Dropping 370gr with a 400gr Lee Mold

[22454]

Guys,
Should I be concerned about my Lee 90241 DC 476-400-RF mold dropping bullets weighing 370.XX grains and measuring .480" or slightly larger?

My alloy is an approximate 3-1 mix of range lead to monotype. Hardness is around 20.

I am thinking I maybe I need to change to 6-1.

Thanks

[flyfrod]

I use the same mold and drop boolits that measure the same. I use WW though and get around 405gr.

[Casting_40S&W]

According to Lee.....

Our published weight is based on a 1 part tin to 10 parts lead ratio.

[44man]

I don't know how the Lee is making such large boolits.
One problem is you don't know what is in the range lead, it might be stuffed with antimony so boolits age expand.
My aged Lee is .4765" to .477" and weighs 394 gr cast from WW's and water dropped.

[5shotbfr]

my lee mold drops exactly the same as 44man's

i'd try casting a few out of just the mono type (known alloy) and see what they come out at.

another question or two .. what are you using to measure the boolits ? . hopefully a micrometer and not verneer calipers .

are the boolits round ?
have you measured to see if the entire boolit is the same dia .. ie base , driving bands .

and finaly double check to be sure the mold blocks are closing all the way

[22454]

Thanks for the feedback.


I am using calipers to measure, not a micrometer. The bullets are coming out round. I am measuring them the morning after the evening they were cast.

I do also cast with a lee .452-255gr mold. These bullets measure .452 with the gunsmith's micrometer at the local gun store and with my calipers. I wouldn't think my calipers would be of more than +-.001. I am open to being educated otherwise.

I will cast the .452s with my new alloy and see how they come out. The alloy I used to cast them before was on the soft side and cast to ~260-263gr. I had leading in the rifling just past the forcing cone for ~.75". The amount left in the barrel stayed the same whether I shot 12 or 50 rounds. I am expecting them to come out ~235gr. I am also interested to see if they come out larger than .452".


I believe the weight issue is due a particular 7lbs of what I though was range lead which was given to me. The tin content must have been higher than I though even though it seemed soft. The range lead I claim myself it mostly from 22lr from a private range.

[mpmarty]

Calipers are great for OAL measurments. Boolits and bullets should be measured on a 0" to 1" micrometer unless you're dealing with 30mm stuff.