Critique this Cast Bullet (.376 cal)

hansol

hansol

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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.

cast.jpg


cast2.jpg


Thanks very much guys -Hansol
 
You might want to do a chamber/leade cast with some cerosafe. The nose looks pretty blunt so you may fit it in the magazine but not in the chamber. A cast will give you a good idea on what profile will work and what diameter you want, usually 0.002 bigger than 2 inches up the throat. I hear mountain moulds will make any design you want but if it doesn't work you're on your own.
 
JerryJeff,

Basically all I did was copy the same profile as a 380 grain Rhino bullet. I also "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.
 
id go with Steel for the block material. Brass scratches to easy, and im not sure about how much it expands when it is heated. which would make it a bit of a pain to get up to temp. and stay there.

Aluminum is ok, heats up fast. not all that much expansion. But like brass is soft, and wears out. long lasting casting blocks are steel.
 
hansol said:
JerryJeff,

Basically all I did was copy the same profile as a 380 grain Rhino bullet. I also "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.
Click to expand...

That's cool, I played around with some different cal designs for some big heavy flat nosed type bullets on his site over the years. I've just never taken the plunge yet. One thing I wonder about is hanging a big piece of lead inside the case. Would that affect the gas check or start deforming the base end of the bullet upon ignition? However, good luck on your mission and show the results please. P.S. loved the shotgun plumber style slugs!
 
JerryJeff,

Actually that's the beauty of this design: in a 350gr, 1.248" length, the gas check is parallel with the end of the neck/start of the shoulder. No lead protrudes past the shoulder and into the case. I too worried about having a lead bullet seated too deeply and essentially melting, so this was what I came up with.

If a guy was shooting a 375 H&H, in theory you could make an even longer/heavier bullet, but my Taylor has such a short neck that I'm limited to around 350 grains it seems.
 
Do you know for sure that a .373" bullet will bore ride? You want that front bore riding portion to enter the rifling not just the throat, for best accuracy. Most of my accurate cast loads, have the bore riding portion well into the rifling. The reason I ask is because using my .30 cals. as an example...they are .310" X .301" a dif. of .009" as opposed to your .003".....just something to figure with. Mountain molds are excellent molds and I have used then with complete success.
 
Aries- said:
id go with Steel for the block material. Brass scratches to easy, and im not sure about how much it expands when it is heated. which would make it a bit of a pain to get up to temp. and stay there.

Aluminum is ok, heats up fast. not all that much expansion. But like brass is soft, and wears out. long lasting casting blocks are steel.
Click to expand...

Obviously you have not worked with brass, way better than aluminum and you won't get tired as quick as a steel mold will. I have over 120 molds in my cupboard and I can't remember the last time I used a steel mold, once you have used brass you will never go back to steel.

Mountain Molds are excellent with great turn around time of about 2 months from the time you send in the order.
 
not a expert on your cal (i cast 30 cal for rifle) so take my advice lightly

have you measured your bore?
as cast bullets like 0.001 to 0.002 bigger than bore dia
and i have found if cast too big can be sized down but if too small are rejects

have you done any barrel twist calculations / ver velocity at what range /muzzle
what is your barrel twist?
what velocity do you expect from this bullet

have you thought about a hollow point bullet / with different pins

If the nose is too big (bore ride section) if you ever have to extract a live round you might end up leaving the bullet in the barrel
why did you go with 3 grease bands
2 larger grease bands might make it easer to lube (and keep more weight to the back but if you have 3 you do not have to lube all 3 (plug holes in sizer die)

why front band at 0.100? (but will allow you a lot of seating depth adjustment with out showing a grease groove (picks up dirt and lint) just concerned with overall length of base

when i load my most accurate 30 cal bullet gc is still in the neck and front band is about 0.040 past the mouth of the case (good visual seating indicator)
 
Mr. Fun,

Thank you for the insight; I very much appreciate it.

Firstly, the rifle is a 375 Taylor, 1:12" twist, 24" length. It's a new Pacnor 375 barrel, so I went with a .376" cast bullet size.

Velocity expected is hopefully around 2000-2200fps, hence the gas check design. I haven't done any twist calculations.

I decided against a hollowpoint design, as I wanted this bullet to be used for hunting big game. On top of that, I don't know if mountain molds makes them.

