Rifle load development next steps

ghbucky · July 10, 2020, 01:28 PM

CAUTION: The following post includes loading data not covered by currently published sources of tested data for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

This is my first time working up a rifle load, so I'm checking in to see if I am on the right track and where I should head next. This is for .223 Remington in an AR rifle.

I've done tests using 8208XBR under 55gr. sierra game king. I stepped up to the max load (25.8), where I saw the first indication of pressure.

I ran out 5 loads each @25.5 and 25.3 grains.

Prior to testing those I checked my zero with 20 rounds of factory ammo.

I am limited on what I can do for test firing right now, I'm limited to an indoor 25yd range. For support I used a front rest and was sitting on a stool trying to be very still...(Metalgod suggested leaning against the divider, I'll use that later).

What surprised me was that both loads shot a bit high and right. I figured I would see elevation differences, but I was surprised to see windage change.

There isn't a whole lot of difference in group size. The 25.3 is a bit tighter, but that could as well be me more than the load.

My plan was to run off 50 or so of the 25.3 and do the 4 hour drive to where I can to a 100 yard range and get into a prone position with some supports.

Any idea why the POI would move right over a factory load?

What should my next steps be?

[edit] I guess the disclaimer may not be necessary, but I thought I'd be safe

scatterbrain · July 10, 2020, 02:10 PM

Quick answer: velocity change will move bullet impact, up down, right or left. Factory loads are hot, it's hard to achieve factory velocities with reloads, I use a chronograph and can not get loads to the speed of factory without having more pressure than I am comfortable with.

ghbucky · July 10, 2020, 02:14 PM

Quote:

Originally Posted by scatterbrain

Quick answer: velocity change will move bullet impact, up down, right or left. Factory loads are hot, it's hard to achieve factory velocities with reloads, I use a chronograph and can not get loads to the speed of factory without having more pressure than I am comfortable with.

But wouldn't you expect to see a lower velocity to move the POI down?

scatterbrain · July 10, 2020, 02:31 PM

Not necessarily, this morning I was shooting a .222 Remington with the same loads, other than half of the necks were sized at minus .002 inch under bullet size and the other half were sized at minus .001 inch under bullet size. I had two 3/4 inch groups about 1-1/4 inches apart, left and right and one was about 1/4 lower than the other.

ghbucky · July 10, 2020, 02:35 PM

OK, so the POI will do what it will do and don't sweat it. Got it.

scatterbrain · July 10, 2020, 02:37 PM

you can always move the group to where ever you want, but you got to shoot the group.

July 10, 2020, 01:28 PM	#1
ghbucky Senior Member Join Date: June 12, 2020 Posts: 1,177	Rifle load development next steps CAUTION: The following post includes loading data not covered by currently published sources of tested data for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information. This is my first time working up a rifle load, so I'm checking in to see if I am on the right track and where I should head next. This is for .223 Remington in an AR rifle. I've done tests using 8208XBR under 55gr. sierra game king. I stepped up to the max load (25.8), where I saw the first indication of pressure. I ran out 5 loads each @25.5 and 25.3 grains. Prior to testing those I checked my zero with 20 rounds of factory ammo. I am limited on what I can do for test firing right now, I'm limited to an indoor 25yd range. For support I used a front rest and was sitting on a stool trying to be very still...(Metalgod suggested leaning against the divider, I'll use that later). What surprised me was that both loads shot a bit high and right. I figured I would see elevation differences, but I was surprised to see windage change. There isn't a whole lot of difference in group size. The 25.3 is a bit tighter, but that could as well be me more than the load. My plan was to run off 50 or so of the 25.3 and do the 4 hour drive to where I can to a 100 yard range and get into a prone position with some supports. Any idea why the POI would move right over a factory load? What should my next steps be? [edit] I guess the disclaimer may not be necessary, but I thought I'd be safe Last edited by ghbucky; July 10, 2020 at 01:34 PM.

July 10, 2020, 02:10 PM	#2
scatterbrain Senior Member Join Date: February 7, 2015 Posts: 160	Quick answer: velocity change will move bullet impact, up down, right or left. Factory loads are hot, it's hard to achieve factory velocities with reloads, I use a chronograph and can not get loads to the speed of factory without having more pressure than I am comfortable with.

July 10, 2020, 02:31 PM	#4
scatterbrain Senior Member Join Date: February 7, 2015 Posts: 160	Not necessarily, this morning I was shooting a .222 Remington with the same loads, other than half of the necks were sized at minus .002 inch under bullet size and the other half were sized at minus .001 inch under bullet size. I had two 3/4 inch groups about 1-1/4 inches apart, left and right and one was about 1/4 lower than the other.

July 10, 2020, 02:35 PM	#5
ghbucky Senior Member Join Date: June 12, 2020 Posts: 1,177	OK, so the POI will do what it will do and don't sweat it. Got it.

July 10, 2020, 02:37 PM	#6
scatterbrain Senior Member Join Date: February 7, 2015 Posts: 160	you can always move the group to where ever you want, but you got to shoot the group.