Handload shots strung vertically - what's the cause?

[tacotime]

45-70, 350 and 405 grain jacketed bullets.  Loaded with Rel 7 (38 grains), shots strung vertically, in a line, about 4 to 5 inches tall at 100 yards, from a consistent rest and grip.  Also with another powder, strung vertically (can't recall which load) maybe 4 inches.  Other loads and powders shot normally, various group sizes.  Charges were all weighed on a RCBS digital scale, monitored for zero.  Did not use a trickler, so I guess there is a + or - 0.1 grain variation expected, plus whatever inherent scale error.  (But I wouldn't think the 0.1 grain variation could string shots over 5 inches at 100 yards). Cases sized, trimmed, deburred, crimped all the same.  Cartridge OAL all very close in length.

Not sure if it was me or is there some other usual cause of vertical stringing?

Thanks.

[SHOOTALL]

lose stock screws ?

[SHOOTALL]

Also 1/10 grain is alot ,

[Larry L]

I just glanced at the data in my Speer manual and it looks like you are well below any max loading, I'm showing 45.0gr max in a trapdoor. I've always heard that a vertical string means you're not pushing the bullet hard enough. Might consider going up on the powder. Always check with whatever manual you have to make sure of the data. If you are attempting reduced loads, use Unique or SR4759. SR4759 is an extremely great powder in the 45-70 if you want to keep velocities to trapdoor specs and would like a reduced recoil load regardless of bullet weight.

[cwlongshot]

Generally speaking. Verticle stringing is a forend problem. But could also be "bouncing" off a hard rest.
How are you shooting, sand bags, bypod???
Also you mention 45-70, but what is the firearm?

[tacotime]

Bouncing off the rest is a possibility, though not seen with the other loads. I think the rest at the time was a flat gallon jug of chainsaw bar oil with a leather glove on top...  ok, maybe not the best.  Now it is a Caldwell shooting rest bag.  I'll re-test.

38 grains of Rel 7 seems faster than factory 405 grain loads, but I recognize possible variable ignition problems with the reduced Rel 7 loads.  I was looking for a load to raise the factory 405 velocity of 1,330 fps to about 1,500 fps.

Rifle is a Ruger #3.

Forearm shouldn't be a problem since the other loads did not show the same issue, but I'll check it.

Thanks for the info, other comments welcome...

[SHOOTALL]

I had a Ruger #1 fore arm could be a pain if not right . To tight or to loose could be an issue.

[Gohon]

A variation of 1/10 of a grain is a lot in a 22 Hornet but in a 45-70 it is nothing. 

[Blackhawker]

Is it cold out where you're shooting?  Barrel warming can cause vertical stringing, especially in cold weather.

Other things, as mentioned above: where you're resting the rifle, consistently resting in the same place, loose fore arm.

[necchi]

Is it cold out where you're shooting?  Barrel warming can cause vertical stringing, especially in cold weather.

Thats the frist thing that came to my mind, like my handis, it's a one shot gun. If I don't wait a few minutes for the barrel to cool I get vertical strings, 

[tacotime]

It wasn't cold but I'm still starting to suspect a warming barrel, in conjunction with the known-finicky accuracy issue related to the forearm of the Ruger single shots.  Don't think there was much time between these 4 shots, less than a minute each probably.  I'll re-test...  thanks!

[jhalcott]

  you COULD be  getting inconsistent ignition due to to low powder charges! You may not even notice that happening, as in squib loads. Hornady#7 edition shows aSTARTING load of 44 grains of reloader 7 with a 350 grain bullet. Perhaps a FASTER powder will help achieve your goal.

[stimpylu32]

  you COULD be  getting inconsistent ignition due to to low powder charges! You may not even notice that happening, as in squib loads. Hornady#7 edition shows aSTARTING load of 44 grains of reloader 7 with a 350 grain bullet. Perhaps a FASTER powder will help achieve your goal.

I tend to agree , after re-reading the OP , it sounds like a powder charge problem , not that Re7 is a bad choice , I love it , just not enough of it . 

stimpy

[tacotime]

The 38 grains of Rel 7 with the 405 at first seemed plenty good for a slightly faster than factory round.  Maybe it was a little stiff in recoil due to my lightened rifle.  Now that I look at the charge in the case, it's awful small.

I'll re-test it this weekend in two Ruger #3's.  If they don't group, up goes the charge (and maybe the bruise).

[tacotime]

Well with limited testing another batch of 38gr Rel7 405's also strung vertically.  I think the charge is just too low. Going up to normal trapdoor listings, 41 to 45 I think was the Sierra range.  I think they will be better, but stiffer of course.

[Lloyd Smale]

i totaly agree. Id doubt if variations as large as a full grain would cause vertical stringing in a 4570 unless your loading right on the edge of extreem pressures

A variation of 1/10 of a grain is a lot in a 22 Hornet but in a 45-70 it is nothing.  

[SHOOTALL]

i totaly agree. Id doubt if variations as large as a full grain would cause vertical stringing in a 4570 unless your loading right on the edge of extreem pressures

A variation of 1/10 of a grain is a lot in a 22 Hornet but in a 45-70 it is nothing.  

I would suggest that  a 1/10 gr difference with a different primer ,  cases that were not trimmed the same length ,cases of differing neck thickness, cases that were of varing capacity ,a crimp of varring degree pressure on the bullet or weakness in the brass any of which could cause a problem .

[Blackhawker]

I still wonder if it's a temperature issue.  My barrels on my Wesson and Harringtons seem to warm and cool very rapidly and will show vertical stringing more often than any other rifles.  Sometimes it really bothers me but it's not as bad in the middle of the summer as it is when it's 40 degrees or less outside.
Did you pay close attention to time between shots and/or if the barrel cooled off too long?

[SHOOTALL]

When you fire a gun pressure peak to cause the bullet to move out of the case. It peaks once more as it enters the rifleing and then it reaches a max peak as powder is maxed out in the aval. bbl or the length of bbl needed to reach peake pressure. Any of the things listed above could effect the bullet some slowing it others allowing it to move faster . Where the bullet hits vertical is somewhat effected by how long the bullet remains in the bbl as it lifts from recoil among other things.