Free advice is always welcomed, and if it’s bad advice, well I probably won’t know. 
I’m developing 338 LM loads for long range fun shooting at an upcoming LRP course at ~ 1 mile elevation. This load is for out to around 2000 yds or so. I’m also working on another load with Warner Tool Flat Line 255.5 gr bullets that have a slightly higher BC and will have an extra 100-200 fps that I will use for anything longer — again all for fun, not competition.
Rifle: Factory Savage action in 338 LM, 24” 9.3 twist fluted light/medium profile barrel with SilencerCo Harvester BB suppressor.
Bullets: Berger 300 Hybrid OTM Tactical
Cases: Peterson (1st Firing)
Powder: RL-33
Primers: Federal 215M
Seating: ~ 3.72” COAL varies a little with the meplats, did not measure the CBTO.
I’ve also tried Lapua cases and the RL-33 load looked pretty good at 97.5 gr. I tried several other powders with the Lapua cases before I got the suppressor, and RL-33 was easily the best for this rifle and bullet. I’ve already stocked up on RL-33 and the Berger 300s. I may still use the Lapua cases. I’m just trying different stuff and having fun doing it.
The photos are some 100 yd groups I shot today with the Peterson cases. None of these groups are great, but the rifle is nothing special, plus I’m highly allergic to the recoil. The only things that are still Savage on this rifle are the receiver, the bolt, and the barrel, and the barrel is on probation.
The first group is only two shots because I used the first three shots to get back on target after bedding my rail. The other four are 5-shot groups. Point of aim on the centered on the red diamond for all groups with no scope dial changes. Did not chrono, saw no pressure signs. I won’t go any higher on the powder charges without measuring velocities. Since I use a Magnetospeed, I just try to find a pretty conservative load that will shoot first by checking several reloading manuals and staying within the safe ranges and checking for pressure signs, then I chrono any loads that looked promising. If the velocities end up at the low end compared to what the manuals show, I may go up a little from there, but very cautiously and with more velocity measurements along the way.
My understanding is that the reason the higher charge weight shot lower on the target is probably because the barrel is flexing down at the 98.5 gr loading and by the same logic it appears that it’s flexing up at the 97.0 gr loading, and these high or low points are where the barrel vertical velocity is slowing to zero and changing direction. It seems like you can really see the barrel harmonics in these groups with the lightish profile barrel and the largish can.
Without any advice from y’all to the contrary, I would probably focus on the 98.5 gr load because the vertical was so consistent — I’m taking “credit” for all that horizontal. On the other hand the vertical component wasn’t that tight at the “top” on the 97.0 charge, so I think some of what I’m seeing is just normal variation due to the weapon system and the shooter. So if all other things are equal is there an advantage to choosing the high point or the low point of the barrel oscillation, and what is the reason? What do all of your more experienced eyes see that I’m missing?
I’m developing 338 LM loads for long range fun shooting at an upcoming LRP course at ~ 1 mile elevation. This load is for out to around 2000 yds or so. I’m also working on another load with Warner Tool Flat Line 255.5 gr bullets that have a slightly higher BC and will have an extra 100-200 fps that I will use for anything longer — again all for fun, not competition.
Rifle: Factory Savage action in 338 LM, 24” 9.3 twist fluted light/medium profile barrel with SilencerCo Harvester BB suppressor.
Bullets: Berger 300 Hybrid OTM Tactical
Cases: Peterson (1st Firing)
Powder: RL-33
Primers: Federal 215M
Seating: ~ 3.72” COAL varies a little with the meplats, did not measure the CBTO.
I’ve also tried Lapua cases and the RL-33 load looked pretty good at 97.5 gr. I tried several other powders with the Lapua cases before I got the suppressor, and RL-33 was easily the best for this rifle and bullet. I’ve already stocked up on RL-33 and the Berger 300s. I may still use the Lapua cases. I’m just trying different stuff and having fun doing it.
The photos are some 100 yd groups I shot today with the Peterson cases. None of these groups are great, but the rifle is nothing special, plus I’m highly allergic to the recoil. The only things that are still Savage on this rifle are the receiver, the bolt, and the barrel, and the barrel is on probation.
The first group is only two shots because I used the first three shots to get back on target after bedding my rail. The other four are 5-shot groups. Point of aim on the centered on the red diamond for all groups with no scope dial changes. Did not chrono, saw no pressure signs. I won’t go any higher on the powder charges without measuring velocities. Since I use a Magnetospeed, I just try to find a pretty conservative load that will shoot first by checking several reloading manuals and staying within the safe ranges and checking for pressure signs, then I chrono any loads that looked promising. If the velocities end up at the low end compared to what the manuals show, I may go up a little from there, but very cautiously and with more velocity measurements along the way.
My understanding is that the reason the higher charge weight shot lower on the target is probably because the barrel is flexing down at the 98.5 gr loading and by the same logic it appears that it’s flexing up at the 97.0 gr loading, and these high or low points are where the barrel vertical velocity is slowing to zero and changing direction. It seems like you can really see the barrel harmonics in these groups with the lightish profile barrel and the largish can.
Without any advice from y’all to the contrary, I would probably focus on the 98.5 gr load because the vertical was so consistent — I’m taking “credit” for all that horizontal. On the other hand the vertical component wasn’t that tight at the “top” on the 97.0 charge, so I think some of what I’m seeing is just normal variation due to the weapon system and the shooter. So if all other things are equal is there an advantage to choosing the high point or the low point of the barrel oscillation, and what is the reason? What do all of your more experienced eyes see that I’m missing?
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