20" .338 Lapua velocity

[bm11]

Searched the shit out of this, couldn't find much for definitive answers though.

There are enough 20" 338's out there now that I'm sure there is some good velocity data. And I want to know what you guys are getting. From memory, there was a 20" AIAX at Gunsite when I was there for the ELR class in October. The guy with that rifle was shooting factory Hornady 285 match ammo. Frank (Lowlight) was shooting the same ammo, and I believe he was getting almost exactly 100 fps faster out of his 27" AIAW.

Which is the reason for this thread. I would totally cut my 27" barrel down if I could still push 300's over 2600 fps with ease. (Getting 2725 now without much drama.) I imagine that a lot could be gained by switching to a slighly faster powder to optimize for the barrel length too.

Anyone with a 20" .338 Lapua throw up your data for me please. Hell, if there are any .338 Norma's out there in a short barrel, toss that up too.

Thanks,

-Bob

 

[D_TROS]

Hey BM,

I have a 22" Shilen barrel, stiller action when loaded with 92gr H1000 & 300gr SMK in Lapua brass I am getting 2725 fps. I would wager 2600 would be no problem, prob even 2650.

I have not Chrono'd this load, but I have drop verification out to 1k with it. I will try to get out and chrono and see how accurate this is in the next month or so.

Regards,
DT

 

[bm11]

Well thats pretty good. I'm using 88.0 grains of RL-25 under a 300 Scenar and am only getting 2725 out of my 27" barrel. Chrono'd as well as confirmed out to 2200 yards.

 

[bm11]

Bumping this up for additional input.

Also- in a 20", would a 1 in 10 be sufficient? It hasn't been an issue at a 27" barrel length.

 

[Straight Shooter]

I had a 23" 338 Lapua and it was trashing Lapua brass at 2650 with Retumbo and 300 grain Bergers. At 2650 the trajectory was more like a 308. I couldn't hit a house at a mile. It is now idling at 2850 in a 30" barrel. Runs easy to a mile now.

 

[bward]

I think 2600 at 20'' should be about where it will be. I ran a 24'' and if I ran much over 2720 FPS I would run into pressure. As far as barrel twist, if you are shooting the 300 Hybrids I would want a 1-9.5''. Any other bullet, 1-10'' should be fine.

 

[Gray]

I was watching Larry Vickers shoot a 20" 338 AX the other day and it was not hitting anything past 1400. To me that defeats the whole purpose of a 338LM. Engaging targets out past 1500-2000 should be easy. Hell my 7mag with 180 Bergers would perform better than what I saw. I'd stick with 26" +

 

[Layton]

I guess it would be more practical hunting if you want to throw that large a bullet and you won't need that kind of range. A local smith here has cut down several to 22" that I know of and he says they aren't loosing that much velocity.

L

 

[AIAW]

I would think that would be plenty. Any "slower" of a twist and you end up with "possibly" lower stabilization numbers on the 300 grainers.

Wish I had valuable data to give you for a 20" tube but I simply don't. My AWSM is 27" 1-in-10 (freshly replaced by the way), but I do know a guy that had a TRG-42 chopped down to 24" and he was running about 90-130 fps slower at MV0. Same charge, same bullet, same brass, same twist. A few inches really makes a appreciable difference with these slow-burning powders.

I'm actually going to try (when it's in stock, you know, next year) some N170 to perhaps replace H1000. It's a tad faster, and not seeing pressure signs quite yet but being at case capacity makes me think I have a few fps to gain perhaps. N570 I've heard good things about, but the grains are massive (like rat turds), plus the power temperature is ridiculous. I bet the throat would move within the first few weeks shooting that juicy stuff ; )

In summary, I do believe that you can stay above 2600 fps with a 20". Definitely going to be much hotter loads, perhaps some N165 or N170 would do the trick? H1000 might get you up there depending on your bullet seating depth.

Bumping this up for additional input.

Also- in a 20", would a 1 in 10 be sufficient? It hasn't been an issue at a 27" barrel length.

 

[turbo54]

I had a 23" 338 Lapua and it was trashing Lapua brass at 2650 with Retumbo and 300 grain Bergers. At 2650 the trajectory was more like a 308. I couldn't hit a house at a mile. It is now idling at 2850 in a 30" barrel. Runs easy to a mile now.

I was watching Larry Vickers shoot a 20" 338 AX the other day and it was not hitting anything past 1400. To me that defeats the whole purpose of a 338LM. Engaging targets out past 1500-2000 should be easy. Hell my 7mag with 180 Bergers would perform better than what I saw. I'd stick with 26" +

Interesting comments, fellas.

I run my TRG42 really easy-like at 2660fps with 300smk, and my experience is the trajectory is NOTHING like a 308. A .75 BC does a pretty good job of keeping a bullet aloft, even if it's initial velocity is only 2660. I've no trouble hitting reasonable sized targets past 1400 yards, and can connect more often than not on a 12"x12" plate @ 1750 yards.

I thought the "whole purpose" of the 338 was to defeat the best body armor at 1000 meters?

I'd bet the farm a 300smk or 300hybrid @ 2650, or even 2500 would do that handily.

Anyway, we can all agree the longer barrel with higher velocity will increase maximum effective range. I think it really comes down to what you are looking to achieve with the rifle. Obviously, if your purpose is ELR past 1500, a compact 338 (or even a 338 in general) is not an ideal choice. However, for most *practical* engagements, I'd think a 20" would be quite nice.

 

[chipsfan]

I just worked up some 22" 338 lapua mag loads with Reloader 25. 300 SMK, Lapua brass, Winchester Magnum Rifle primers. Stupid low sds, but crappy velocities. At 2488 I had mild pressure signs. I'm going to try H1000.

 

[shadydiesel]

My first load in my 24" gap (1:10 twist) was 300 Berger, 92 grains of rl33 and fed215m in Lapua brass. I was running that load really light at 2580fps and it was great out to 1850. I'm 5000ft asl which helps a bit.