NOE 379449 PB

[Brad]

I decided that since I won't be shooting my 375 Win as much with heavy loads as I will lighter ones that a plain base mould made sense.
I ordered a 5 cav NOE 379449 PB mould. Got it cleaned, lubed, and cast a hundred or so. I later went and file a very slight bevel on the inner top edge of the blocks, I was getting too many slightly rounded bases.



You can see the one on the left has a slight rounding to the base. The one on the right is nice and sharp. The middle one has an almost perfect base but has a sight crescent that didn't fill ot as it should. This is usually a sign that the mould needs a bit better venting. A very slight bevel on the upper inside corner of the blocks allows that venting.

They drop at .380 and will easily size to .379 for the rifle. I think that as long as I keep them under 1400 fps there will be no leading or accuracy problems.

 

[Ben]

a bit better venting

Yes, I'd bet that is your problem on that mould !

 

[Brad]

A really tight fit sure looks nice but the air has to go somewhere. I will try and run more tomorrow and see if I have enough venting now.

 

[Ben]

Can you flip the sprue plate back and forth with your little finger when the mould is cold ?

 

[Brad]

Yes. I like them snug enoug to not flop around but loose enough to easily swing.
I also noticed a mark on the top of the mould from the plate so I filed a bit more bevel n the plate to reduce the marking. The mark lead right to a cavity and in time might have left a burr making bullet drop an issue.
I have decided over the years that all new moulds need a good look over and some tweaking to perform best.
As much as Lee moulds have some issues I really like the mould top venting they are using on the new 6 cav moulds.

 

[Ben]

Brad,

Probably a venting problem.
I've ( on occasion ) had to file with a fine cut flat Swiss file a slight bevel ( about a 25 degree angle ) on the tops of the mould blocks to allow air to escape under the sprue plate.

As a matter of fact, I did a Lee mould like that today and it made a world of difference in the appearance of the base of the bullets.

 

[Brad]

That bevel is exactly what I created. Done properly, which means minimally, it doesn't cause finning but does dramatically improve base fill out.

 

[Ben]

Exactly, well spoken.

Just the right amount and you're in business with a stubborn mould.

 

[KHornet]

He showed me one of the end product. Super nice bullet for either of his 37 Cal rifles.

 

[35 shooter]

Brad that is a super nice looking bullet. Bet it's going to shoot great for you.
I'll be watching for the results on this one.

 

[Ian]

Lee "two-bangers" of recent production have the vented tops, too. LBT and BRP had cavity top venting as well, I find it's probably more effective at giving "trash" a place to go and not gall up the sprue plate as it is an actual vent, "breaking" the inside top mould halves with a file seems to take care of that as long as you don't "pressure cast", then you'll have ears on your bases.