From driving ban to tip?

[Willyp]

I have cast some boolits and like checking them by putting them into the bore at the front of the barrel. If they drop into the bore,the boolit ahead of the driving bands,[imho]they are too small in dia?
Here is where i need ideas! How tight should the boolit fit,past the ogive,or does it not have to be a squish fit,to ride the bore?
How do you bump a boolit up a bit?
Will the driving bands stablize the whole projectile,when fired?
Maybe i'm going at this the wrong way,this is why i've ask. I am getting too many castings that fit my bore very loosely!

[gray wolf]

Maybe i'm going at this the wrong way,this is why i've ask. I am getting too many castings that fit my bore very loosely!
Yes your going about it the wrong, you got the wrong end of the horse going into the stall.
better yet slug your bore.
It's the driving bands that need to be 1 or 2 thousand over groove diameter. not the portion above the drive bands, unless it's a bore rider but I don't think that is what we are talking about.

[mikeym1a]

for slugging your bore, here is a nice tutorial; http://7.62x54r.net/MosinID/MosinSlug.htm

[Maven]

"I have cast some boolits and like checking them by putting them into the bore at the front of the barrel. If they drop into the bore,the boolit ahead of the driving bands,[imho]they are too small in dia.?"

Willyp, That's Robert Sears (NRA) quick & dirty test for bore riding CB's. And yes, if they drop in the muzzle (of their own weight) up to the driving bands, accuracy will be less than stellar: The noses should be engraved/marked by the rifling, but that doesn't tell you what diameter you'll need to size them to. As others have said, you'll need to slug your bore for that.

[fouronesix]

I have cast some boolits and like checking them by putting them into the bore at the front of the barrel. If they drop into the bore,the boolit ahead of the driving bands,[imho]they are too small in dia?
Here is where i need ideas! How tight should the boolit fit,past the ogive,or does it not have to be a squish fit,to ride the bore?
How do you bump a boolit up a bit?
Will the driving bands stablize the whole projectile,when fired?
Maybe i'm going at this the wrong way,this is why i've ask. I am getting too many castings that fit my bore very loosely!

Almost sounds like a problem with definitions. A bore rider design is one where the portion of the bullet forward of the front drive band (the nose section) is at or sightly larger than the land diameter-- so it rubs, touches or is slightly engraved by the lands when the cartridge is chambered thus being supported during its travel down the bore. A non bore rider design is one where the nose portion is smaller than the land diameter so does not normally contact the lands.

First, the muzzle is the wrong end to check. Seat a bullet into a sized case to whatever depth you will seat it for a loaded round. Carefully chamber the test round and extract. If it is a bore rider (bore riding nose) the lands should show small steaks of contact on the wide, parallel nose section. If it is not a bore rider design then the nose portion, the part of the bullet that is forward of the front drive band, may not show any land marks and that is normal for non bore riding designs. But given the extremely wide range of mold/bullet designs plus the wide range of rifle chamber designs/dimensions and throat, leade and bore dimensions and wear... nothing is written in stone.

Oh, I guess you can bump up the nose section and some do, but I have no idea how that is done while maintaining concentricity of the nose.... without investing in a separate swaging die that supports the bullet shank while swaging the nose. An example of an undersize bore rider can be found in a common 30 cal. mold. The Lyman 311299 is supposed to be a bore rider (bore riding nose) for the average 30 cal rifle. However, many or most times the 311299 nose diameter is smaller than the average 30 cal land (bore) diameter. That creates a slumped nose situation during its travel down the bore. However, the Lyman 314299 usually drops a nose that is a proper bore rider in many 30 cal bores. Then it's a matter of sizing the drive bands of the 314299 down to the best fit for the 30 cal while maintaining the benefits of a bore rider (bore riding nose).

[Shiloh]

Nice tutorial from the Mosin website.

My 311299 cast to small so I sold it. Noses at .298-.299. Went with the 314299 for the '03 Springfield and Krag.

Shiloh

[fouronesix]

Nice tutorial from the Mosin website.

My 311299 cast to small so I sold it. Noses at .298-.299. Went with the 314299 for the '03 Springfield and Krag.

Shiloh

Yes, I think this has been discussed here several times. Haven't been to the Moosey Nugent site but wouldn't doubt good info there about this issue.

[Willyp]

foronesix, that helped me alot. Thankyou guys.

[gmsharps]

for slugging your bore, here is a nice tutorial; http://7.62x54r.net/MosinID/MosinSlug.htm

Great info

gmsharps

[chutestrate]

The site is very informative, but I'm a little confused. The author states the grooves are what are important. "What is important in bullet selection is the groove diameter". However, it shows his caliper measuring the lans. It's just me, but what am I missing? Wouldn't I need to measure the grooves instead of the lans?

[fouronesix]

The site is very informative, but I'm a little confused. The author states the grooves are what are important. "What is important in bullet selection is the groove diameter". However, it shows his caliper measuring the lans. It's just me, but what am I missing? Wouldn't I need to measure the grooves instead of the lans?

The "lands" on the slug are the grooves of the bore and the "grooves" on the slug are lands of the bore! :)

[chutestrate]

Oh boy, going back to sleep now. guess it was too obvious.

Thanks!!!