bore riding vs non bore riding recommendation

[danielasmith223]

so i am about to buy my first cast an i was wondering if i should go with a bore riding or non bore riding cast. MY friend and i have yet to slug our barrels, how ever we want a cast a bullet that will works well for both of us. it is to my understanding that bore riding bullets are more versatile due to there slightly larger groves. is this correct?

I am currently looking into this cast

http://www.midwayusa.com/product/562844/lee-2-cavity-bullet-mold-c312-185-1r-303-british-312-diameter-185-grain-1-ogive-radius-gas-check

[Iron Mike Golf]

Bore riders do a couple of helpful things:

- the nose acts like a pilot to help center the boolit in the bore
- you can seat them further out. That lets you ensure the gas check is in the case neck. Helpful for cartridges with short necks and guns with little freebore or short throats.

The downside is you might not be able to push them as hard, owing to the reduced bearing surface.

[Maven]

"It is to my understanding that bore riding bullets are more versatile due to their slightly larger grooves. Is this correct?"

Not quite, Daniel. Bore riders are 2 diameter bullet designs: a smaller, nose section which rides atop the lands; and a larger body with several lube grooves. By contrast, Loverin designs are essentially all body with lots of lube grooves. Which is better for your two guns? That can't be answered until you've slugged both of them and are certain that the bullet design/mold will cast large enough to fit the larger bore. Btw, a bore rider with a nose which doesn't ride the bore, i.e., one with a too small nose diameter, will only give good accuracy (v. very good or excellent) and at lower velocity than one which fits properly.

Iron Mike Golf, A properly fitted bore rider may not tolerate high velocity in comparison to say a Loverin, but not because of it's shorter bearing surface, but because it has fewer lube grooves than a Loverin.*


*The bearing surface of a bore rider with a nose section that's large enough to ride the bore, should be the entire length of the CB, shouldn't it? You can wipe liquid alox on the nose if more lube is needed if you want them to go faster.

[madsenshooter]

I honestly get better accuracy out of bullets that have a nose that engraves. I even try to get molds that produce a bullet with a "borerider" that engraves a little. For example, my Krags have mostly .301 bore diameters, the NOE 311284 drops with a "boreriding" nose of .302. I have two other NOE molds, 311365 and 316365. The nose on 311365 is .305 in diameter, the nose on the 316365 is .310 diameter, same as the groove diameter of my rifle. I've shot them with the bands sized to .311 in otherwise identical loads. I got 2000fps with the smaller nosed bullet, but only 1600fps with the larger nosed bullet, because of the increase in bearing surface. I could also tell from looking at the cases that pressure was considerably higher with the larger nosed bullet, which by the way, was more accurate for me. With the small nosed bullet I have to seat out beyond the Krag's max magazine length before the nose hits the rifling, but with the bigger nosed bullet I am into the rifling well below max length. So they could be used for rapid fire without having a jump to the throat. Does this help any with your choice? Probably not, but it might help you see there are lots of considerations.

One thing I found with a true boreriding nose, when experimenting with the Eagan MX2-243 in a 6x45 AR, is that one needs a bit more driving band than the Eagan design provided. I was limited to 1600fps shooting the bullet as designed, but by enlarging the nose so that it engraved too, I was able to get up to 2300fps with accuracy that would hold a coyote's head at 200yds. A borerider is a design that will lower the pressure needed to make the bullet go, but it will also reduce the pressure the bullet can take without stripping the rifling.

[Le Loup Solitaire]

In the world of bullet design, as pointed out by Col. Harrison in his research into the use of cast bullets in 30 cal rifles...in the NRA handloading book, bore-riders were found to be generally more successful in 2 groove barrels such as found in the O3-A3 rifle and the 1917 rifles as well. In these rifles the lands occupy at least half-if not more of the bore circumference. At least half the length of the bullet is the bore-rider section so that that it can ride on the lands and be guided by them while traveling down the barrel. The relatively shorter bullet body occupies the grooves. If the nose is less than .300-.301 then it is prone to slumping-off the long axis and going down the barrel in a tilted posture...it comes out of the barrel that way and shoots cockeyed. A similar situation exists if the bullet body is too small...generally .309-.310 is needed. Bullet fit is important and bullets of improper dimensions will not shoot accurately. Bullets of approximately half-half bullet body & bore riding nose will work well in barrels of 2 groove, 5 groove as well as 4 groove configuration. Bullets such as Lyman 311334, 311332, 311335 and Saeco 301 are all bore riders. Lyman 311284 and 311291 are examples of half and halfs. The Loverin designs also do well, especially in four and six groove barrels All are capable of excellent accuracy with properly adjusted powder charges. Suggest reading some of Harrison's background work and references in Cast-Pics prior to choosing a mold. LLS

[Iron Mike Golf]

*The bearing surface of a bore rider with a nose section that's large enough to ride the bore, should be the entire length of the CB, shouldn't it? You can wipe liquid alox on the nose if more lube is needed if you want them to go faster.

What I was getting at was bearing surface against lateral shearing forces imparted by the lands. So, it's sides of the lands, not the top (where the bore riding occurs). Of course, lots of variables involved. That's why I said "might".

[HARRYMPOPE]

that is a good fat 30 caliber design.it has a chubby nose and is a good choice for many milsurp 30's
you can slug the bore and throat if you want but still just filling it up with as fat of a slug as it will take is good enough.the lee 155 Harris bullet is often the other simple answer for many 30 calibers.

george

[RickinTN]

I bought that same mold a couple of months ago thinking/hoping it would cast a larger diameter nose than my 309-180 mold for my '06. This is not the case. The 309-180, using an alloy of approximately Lyman #2, gives a body diameter of between .310 and .311 depending on where the measurement is taken and the 312-185 gives a body diameter of about .313". The nose of the two is a different story. The 309-180 drops with a nose between .300 to just a touch over .301" depending on where the measurement is taken. The 312-185 drops with a nose of .299" to not quite .300". There is about .0015" difference in the two with the 312-185 producing the smaller bore-ride section of the nose. I guess I didn't realize or appreciate how "fat" the nose of my 309-180 bullets were until I tried the "larger" 312-185. Molds do vary, and your results may and probably will be different than mine with two different molds and in a different alloy, but I thought I should share my experience at least with my two molds.
Good Luck with your trials,
Rick