Vertical stringing

[chino1969]

I'm looking for some advice because I know I've read an explanation for this before. I'm working up a live varmint load for the ferocious Pennsylvania groundhog. The load consists of Varget, Wolf small rifle mag. primers and Hornady's 87grn. V-Max. I shot this load the other night with calm conditions, no mirage; excellent conditions. The range was 200 meters, Rem. trued 40X single shot, sleeved bolt, etc., Kreiger 1:7.5' 6mm BR light varmint barrel. This rig is solid, having shot many heavier loads very accurately. There is nothing mechanical or optically deficient in the set-up. So here's my question: As I was working up the loads my groups were stringing verically upward. Any ideas out there? My first instinct is to try a Federal small rifle primer but I seem to remember the cause for vertical stringing to be something other than primers.

Any help would be appreciated.

Lou Baccino

 

[Chuckhunter]

Chino, this may be what you're looking for. http://www.6mmbr.com/verticaltips.html

If you are sure your bags and scope are not the problem, I would look at primers first, as it appears to be an ignition problem, even though Varget is not a hard powder to light up. My 6X47 ackley was doing the same thing so I kept upping the charge with 107 Sierra SMK's, when that didn't work I tried large primers and worked back down, problem solved. Even though I can get 3200 fps, the gun is telling me it wants to shoot between 3050 and 3100fps. I also discovered that my gun likes to be held lightly and not shot with free recoil.

 

[chino1969]

Chino, this may be what you're looking for. http://www.6mmbr.com/verticaltips.html

If you are sure your bags and scope are not the problem, I would look at primers first, as it appears to be an ignition problem, even though Varget is not a hard powder to light up. My 6X47 ackley was doing the same thing so I kept upping the charge with 107 Sierra SMK's, when that didn't work I tried large primers and worked back down, problem solved. Even though I can get 3200 fps, the gun is telling me it wants to shoot between 3050 and 3100fps. I also discovered that my gun likes to be held lightly and not shot with free recoil.

Thank you, that was the article I was looking for. I'll try a primer change and report.

Lou Baccino

 

[tenring]

You did not say what powder and how many grains, nor your OAL. Vertical is often - but not always - a result of not tuning the load properly. Try up or down one or more tenths grains. Also review what Speedy says, as follows:

'Find the Sweet Spot--A load that is too light or too heavy can cause vertical problems. When you've tuned the load right, you should see a reduction in vertical. Even 0.1 grain may make a difference, as will small changes in seating depth.'

 

[chino1969]

You did not say what powder and how many grains, nor your OAL. Vertical is often - but not always - a result of not tuning the load properly. Try up or down one or more tenths grains. Also review what Speedy says, as follows:

'Find the Sweet Spot--A load that is too light or too heavy can cause vertical problems. When you've tuned the load right, you should see a reduction in vertical. Even 0.1 grain may make a difference, as will small changes in seating depth.'

Tenring,
My bullet is touching the lands and I believe I started somewhere around 30.1 grns. and began going up by .3 grn.; I'm not near my notes. All of the groups were vertical as my charge went up. As I reached the upper window, the groups opened up but yet they were still vertical. My best groups appeared around 30.4 & 30.7 grn.

Lou Baccino

 

[AckleymanII]

Lou, I would try using a hotter primer if you can find them, like the CCI 450.

Try jamming the lands hard, .020-.030.

Change powders, in that order.

 

[chino1969]

Lou, I would try using a hotter primer if you can find them, like the CCI 450.

Try jamming the lands hard, .020-.030.

Change powders, in that order.

Keith,
Thanks for the input. I'll try CCI 450 primers and see what happens along with jamming into the lands. If that doesn't work, I'll change powders.

Lou