New 6mm HP mould

[Glen]

I just got my 6mm mould back from Erik, and he did an excellent job with his inset bar HP conversion. The starting mould was the RCBS 100 grain GC. We shortened the bullet a bit, and put in the HP cavity, so I'm guessing that the final HP will weigh 92-93 grains. I am aiming for ~2000 fps from my 6mm PPC Contender. This is going to be a fun project!

 

[Ian]

Looks like coyote medicine to me!

 

[fiver]

Glen:
wasn't you working on a 30 cal high speed project not too long ago?
how's that going?

if you pull this one off I might go back on my word about not doing a 6mm boolit in the 243.

 

[Ben]

I just got my 6mm mould back from Erik, and he did an excellent job with his inset bar HP conversion. The starting mould was the RCBS 100 grain GC. We shortened the bullet a bit, and put in the HP cavity, so I'm guessing that the final HP will weigh 92-93 grains. I am aiming for ~2000 fps from my 6mm PPC Contender. This is going to be a fun project!

View attachment 1589

Erik's work is on the level of " art " in machine technique and skill level.
He has done several molds for me, he is the BEST ! !

Ben

 

[Glen]

Yes, I was working with a Husqvarna .30-06 with a 1 in 12" twist, to see how much faster I could push a cast bullet than with the standard 1 in 10" twist. Haven't done much with that in the last month or so, but I have gotten very good accuracy at 2150-2200 fps with the RCBS 30-180-FN. I need to get back to that and see how much higher I can go...

 

[Glen]

As for the 6mm HP, I'm kinda thinking about making another trip down to Arizona to go after javelina.....

 

[Uber7mm]

That's a pretty mold. Have you had a chance to test the HPs out yet? A milk jug water test or wet phone book recovered slugs would be interesting to see.

 

[Glen]

Just got it in the mail yesterday, haven't had a chance to cast with it yet (hope to this afternoon, or tomorrow).

 

[JWFilips]

Glen,
Now that is a nice Bullet! I have no doubt that it is going to be a great shooter ( I'm even betting better then the solid version) Can't wait to see your results
Jim

 

[Glen]

My estimate of the weight was off (that's what I get for not casting with the parent mould first). The HPs drop from the blocks right at 100 grains.

 

[Glen]

Checked and lubed they weigh about 102.5 grains. My 11" 6PPC Contender barrel has a 1 in 10" twist, so I am hoping to be able to get 1800-1900 fps with very good accuracy with this combination.

 

[Ben]

Glen,

That looks like a great combination.
Will you please keep us posted on the performance of that bullet ?

Ben

 

[Glen]

Will do. I hope to get out and go shooting this next week.

 

[KHornet]

Will be very interesting in your results. I am a fan of the 243, but have never been able to get the long heavy ones to shoot worth a hoot. Am giving it another go round with much faster loads than I have used in the past to see if they will stabilize and group!

 

[Glen]

Just getting the gun sighted in, and started working up loads. This target was shot at 25 yards, and the load is doing right at 1800 fps (1 in 10" twist). There might be some potential here....

 

[KHornet]

Sure looks like a good start Glen!

 

[Glen]

So far, groups at 50 yards are running about 1-2". What concerns me is the bullet holes are not quite round, which suggests that the bullets are not fully stabilizing. I'll need to shoot this one at longer ranges to learn more.

 

[Glen]

Update on the 6mm HP -- this bullet comes out at .935", checked and lubed. According to the Greenhill Formula, the longest 6mm bullet that a 1 in 10" twist will stabilize is .893", which suggests that we're about .042" too long. Before I send the mould back to Erik and ask him to modify it to any new design parameters, I'm going to do a few experiments. This morning I sat down and made a "trim die" from a chunk of an old shot-out 6mm barrel. I cut it off, faced it off, and trimmed it back to .893". Then I bored it out with a D bit (.246"). I'm going to use this just like a brass trim die, and place a sized/lubed bullet in the die and file the nose back to .893" and then load up 10 and shoot a pair of 5-shot groups. Group size and hole roundness (compared to the parent HP) will gauge the success or failure of the hypothesis.

 

[Rick]

Glen, I've always considered the Greenhill formula as a get in the ballpark number. Being .042" over the Greenhill ballpark figure seems pretty close, your only shooting this bullet at 1800 fps would not a bit more velocity round up those holes compensating for a slightly long bullet?

.

 

[Glen]

Short answer -- no. Higher velocities resulted in larger groups and more oblong holes. Longer answer -- we have two countering forces here -- the rotational velocity necessary to stabilize long bullets, and the ability of a cast bullet to withstand the rotational forces imparted by a fast twist barrel (i.e. stripping). If I were to cast these with straight linotype, or heat treat up to BHN of 30, then yes, pushing the velocity up a bit might help -- but then they would lousy varmint bullets. So I am looking for a solution that will provide top-notch accuracy and still allow for explosive expansion.