Vertical stringing

[Boozer]

Hi all-

I lurk here all the time, and am just getting started in longer (it's all relative) range shooting. I recently was able to go through my factory deer rifle and perform some of the basic accurizing work. I have a Remington 700 BDL, in 30-06 with a Leupold 3x9. Pre-accurizing the rifle would only hold a ~4" group at 100 yds. I bedded the action with devcon (no pillars), lightened and adjusted the factory trigger (2 lbs), made sure the barrel was floated, and lapped the locking lugs to ~90% contact. I took it out to see how I did with all my improvements, and it did help pretty significantly. After a getting warmed up, and trying really hard to be conscious of my hold, cheek weld, breathing etc. I was able to get it down to a 3/4" wide by 2" tall 6-shot grouping at 100yds. This was off of fairly stable bench, with sand bag under the front, and my fist under the rear.

Question time – Any ideas for what could be causing the vertical stringing? The shots did not "walk" up, they were high, low, low, high etc. This leads me to believe it is probably not heat warping, and I tried to wait a few minutes between shots to allow the barrel to cool. I am thinking that my hold may be the issue, I've read a lot about a hard front rest potentially causing vertical issues, but my shooting wasn't nearly as accurate when I hand my left hand on the forearm (trying to rein in the kick-up), it was better, when I had it as a fist under the stock. Also, lots of people shoot off of bipods, with their fist under the rear, so don't understand how that could be causing it.

All this shooting was done with 165 gr Remington core-lokts. I know that this isn't exactly match grade ammo, but it's what I have on-hand. I will eventually try some nicer ammo, but I can't afford to get into handloading right now.

Any help or tips would be appreciated. I'd love to figure out this issue, and end up with a sub-moa rifle!

Boozer

 

[varmintH8R]

I would recommend shooting off of a solid rear bag as a first step. Something filled tight with sand and some ears will do the trick. Set up so that the rifle will hold a natural point of aim without you manipulating it. Keep working on your mechanics the way you discussed above, and I would guess you will see some if that stringing disappear.

If not, the only cure is all-in precision reloading!!

Let us know if and how you solve it.

 

[Boozer]

I'm not sure how these bags are supposed to work. I was using the type meant for shooting (with the ears), but it seems that inevitably, they are always too low, or won't put the natural point of aim in the right spot. I understand the point of your comment though. Try a solid rear rest instead of the fist. Maybe next time I'll bring a phone book or something to shim it up to the right spot.

 

[varmintH8R]

Not the best picture, but this is what I shoot off of for sight in or yard varmints on rifles that don't have a bipod. It is basically a cheap fold out front tripod and a rear bag from Protektor. Even on my LR rigs with bipods, I am typically able to get a sight picture by moving the rear bag a little farther back on the stock.

Sounds like you have a really tall front bag or a really short rear bag (or both).

 

[TH]

Nice Picture looks like the cab of a pick up truck

 

[Boozer]

This is similar to what I have. I don't think the front bag is tall enough. Regardless, I think i get the point. I'll try to figure out something more solid to shoot from, and see if that helps. Any other ideas of what it could be? Just trying to work all the gremlins out.

That is a nice rig by the way....

 

[varmintH8R]

Any other ideas of what it could be? Just trying to work all the gremlins out.
[/quote]

Try not to change more than one thing at a time, but you can also look at playing with:

Go shoot at 300yds. See if your verticle stringing grows proportionally (ie now 6 inches).

Change torque on your action screws. Check out post #6 here:
[url]http://www.longrangehunting.com/forums/f37/torque-recomendations-29756/[/url]

Also, make sure your bases and rings are tight/torqued properly. Blue loctite!

See if you can find a buddy to make some reloads for you tailored to your gun.

Mount another scope on it to make sure you don't have something wonky in your glass.

Have a buddy shoot it and see if his results are the same.

I'm sure I'm missing things, but somebody will pick up my slack. Good luck to you!

 

[BackpackHunter]

When you set up your front and rear rests make sure your sling mounts aren't resting on them. Also make sure your rests are far enough away from them, that they don't make contact during the recoil. They can act as pivot / deflection points and cause weird things to happen with your shot group.

 

[lhouston78]

A few things can still be the problem. First the barrel may just be that bad from the factory, or it may not like the ammo or bullet you are shooting. When reloading vertical is normally saying you are not in the sweet spot and need to change powder charge. It could just be your shooting, but if you have not had these problems before with other guns it is probably something with the ammo.

 

[wackinandstackin243]

I have had the same problem with verticle high then low myself. It was only with 22-250 caliber. It was with 4 different rifles ( 2 remingtons 1 winchester, and 1 ruger) and several different powders and bullets. I dont think it is my bags because my 223s and 243s dont have any problems.

 

[varmintH8R]

I have had the same problem with verticle high then low myself. It was only with 22-250 caliber. It was with 4 different rifles ( 2 remingtons 1 winchester, and 1 ruger) and several different powders and bullets. I dont think it is my bags because my 223s and 243s dont have any problems.

That might be the rifle gods telling you something. Try a 220 Swift!

 

[wackinandstackin243]

I did get a 220 swift and got along much better. However I still like a 243 better than the high velocity 22s. But just like the original post I would like to know exactly why the verticle shots are happening.

 

[Boozer]

I spoke to a local gunsmith who checked my firing pin protrusion, headspace, and said they all "looked good", however he said that I should not have bedded the first 2" of the barrel forward of the recoil lug, and might be causing my problem. I had seen recommendations go both ways on that issue, so I figured I'd give it a shot.

I took the action out of the stock, (noticing that the action screws were pretty loose) buzzed it out with the dremel tool, reassembled (tightened the action screws had loosened) and went shooting again this weekend. Grouping size at 100 yds didn't improve, in fact they were a bit worse ~3" groups. This time there wasn't really any vertical pattern at all, fairly random.

Not sure if it was the removal of the bedding, tightening of the screws, or the fact that I now have ~30 rounds down the tube without cleaning out the copper fouling.

This is a bit frustrating... At this point my groups aren't any better than when the gun was straight from the factory. Maybe I have a crap barrel? I know the ammo I'm using isn't top notch, but surely it wouldn't be causing that much of an issue at 100 yds.

 

[Jcub]

A solid rest will do wonders for your groups. Take all human error out of the equation, then work from there.

I understand you are on a budget, so that would be the 1st investment I would recommend, that or reloading equipment. When plausible of course.