Help with bullet weight for 300m

[Hipshot]

While waiting for my new 6BR barrel to be installed on my previously used .243 for 300m competition I am doing some planning and hope that there is some good advice to help me avoid unnecessary shooting.

Background: I shot my .243 searching for the magic formula by experimenting with bullet weights from 80 to 107 gr from Lapua and Berger, primarily, with a few Sierra's. Powder types and weights were changed in a scientific manner. Seating depths were changed. All results were documented. Only one formula worked well, and that was at my first match, and the exact receipe a month later did not reproduce the same results. The results of my experimentation were from bad to awful. Everything was documented.

I'm aware of BC and wind effects on bullet flight. Throwing the highest BC bullet downrange is not necessarily the best; the range is important, too. .22 bullets having a lower BC than 6mm are able to produce as good or better results at 300m, so BC is not the only criteria.

New Deal: My inclination is to shoot a lighter bullet so as to keep powder weight down; my theory is that will help prolong the barrel life. My new barrel is going to be a 1:8 Shilen so several of the upper weight bullets will function. But, is it necessary to go to 100+ gr bullets to achieve good accuracy at 300m?

IF it is possible to settle on one bullet then my experimentation variables are reduced and I might be a happy shooter sooner.

Any advice?

Hipshot

 

[RoyinNC]

For 300m and less, I'd definitely go with a lighter bullet, probably in the 65 - 70 grain range in a 14 twist barrel. This is the combo used by benchrest shooter out to 300 yds. .75" groups are common and .5" not unusual at this range.

FWIW..... Roy in NC

 

[Wild_Bill]

Sorry i would disagree with using light bullets at 300 yesterday i shot some loads through My 6mmDasher at 300 and the first were in .235" and the next two opened it to .849" so plenty accurate enough for 300. Seccond barrel life if you run a heayier bullet eg a 107gr Sierra with a mild load say 3100fps using a slow powder like H1000 your barrel will last longer than punching out 80gr bullets at 3300fps. Searck about what David Tubb ises at the closer ranges 107gr Sierra he designed the 115gr for past 600yards. You have a choice of three bullets that i know that work in order 107gr Sierra, 105gr Lapus and 105ge A Max. there the ones i would try in that order especialy if you are setting up with an 8 twist you will have an advantage in any wind conditions over the lighter bullets. You could also be better running closer to 3000 fps and the barrel will last even longer.

Cheers Bill
Australia

 

[flatlander]

I've just scratched the surface with light bullets in my Dashers - they all three have 8-twist bbls., and were originally intended for use with bullets in the 105/107gr. range. Got 300 of both of Hornady's 87s,BTHP & V-Max) last year, and have loaded a few of each,along with a few Sierra 85 BTHPs)with H4895 & Varget. Looks like the max velocities out of 28" bbls. with these two powders will be around 3200fps. At 300M, I don't think there's going to be much difference,at least out of my barrels) in accuracy, though if I had to choose one of these three, I'd go with the V-Max. The one-and-only 5-shot group I've shot at 600 with 87 V-Maxes had four in under an inch of elevation, with the 5th shot about 1.5" lower.

The stock on the rifle that shot that group is a surplus H-S Precision Laredo, and without teflon tape on the forend & heel, it doesn't slide freely on my leather bags; I usually feel like I'm fighting the rifle & bags trying to center the crosshairs when group shooting. I think tape would net me better group results with less effort. I'm not trying to make excuses for mediocre shooting here, but would like to qualify my opinion that the V-Maxes have decent accuracy potential.

The other light bullets I've shot were: Hornady 65gr.V-Max, Estes 65gr. FBHP,custom BR bullet), and Sierra 70gr. MK. Loaded all three with the same 32gr. charge of H322, which proved to be too light to expand cases enough to seal the chamber - all cases were covered with soot. Avg. vel. was only around 3200fps, though ES & SD numbers were very good. Groups weren't outstanding - about all I can say is that all holes were touching at 100yds,comments on stock above applies here also). I pulled the remaining bullets and bumped the charge to 33grs., but haven't shot them yet. These bullets are all jumping at least .070" to the lands, as my chamber's throat is intended for heavier bullets.

I intend to do more shooting with these light bullets when we get our fall harvesting & planting done, and the last LR prone match of the season is over. I'd sure like to try the 87 V-Max on some of the more cautious prairie dogs that survived the summer by only coming out of their holes when shooters are a 'safe' distance away.