This post is intended to save a new reloader time, money and energy and show how we have produced a consistent 5 round group 1/2 moa factory rifle with extreme spreads 15-25 FPS and SD of 6-7

A huge part of this data is how we started with just full length sizing and no other Bench rest techniques and then switched to all bench rest techniques. A big difference on average 30-50% better group size, 30-50% lower on extreme spreads, and eliminating flyers from the groups

The Berger Bible (manual) will help you tremendously with developing a load.
Tubbs reloading video part 1 and 2 on youtube is your next stop even though its 18 years old it’s great
Sniper 101 on youtube will teach you more about shooting than anyone else can for free it’s like 87 part video series

All this being said, our goal was to develop a sub ½ moa load that was consistent at least 5 round groups and an extreme spread of less than 20 fps. Both were accomplished but it took over 8 trips to the range and over 320 rounds sent downrange. I will attach all stages of development and our thought process through the testing.
Ruger Precision Rifle .243 with a Vortex HST 6-24 Match rings and level, atlas bipod
Lapua Brass
We are shooting the Berger 105 vld, and tried over 9 powders

I didn’t read the berger manual till after the testing, I wouldn’t have tested so many powders. I would have found a few with good fill ratios and velocity and just tested those, berger will tell you most powders can be developed into a good load and all powders are temperature sensitive. '

We tested 9 powders, IMR 4831, 7977, 7828, 4350, 4064, Extreme powders retumbo, h1000, h4350 H4831 SC, and many different primers, S&B, 210, 210m, 200, 200 Br, 215, 215m, 250

We started at .026 from lands for one reason because the Ruger Magazine can handle .015 from the lands but that’s about it and the bullet tips are scraping the magazine. You can get other magazines for more length, but we kept the gun all factory.

Velocities were tested with a Magnetto sporter which is great, those 100$ chronographs are junk is what we found out. The magnetto does appear to have some effect on your bullet

All powders were a grain off of Berger Bible Max Load

100 yard
All four round groups except H4831sc
IMR 7977 average about 2900 with 48 ES 1.8 MOA
H4350 2700 63 Es 1.5 MOA
IMR 4350 2840 ES 29 .9 MOA with rounds almost identical ES
IMR 4831 2800 ES 51 .69 MOA
H 4831 SC 2870 ES 64 .394 MOA 5 round group submitted to the ruger challenge Number 7 100 yards 5 shot
H1000 2900 ES 50 1.2 moa
RETUMBO 2970 ES 49 1.0 moa
IMR 7828 2800 ES 25 .600 3 bullets less than .250 moa

So H4831SC factory gun, shot lights out so why not just stop. Its extreme spread is horrible so lots of development to go

So the next test was to see an Optimal charge weight test with H4831
because it was the most accuarate

Research OCW needs to be done
Low powder charge to close to max and your looking for a load that when temperatures spike or get colder are still hitting on the same horizontal plane
That first group shot high so the scope was adjusted down
OCW 1.1, 2, 3
.702 moa, .605, .586, .799, .675 from 42.3-43.4 grains of powder
This whole development was done in 30-35 degree outside temperatures.
There are 6 more stages to post time. I will try and update daily

I will try and get some pics up