PC and the lube groove

[Mal Paso]

I find it curious the first thing some want to do after converting to PC is eliminate the lube groove like it fixes a problem and doesn't change the bullet. Eliminate the groove and the weight increases or the design changes and you have a different bullet that may be more or less accurate than the original. Elmer Keith made the point that bullet grooves give the lead displaced by the lands a place to go and reduces overall bullet distortion. I would think distortion of the bullet base would be greater in a slab sided bullet.

Is there a benefit to a shorter bullet of a given weight or some other fine point I'm missing? Maybe the grooves don't coat well?

I haven't seen this discussed anywhere. Thanks.

[RogerDat]

Interesting question. There are bullet molds now out that are smooth sided intended to be used with HiTek or PC instead of a lube groove. Haven't tried one myself. Hopefully someone who has used one will chime in. I will say I like the lube grooves, it provides an option if I don't feel like doing PC. I also wonder how a smooth sided bullet would do with a tumble lube. I like the speed of shaking a bunch of bullets in some tumble lube and coming back the next day to ready to load lubed bullets. I'm lazy that way :-)

[sureYnot]

More contact with the bore and more weight without increasing the length.

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[mdi]

Interesting thought, Mal Paso. At first I thought the "new" molds for PCed bullets was much of a marketing idea. I agree that the lube grooves do more than hold lube (as mentioned by lead movement due to squeezing/swaging, and a compression effect from pressure on the base). While I never went so far as to get a grooveless mold for my PCed bullets, I would like to see a good, factual test of some same weigh, same diameter, same shape PCed bullets, grooved vs. grooveless. Including velocities and accuracy comparison...

[blackthorn]

Quote " I would like to see a good, factual test of some same weigh, same diameter, same shape PCed bullets, grooved vs. grooveless. Including velocities and accuracy comparison... "

It seems to me that you cannot have all of the above in a bullet with/without lube groves. Changing the shape (filling the groves) either adds weight or the bullet must be shortened to adjust and the result is a different bullet.

[popper]

I have the 31-165 A and C, C has greatly reduced but not eliminated grooves. PCd both I can't tell the difference in 308W. Pushed to jax max fps I can't tell the diff. @ 100. I did get MOA @ 200 with the C version which is all I cast anymore. I use a hard alloy so a more standard 50/50 may not do as well for comparison.

[mdi]

OK, a test with a 147 gr. 9mm bullet with grooves and a 147 grainish bullet of the same design without grooves. My nits don need pickin"...