MP Moulds - WOW!

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Petrol & Powder

Well-Known Member
Michael said:
What flavor did you get, for your.... 1st .... one?
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.358"-165-RF, 4 Cavity HP Mold
Brass

I got done a little early today and managed to cast a little with it.
After degreasing the mold and rejecting about 2 dozen bullets it settled down and made beautiful bullets.
I had the Penta pins in place, no problems. I'll probably switch those out for the round HP pins.

With the Penta HP pins the bullets drop at 157.7 grains with my alloy before filling the lube grooves. I couldn't ask for a better weight.
They mic right at .358" and I size to .357"
Doesn't get much better than that.
And the mold is priced right. It really is a good value.
 
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burbank.jung

Active Member
Congratulations. Yes, they are a piece of art. Don't forget to heat cycle you mould. I used my oven since there's no lead on it. I didn't smoke mines and my bullet weights were very consistent.
 
Spindrift

Spindrift

Well-Known Member
I also have the MP 358-165, mine is a plain base, solid 4-cavity. I use them for low recoil loads in my .35 Whelen, with good accuracy.
 
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Petrol & Powder

Well-Known Member
I was getting some weird flyers with the penta (five point) HP and CFE Pistol powder. I don't know if that was the mold, powder, or some unknown variable. I’m going to try Bullseye powder and use up the remaining penta HP bullets and see if that's better. I switched out the penta pins for the more conventional round HP pins and will cast some of those later.

I'd like to find a good +P load for this 158(ish) grain bullet, preferably with Bullseye or HP-38 (WW-231)
 
358156 hp

358156 hp

At large, whereabouts unknown.
Snakeoil said:
Checked put their site. Nothing smaller that .28.
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His cataloging is kind of deceiving. He lists moulds by his specs, and not by nominal size. His way is more honest of what you can expect, but you have to check his list a couple of thou larger and smaller to bracket what you've looking for.
 
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Petrol & Powder

Well-Known Member
I'm not sure why the hex (6 points) or the penta (5 points) pin would produce less accuracy but I suspect it may be difficult to maintain uniformity between hex and penta pins and easier to make cone shaped pins uniform. Just a guess on my part.
 
Matt_G

Matt_G

Curmudgeon in training
Petrol & Powder said:
I'm not sure why the hex (6 points) or the penta (5 points) pin would produce less accuracy but I suspect it may be difficult to maintain uniformity between hex and penta pins and easier to make cone shaped pins uniform. Just a guess on my part.
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I can't help but wonder if aerodynamic turbulence has something to do with it.
Bear with me a minute.

Since the bullet is spinning, those flats and corners inside the HP cavity can't be real conducive to a constant, steady airflow.
Seems to me it's gonna be pretty turbulent, therefore the aerodynamic forces involved will vary millisecond to millisecond.
You wouldn't have that issue with a round concentric cavity.
Just my goofy a$$ theory.
 
Spindrift

Spindrift

Well-Known Member
I can’t say I have noticed any difference in accuracy potential in penta points vs conventional HPs. I haven’t done any really systematic testing, though. Might have to do that!
 
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Petrol & Powder

Well-Known Member
My guess is balance, not aerodynamics, is involved.

I doubt the airflow in front of that blind hole is significant, but I believe small differences in wall thickness could be important to a projectile spinning at high RPM's during flight. Again, just guessing.
Sort of the same way a small void in a bullet can have influence on trajectory.
 
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