Regarding the grease bands, I went with 3 only because the base length + band + groove+ band lengths combine to make the bullet seat into the case neck properly. I really have no idea as to what 2 grooves vs. 5 grooves does, it was simply just to make a "crimp groove" line up.

The front band was another thing that I just threw in there for good measure, without really thinking about it. I understand now it helps with bearing surface, so for my second "version", I made it a heck of a lot longer.

cast3.jpg


Anyway, I suppose what it comes down to is that I want a heavy-for-calibre boolit that will lay major hurt on anything within 300m (rainbow tranjectories don't matter). So any suggestions as to designs to look at or things to watch out for would certainly be appreciated.
 
I'd make sure that the twist is fast enought to stabilize the long bullet and perhaps you could turn out a few dummy bullets on a wood lathe, just to make sure that the nose will feed through your rifle.
Brass moulds can cast very well and you're not going to cast them by the thousands as if you were a heavy competitor.
I've heard nothing but good things about Mountain Moulds but have never seen one.
Good luck on your project.
 
hansol said:
Firstly, the rifle is a 375 Taylor, 1:12" twist, 24" length. It's a new Pacnor 375 barrel, so I went with a .376" cast bullet size.

Velocity expected is hopefully around 2000-2200fps, hence the gas check design. I haven't done any twist calculations.
Click to expand...

Not an expert but did do some basic calculations and if your ballistic coefficentient is on the low side at .22 with a muzzle velocity of 2000 fps
Some bullets are better than that (so middle of the ground with the info)

With 100 yd zero 200yd -11.2 inch / 300 -40in drop
With 200 yd zero 100yd +5.6 inch / 300 -24in drop
With a300 yd zero 100yd +13.6 inch / 200 +16in high
If you up the velocity or have a higher BC it will be flatter shooting
You should hit 500 yds at 900 fps which should still be stable

for a plinking load you could go as low as 1600 fps at the muzzle and still be stable at 300 yds

hansol said:
Regarding the grease bands, I went with 3 only because the base length + band + groove+ band lengths combine to make the bullet seat into the case neck properly. I really have no idea as to what 2 grooves vs. 5 grooves does, it was simply just to make a "crimp groove" line up.
Click to expand...

Why do you need a crimp groove? I am shooting a semi lead bullets and only taking out the flair in the brass
I realize a big bullet with lots of recoil might move the bullet in the case
But traditionally only revolver rounds or rounds that might go in a tube mag get crimped

The front band was another thing that I just threw in there for good measure, without really thinking about it. I understand now it helps with bearing surface, so for my second "version", I made it a heck of a lot longer.

cast3.jpg

[/QUOTE]

I think you need to slug your barrel and measure the bore dia and get a mould that has a nose smaller than the bore dia

Reason if you want it bigger you can all ways lap it larger
Also lead bullets will bump up when you fire it
You said your rifle had a small chamber

What powder are you going to use ???

There are so many variables that I consider my self a rookie and don't want to lead you astray:eek:
 
Slug had a good idea

if you could find some 3/8 alum or brass round bar and get a local machinest to make a dummy bullet for you (with or with out grease grooves) and you could try it in a case and see if it will even chamber
 
I am no expert either. My way of design would be slightly different; that lenght of bullet is going to be susceptible to great bending force if hitting masive bone. I see that bullet no longer than 1.125" (3xdia) and more stubby; grease grooves as shallow as posible and bore riding dia of .340" enlarged to about .366" or so, that bullet would end up being in 325 gr weight range or so, which is plenty more stable with low velocities and much stronger internally. My 2c.
 
Hi guys,

Thanks for all the info. As has become rather clear, I am quite new at this. :)

For starters, my rifle slugs out to .3745-.375

Why do I need a crimp groove? I suppose I don't. I just assumed that was how cast bullets worked: you crimped the neck around one of the lube grooves/crimp groove. I guess I was just so used to using the cannelure on jacketed bullets that I figured you do the same on cast. Good to know that this isn't necessarily the case.

Regarding powder, I figured I would stick to IMR 4064, as that is what I've used for jacketed, and what most of my load data is based around.

Good idea on turning aluminum stock to see if the bullet will even chamber. I think i might just do that.

Gunrunner, thanks for the input. Your logic makes sense to me, so I will trim back the length.

Thanks again guys for all the constructive criticism. I really do appreciate all the help, as it would be quite a bad feeling to custom make a mold, only to have it throw crappy/unworkable boolits.
 
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