ATRS .338 Lapua AI load info

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LloydM

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I am happy to shoot in pretty much any weather conditions, but I only do load development on calm days. Unfortunately calm days are very rare in my area so I want to be prepared to make the most out of the next one I see - if I ever do see another. Since the ATRS .338 AIs are all basically clones, I was hoping some of you might share some load info to help get me into the right neighborhood -especially when it comes to seating depth / COL and powder charge.

I am shooting an ATRS .338 Lapua AI based on a Rem 700 action with a Rock Creek barrel. I have only bothered with 300 grain SMKs and US869.

Thanks in advance for the help!
 
Toomanyguns said:
Why not ask the person who built it/sold it to you? Very good source of quality information he be.
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I supose the biggest reason is because it is Tuesday. ATRS is closed on Tuesday, and I am impatient and bored today. When I bought the rifle Rick more than pointed me in the right direction, but that was a while back and I frankly just forget.
 
I size mine for the mag box on the rifle. Start with 110 gr of US869 and work up. The most I have ever used is 112 grains.

I'm betting you will find a sweet spot somewhere between 110 and 111.5 grains.
 
Ever try seating the bullets out towards the lands? I know that if you go this way they won't fit in the magazines and you have to operate single shot, but do you gain anything by seating them out longer?
 
Hey

:D I have pretty much the same deal only on a nesika action......

110.5 gr of us869.. 300smk, fed 215m, mag length, yields 2983fps. Shot 3 inch group 2 weeks ago at 660 yrds. Will do around 1/2 group at 300m if a person does his part during calm conditions. (Witnessed by CGNers) And I will admit I am not the best shot.

My buddy has the same rifle, and he shoots the same load and 3013 fps......

Yielding good accuracy.


Although, unlike toomanys guns, mine doesn't shoot 1/4moa at distance, all day, every day!!:nest:
 
Load

I've had good success with H-1000 and 300 SMK started at 95 gr and worked up to 97gr - 2960fps out of a 30" Rock Creek. I've tried US 869 and Retumbo and found H-1000 to be the most consistent. As for OL I went .005" of the lands for single feed and to mag length to see what would happen. I did not notice a large difference in accuracy.
 
Thanks for the info. What are you guys using for mags? I would like to use a larger magazine if one was available, but the 3 rnd HS mags are the only ones I know of which will hold a .338 Lapua AI. Also, would someone mind letting me know what OAL you have been using; in order for rounds to function through the action properly I need to keep my OAL shorter than I would expect.
 
I'm replacing my Nesika action for an ATRS action and going with a single shot configuration. There isn't a mag system out there yet that can accommodate a long seated 338LM AI long seated for accuracy and maximum output. I'm running 111.5gr us US869 doing about 3065fps.
I'm still drilling through 3/8 steel at 1230yds while the standard 338 burning the same powder at 101.5gr is only denting.
 
I do not see quite that velocity with 112 grains. I'm closer to 3050.
Cartridges work just fine in my mag with that load of powder and accuracy is more than acceptable.
I have no intention of chasing after the supposed latest greatest.
 
Seekins makes a longer magazine but mine is built on a Stiller single shot action and I shoot 110.5gr of US869 behind the 300MK. I get just over 3000FPS out of my 30" barrel.
 
I know seekins makes longer magazines, but ATRS no longer carries them, and I don't think they send anything across the border anymore. The biggest complaint I heard about the seekins mag system was that it rattled a little - this would not have been a big deal to me.
 
Toomanyguns said:
I do not see quite that velocity with 112 grains. I'm closer to 3050.
Cartridges work just fine in my mag with that load of powder and accuracy is more than acceptable.
I have no intention of chasing after the supposed latest greatest.
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I think, for the most part, it boils down to what the gun is used for. In a hunting situation, a mag system can be very important. I rarely hunt with my gun and whatever I point it at is going to be a very long ways away so a single shot for simplicity is my new preference. I'll save the mag system for the Nemesis 50 I've got my eye on.

I recently re-did my load developement just to insure I still had the optimal accuracy and went from 110 - 112.5 and still my most consistent group was 111.5gr.
 
11.5 was a number that "da man" also shared with me. I may have to try it.

I do understand the simplicity of a single shot set up. Can't argue with that. I operate quite often as a single shot. Once she is dialed I like to load the mag and practice rapid target acquisition and follow up shots.
 
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