measure both at every step along the way. I figured I'd go with the 20" to get closer to book fps and once it was good, it would "just work" in the 16" but with a velocity penalty for the shorter barrel.
Maybe what I want to do is impossible w/o exceeding max load by 6.25% and making carbon copy M193?
Or is there a way I can make rounds that will give me the same POI as M193 at various ranges in both rifles?
As of right now:
Load is 25.0gr H335, 55gr Hornady FMJBT, LC brass, CCI #41.
20":
M193 - 3270 fps
Mine - 3034 fps, 17.4 std dev, 50 yds = same POI, 100 yds = same POI
16":
M193 - 3022 fps
Mine - 2834 fps, 28.1 std dev, 50 yds = .9" low, 100 yds = 2.9" low
Since I shoot both rifles interchangeably, I want the same load to work in both. I don't want to have my ammo segregated into "stash", "load for 20", & "load for 16" lots. If this is possible while staying within published .223 data, what method for working up the load would be best?