Ask the Bullet Designer BobK

[2 Dogs]

Jan 20, 2018 15:53:24 GMT -5 bcelliott said:

Bob, I'm just getting into casting, and Fermin has gotten me in the habit of signing up for your mold designs in the group buys. I was wondering if you could design a 640 hp bullet for the .41 magnum with dual crimp grooves. I have both a Ruger Bisley Blackhawk and Ruger Redhawk in this caliber. The Bisley accepts approximately a .41 nose and the Redhawk will take a .52 nose. I'd be interested in bullets anywhere from 220-280 gr, perhaps one on the low end and one toward the high end? I'm trying to maximize case volume to drive them fast, especially in the Redhawk. Thanks!

We are going to be running a 41 caliber design soon.

[bcelliott]

Thanks, Bob and Fermin. I will wait for the new .41 design. The only Redhawk nose-length bullets I've found have been loaded by Garrett, and they are .429 and .452.

[clintsfolly]

Well I remembered that I got a tracking # on my new mold it,s setting in NewYork. Been there since 1/11 and hasn’t moved or been updated. 🙁

[jdoc]

Jan 21, 2018 13:57:54 GMT -5 clintsfolly said:

Well I remembered that I got a tracking # on my new mold it,s setting in NewYork. Been there since 1/11 and hasn’t moved or been updated. 🙁

You're not alone.  Mine is right beside yours.

[bcelliott]

Please pardon me if this has been previously discussed, but what makes a design a 640? In other words, how is it unique from other cast bullet shapes or styles, and also, why might this design be predicted or have proven to be a faster killer than say a LFN bullet cast with the same alloy? Just from looking at the three .32 group buys (all of which I have ordered!), both the nose length and meplat diameters are variable. Thanks.

[2 Dogs]

Please pardon me if this has been previously discussed, but what makes a design a 640? Again, I am not Bob, and I do not pretend to speak for him, but to answer your question, what makes a 640 is the way the nose of the bullet enters the forcing cone and then the rifling itself. In other words, how is it unique from other cast bullet shapes or styles, already answered and also, why might this design be predicted or have proven to be a faster killer than say a LFN bullet cast with the same alloy? I don't think anyone has a stop watch on it or anything. And in all cases there is always the exception to the rule. However, the 640 by design can be set up in any way one might need a cast bullet to be set up. In other words, the design can answer any call from a solid, to a soft nose, to a cup hollow point or to a large cavity HP design to shed it's petals yet with enough shank to fully penetrate the medium in question Just from looking at the three .32 group buys (all of which I have ordered!), both the nose length and meplat diameters are variable. True, however, the ogival design is what is unique about each design with all of the other factors taken into consideration. Thanks.

[boolitdesigner]

^^^^^^^ Fermin did pretty well at answering the question. Several others have asked basically the same question in different terms. Read the whole thread and it should be clear.

[bcelliott]

Thanks, Fermin and Bob.

[clintsfolly]

I have tried to email MiHec to find out if he will take anything but PayPal for group buys? I have used credit card to buy from his E store.

[bushog]

So...I see Miha is now offering molds in a "Hi-Tek" version which I'm gathering is a non-lube grooved configuration for powder coating.

Does anybody have any experience with these molds made for powder coating only?

[2 Dogs]

Ok BobK, your favorite galena gnome gotsa good query for you!

Describe how you would go about the best cast 9mm cast hollow point bullet. Would you alloy a 115 grain cast HP differently from a 147? How would you determine what diameter to size for a individual 9mm pistol?

Thanks!

[boolitdesigner]

Feb 1, 2018 11:21:18 GMT -5 2 Dogs said:

Ok BobK, your favorite galena gnome gotsa good query for you!

Describe how you would go about the best cast 9mm cast hollow point bullet. Would you alloy a 115 grain cast HP differently from a 147? Considering the pressure levels are about the same... No! Harden to the point it doesn't lead and no more. Of course, you can harden by alloy constituents or by having little antimony and less tin via heat treating... either by oven or water dropping. How would you determine what diameter to size for a individual 9mm pistol?
9mm barrels vary from 0.354" to 0.359" in groove dimension. Adding to the problem is chamber size. Slug the throat of the barrel to get groove size and try a bullet that size to 0.0005" above that..... then load one and see if it fits.

Thanks!

My 9mm barrels are usually happy with a 0.3574" bullet.

[sixshot]

Greg, I've been shooting a 9mm, non lube groove bullet for 2 maybe 3 years now & it works great. I also shoot it in my 38 specials & all of them, both 9mm & 38 special are sized .3575" with fine accuracy. Mine weigh right at 140 grs powder coated.

Dick

[2 Dogs]

Another one Bob, let's start with a clean slate here and just pretend for a minute you had not yet designed your 32 caliber 640 bullets.

Looking specifically a the Ruger 30 Carbine Sixgun (not interested in making it work in a M1 Carbine), with it's magnum payload case capacity, brute strength cylinder, and generous nose to crimp dimensions, what would you consider to be the best cast bullet or bullets for that vehicle? Remember, the New Models allow for the 32-20 case with it's rim to be used and thus would possibly benefit from a crimp groove so we might have a OM bullet and a NM bullet. Thoughts?

[boolitdesigner]

^^^^^^^^^^ Since it has different parameters, a new design of course.