Issue zeroing 338 LM at 100 yds

[TRey16]

First, let me say that I know shooting a 338 LM at 100 yds is a little silly, but in my area (Sunnyvale, CA) it's anywhere from a 2-5 hr drive to the ranch I do long range hunting on or to a range that goes out beyond 100 yds. So my initial load development needs to be done at 100 yds.

Current rifle build - Surgeon 1581 XL action, X-treme Shooting Mod 22 trigger, Bartlein 28" 9.3 twist barrel, APA Little Bastard brake, XLR Evolution HD chassis, Spuhr ISMS 0MOA/0MIL mount and Vortex Razor HD II 4.5-27x

I took it out on Saturday to do barrel break in and ladder testing for powder charge (H1000, Lapua brass, Berger Elite Hunter 300gr, CCI 250 primers) and the problem is that at 100 yds my POI is ~7.5 mil higher than the lowest the elevation turret will go.

I've seen a number of guys say they've been able to zero their 338 LMs at 100 yds with 30MOA of cant between their scope base and mount (the Surgeon has 30MOA built into the base and I've got 0MOA on the Spuhr), so outside of doing a **** job when I mounted the scope, I'm a little lost.

I'll be remounting the scope before I take it out tomorrow night for round 2 to see if that helps. Curious if anyone has ideas outside of "zero it at 250 yds". Thanks guys, will post pictures of it pre-Cerakote later.

Tyler

 

[el matador]

7.5 mils is over 2 feet at 100 yards. That's a lot! Might have to zero at 1000 yards

The only thing I can think of is maybe the zero stop is preventing you from dialing down any further. That scope has plenty of adjustment to be using with a 30 moa base. Vortex says it has 33 mils total adjustment with 10 mils per rotation. If you don't have more than 3 full turns of adjustment it's hitting the zero stop.

 

[WAMBO]

In the instructions that came with the scope it tells you to take off the elevation turret and to adjust the screw inside the top of the elevation post to obtain your zero then when you put the turret back on set to zero you are all set with just over 1 moa up from the bottom of your elevation travel.
If you go to the Vortex website they have a video that explains everything you need to do.

 

[TRey16]

Thanks guys, haven't shot it again yet, but I think the issue was that the internal zero stop turret was set almost a full turn up from the bottom. Seems a little odd to ship it from the factory like that, but I'm going to call them and see what they say.

Second issue, now that I've got the internal turret cranked down to the bottom, I re-counted my total clicks and they dropped from 310 before the adjustment to 285 after the adjustment. Not sure why, but will be talking with Vortex about that too. Thanks again and will report back after shooting it tonight.

Tyler

 

[tbrice23]

TRay,
That's a good looking bastard.
How much does that rig weight?

 

[revturbo9967]

to add some info, i have a 4.5-27 gen 2 on my 338 LM and ive found even with a brake, the recoil loosens the screws in the caps for the internal adjustment. no matter how tight they were id find them loose or almost loose. i went to the hardware store and bought longer screws so there was more contact along the threads. havent had them loosen up since. i dont know what they send them with such a short screw with such a long threaded hole.

 

[TRey16]

@tbrice23 thanks man, planning to have it Cerakoted in a combination of Desert Sand and FDE within a couple weeks. With an unloaded mag she's coming in at 18 flat. My original plan was to build a lightweight 300 RUM/WM, but things escalated quickly and I decided the 338 would be more fun. The 300 will have to wait till my next build.

@revturbo9967 I noticed the same thing when I made the adjustments last night, all 3 screws were super loose. Do you remember what size screws you ended up replacing them with?

 

[revturbo9967]

@tbrice23 thanks man, planning to have it Cerakoted in a combination of Desert Sand and FDE within a couple weeks. With an unloaded mag she's coming in at 18 flat. My original plan was to build a lightweight 300 RUM/WM, but things escalated quickly and I decided the 338 would be more fun. The 300 will have to wait till my next build.

@revturbo9967 I noticed the same thing when I made the adjustments last night, all 3 screws were super loose. Do you remember what size screws you ended up replacing them with?

i honestly dont know. i just went to the hardware store and matched up a longer set screw with the same pitch. its probably metric but it has to be around an 8-32 size if i was guessing

 

[TRey16]

@revturbo9967 I talked with Vortex's R&D guy today on the screws. He said that within the last ~6 months they upgraded the set screws from 4mm to 12mm and that solved the issue (mine has the longer screws). He also said to torque them to 8-12 in lbs.

We also talked about the zeroing issue I was having and it was the "zerostop" being set in the middle of the range. I've got it cranked down to the bottom (he confirmed that I should be getting 28.5mil (285 clicks) on the external turret) and am heading out to shoot it again tonight and have my fingers crossed that I'll be able to zero at 100 yds for ladder testing.

What loads have you been running through your LM?

My current lot of components to test are:
Brass - Lapua
Bullets - 300gr Berger Elite Hunters and 300gr SMKs
Powder - lots of H1000 and 1 lb each of IMR 7828, VV N165, N560 and N570
Primers - CCI 250s (can't find 250Ms to save my life)

 

[revturbo9967]

Took mine a while to shoot worth a **** . I couldn't get the 300s to work well. I'm running Berger 250 eh , lapua brass, 88.5 gr of retumbo and 250m primers .getting around .6 moa right now at 100 yards which is good enough for me. I had to fight with my rifle to get it to produce this though. I almost chucked it in the river a few time lol

 

[revturbo9967]

to add, my rifle is a factory weatherby mkv, not a custom job. i haven't checked velocity yet . i will be re barreling this much sooner then it needs probably.

 

[TXAoudadKlr]

I know you've got 6lbs more weight over mine but how's that brake working for you? What's the chassis weigh on its own?

 

[TRey16]

@TXAoudadKlr The brake is doing work man, the 18 lb weight is definitely soaking up a lot of the recoil, but it kicks only a little more than my ~14 lb 308 and a lot less than my ~9 lb 270. I was really surprised when I pulled the trigger the first time, would have thought it was a dud if there hadn't been a huge cloud off the berm. I think XLR has it listed as 4.4 lbs, once the folding attachment comes in (back ordered) that will add another 0.4 lbs.

What's your build list to get to 12 lbs? I don't have my spreadsheet in front of me, but I think I could have saved 3-4 lbs if I had gone with the ATACR F1, NF ultralight rings and the Manners EH-1.

 

[TXAoudadKlr]

I have a LWLR from Defensive Edge that I got for my dad. It has a 1:10 30" hart barrel sendero contor with barrel fluting, HS precision sendero stock, DE 4 port brake and a NSX. I'm looking at adding weight(with in reason) or swapping out for a more aggressive brake before I hand it over to him. Just kicks a bit too much for my liking for him.