Hi-Wall Vertical Stringing ?

[August]

Shot the new 38-55 today.  My "groups" were about two inches wide and 12 inches tall at 100 yards.  Load = 17 grains 4759 under a Bear Creek 255 grain moly in .277 diameter.  Bore of rifle is .276.  Primer was Federal Match Rifle.

No sign of bullet instability or tumbling.  Charges were hand weighed on RCBS electronic powder measure to 1/10 grain consistency.

Any suggestions about where I should look for gremlins?

Thanks!

[Delmonico]

Start with the forened, make sure it is tight and the bedding is not uneven.

[Ranch 13]

+1 with Delmonico, also make sure that you're resting the forearm, or barrel exactly the same for everyshot.
How does it shoot with other loads?

[Sir Charles deMouton-Black]

i THINK YOU HAVE THE BORE/BULLET DIAMETERS ABOUT 1/10TH INCH TOO SMALL,  cOULD THAT BE YOUR PROBLEM.



That sounds like the regular Schuetzen load for the 38-55.  It should get you cloverleaf groups!  I might make a WAG and suggest experimenting with placement of the rifle on the front bag.  Consistency of hold could be the gremlin.

[August]

Sorry about the brain fade on the dimensions.  Bore is .376 and bullets are .377-378.  Again, no signs of tumbling -- all holes perfectly round.  Also, I'm getting two inch groups with my marlin (aperture sights also)  using the same load, with bullet sized up to the appropriate diameter for that rifle. I'm gonna shoot the rifle without the forend next time I go to the range, resting it on the hanger and see what I get.  Then, I'll work out from there.

Most BPCR guys around here rest on the barrel, itself.  They say it cancels out vibration.  I get that, but don't want to scuff the bluing on my new rifle. 

Thanks for the input!!!!

[French Jack]

Unless the barrel is loose or out of true, up and down stringing is usually due to velocity variations. If velocity is not the culprit, sometimes placement on a rest can wreak havoc.  My suggestion is to try holding the forearm as if shooting offhand, and resting that hand on the rest.  Some rifles need to be grasped firmly so recoil is more consistent, than allowing them to free recoil.  Single shots with a two piece stock seem to be one of the worst in this regard.

[Delmonico]

A 2 piece stock that the forend puts pressure on the reciever will srtung them up and down a lot.  A good way to tell if it is the forend is to just take it off and shoot it.

[Sir Charles deMouton-Black]

Another thought!

When I shot a similar load in mine, I used a pinch of dacron teddy-bear guts over the powder to keep it back against the primer.  Not everybody agrees with this.  At least tip the barrel up each time before gently laying the rifle on the front rest to let the powder settle at the back of the case.