horizontal stringing

[burrhead]

I'm working up some loads for a Remington 700 in 22-250. I'm getting horizontal stringing with moderate loads of H380 behind Hornady 50gr Vmax and 52gr Amax bullets. I'm making nice, straight, five-round lines about 3/4 to 1 1/2 inches long. The gun, made in the 60s, has a varmint barrel and is glass bedded in a wood stock.
Other than the very possible user error, what could be causing this?
TIA

 

[sricciardelli]

Change your seating depth...

 

[burrhead]

Interesting. I can't practically seat the bullets far enough out to reach the lands so I seated them so that .224 of the bullet is in the case. That gives me an OAL of 2.462, 0.112 over Lyman calls for. I'll try playing with the depth. Just how does seating depth affect stringing?

Thanks.

 

[Archie]

Burr,

Another thought is to try more or less powder. You say you are at a "moderate" level.

Some loads work better, which means some don't work as well.

You might also check the scope and mounts. A loose mount will drive you nuts.

 

[kurt IA.]

How hard was the wind blowing? This is my first guess. Next would be stock pressure on the side of the barrel. Then scope. Has it done this with other loads?

 

[burrhead]

Archie, I've just started load development and only put 25 rounds through it today. That's 5 different powder charges. At the moment I'm about 12 to 15% below max, depending on which manual I use.
Kurt, no wind, scope's tight, not sure about stock pressure; I'll check. Before this I've only put 30 rounds of Remington 50 grainers through it and got, more or less, 1" round groups.
The perfectly sraight, horizontal srings just seemed odd to me.

 

[labgrade]

Check for stock pressure/full free-float by folding over a dollar bill (any denomination ), hold both sides & run it from the stock fore end towards the action. See if there's any binding - fix it if there is.

How's the rifle mounted when you're shooting? Sand bags, bipod ... ?

Try this dry firing exercise. Get target picture, etc. just like normal shooting, but not loaded. Concentrate on sight picture & watch where your cross hairs end up when the striker falls. Many times you can see that the cross hairs end up in a very different place than where you were aiming. That's where the bullet's gonna end up.

 

[Art Eatman]

There ain't no such thing as "always": A rule of thumb is that vertical strings are caused by some problem in the bedding; usually with the forearm.

Horizontal strings are commonly caused by a bit of canting of the rifle, not uniform from shot to shot. It helps to make sure the crosshairs are aligned with some horizontal and/or vertical line on the target. Square-grid targets are best, of course.

I use a carpenter's level to make a heavy line across my target board. I then align the paper target to this, to have a near-exact horizontal/vertical condition.

Art

 

[sricciardelli]

Burrhead...

Assuming that there are no problems with your firearm, stringing can be caused by bullet seating depth...

If you have horizontal stringing, decrease the seating depth. If you have vertical stringing increas your seating depth.

If you have a bedding problem, you will experience stringing also, however, it will show in both directions.

If you are canting the rifle, but using the same point of aim for all shots, the center of the group will be off, but the resulting group will not be strung-out.

I am assuning that you are satisfied with the load you are currently using, other than the stringing...if you change the load in any way, then you will have to start all over again.....

 

[Steve Smith]

If you are canting the rifle consistently, then it won't show if you're only shooting at one distance. If you're inconsistent, then you'll see an arc, not a horizontal line.

 

[kurt IA.]

Your right, it is odd. Let us know what you find, I have only seen this one other time, it was stock pressure.

 

[C.R.Sam]

Lateral stock pressure and rising barrel temp?

Me curious too.

Sam

 

[labgrade]

Basics first.

Bedding, scope mounting screws all nice 'n snug? & check that barrel clearance for free-float.

& shooting technique. You say that you're used to 1" groups & now you're getting 3/4 - 1-1/2" ... really not that much difference between the two. If you went from 1/4" to your latter, I'd suspect something else.

Without everything (all the basic shooting techniques) almost exactly the same every time, you will find it difficult to realistically critique any load.

FWIW, I've an old .22-250 that sucks up the Sierra 53 match, but doesn't care one bit for the flatbase 52.

 

[Bogie]

I shoot benchrest...

Vertical stringing is load - You're not tuned to your rifle's sweet spot.

Horizontal stringing is operator error. Could be several things. Wind is one. You'll be surprised at how much a group can vary at 100 yards, even on a "calm" day - a few mph wind going one way can switch to a similar speed in the other direction, and before you know it, you've shot a 1" group... (and we use 68 grain bullets, moving at about 3400 fps...). Get some coathangers and strips of surveyor tape, and stake a few out, maybe at 25, 50 and 75 yards (if shooting 100 yards), and only shoot when they all point in the same direction, at the same intensity. You'll be surprised.

Could also be how the rifle is supported - can it slide freely on the bags? Does it track straight back, or is it moving side/side when you pull it back? Is your shoulder placement consistent? Are you holding it the same way ever time? Are you pulling the trigger the same way every time? A lot of times a stiff trigger will result in horizontal, since you're putting pressure on the stock there...

 

[Big Bunny]

The nut behind the butt?

I would go for a change in the weight of powder/projectile or could be operator error.

Weight up or down - find the optimum for your barrel and then stick with it [and pass it on to next owner!].

 

[Art Eatman]

The prevailing wind at Burrhead's range is from behind, or quartering from the rear. We also commonly have an almost dead-calm condition quite often; mid-morning and late afternoon.

Art

 

[Bogie]

Those "dead calm" conditions can be spooky... At the range at Holton, Michigan, be advised NOT to shoot in their dead calm - it ain't - you'll get strange fliers...

I'd guess he's putting pressure on the thing while pulling the trigger.