Leading at muzzle

[Rick]

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

Running out of lube would normally be the leading in the rifling near the muzzle. BUT . . . This is leading ON the muzzle.

Alloy issue is a logical assumption. As a SWAG and some place to start, up the Sb to 5% and the Sn to about 2%.

How long is the barrel?

 

[Brad]

26" tube.
The bullets I fired in the 06 today were cast from a 6% Sb, 4% Sn alloy by fiver. They handled the pressure and velocity just fine. I have a recipe to mix up a similar alloy from stuff on hand. I figure 100 pounds of it set aside for HV use is a good idea.

Sometimes we learn from our mistakes. This is one of those times.

 

[Ian]

You did run out of lube, and dang near ran out of bullet metal! But it still actually worked pretty well all things considered. Easy to tweak from there.

Back to alloy again. What does Brad need? Obviously tougher, and like Fiver wrote water-hardening isn't going to do enough with that particular low-antimony alloy. I like to use low-antimony alloy, heat treated, (like 2.5/1.5 alloy HT'd to 19-20 bhn, made from 3/2 clippy weights/soft scrap and 1% tin thrown in on top) because it doesn't lose so much metal to drive side abrasion as something like straight wheel weights does. BUT, when you need a tougher alloy to handle the rifling at high speed/steep angles, that means more antimony automatically......but how much or how little tin to go with that to keep the abrasion losses down? 4/3? 5/2.5? 6/4? #2? I think that question is absolutely key to all this HV work.

 

[Rick]

I figure 100 pounds of it set aside for HV use is a good idea.

Sometimes we learn from our mistakes. This is one of those times.

One lesson I've learned from my mistake was don't blend 100 pounds of any alloy until you've tested it well and know it is exactly what you need. I'd recommend maybe 20 pounds. You can always make more if it works well but you don't want all your eggs in one basket.

 

[Ian]

Double extra like for Rick's post^^^^^^^^^^^^^

Forgot to add.....one problem Brad did NOT seem to have was getting the bullet into the rifling straight and keeping it straight, so he got everything else in the system pretty much right or they wouldn't have grouped at all at the speed he was pushing them. That was my other clue that it wasn't a fit problem, the lead was coming off later in the barrel and not from losing obturation, either, as evidenced by clean rifling.

 

[Rick]

Would almost be worth the drive to Brad's for a chance to run the bore scope in that barrel from both ends. A bore scope is a terrible thing to have because it often tells you things you really didn't want to know. On the other hand it also tells you much that you NEED to know but it almost always tells you things that are a surprise.

 

[Will]

Brad my howa looked the same way when I shot some air cooled 50/50 bullets a few weeks ago fire forming brass.
I figured I had a barrel full of lead but to my surprise it was only at the crown. There were several of those bullets that didn’t hit the the 4’x4’ target backer.

 

[Brad]

These were not very accurate either. They did hit the berm but beyond that I can't say much about them.

 

[Ian]

Oh, oops. I thought those grouped, had the '06 and 375 confused, sorry. Maybe I'd better retract my conclusion about the launch.

 

[Brad]

The 375 hit paper a couple of times but it was a 2.5' square paper.
The fact the 06 did fine at a higher pressure than the 375 tells me alloy is the difference. 06 bullets cast froma far richer alloy, 4/6 compared to .75/2 or so.

 

[Will]

So after reading all of this does anyone think using just plain old heat treated wheel weights would get you there?
It would sure be nice I’ve got 55 gallon drums of those, I just can’t find pure lead.

 

[Brad]

Not at these load levels. I think 4-5% Sb and 2-3% Sn are needed.
Wheel weights with a little tin would get you closer but not there.

 

[Rick]

Brad's assumption on his alloy is 2 or 2 1/2 percent Sb and 0.5 percent Sn. That pretty much is CWW. Though he didn't say I assume he shot them air cooled. Heat treating would probably benefit him but I don't think it would get him there. From Fiver's post it sounds like he tried it and it didn't work for him. I think he'll need to enrich the alloy with a bit more antimony and tin.

 

[Brad]

They were air cooled.

 

[Ian]

They were air cooled.

DOH!

Well that 'splains a lot. I thought surely you had water dropped them. Brad, not Shirley.

I can attest that the AM-185G, from water-quenched WW +2% extra tin, will do very very well at 2400 fps (under an inch for ten at 100 yards if I didn't get excited and flinch) but in my test rifle required cleaning the antimony wash out periodically and the bullets were too hard for hunting, so I ditched it during my testing 5-6 years ago. I believe the antimony wash building up was more a feature of that particular barrel being rough and being new than anything else.

 

[Rick]

DOH!

Great minds think alike.

 

[Brad]

I haven't water dropped in years. I can easily try heat treating some but I don't know if that will be enough.

I think a tough alloy is needed. I have some ideas, just need to make time. Might need to wait until after the vacation.

 

[Brad]

Great minds think alike.

Great, you two agree. That never works out well for me.

 

[Rick]

Brad think, what's your alloy? 11-12 BHN at best? At 2400 to 2500 fps? Really? CWW +2% Sn air cooled works out really well for me to 1900 to 1950 fps but that's a far cry from the pressures and velocity your running.

 

[Brad]

I'm not sure what I was thinking? Not much apparently.

I have a few ideas on an alloy to try. Will try to get some cast this weekend. Gonna be too miserable to go anywhere. More snow on the way.