Critique this Bullet Design (.376 cal)

[hansol]

Hi guys,

I'm just wondering if some of the cast bullet shooters here can critique this bullet I've designed. It's a 350gr "round nose" gas check design for my 375 Taylor, hence the .376 diameter. I'm planning on having Mountain Molds make this for me, and am thinking about using brass as the casting block material. Any info would be appreciated, both on the bullet as well as the casting material, as I don't know much about about either. (I've done casting for my ridiculous shotgun projects, but never for rifles)

I will be crimping around the "2nd" lube groove (at .31855 length to fit in the .330 length neck), and have the the third groove exposed. The 375 Taylor has a short neck compared to the H&H, so this "arrangement" seems to work well.

http://i129.photobucket.com/albums/p204/hansol04/cast.jpg

http://i129.photobucket.com/albums/p204/hansol04/cast2.jpg

Basically all I did was copy the same profile as a 380 grain Rhino bullet. I "long-seated" that bullet, chambered it, and let the throat "seat" the bullet to where it wanted. It worked out to the bullet having an over-all length of 1.248". So I just copied that.

[RobS]

If you are looking at a flat nose design you have it. I don't know what distances you are planning on shooting but the bullet you have designed will have to be run fast to combat the lack of aerodynamics; I see it doing well at 200 meters and down with 200 really maxing it out unless you have a bullet drop compensator type scope (if you are using a scope). It does look interesting and should put a heck of a smack down on whatever it hits that's for sure.

As for mold material: Larger bullets generate more heat so brass may not be what you need and aluminum could possibly be of a better fit as it dissipates heat better. Take a look on the mountainmold site under the heading on the left "Mold Construction" If you email Dan, he will be more than happy to give you his opinion on which mold material would be best for your intended purpose.

[hansol]

Hi Rob,

Thanks for the input. Basically I figured the bullet would be for "plinking" at ranges of 100-200m. It's for my 375 Taylor hunting rifle, which is scoped. I figure if the bullet shoots well, then I might use it for hunting too, hence the flat nose/heavyweight design. I'll be using a gas check, and am hoping to get speeds of 2000fps hopefully. I'm not very familiar with shooting cast boolits in rifles, so I'm not sure if I can get this speed without causing leading, however.

Shooting jacketed bullets these days is getting stupid expensive. Basically I can buy 50 jacketed 300gr bullets for the price of a Mountain Mold... And seeing as I can get wheel weights for free, it seems a better choice to start casting for my rifle too, not just for shotgun slugs.

[RobS]

I feel you on the expense as everything is going up and up. I think you should be able to manage 2000 fps with proper powder selection.........Maybe RL 15 or something of the like. One thing is for sure you're going to feel it from the back at 2000 fps as you probably already know shooting J-bullets past that velocity. I use to shoot an 335 grain NEI bullet in the 375 H&H at 2100-2150 fps and I only torched off a few of those per range session. :bigsmyl2:

I've had better accuracy pushing the high end loads with water quenched WW bullets, but your gun may be just fine with air cooled.

[Cap'n Morgan]

I would replace the radius at the front with a tangent ogive, and maybe increase the meplate a little. Ballistic coefficient would be the same or better, and chambering would most likely improve.

[Bass Ackward]

Morg hit it for ya. If this is a copy that feeds you are good to go. This is a way longer nose than I would design cause taper (diameter) is going to depend on Dan's cut and I hate relying on something I can't size for a design. So I, myself, would rent a throater reamer and lengthen my throat for a more conventional go at it.

Instead of critiquing "your" design since I don't know the gun, I will recommend.

When I go through this process, I design a bullet. Then I print it out and set it aside. Every week I come back and without looking at previous efforts, try to design it again and go with what I see in my mind. Then after 4 or 5 weeks, I go back and compare what I did on all the designs and how my mind created new ideas / changed over the time.

If they all look very close, you will probably be happy with the mold / design. If all 5 look different (with different defined by you) then I would stop for a couple of weeks to re-evaluate and then do it again. By then you aught to be able to have run all the differences through your mind and picked what REALLY was important to you.

[hansol]

Hi guys, thanks for the input so far. I'm basically entirely new to the cast bullet design thing, so to be honest, I am mostly just going on a few assumptions/ideas:

-It's a 375 rifle (not a 38-55 thingy, hence the .376 diameter)
-2000-2200fps velocity
-For laying heavy hurt on stuff inside 300m (rainbow trajectory is not a big deal)

Mostly, I'm assuming I want a long bearing surface, so that the boolit centers itself well in the bore? I also assume I want a weight-forward/very heavy/wide meplat design for hunting?

The rifle itself is an FN Browning Mauser chambered for 375 Taylor (338 win mag necked up to 375). 24" barrel, 1:12" twist.

Here is version 2. I like this one a bit better I think, as there isn't near as much strange taper to it, and I think is a better bore rider. Anyway, like I said, I am an inexperienced amateur with these things, so I really appreciate any input you guys have about what will work/won't work with my expectations. Photos are always appreciated :)

http://i129.photobucket.com/albums/p204/hansol04/cast3.jpg

Regarding the boolit "length": Essentially all I did was long-seat a 380 grain rhino copper jacketed bullet in a case. Then I chambered the round, causing the throat to re-seat the bullet to its "preferred" length. I then took a micrometer out and measured the dimensions of that, and transfered those to my first design.

[Bass Ackward]

Regarding the boolit "length": Essentially all I did was long-seat a 380 grain rhino copper jacketed bullet in a case. Then I chambered the round, causing the throat to re-seat the bullet to its "preferred" length. I then took a micrometer out and measured the dimensions of that, and transfered those to my first design.



I think that you want to seat to that perfect length and then see if it feeds. By feeding, I don't mean being gentle with it.

Personally, I do very well with .200 - .220 meplats at 2000 fps on up in my 35 with 200 to 225 grainers. That's only a 58% meplat for you. The point is that if you need to cut down on the meplat to get it to feed properly, you have some wiggle room.

The whole reason here is the belt that can limit your options pretty quick. And you don't want to be having to fool with the rails just because of a mold.

Since you are still unsure, my advice in my first post seems appropriate.

[1Shirt]

If in fact you do have it made, I would be interested in trying a few in my H&H, and would like to buy enough to do a reasonable test. Say 25-50.
1Shirt!

[StarMetal]

I would do a chamber cast to get the exact dimensions. I would, and I imagine that you have already, get the bore and groove diameter. Then with this information set the dimensions of the bullet that you have drawn up. You want to fit that throat diameter if the neck area of the chamber will let the case chamber and still have some clearance to let the case expand to release the bullet. Being that bullet has a long bore riding nose on it, it is important that the nose fits the bore. This is dependent on the alloy too.

[hansol]

Hi guys,

Once again, thanks so much for all the input. Bass Ackward, it's not that I'm unsure, it's that I don't know enough to know if I should be unsure! :)

Anyway, yes, I have slugged the bore, and am at .3745-.375 diameter. The barrel is basically brand new, with less than 200 down the pipe.

I know that with the copper jacketed rhino bullets seated to that "perfect" depth, it fits in the mag well, and will feed with no problems. I made up 3 dummy rounds to that length, and they all would fit in the mag well and feed. Of course the difference is they are a tapered roundnose design, so I would assume the flat nosed boolit might handle it differently.

I think what I might do is make up a few dummy rounds, turn them on the lathe, and see how they do.

[Bass Ackward]

I think what I might do is make up a few dummy rounds, turn them on the lathe, and see how they do.


If you have that capability, then better safe than sorry.