Tipping .30 230 or .338 300s

[PowerstrokeOBX]

I see tipping is pretty popular on 6mm and 6.5mm but I hardly ever hear of tipping the big bores. Anyone have any experience in tipping the 300s or 230s? Are you still seeing a 5% increase in BC?


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[DAVETOOLEY]

You get at most 2-3% increase in BC in the larger calibers which is not worth the trouble. What you do gain which is more important is uniform BC's. I wasn't the first to explore the importance of meplats but I brought it to the attention of the 1000 Yd. BR group many years ago. I even went to the expense of buying an Oehler 43 to measure BC's and what effect meplat shape and uniformity had on long range ballistics. I made and sold a trimmer to trim the fish mouths off hollow points. I did testing for Sierra and installed plastic tips in MK's from 22 cal. to 338. All BC's went up and uniformity from bullet to bullet improved. From real world testing with Hornady .338 285's and Lapua Scenar's the secondary tip at the very least minimizes the effect of misshaped meplats on BC's if it doesn't eliminate any variation in BC attributable to the meplat.

 

[PowerstrokeOBX]

Tipping .30 230 or .338 300s

You get at most 2-3% increase in BC in the larger calibers which is not worth the trouble. What you do gain which is more important is uniform BC's.

I even went to the expense of buying an Oehler 43 to measure BC's and what effect meplat shape and uniformity had on long range ballistics. I did testing for Sierra and installed plastic tips in MK's from 22 cal. to 338. All BC's went up and uniformity from bullet to bullet improved. From real world testing with Hornady .338 285's and Lapua Scenar's the secondary tip at the very least minimizes the effect of misshaped meplats on BC's if it doesn't eliminate any variation in BC attributable to the meplat.

Mr. Tooley,

Thank you very much for posting! I would agree it would be worth tipping for .01-.02 BC or 2-3% increase.

I am very interested in your research on uniforming the tips for a more consistent BC. Do you happen to recall the amount of deviation of non uniformed bullets vs uniformed/tipped bullets? Specifically .30 and .338 projectiles.

 

[DAVETOOLEY]

I started in short range BR then about '93 got involved in ELR varmint hunting. That was back when we had no PDAs, no laptops and one ballistic program. We just sort of winged it and developed techniques to make the drop chart match empirical data gathered in the field. We were shooting out to 2400 yds. sometimes further. In '95 we started shooting 1k comp's and with the help and friendly competition with the PA 1K club in a few years we had equipment and ammunition that was far better than anything to that point. As accuracy improves flaws in individual components surface . For several years we would routinely shoot groups with the majority of shots wadded up in a very good group only to have flyers dead center but go high or low. These were experienced shooters and reloaders doing everything possible in the pursuit of accuracy. I heard about a test Dr. Ken Oehler and a F class shooter, Larry Bartholome had done and gave Larry a call. He was kind enough to forward me all his data. I spent several evenings looking over the data. One thing became very clear. Each bullet is unique. Each bullet design was unique. The question is why are they different and what design was working best. The data gives the highs,lows and SD of velocity and BC. I started looking at the data for bullets with the highest and lowest BC spread. Ranking each shot, fastest to slowest at the muzzle and then at 1K yds. It became clear for the groups with the highest BC spread there were one or two extreme shots that were out of the norm. Here's were design came into the picture. The bullets with the highest BC spread were HP's. The bullets with the lowest spread were Hornady Amax's and some custom bullets with small diameter meplats. That pointed to the meplat as the problem. I came up with a trimmer that indexed off the ogive and trimmed the meplats so they were uniform. Going into this I didn't really consider what was happening in flight to account for these variations. One day at a 1K match after looking at multiple targets shot with the same rifle and same ammo with non uniformed bullets vs targets shot with trimmed bullets one thing became clear. Untrimmed bullets exhibited more yaw, the meplat was cutting a hole off center. Trimmed bullets had less yaw, the hole cut by the meplat was centered. I then knew why there was an improvement. In flight yaw.

You asked for numbers. I've seen as much as .030+ variation out of the same box of bullets and with very good HP's running around .015+ . I consider .015 or less very good. Not many can do that.

Here are some numbers for a custom flat base bullet that is very accurate and very consistent at 1k yds. I reference this bullet because of it's accuracy and consistency. Actual BC numbers are a little low compared to the BC measured with Doppler radar but for comparative purposes everything was shot the same day with the same equipment. W/tip means I installed Sierra green tips.

30 ca. 187 Gr FB

unaltered BC .482 spread .013 one shot added .004 to the spread
trimmed BC .463 spread .006
w/tip BC .513 spread .010 one shot added .003 to the spread

Hope this helps

 

[damoncali]

Here are some numbers for a custom flat base bullet that is very accurate and very consistent at 1k yds. I reference this bullet because of it's accuracy and consistency.

I've never messed around with flat based long range bullets, but have notice the BR crowd seems to like them. Is the benefit just that the simpler manufacturing process is able to make bullets with a more consistent balance, and that the BC penalty from not having a boat tail is offset by machine gunning the groups?

 

[DAVETOOLEY]

Coming from the short range BR game and having made hundreds of thousands of bullets from 22-30 cal. I knew it's easier to make a good FB bullet than a BT. When I started lobbying for a good FB bullet we were shooting so well that speed and BC didn't win you many matches. It was all about accuracy. Randy Robinette stepped up and got a point up die. I remember a few guys laughing out loud when I proposed this project. Using those bullets I hold the NBRSA 1k. Heavy gun small group record and the IBS Heavy gun group record is held by one of those guys who was very entertained by the idea originally. Now he's a believer. Accuracy first then I can learn how to shoot/manage the conditions. Those bullets are great to 1K. BC is .525 so it's enough to get the job done but are just scary accurate and easy to tune.