Bore riding bullets??

[RyanJames170]

So on bore riding bullets, is a bad for them to be engaged to some degree by the rifling? If so how much is to much? What issues dose it cause?

[Ozark mike]

Id set em back .005 but i have limited experience on this topic

[Dapaki]

Such a simple question with SO MANY answers!

Example: My 7mm-08 loves 130gr cast boolits, I GC & PC them then load them so they just kiss the lands. Its a Handi so the OAL matters little. Pressures look GREAT, primers are still rounded on the edges and Im getting a touch under 2k for velocity.

[Wayne Smith]

If they don't stick in the bore when you take the shell out without firing don't worry. If they stick and are accurate, always fire the shell in the chamber!

[charlie b]

I've had some that were difficult to chamber and they still shoot well.

FWIW, I usually determine where the lands are by 'coloring' the bullet with a Sharpie. When my bullets are sized to just fit in the bore the thickness of the Sharpie makes them difficult to load.

I use a nose size die to get the bullets just right. The bullets touch the bore and then I seat the rear portion so it lightly engraves as well. Best bullet shapes for this have a tapered portion from the bore riding section to the first drive band.

[RU shooter]

If they don't stick in the bore when you take the shell out without firing don't worry. If they stick and are accurate, always fire the shell in the chamber!
Pretty much sums up how I do it . On a bore riding bullet like the Lee 30 cal 170 fn let's say the nose portion needs to be in contact with the lands. When you chamber a loaded round and extract it you should be able to see a light scuff mark made by the lands the whole way around
The dia. Of the nose portion don't need to be deep but contact is needed to hold the bullet straight on it trip down the barrel on bullets with a shorter nose like the Lee 150 or 160 rn its more balanced the rear is longer than the nose so not as important . But if it chambers and extracts without pulling the bullet it's good even with deeper engraving from the lands

[mdi]

Hmmm. How many of the above posters really know what a "bore riding" bullet is and how it is supposed to fit? A couple?FWIW a bore riding bullet has a section that does not engage the rifling, it rides in the bore...

[stubshaft]

Hmmm. How many of the above posters really know what a "bore riding" bullet is and how it is supposed to fit? A couple?FWIW a bore riding bullet has a section that does not engage the rifling, it rides in the bore...

Very true, but, obturation will cause the nose to be lightly engraved by the rifling.

[Oldfeller]

Why this confusion continues is the use of the term "bore riding" bullets --- these are "land top riding" bullets.

If you used the right words folks would understand them better.

A "bore riding" bullet is a throat-fitted loverin style slug that is insta-sized by acceleration in the throat (by obturation slug up) ..... followed by push sizing the throat sized slug down into the fully engaged rifling to become a true bore riding projectile.

(Mann called them putty plugs and it explained many of his "short barrel test" deformation results)

And, if you think the "reduced nose diameter" even exists past the instant of ignition I suggest you stop a low velocity bullet or two in water jugs and look at the full depth rifling marks on that "reduced nose diameter".

:coffee:

[Maven]

I tried to post about this yesterday, but got caught amidst the server changeover. To wit, bore riding bullets are also know as two diameter bullets as mdi suggests. If the bore rider in question fits [your gun] correctly, it will be engraved the rifling, lightly or deeply, depending on the nose diameter of the bullet and the depth of the rifling. I suppose it's up to the shooter to determine just how much engagement is wanted.

[Bad Ass Wallace]

My best example of a 'bore rider' is the 375gn boolit for my 38/55. The entire nose contacts the rifling and it shoots great!

https://i.imgur.com/G1Y3yr2l.jpg

[Good Cheer]

My favorite is for a 45 Colt rifle.
http://i.imgur.com/lBq6Eld.jpg (https://imgur.com/lBq6Eld)
The crimp groove to front of first land is to SAMMI specs to kiss the rifling.

[charlie b]

Why this confusion continues is the use of the term "bore riding" bullets --- these are "land top riding" bullets.

If you used the right words folks would understand them better.

A "bore riding" bullet is a throat-fitted loverin style slug that is insta-sized by acceleration in the throat (by obturation slug up) ..... followed by push sizing the throat sized slug down into the fully engaged rifling to become a true bore riding projectile.

