Vertical stringing, gas gun, factory ammo

[Andy Warhog]

Shot at 725 using black hills 69gr remanufactured. Light wind @ 6 o'clock. Had a vertical spread of 12" in the first pic, didn't measure the 2nd. Seems like a lot. What did I fuck up or could it be velocity? Anybody know the SD of these rounds? I don't have a chrono.

 

[One-Eyed Jack]

Looks like barrel heating.

 

[Andy Warhog]

How long are you waiting between shots then? I was prone in the snow, 28° out and 5-10 seconds between each shot. The one way at the bottom of the first pic was my 3rd shot of that string

 

[Sterling Shooter]

Without chronographing your load you do not have any but a "it could be" answer. If not the ammo, or along with it, vertical stringing is caused by: varying the rifle butt position in the shoulder, a very low position, position of left elbow wrong, varying head pressure, poor follow through, changing sight picture, changing sight alignment, changing distance of eyeball to eyepiece, and failure to maintain proper eye/sight alignment. The key is be cognizant of the five factors of a steady position: grip, non-firing hand, elbows, rifle butt, and stock weld. Make the shot to shot relationships between you, the gun, and the ground consistent.

 

[RTH1800]

Sir,
You indicate an interest in accuracy, but seem to have done little to gain it.
Get some data. What is your velocity spread? What are your hundred yard and three hundred yard groups like?
Get a target, not a piece of scrap metal. banging on a car door is not conducive to extreme accuracy. That is why targets are used. On the target, get an aiming point, not an aiming area.
The back wind will cause vertical stringing, but you have far too many variables/unknowns to indicate how much.

 

[Andy Warhog]

It shoots about 1 1/2" at 250, I don't really shoot closer than that unless I got to a public range with someone. I'm trying to work backwards and get a ballpark velocity, I still haven't been able to get access to a chronograph. The only thing I'm not 100% confident on is my cheek weld. I have a hard time keeping the same spot through recoil with my beard. I'm still getting used to it.

 

[gixxer822]

There's a lot of variables to pin it on the ammo, gun or u yet. If u can't get a good cheek repeatablity is hard and it could be minor scope shadow or parallax. Do u always shoot this ammo? Are u loading the bipods? Heating up the barrel is quite possible. I always blame myself before the equiptment cuz it's usually me. Good luck

 

[RTH1800]

Cheek weld can really add to it. Need to get those variables isolated. A perfectly focused scope will reduce or eliminate the check weld issue. I do think you should try to get some shorter range groups so you have a baseline and can reduce the wind/weather induced problem issue. Good luck with the process.

 

[Andy Warhog]

I have only shot a few hundred rounds of this ammo. I have the bipod loaded, no rear bag. Sight picture and parallax are clear. I guess I'll just have to shoot some more and see if I can isolate what's happening. How long is long enough between shots to avoid barrel heat issues? Thanks for the help guys

 

[peaceatwar]

What are the specs on the gun?

 

[Andy Warhog]

POF 16", NF 3.5-15x56, harris, prs

 

[Sterling Shooter]

I have only shot a few hundred rounds of this ammo. I have the bipod loaded, no rear bag. Sight picture and parallax are clear. I guess I'll just have to shoot some more and see if I can isolate what's happening. How long is long enough between shots to avoid barrel heat issues? Thanks for the help guys

Isolate what's happening? To do that you will need to properly record your shots in a score book. You may also need some training on the topic of shooter/target analysis. At the least, plot your calls and strikes. Practice at a closer distance from which the strike can be viewed through your spotting scope. An MR-31 target is ideal. The shot call/strike corollary, as well as the pattern of the group will direct you to the arena of inconsistency where shot errors are originating from, likely, something to do with the principles, position, or forces which effect trajectory. BTW, heat from the barrel is likely not your issue unless you have a bad barrel.

 

[peaceatwar]

Isolate what's happening? To do that you will need to properly record your shots in a score book. You may also need some training on the topic of shooter/target analysis. At the least, plot your calls and strikes. Practice at a closer distance from which the strike can be viewed through your spotting scope. An MR-31 target is ideal. The shot call/strike corollary, as well as the pattern of the group will direct you to the arena of inconsistency where shot errors are originating from, likely, something to do with the principles, position, or forces which effect trajectory. BTW, heat from the barrel is likely not your issue unless you have a bad barrel.

Also check the torque on your scope. I had a simliar issue with a SCAR and I was able to isolate down to barrel heat(SHITTY THIN FN BARREL) and my scope not being properly torqued.

 

[Andy Warhog]

Also check the torque on your scope. I had a simliar issue with a SCAR and I was able to isolate down to barrel heat(SHITTY THIN FN BARREL) and my scope not being properly torqued.

Yeah those barrels are super thin. I'll double check my scope just to make sure, it's in a qd mount and hasn't had any issues on other rifles, I'll check the locking levers too. Thanks for the suggestion. I really think it's my beard though. I'm going to try some medical tape or something and see if I can get anywhere with that. I was able to call my shots and watch them splash on all but the one at the bottom, I thought I pushed that one low and left with the others. More snow and no work today, might have to go play a little bit.

 

[Sterling Shooter]

Yeah those barrels are super thin. I'll double check my scope just to make sure, it's in a qd mount and hasn't had any issues on other rifles, I'll check the locking levers too. Thanks for the suggestion. I really think it's my beard though. I'm going to try some medical tape or something and see if I can get anywhere with that. I was able to call my shots and watch them splash on all but the one at the bottom, I thought I pushed that one low and left with the others. More snow and no work today, might have to go play a little bit.

Well, were your shots on call?

 

[Andy Warhog]

Well, were your shots on call?

No. They were all off of my point of aim, and I knew that but I still held it, but the 5th shot of my string in the top pic was off my call but I thought I pushed it low and left which SHOULD have put it near the other 3 that trail off low and left of the group

 

[Sterling Shooter]

Shots not on call, along with vertical spread suggests ammunition with a somewhat high ES. A 50 fps change in velocity is worth about 1 MOA. At 700 yards that would mean about 14 inches from highest to lowest shot, if, for example, your average muzzle velocity of let's say 2700 fps was actually anywhere from 2650 to 2750 from your entire string of fire.

As a long range competitor, shooting a match conditioned commercial equivalent of the M16 service rifle, with irons and sling, I am cognizant of the need to hold elevation to allow for a good score even when I don't get the wind just right. And, since it's almost for sure I will not get the wind just right, I massage my ammunition for single digit SD and ES, as well as attempt to dress up my sight picture to perfection.