Bore Ride Question

[Suo Gan]

Tell me about bore riders

[felix]

Softer the boolit, the bigger the nose. You are looking for a non-deforming nose during ignition. Won't matter much if your are designing a boolit for a BR gun where everything is perfectly centered and assured by a tight neck. ... felix

[Suo Gan]

I found this old thread helpful.
http://castboolits.gunloads.com/showthread.php?p=178811#post178811

[Le Loup Solitaire]

The bore of a rifle barrel has two features in it; the grooves and the lands. In a 30caliber the distance measured from the bottom of the groove in one side to the bottom of the groove on the exact opposite side is supposed to be .308". the land measurement is a little less; from the top of a land to the top of the land on the exact opposite side is generally .300". Of course those measurements can vary with wear etc. But the point is when using cast bullets and talking about a bore-rider, the bullet in question has two parts to it....the bullet body which is fatter and rides in the (deeper) grooves and the nose or bore-riding (skinnier) section which rides on top of the lands. In a rifle barrel that has the above dimensions, a bullet body could be .308-.310 or even larger, while the nose or boreriding section should or could be .301, .302 or more if the lands were worn. This is the reason that "slugging" a bore is often recommended to determine what the internal measurements of a rifle bore actually are. LLS

[montana_charlie]

If bullet diameter in the lube groove is equal to bore diameter, and the diameter of the driving band is equal to groove diameter, the lube groove is only four thousandths deep.
That won't hold much lube...

CM

[Char-Gar]

Bore riding is a term that applies to the nose of the bullet and has nothing to do with the body of the bullet.

Bullet fit is somewhere between an arcane science and pure magic. But in general, the nose of the bullets that rides on the barrel lands should be land diamter or several thousands over. If the nose gets to big and the alloy is too hard, the round will be difficult to chamber and the bullet will stay in the barrel if a loaded round is extracted.

The bullet body should be exact throat size or .0005 under. This is the best of worlds.

There are a number of other variables such as the temper of the metal, the burning rate of the power etc. etc. etc. But in general the above will give you decent fit with most alloys and powders and will be a good place to start.

Good luck on your bullet design. We all get there in time and that is when you know there is no turning back. You have the bullet monkey on your back, for sure and for certain.