Reloading 38-55, an odd issue.....

[bigbossman]

I ran into a puzzling issue with my 38-55 reloads a little while ago. I solved it, but don't really know the root cause of the issue.

Background:

I have an original Winchester 94 rifle, built in 1901, chambered in 38-55. The bore slugs to .379, and I use .380 diameter cast lead 240gr LFN bullets. I load them with 10gr of Unique. This is a tried and true load, and I have the trophies and pins to prove it. I've literally been shooting and winning with this load for a decade.

A few months ago, I bought another Winchester 94 rifle, built on a post 64 receiver with a NOS barrel, chambered in 38-55. The bore on this rifle also slugs to .379, and I use the same load - .380 diameter cast lead 240gr LFN bullets on top of 10gr of Unique. To my surprise, the tried and true load that groups great in the original rifle displays shotgun-like patterns in the new rifle with frequent key-holed bullet strikes on the target. Same load, same bore diameters on both rifles, drastically different results.

The fix was to change the powder. I worked up two loads with two different powders, 4198 and 4227, and that gave me nice tight groups with both rifles using the same components. Problem solved, but I am scratching my head as to why seemingly identical rifles with identical bore diameters and using the same load shoot so differently, and I'm especially puzzled as to why a powder change solved the issue.

Burn rate? Barrel twist rate? Any ideas?

['ol shooter]

That's worthy of some popcorn. Maybe a difference in freebore?

[bigbossman]

That's worthy of some popcorn. Maybe a difference in freebore?

I thought of that so I tried the shorter brass, and then the 2.125 brass. That had no effect. Also - I should add...... both bores are bright and shiny. No pitting, frosting etc.

[bruce381]

something you are not seeing?
me I would have sold it off

[bigbossman]

....me I would have sold it off

[2761377]

my vote is barrel harmonics. the new barrel does not like the way Unique makes it vibrate.

much like a tuning fork, a barrel needs to be "hit" in the correct manner to produce the true note. clearly, this is an over-simplification. but I think it illustrates the idea by exaggeration.

hth

[Imageview]

I?d agree harmonics is probably a big cause, along with minor variations in manufacturing. Assuming the twist does indeed turn out to be the same.

[pacrat]

Gunz are often like wimmenz. Sometimes they just don't like something.

All the cognitive reasoning and logical thought processes based on accepted ballistic facts just don't matter.

[sghart]

It would be interesting to see chamber casts from both rifles and the measurements of the freebore and leade.

I would try a pound cast of the throats with soft lead.

[divingin]

Twist rates the same?

[Spyder]

Curious about possible causes also.

I've got an old Marlin 25-20 that's been reamed to .255 Dean with similar issues. I haven't messed with it in a year and a half but it's getting close to time where I'll be able to spend evenings in the shop on projects.

It shoots factory 25-20 ammo just fine when fire forming brass to Dean, but when I load the Dean rounds (Had Hornady make up a set of custom dies based on chamber cast), they keyhole. I only tried a single type of powder before running out of time to solve it, so I guess I'll have to tinker with variety. And there's no 255 Dean load data anywhere out there, so that makes it fun too.

[Tankhatch]

My guess your 94 made in 1901 barrel has "cut" rifling and your post 94 has a differently made barrel rifling. Link is to NRA article on barrel rifling methods.

https://www.nrafamily.org/content/3-methods-of-barrel-rifling-pros-vs-cons/

[ironhorse1]

Winchester started using nickel steel barrels about 1894 in the 30-30 chambering.

However they kept using high strength steel in the 38-55 as it worked well with lead bullets.

If your NOS barrel is nickel steel then that may be one reason for the difference.

I have a pre 1900 38-55 barrel marked H3 38-55. The 3 is facing down. There is an oval with VP inside and a small triangle with maybe a 1 inside. No smokeless or nickel steel markings.

A 32 WS barrel has pat 1894 nickel steel and made for smokeless powder. I believe that this barrel is about one hundred years old.

Nickel steel and made for smokeless powder will be stamped on the barrels made later in production.

irh