vertical stringing ammo related causes?

[saskgunowner101]

Just looking for thoughts on vertical stringing causes. I'm not going to blame the rifle, as the last 4-5 loads worked fine.

It's a Handi rifle chambered in 357 magnum. Standard 158 grain cast semi wadcutter with a gas check, just a touch longer than standard c.o.l. with slight crimp. Running 7.2 grains of Herco. I only shot 2-5 shot groups, but the results were puzzling. In both cases, 2 bullets near each other, and then straight vertical stringing. I was resting off a trailer at 25 meter with a fairly steady hold, so I'm not blaming me or the rifle at this time. The cases were slightly sooty though.

Has this happened to you, and where do you go next?

Bullets well lubed, made from wheel weights .360 sized to .358, nice strong rifling engraved on captured bullets. More powder? More crimp? More cowbell? Any thoughts appreciated.

 

[Ganderite]

Try 8.0 gr Herco. Your load might be too mild for enough pressure to be consistent.

 

[bearhunter]

Try 8.0 gr Herco. Your load might be too mild for enough pressure to be consistent.

This and if you aren't already, get some MAGNUM primers.

I use 8.3 grains of Herco over magnum primers with a similar bullet in my converted Martini. It likes this load a lot. My load is over max for hand guns but should be just fine out of a rifle. Like all flake powders, pressures spike fast with very small incremental increases. Start with Ganderite's suggested load and see if it works for you.

Herco is noticeably slower than Unique and needs more to get the best results IMHO. Far to slow for most pistols, again IMHO. Unique is a better option for pistols.

 

[stampede]

I agree with Ganderite.

Most likely cause is inconsistent velocities. Lower power loads are prone to this. Since it is a single shot, do you hold the bullets the same way each time you load ? Powder position in under filled cases could also be a cause of inconsistency and vertical stringing.

Can you borrow or buy a Chrono to confirm velocities ?

By the way, I have a Handi Rifle as well. I found that mine will chamber 360 DW brass. I load these to 357 magnum (14.8 gr 2400 for 158 gr jacketed) and find them very accurate. The longer Dan Wesson case gets the bullets closer to the rifling lands.

 

[saskgunowner101]

Some good food for thought here. I'll bump the charge to 8 grains and see if the wonkiness goes away. I have a good stash of small pistol primers, but if I can't get it under control, I'll try some magnum primers.

I thought Herco was right beside Unique for burn rate (back to the books for me!), so I thought I'd try and make something of it. My 45-70 likes Unique too much for powder puff loads, so I was saving it for that.

I was shooting off the back of my wood trailer, so rifle pointing at a downward angle, maybe that wasn't helping my situation. Funny thing about the chronograph. I'm boring when I reload, I find my good loads, chronograph them, then load a billion of them. So it's only once in awhile I actually need one. Buddy ended up shooting mine, and just gave me cash. Dummy me bought something else, so here I am.

Hopefully a charge bump will patch me up though.