How much compression is TOO much?

[Jbar4Ranch]

OK, the "rule of thumb" is: vertical stringing = not enough compression. What happens if you go to the other extreme and use too much compression? How much is too much? Using a Lyman 355 grain cast bullet in .38-55, and Lee dippers to measure the charge, I get ~.250" compression with the 3.1cc dipper and ~.120" compression with the 2.8cc dipper with no discernible difference in accuracy at 100 yards, which is all the farther I've shot this new bullet so far. So what happens with too much compression?

I'm using a compression die, Goex CTG, and .030" Walter's wads with the bullet seated out to touch the rifling in my H&R Target, which leaves about half of the top lube groove exposed.

[Lead pot]

When your groups get bigger again your compressing to much.
Vertical stringing is most likely fouling control.

[JeffinNZ]

When the brass bulges!

[northmn]

The 38-55 was originally developed as a Schuetzen cartridge. Many loaded it by putting a card over the powder on a full case (where the 55 came from) and muzzleloading the bullet. Others made a breech seater that would push the bullet in place and then load the cartridge full of powder. They used less compression. I have always weighed compressed BP charges to get consistant compression. Better shooter than myself do measure but use more refined measures. I would suggest getting one of the BP powder measures with a sliding funnel for more consistancy. The 38-55 was designed under the target shooters rule of using heavy bullets with lighter charges for more accuracy. As Jeff said, you can load till the case bulges.

Northmn

[Southern Son]

Jeff, you beat me to it. I was working up loads for a Lyman Postel. When I went to chamber the top loads, they didn't fit. Pulling the boolits was easy, getting the powder out was not. I ended up soaking the powder in water then using my rechargable drill.

[BPCR Bill]

OK, the "rule of thumb" is: vertical stringing = not enough compression. What happens if you go to the other extreme and use too much compression? How much is too much? Using a Lyman 355 grain cast bullet in .38-55, and Lee dippers to measure the charge, I get ~.250" compression with the 3.1cc dipper and ~.120" compression with the 2.8cc dipper with no discernible difference in accuracy at 100 yards, which is all the farther I've shot this new bullet so far. So what happens with too much compression?

I'm using a compression die, Goex CTG, and .030" Walter's wads with the bullet seated out to touch the rifling in my H&R Target, which leaves about half of the top lube groove exposed.
Jbar4, what is the twist rate in that barrel?

Bill

[montana_charlie]

Jeff, you beat me to it. I was working up loads for a Lyman Postel. When I went to chamber the top loads, they didn't fit. Pulling the boolits was easy, getting the powder out was not. I ended up soaking the powder in water then using my rechargable drill.
All you had to do was pull the decapper out of your full-length sizing die...back the die out of the press a ways...and partially resize your (powder filled) cases, just enough to let them chamber.
Then expand the mouth (if needed) and reinsert the bullet.
CM

[Jbar4Ranch]

Jbar4, what is the twist rate in that barrel?

Bill
I believe they were 1:18.

[BPCR Bill]

Jbar4, current wisdon is that that twist rate is not fast enough for that boolit. My Uberti is a 1:18, and I shot the 330 grain Lyman. Accuracy was OK, but nothing to write home about. I have since gone to a 250 grain Lyman,or a swaged 250 grain PP, and they shoot much better. My compression is settling the powder with vibration, usually a vibratory etching tool held against the loading block, or holding the block on top of a running tumbler. I found out the chamber in that rifle was for the long 2.125" cases. Get some cerrosafe and do a chamber cast, see what you chamber will accomodate. I also went to large pistol primers, I found my extreme spread closed up considerably. I have some 250 GG boolits I can send you to try if you don't have any. These are some of the things I have done, and I believe you don't have to go to extremes with powder compression. IMHO.

Regards,
Bill

[Jbar4Ranch]

I've been using a 255 grain Lee bevel base flat point with Goex CTG and commonly get groups of 7-8 inches at 500 yards when conditions are perfect. I thought I'd try the heavier bullet and see how it compared, but I haven't shot it at five hundred yet.

[BPCR Bill]

That's some very good shooting for a 38-55 at 500 yards! I have cast some of those boolits as well but have yet to shoot them. The 330 grain boolit will like a 1:15 twist much better. I shot that at the 500 meter rams and could never hit it consistently no matter what I did, barrel 1:18. I shoot that rifle for Schuetzen matches now, and not over 200 yards. I stick with the lighter boolit, and so far I've been able to get some very good groups with the PP 250 grain. I'm still developing some loads and am waiting for a break in the rain to go shoot some more.

Regards,
Bill

[zampilot]

I just put together some 3Fg 40-65 loads and the compression to get the bullet properly seated was .635 (bullet) - .250 (powder depth in case) - .060 wad = .325 compression. I dont know how they shoot though!:drinks:

[Jbar4Ranch]

That's some very good shooting for a 38-55 at 500 yards!
Considering the rifle and sight setup, it's doubly amazing... maybe triple! :lol: It's an H&R .38-55 Target with the chronically undersize chamber mouth and oversize bore plus a bit of Woodshop 101 creativity thrown in to mount the sight.

http://img.photobucket.com/albums/v93/jbar4ranch/HRsight.jpg

The dang thing works though, and shoots better than any of my other single shot buffler rifles.

[BPCR Bill]

I saw a rifle at a Schuetzen match last year that was incredibly ugly, completely homemade right down to the barrel. The cartridge was a 44 mag case necked down to .30 caliber, the reamer and dies were homemade as well. The stock was some old oak from a stair case, and looked like it was shaped with an axe. That rifle was supremely accurate. I've learned to never mock a mans guns, no matter how they look! You have a keeper there my friend!

Regards,
Bill