Mold Design for Bottleneck Cases

[5Shot]

For a bottleneck case, should the bullet shank be designed so that it does not extend into the case body, in order to keep from contaminating the powder?

On heavy for caliber bullets, this results in a fairly long nose, and correspondingly smaller drive bands and lube grooves. Although I don't know if it is enough to matter.

[btroj]

It isn't quite that simple. The bullet needs to fit Ina specific case in a specific chamber in a specific rifle.

the dimensions of the chamber and throat make a difference. Does the throat have much freebore? The leade and matters too. Is the chamber longer than needed?

Ideally I want the gas check at the neck/shoulder junction or above but it isn't always possible. Somehow I keep getting reasonable results anyway.

What you are describing is great, if you are will to have a mould cut for a specific gun. I want moulds that are multitaskers.

[5Shot]

It will be a one gun mold, as I only have one 35 cal rifle. The portion past the front driving band is going to have a bore ride section to keep it from tipping, and I would prefer to have the base of the gas check at the neck/shoulder junction as you describe. I can design it that way on the Mountain Mold Program, but I was a bit concerned about the driving band situation.

Is there a magic number for the bearing length in relation to the caliber?

[MikeS]

Well, there's no rule saying that driving bands have to fit completely within the neck of the case. What I mean is simply if you specify a larger first driving band, and have it sticking out of the case, as long as your rifle can handle a longer boolit, just be sure to keep the lube grooves within the neck of the case. If you're going to use a crimp groove, there's no reason it can't be behind the first driving band, and if you specify that the first band should be fairly long, then it would keep the lube grooves within the neck, and allow you to seat it with the whole boolit in the neck, rather than back in the powder area of the case. I'm not sure if I'm explaining this properly, but I have a perfect idea of what the boolit would look like, but can't quite translate it into words. If you're concerned about having a large driving band due to lube concerns, you might consider going to Accurate Molds to make your mould, and get a hybrid tumble lube / conventional lube boolit, and tumble lube the boolits after running them thru your lubesizer. I say switching mould makers, simply because MM doesn't like or make TL designs, but AM will make TL designs, and mixed TL/LG boolits.

[runfiverun]

there is an area in front of the case before the rifling begins called the throat area.
now you do not need a drive band to fill this area.
you don't need the nose to not fill this area either.
but there can easily be a smooth sided area on the boolit that does fill this area, in fact it would be a very good idea to do so.

make an impact of the area from the front of your case into the rifling and send that slug to veral smith.
call and talk to him, explain the alloy you are going to use.
he will cut you a correct mold for the gun.

at the least make the slug and see what you are dealing wiith so you can design a mold with the correct measurements for your rifle.

[5Shot]

Thanks for the responses.

I am planning on having a driving band in front of the crimp groove to aid in engaging the rifling, as well as a bit of a bore ride nose.

I am also going to make a throat slug prior to ordering the mold so I know exactly what dimensions I am working with.

All the suggestions are appreciated.

[Larry Gibson]

Thanks for the responses.

I am planning on having a driving band in front of the crimp groove to aid in engaging the rifling, as well as a bit of a bore ride nose.

I am also going to make a throat slug prior to ordering the mold so I know exactly what dimensions I am working with.

All the suggestions are appreciated.

Use enough lead, or what ever, so it also fills the neck and shoulder area of the chamber. This will give the proper dimensions. As mentioned, idealy, you want the GC (or the top of it at least) to remain in the case neck and the front of the driving band to just kiss the lands.

Larry Gibson

[5Shot]

Use enough lead, or what ever, so it also fills the neck and shoulder area of the chamber. This will give the proper dimensions. As mentioned, idealy, you want the GC (or the top of it at least) to remain in the case neck and the front of the driving band to just kiss the lands.

Larry Gibson

Got it! :cast_boolits:

[Blammer]

Just don't make it so long that it won't fit in the mag well.