Vertical stringing 338LM at 424 yards

[navy1942]

I have researched and concluded vertical stringing is MV related. I'm not super sniper, but I can hold my own. ASW 338 is zeroed at 300 yards. My first few days of shooting handloads 300g Lapua Scenar over 92.2g H1000 had good results. Now the results are terrible. I'm right and low because I didn't adjust for distance or the 14mph wind @ 260. What I'm concerned with is the vertical dispersion. Do I need a new power scale? I notice the weight flucuates almost every time I take the pan off, up to 4/10th grains, but goes back to zero when I put the pan back on. Thanks for your input!
Distance 424 yards with a 10 round string from the magazine.
The tool

The results

 

[turbo54]

Re: Vertical stringing 338LM at 424 yards

With a BC of ~.77 or so, you'd need 300fps of extreme spread to be able to blame that 2moa of vertical on variations of MV. Not likely.

Looks like the rifle/load CAN group - it is most probably Shooter error. No offense intended.

 

[SniperCJ]

Re: Vertical stringing 338LM at 424 yards

Vertical stringing is typically a breathing issue, not MV. My vote is shooter error

 

[Kevlars]

Re: Vertical stringing 338LM at 424 yards

+1 on shooter error.

 

[jpspeeddemon]

Re: Vertical stringing 338LM at 424 yards

breathing, inconsistant bipod load, tense shoulders will cause vertical stringing. As suggested, see if you can id some of these things, as shooter error is probably the culprit. No problem, just work on them.

 

[Who Dat]

Re: Vertical stringing 338LM at 424 yards

I agree with JPSPEEDDEMON, you can work on all of these traits without firing a round. Get prone and start dry firing, work on your breathing know what the term normal respatory pause means. Trigger pull, body alignment, grip, stock placement, cheek weld all work together for a well placed shot. You will need to master these skills because with long distance shooting you will have to learn ballistic calculations and make corrections for wind and distance. Take your time we all started there at one time. That is a very accurate rifle you have there good luck.

 

[Knife]

Re: Vertical stringing 338LM at 424 yards

First off, Roll Tide. Secondly looks like it could be a breathing issue. Are you breaking your shots at the bottom of your breathing cycle? Maybe this video will help out.

http://www.youtube.com/watch?v=IUEzzVi4YKA&feature=channel&list=UL

 

[excaliber]

Re: Vertical stringing 338LM at 424 yards

When I shot on the benchrest circuit, we came to the conclusion vertical stringing could sometimes be fixed by adding velocity. If your at pressure now, then you can`t go up in powder charge. Then change powder. I don`t think you have have found the right node.

 

[turbo54]

Re: Vertical stringing 338LM at 424 yards

I'm confused - are there 2 groups on the paper, or just one?

Looking at it again, looks like 2 groups, one close range, and one at 425 - bith with vertical stringing.

When I made my first post, I was thinking this was one group with several shots nice and tight, the rest showing lors of vertical.

I think you need to revisit load development - thats not grouping very well.

 

[turbo54]

Re: Vertical stringing 338LM at 424 yards

I'm confused - are there 2 groups on the paper, or just one?

Looking at it again, looks like 2 groups, one close range, and one at 425 - bith with vertical stringing.

When I made my first post, I was thinking this was one group with several shots nice and tight, the rest showing lors of vertical.

I think you need to revisit load development - thats not grouping very well.

 

[Enough Said]

Re: Vertical stringing 338LM at 424 yards

Calibrating your scale before loading? Zeroing your pan each time?
H100 is generally 3 granules to the 1/10 grain. You measuring at the top end or the low end of the tenth?

Breathing.
Trigger jerk.
What's your trigger poundage?

Stock weld inconsistent?
Crisp edge-to-edge?
Having to pull stock weld back to get crisp edges?

Parallax adjusted to proper yardage?
Reticle focused properly at the eyepiece?

Hmmm... what else... Anyway, things to think about.

 

[gstaylorg]

Re: Vertical stringing 338LM at 424 yards

If I'm reading the scale on that target correctly, that's a vertical dispersion of something like 7" @ 424 yd. You'd have to be puffin' pretty hard for that to be completely attributed to breathing. Just sayin.

 

[ChrisF]

Re: Vertical stringing 338LM at 424 yards

I would check all the ring screws are tight , watch for the buttpad slipping & also forget about your digital scale ,and burrow a normal balance type scale and weigh all charges .

Also you could place a sandbag at the front & rear , and shoot again .

Later Chris

P.S. I presume you are using a suppressor or brake , as I cannot see the muzzle end .

 

[E. Bryant]

Re: Vertical stringing 338LM at 424 yards

Put the loads across a chrono - without velocity data, we're just guessing at the cause.

 

[navy1942]

Re: Vertical stringing 338LM at 424 yards

Thanks guys! I was completely focused on a technical problem around the load. Since I learned the basics of marksmanship some 35 years ago I've never had a problem like this. The .22, 30-30, 30-06 and .308 rounds don't have the big push of the LM and in arrogance never considered my own mechanics but the .335LM has been giving me a wallop and it was HOT and HUMID so my mechanics were very likely less than stellar.

I also should have said that all action attachment points were torqued to 65inlbs out of the box and checked after each session, they have not moved. The scope at 45 for the base and 20 for the rings also haven't moved.