(Mann called them putty plugs and it explained many of his "short barrel test" deformation results)

And, if you think the "reduced nose diameter" even exists past the instant of ignition I suggest you stop a low velocity bullet or two in water jugs and look at the full depth rifling marks on that "reduced nose diameter".

:coffee:

First, bore riding is a bullet with a nose that rides on the bore, ie, touching the lands but not engraved into the grooves. It 'rides the bore' as it is chambered. The bore is defined by the 'tops' of the lands.

Second, yes, the bullet should upset into the grooves when fired.

The bore riding portion is to allow a long, heavy bullet to be chambered in a rifle that has a short neck and/or throat. The forward section needs to be sized closely to the bore to make sure it stays 'straight' on loading. That way at least you have a chance that it will upset evenly into the grooves.

[Dapaki]

Well, well, well, learn something new everyday! I was always under the impression that a 'bore rider' was a boolit that the nose was smaller than the lands distance and the driving band is where you kissed the lands when loading the cartridge?

This .310 runs .297 on the nose and just slides over the lands.

264184

[samari46]

My Finn 1935 Model 39 uses Lyman's 314299 sized to .3135 and every so often I'll push one down the barrel and check for any dimensional changes. With the above bullet seated out as far as it can go it will not fit the magazine. Instead I let the bullet sit on the loading tray or follower and let the bolt push into the chamber.
In over 3000 rounds have not had any problem too date. But back to the OP's question. When pushing the bullet through the barrel will show mild to moderate engagement but the body of the bullet shows very definite engagement. I'm not trying for world record groups. I usually get 2" groups @100yds. Frank

[bluejay75]

My favorite is for a 45 Colt rifle.
http://i.imgur.com/lBq6Eld.jpg (https://imgur.com/lBq6Eld)
The crimp groove to front of first land is to SAMMI specs to kiss the rifling.

What boolit is this?

[charlie b]

Well, well, well, learn something new everyday! I was always under the impression that a 'bore rider' was a boolit that the nose was smaller than the lands distance and the driving band is where you kissed the lands when loading the cartridge?

This .310 runs .297 on the nose and just slides over the lands.

264184

Do both. The bore section touches in the bore and the rear driving bands are engaged into the rifling when chambered.

[Dapaki]

Do both. The bore section touches in the bore and the rear driving bands are engaged into the rifling when chambered.

Soooooo, it's a bore rider?

[charlie b]

Soooooo, it's a bore rider? Yes it is.

[MT Chambers]

I call 'em bore riders anyway, you do not want the bore rider portion to be loose in the bore, you can test this somewhat by trying the boolit into the barrel from the muzzle end.

[Alferd Packer]

A round ball that is a bore rider should be able to be shot as a catsneeze load powered by a primer only.
There is no body on a round ball to engage the rifling.
However, shot with a heavy enough load, the bore riding round ball can be made to obturate, actually starting to flatten and can be made to engage the rifling, making it lead the bore.
The same can happen with bore riding noses on bullets with a body made to engage the rifling.
The powder load must not be too heavy or the body of the bullet will start to catch up to the bore riding nose making it bump up to engage the rifling before the bullet makes it out of the bore.
That's why its recommended to follow the loads that work for this type of reloading and don't attempt to use jacketed bullet powder loads.
They will be too heavy in most cases.
Also pay attention to the post by MT Chambers regarding size of the bore rider and fit into the bore.
You need to have a micrometer and learn to read it to measure these bullets.
Fit to bore size and understanding fit to rifling engagement are essential to know.

[Alferd Packer]

Another thing is when you read a reloader say that this size bore riding nose works perfect for him.
That only pertains to HIS firearm.
Yours may be the same caliber, but each firearm is a law unto itself.
You reload for your own.What works for him, very likely won't work for you because all these guns are made one at a time , sometimes on different machinery by different people making them differ by large amounts as well as small amounts.
Factory loads are made to just safely operate in a lot of similar hi.
We as handloaders can experiment finding powder and bullets that fill in the gap that makes our own firearm shoot a little straighter or recoil less with lighter loads and sometimes save some money.
But, always remembering that what works for another fellows firearm, just may not improve yours.
So approach all loads with caution as well as all advice.
Think before doing it and verify by asking questions and reading those reloading manuals.
Many different mauals.
Be safe.

[charlie b]

That, in a nutshell, is why it is best to slug your throat and bore so you can size your cast bullets to fit your rifle.