Finding a way to get hard PC'd boolits from regular COWW alloy

Rick

Moderator
Staff member
#21
I've not used this alloy but my best guess would be if it's a GC design bullet to use the check. Testing could prove that wrong but at the velocities your looking for I would start with the check.

Next, keep in mind that a BHN number is completely relative. It is not only possible but likely that two different alloys will have the same BHN reading and each will behave/react differently in the same load based on what is in the alloy. A BHN number is basically only useful when comparing similar alloys.
 
#22
15lbs of reclaimed shot and 5lbs of Roto-Metals Super Hard Alloy gets me right about 18bhn without having to heat treat or water quench. It works for me for my HV target shooting but I wouldn't recommend it for hunting.
 

fiver

Well-Known Member
#25
you still need a gas check, square bases are a must.
ww's are okay but not strong enough to take the slam after the jump across the 5.56's throat.
that open area between the case mouth and the rifling needs a strong bullet alloy to take the pounding and get into the rifling before being moved along.
I use an alloy of 15-16, 22 bhn lino failed because it isn't balanced enough, 18 bhn water dropped ww's failed because of the slam more bhn doesn't help.
somewhere around 5% of both tin and antimony with some arsenic is a much denser stronger alloy.
copper helps the toughness.

it is the throat and bullet shape that determines alloy selection for the pressure your going to see.
 

fiver

Well-Known Member
#27
I'm sure a high antimony alloy will.
the thing is as soon as you punch it into the rifle the antimony crystals break down and allow the lead to flow over itself easier.
this is why extruded lead [like Pipe and window came] uses 3-5% antimony as part of the mix.
 

Ian

Well-Known Member
#28
If I have more than 2.5-3% antimony, I find the tin needs to be at least half as much. Less than 2.5 antimony, the tin can be as low as .5 and it still works great, just not as fast as beefier alloy. When NOT jumping a huge throat, just finding center from 10-15 thousandths away, a low Sb alloy, quenched to around 20 bhn, shoots great when you find the point where it just bumps enough. Tin strengthens the matrix so much and shifts the mix from high draw to high mush and it can withstand a lot more compression without suddenly crumbling into putty when the matrix crushes.
 

waco

Springfield, Oregon
#31
I'll snag a chunk of 1/4" steel rod from work tomorrow and try to "Man Up" over the weekend and do this. I'll be honest. It scares me....:oops:
 

Will

Well-Known Member
#32
It did me to the first time I did it Waco.

I used lots of electrical tape to keep the steel on steel contact to a minimum. I also beveled the end of the rod so no sharp edges could catch on anything while going down the bore.

I ended up ordering 3 different diameters of drill rod from mcmaster carr.

I plan to do the howa Monday
 

Will

Well-Known Member
#35
I have to admit I left the gun shop without it twice before buying it the third time.

It was one of those that I went home and couldn’t get it off my mind. So I just gave in and took a chance.