It is one target and all 10 came from a full magazine with the shots seperated by the time it took to slowly rotate the bolt so I could catch the brass before it went flying out. My first 150 shots in the weapon were factory Cor-Bon and handloads that were basic SAMMI specs, using N570 and H1000, the groups weren't great but they didn't have the vertical spread. That is why I thought my powder scale had gone wacky with these loads (Which I settled on using the ladder test then chronographed the different seating depths for speed). As you can see, I also didn't have the bipod in play nor did I have to deal with recoil. It is a shame I can't lug that Hyscor rest around with me all the time!

In addition to refocusing on my mechanics, especially breath shot cycle, I'm going to pull apart the other 20 rounds I have and remeasure trim length, COAL to the ogive, seating depth and powder charge.

Thanks again guys! I sometimes think I'm the smartest guy in the room, but as my wife likes to remind me "If you are so smart why do you have a problem!"

I will post the new results as soon as I can.

 

[Enough Said]

Re: Vertical stringing 338LM at 424 yards

One question - where's the rifle's recoil going when it's in that shooting contraption?

Think about it.

Then get rid of it. You will never become a better shooter if you are not driving the rifle.

 

[Cigarcop]

Re: Vertical stringing 338LM at 424 yards

Just my 2cts but if your set on that load, I'd move the bullet away from the lands (further in the neck) maybe .010 and see what happens.

 

[navy1942]

Re: Vertical stringing 338LM at 424 yards

I only use the contraption for the ladder test... It takes my mechanics out of the way. All other shooting is done with the bipod....

 

[navy1942]

Re: Vertical stringing 338LM at 424 yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cigarcop</div><div class="ubbcode-body">Just my 2cts but if your set on that load, I'd move the bullet away from the lands (further in the neck) maybe .010 and see what happens. </div></div>

I have gone from .025 (as close I can get with the magazine) out to .050 in .005 increments. .045 had the node, and the fastest MV with 92.2 grains of powder (which went from 91 to 92.4)

 

[Who Dat]

Re: Vertical stringing 338LM at 424 yards

I would not use the lead sled and I will not go into details on that. Get on some sand bags to get it on target and then once dialed in transition to the bipod. Use the monopod on it so that you get a good three point stance. I use the same powder with my 338 Lapua, start with your minimum powder load and stick with the industry specs for overall length on your ammo. I know when I was doing my load development using H1000 it can be a little finicky. The rifle that you have was designed for great accuracy using factory ammo without extending the overall length of the ammo unless your magazines are CIP length. Start at the minimum load and work your way up until you start seeing pressure signs and then stop and then work your way back down trying to find what your rifle likes. Remember the hotter the load the more brass flow you are going to get and you will be trimming it back alot and it will not last. I trim mine back no matter what even if it does not take anything off the case when I trim it. You have to be able to handle the recoil though or all is for not. Check out this link on the hide and scroll down through it and you can see alot of guys took some time on their load development.
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3231948&page=21

 

[KYS]

Re: Vertical stringing 338LM at 424 yards

Get rid of the vise and you shoot the rifle. The weight of the rifle and recoil are going to make it hop out of the vise. Plus, to me, it looks as if you don't have it fully adjusted out to support the weight of the forearm correctly.

 

[navy1942]

Re: Vertical stringing 338LM at 424 yards UPDATE

1st, a BIG THANK YOU for all of the advice, ideas and opinions.
2nd, I think I've made a huge improvement.
Mechanics: Very, Very bad. Shooting a .308 I'm very proficent at and my mechanics are exact:square behind the rifle: cheek weld: trigger finger position: relaxed shooting hand and rock solid foundation.
With the .338LM I was cockeyed, and tensed up tighter than dick's hatband. My grip was so tight my hand was sore the next day and I never had a perfect view through my scope. I was afraid. So, I got unafraid. I made up a pad for my shoulder and went to work on each part of the prone shooting position. I also went to 3 shot groups instead of 5 or 10. The pounding was not helping my mechanics

Seating depth: I have to admit, I was going to ignore this advice, but the Good Lord nudged me and said don't be so hard headed. I'm glad I listened. Photos below will have the load and seating depth. To start: Chamber length to lands is 3.020. Mag length of 3.716 means I cannot seat closer than .025 off the lands. But close seems to be the problem. Based on 100 yard shooting I thought .045 was the best - WRONG

Keep the advice coming. I'm going to play with the depth a little more to get it really tight.

Some photographic results:

First my range. 450 yards is the longest I can shoot, but 425 yards keeps me out of the ticks, chiggers and snakes in the grass!

Target board close up

H1000 94gn seated .080 off lands Avg=2839.6fps ES=9

H1000 95gn seated .080 off lands Avg=2885fps ES=56

H1000 95gn seated .090 off lands Avg= 2925.3fps ES=19

VV 93gn seated .080 off lands Avg=2820fps ES=49

VV 93gn seated .090 off lands Avg=2812fps ES=18

Finally I reseated some Cor-Bon factory loads to .060 Avg=2906 ES=17

 

[Who Dat]

Re: Vertical stringing 338LM at 424 yards UPDATE

Keep up the good work, you are looking better then when you first posted. Work on the dry firing skills, sometimes to much thinking about recoil will really effect your shooting. Twenty minutes of dry firing a day and working on body dynamics will make a huge difference. Bottom line is you should be able to fall a sleep while welded to your stock it should be that comfortable.