Need a little help with new 338 Lapua imp

[backyardsniper]

Got my new 338 lapua imp in and have been doing some load testing. I know that H1000 is not the optimum powder but I have that and some US 869 on hand. My improved is the Dave Kiff 37 degree shoulder with his bore rider design. I'm getting excellent accuracy with about everything I have sent through it, but nothing special in the velocity dept. I have a 27" brought on 5C on a stiller tac 338 action manners 100% carbon T5. I have gone up to 94.5 gr of H1000 with 300 berger at 3.775 OAL no pressure yet but only 2760fps. 98 gr H1000 with 250 berger at 3.750 gave 2902fps. Here is where it got weird for me. I pushed the OAL out to 3.950 and went up to 96gr of H1000 and my velocity dropped to 2580fps. If anyone is running a similar set up to this I would like to get some load info. How hot are you running it, and what powder is working for you. I know reloader 33 is supposed to be very good but I have a bunch of H1000 and I think I will run the 250gr bullets if the H1000 is gonna work for them. I have been as high as 100gr and had no pressure signs, so if I can get the 250's over 3100I'll probably just run with that until I can get some rl33 or retumbo. Any advice you guys got would be greatly appreciated

 

[dkhunt14]

I used US869 with the 300 grain bullets. I have a 36 inch barrel and when it got cold I had erratic results. It was a very dirty powder. Then I went to Retumbo and my gun didn't like it. I went to H1000 and the accuracy was great put I hit pressure at 2980. I then went to R33 and went to 3070 with no pressure. Accuracy was better and velocity was consistent. I maybe could have gone farther but I shoot the 300 Grain Elite and when you go over 3000 you might have slump of the bullet. So I backed it down to 2993 with 104 grains of R33. That load shot 7 of 8 shots in 4 1/4 inches at 1000 and the one shot opened it up to 6 1/4 inches. We also tried the R33 in a 338 RUM IMP. and it shot faster and more accurate then Retumbo with no pressure. Matt

 

[scf]

Plus one for RL33. My standard 338L is running just over 2800 with 300 OTM in a 28" Brux and is not at max by any means. I stopped at this velocity because it shoots really well. I think I saw a post on here somewhere that said Wideners had some RL 33. I ve used it in 7 STW, 300 RUM and 338L with good results in each. Only issues were considerable differences between different lots.

 

[scf]

Another issue might be the chrono. The only ones I have any reasonable confidence in are the Oehler, PVM and Magneto Speed. I had a Shooting Chrony that varied greatly depending on light angle.

 

[kaseyfied]

I have a new lapua improved. Just started load workup on it. Rl33 is doing very well. I'm at 107 grains now after fireforming brass and it shoots 1/4 inch all day. Why 250 grain bullets? That rifle is made for 300 grain pills. I'm sure u can find a buyer for the h1000. I doubt with 98 grains of h1000 your not at 2900

Kasey