Leading at muzzle

[Brad]

I find this isn't leading AT the muzzle then I don't know what is.

I need to investigate a few things. Either the alloy was way too weak for what I was doing or the size was off.

 

[RBHarter]

I'll start with ;
The plain base swage slough ring .
Band whiskers .

I don't know , I have seen it a number of times in loads approaching the alloys break point with PB .

I saw a very similar bit with a shouldered flash hider that had a gap between the shoulder and the crown but that is a whole different bucket o snakes .

 

[Brad]

Dry patch down the bore showed no signs of leading in the bore. A few strokes of a brush then another dry patch and nope, no bore leading.
Each shot fired had a large cloud of white smoke. I'm sure there was some vaporized lead in that smoke and some was deposited on the crown as seen in the photo.
Alloy is too weak is my guess. A too small bullet would have likely shown leading down the bore.

 

[creosote]

I'm impressed with such a good picture of the bore, and completely baffled at what rifle that is. With the snazzy crown.

 

[Brad]

Photo was taken using the flash on my IPhone.
Rifle is a CZ550 in 375 H&H.
Load was an MP 270 gr bullet, gas checked, and enough RE17 to get into the 2400-2500 fps range. Recoil wasn't bad but was getting up there.

Load didn't group for diddly.

I will add more Sb and Sn to my alloy and cast some more. Then I need to let em age for a bit.

 

[freebullet]

That's interesting, wonder what the crown looks like under the lead. Never seen a clean bore with edge build up like that.

Usually find antimony wash, or lead from throat out if I messed up the alloy or crimp.

 

[Brad]

Crown is round and smooth under that. I think it is deposited lead vapors.
It cleaned off with a fingernail.

 

[freebullet]

Heck of a build up for particulate collection but I think your right.

 

[Ian]

Leading edge failure in the extreme. High pressure on the gas check the whole way kept the bore obturated and cleaned out the bore behind the bullet, so no deposits inside. Need a tougher alloy, slower powder, and more/better lube. Got any Felix lube?

 

[Brad]

I think I have some Felix kicking around. This will as with a version of 68B.

Alloy was way too weak. This wasn't even a 3/1 alloy.

 

[fiver]

water dropping don't help when you do that either......... just sayin.
of course I never dun nuthin like this.

 

[Rick]

How many lube grooves does that bullet have? What is the Sb percentage in your current alloy? How much Sn?

 

[Ian]

If you look real close at the scuff marks on the tops of the lands one might surmise that more than half the engrave was worn away from the body of the bullet. Thank goodness for gas checks! If you could recover some of those bullets I bet they'd tell quite a tale, but they're probably six feet into the berm and mangled into oblivion.

 

[Brad]

How many lube grooves does that bullet have? What is the Sb percentage in your current alloy? How much Sn?

No idea for sure but maybe 2-2.5 Sb and .5Sn. Not near tough enough.
One large lube groove.

 

[Brad]

Bullets were not to be found. I looked quickly but with someone else shooting didn't have long.
I did find a 30 XCB, will get photos later.

 

[Rick]

How many lubes grooves in that bullet?

 

[Brad]

One, and a big one at that. Think of a 30 Sil on steroid.

 

[Rick]

Oh yeah, now he posts a picture of the bullet.

 

[Ian]

That one holds enough lube that any of the soft SL-68-ish series of lubes should be more than adequate....provided the alloy doesn't just peel off where the bullet is driving hard against the edge of the lands.

 

[Brad]

Oh yeah, now he posts a picture of the bullet.

Took me a few minutes to go find the picture.

And yes Ian, it holds a ton of lube. This one got a soft lube that works well. It was an alloy failure. All signs point to that.

In the past how many would have said lead on the muzzle was a sign of "running out of lube"?