Keyholing with PPU SWC, Marlin

[strangesam]

I've a new to me, Marlin 1894, for which I won't be reloading (as I really don't have the room at home, tiny modern house). It has a new (probably less than 250 rounds) microgroove barrel.

I've been testing a couple of types of factory ammunition, all .38 special

Magtech FMJ Flat 158gn
Magtech LRN 158gn
PPU Lead SWC 158gn


Last night I noticed a number of what looked like tumbling rounds at 10-15m (was practical night) using the PPU SWC. Is that normal?

I final test @10m had 3/11 PPU rounds showing rectangular holes/tears, while all the Magtech LRN holes were nice and circular.

Is this just a thing that happens? I've never really had any ammunition or rifles (.22lr/303) which have exhibited key-holing before.

[dromia]

First check the barrel for leading.

Either way the bullets are too small diameter or too hard not setting up in the micro groove rifling. Such rifling needs a throat diameter soft bullet.

[GeeRam]

I've a new to me, Marlin 1894, for which I won't be reloading (as I really don't have the room at home, tiny modern house). It has a new (probably less than 250 rounds) microgroove barrel.

I've been testing a couple of types of factory ammunition, all .38 special

Magtech FMJ Flat 158gn
Magtech LRN 158gn
PPU Lead SWC 158gn


Last night I noticed a number of what looked like tumbling rounds at 10-15m (was practical night) using the PPU SWC. Is that normal?

I final test @10m had 3/11 PPU rounds showing rectangular holes/tears, while all the Magtech LRN holes were nice and circular.

Is this just a thing that happens?

Most of the .357/.38 underlever's in our club (mix of Marlin, Rossi & Henry) don't seem to like any SWC or flat bullet ammo, only LRN's.

[FredB]

What Dromia says.
Bullet nose shape is irrelevant on sub-sonic rounds, unless there are feeding issues.
Bullet fit in the throat is everything.
Fred

[Sim G]

As said, soft and large is the way with Marlin micro-groove barrels as a rule of thumb. As you're not going to reload, jacketed factory for you.

[strangesam]

Thanks, sounds like its not unusual, just ammo sensitive.

I know the FMJ Flat 158Magtech works, so I shall buy some more of that.

[Paul101]

I find 10m is too close to stabilise , try 20m groupings

[FredB]

If you reload. you might be able to afford a larger house.
Fred

[strangesam]

If you reload. you might be able to afford a larger house.
Fred

Worst case I probably spend £2k per year on ammo. Even if I saved 50%, thats longer than my remaining lifetime to afford a bigger house. (something 4 bed in a half decent area near me starts at £500,000 and goes up rapidly).

My best hope is inheritance, the lottery, or the wife moving up the career ladder again.

[Andy]

My Rossi 92 would do the same at 25m with ppu swc.
I reload now with the ppu brass and 158gn rnfp GM lead.
Problem gone. it just didn't like semi wad cutters.