338 lapua improoved shooter!!!

[tom m.]

well, i have shot a 35*shoulder, .010"taper lapua imp. for a few years now. with the new bergers here, i decided to re-work my load, and try some different stuff.

ok, i feel like a real dumb *** for not trying it before, but you guys that have an imp. lapua might give h50bmg a try. i was SURE 2,980 was max max max, out of a 30 inch tube with 300 grainers. well.....it's not, try this stuff if you have room.

i will still settle on the most accurate, as always, but i thought i better share this.
tom

 

[Fiftydriver]

I am getting between 2950 and 3050 fps with my 338 AX in a 30" barrel, just depending on specific barrel. I use Retumbo and it has produced the best velocity and accuracy combination hands down.

I did try H50BMG and it did shoot very well. I could not get up to the working pressures I wanted and it was a bit dirty because of that and velocity topped out at around 2900 fps, about the same as H-1000 and RL-25 but these two pressured out a bit faster for lower load density.

One thing that may be a factor is that I am loading my AX to an OAL of around 3.670" and that is likely why 50BMG is just to slow. Seat that bullet out to 4.000" and it changed things dramatically.

The limited testing I have done so far with the Berger 300 gr Hybrid, it seems to be running around 50 fps faster then the SMK and I have pushed then right up to the 3100 fps level but accuracy was quite unimpressive. Best groups came in at 2875 to 2900 fps for the Berger, while the best groups with the SMK came in at 2950 to 2975 fps.

It just goes to show you though, every rifle is different and thats why its never a bad idea to try something that would seem to go a bit against conventional wisdom.

let us know how your accuracy testing goes, very good velocity performance.

 

[tom m.]

kirby,

my reamer has a .311 freebore. it puts the new pressure ring on the 300 hybrid just above the neck shoulder junction. i would call compression at about 109.50grns. witch is cool because i hit sticky bolt lift at 108.50gns, at a velocity of 3,056. i liked the 107.5 at 3,037ave and 11 e.s., now i will go tune seating depth at long range.

i was amazed, i thought my ohler was broke, so i borrowed my friends ohler and it said the same thing...and on the same day, an extremely hot load of h1000 was doing 2,960, witch is what it should have been. the thing just became a whole new caliber, now i have to get my fingers on some of that new rl-50, haha.

*note, if i was to design a reamer from the ground up for this bullet, i might go around .300-.305 freebore. this would/should put the pressure ring right down at the junction, and still leave boiler room.

keep in mind, my chambering/rifle may be totally different than someone elses. please use caution, but if you can fit 6-8 grains more than your current retumbo load, then it might be worth a peek.

tom

 

[tom m.]

i forgot to add..

this is a mark 5 i had around, so i really have never expected better than .5 moa out of the darn thing. when lawtons get my "real" one done, it might be different. i will wait until the next br match to test seating depths at 1000. we go to missoula again june 12 and 13, and i will test there at that time.

tom

 

[tom m.]

been a while, but i finally went back to smk's to see if the gun was broken.....h50bmg works very well in my setup...remember .311 freebore, and feed it single shot..accuracy is there, es is there, and velocity up to 3040+, in my 30" krieger. actually, the 3042 load had just a slight click, but i won't push this old mark 5 too hard. 1/2moa at 1000 easy, and in the .3's with every load from 2925fps to 3040fps at 100.

kirby, you would be right...the c.o.l. you listed would have compressed the heck out of the charges i am running. i measure to the ogive, but the boattail junction is just at the neck shoulder junction. my hottest load was 107.5, and it still had wiggle room.

tom

 

[B23]

tom, any chance you have tried any US869 as well as the h50bmg with the 300's?????

 

[tom m.]

no sir, i have some around here though. i have always been a fan of extruded, but may give 869 a look at some point.
tom

 

[Desert Fox]

How far you're going to shoot that thing. I kept my velocity to around 2875 to 2900 with 95 grains of Retumbo and I never felt the need for more speed. My barrel has 9.35 twist so I can't really push this thing hard.

 

[jmden]

been a while, but i finally went back to smk's to see if the gun was broken.....h50bmg works very well in my setup...remember .311 freebore, and feed it single shot..accuracy is there, es is there, and velocity up to 3040+, in my 30" krieger. actually, the 3042 load had just a slight click, but i won't push this old mark 5 too hard. 1/2moa at 1000 easy, and in the .3's with every load from 2925fps to 3040fps at 100.

kirby, you would be right...the c.o.l. you listed would have compressed the heck out of the charges i am running. i measure to the ogive, but the boattail junction is just at the neck shoulder junction. my hottest load was 107.5, and it still had wiggle room.

tom

Wow...I've got mine on the lands with the 300SMK boatail junction at the neck shoulder junction and 102g of Retumbo leaves enought for just a squeak more. Can't imaging getting 107 g + of H50 in there. I might try it if I could. Guess I'd better go out to the shop and measure out 107g of H50 and see if it goes! I did try h50 with my rum and 210 bergers and found I couldn't get the velocity (as expected), but it seemed very accurate over a wide range of powder loads. Tried it with the 240SMK as well, but not enough to give a whole lot of qualified answer... Keep us informed as to how that load does.

Edit: wouldn't have believed it if I hadn't seen it, but I stuck 107.5g H50 in there, tapped the case a few times and seated the 300SMK boatail junction to the neck/shoulder junc. and there was a bit of crunching, but when all was said and done, shaking the case next to my ear revealed a just bit of powder rattlin' around. Huh...

 

[tom m.]

well,

true, velocity isnt everything, if not meaningless. been shooting upper 2900's for a couple years with retumbo, and even the 10 twist has worked out to 2600 yards. i like the pressure, or lack of, i am seeing at equal velocities though.


i have never ran 102 retumbo, mine pressured out bad at 101ish. i actually have wiggle room in my cases at 107.5 h50, about the perfect amount really.

tom

 

[jmden]

well,

true, velocity isnt everything, if not meaningless. been shooting upper 2900's for a couple years with retumbo, and even the 10 twist has worked out to 2600 yards. i like the pressure, or lack of, i am seeing at equal velocities though.


i have never ran 102 retumbo, mine pressured out bad at 101ish. i actually have wiggle room in my cases at 107.5 h50, about the perfect amount really.

tom

Hi Tom,

I'm not running 102g Retumbo at this point, just using that as an example. I'm still in load development stage, but 101.5g is getting me into Kirby's 'sweet spot' in terms of 2950-2975fps accuracy window. The 2 I tested at that charge had duplicate speeds on the chrono and the 'group' was exactly horizontal--like to see that. Still early. I've got several pounds of the H50. Might have to load up a couple and check, because I sure appreciated the accuracy and consistency I saw when I used it... Thanks, Jon

 

[tom m.]

just something to try if you have the room...i am finding it is more about bullets with mine, when the gun seems broke, smk's still fix it. testing some others this weekend, but had to go back to retumbo, they are loooooong.
tom

 

[jmden]

just something to try if you have the room...i am finding it is more about bullets with mine, when the gun seems broke, smk's still fix it. testing some others this weekend, but had to go back to retumbo, they are loooooong.
tom

So you are testing some bullets longer than SMKs? And had to go back to using Retumbo on those longer bullets?

 

[tom m.]

well not longer overall, but they seated deeper in the case. yes, way to compressed to get h50 up to operating temp.