Range Report FULLBORE Bullet Article

[BryanLitz]

I've posted a new article to my website titled: 2009 FULLBORE Bullet Update

This article provides analysis of 8 different 30 cal 155 grain bullets that are commonly (and uncommonly) used in Fullbore competition.
The article starts by providing the tested BC's for each bullet, then goes on to analyze the effect of the different BC's on wind deflection and score for 1000 yard (US) prone and F-class targets.

Analysis is provided on MV and performance from service rifles, which will also be relevant to those who use shorter barrel bolt rifles. Stability requirements for this current crop of FULLBORE bullets is also discussed.

There is no mention of the bullet's terminal performance. The article addresses the external ballistics specific to Fullbore competition.

Enjoy,
-Bryan

PS, Please let me know ([email protected]) if you notice anything 'fishy' about the .pdf. Sometimes the font goes haywire, don't know if it's a browser problem, embedded fonts, etc. Thanks.

 

[kombayotch]

Re: FULLBORE Bullet Article

Nice article Bryan!

Have you ever run any tests to see how much pointing the tips of the Fullbore and of the Scenar with the Whidden die would improve them?

Kris

 

[MitchAlsup]

Re: FULLBORE Bullet Article

Very informative, thank you very much.

 

[9H_Cracka]

Re: FULLBORE Bullet Article

I love it Bryan! Thank you!

 

[Grump]

Re: FULLBORE Bullet Article

I thought that service rifles could launch the 155s between 2775 and 2800 at safe pressures...22-inch at least.

 

[tikkafan]

Re: FULLBORE Bullet Article

That was a really great article.

The question this brings up for me is why do bullet makers still cling to the G1 drag model when the G7 drag model is by far the better model? Berger is the only one that I'm aware of that advertises G7 numbers.

 

[Greg Langelius *]

Re: FULLBORE Bullet Article

Excellent article.

Reducing it down to its core gist, I get this set of impressions.

Bullets are made precisely enough for manufacturing precision, as a variable, to be left out of the discussion.

BC is critical to flight time. The shorter the flight time/the higher the BC, the less deflection.

Highest BC is no guarantee of a better score. Assigning a mathematical value as a constant to define the limits of the shooters' capability, entering random wind effects will render a deflection value that follows a bell curve, which is statistically limited to the number of instances and the true randomness of the random value generator. On reflection, this seems like a sorta circular argument, but it also seems to accurately reflect observed outcomes. The more consistent the shooter, the moreso the reflection.

I really didn't take away anything from the article that I didn't arrive with. That's a good thing. It tells me my basic undestandings have a basis in reality.

I would like to see a repetition of this article with 6.5mm bullets, so the F Class Fullbore audience gets some help too.

Greg

 

[BryanLitz]

Re: FULLBORE Bullet Article

Thanks for the feedback guys.

Kris,
Pointing meplat's will improve the BC by around 2 to 4% depending on the ogive profile, and how wide the meplat is to begin with. Of the 8 bullets tested, they can all see a BC improvement by pointing except the AMax and the new Sierra which already is pointed from the factory.

The improvement in pointing won't turn night to day, but it is an improvement in net BC and it also can improve uniformity as well. Again, not a huge amount, but it is an improvement. The process of pointing is also quick and easy so I point every bullet I shoot in competition.

Ty,
There are several reasons why the other bullet companies are reluctant to move to G7 BC's. One is simply because the G7 BC is a lower number. To those who view BC as a marketing tool, providing a lower number is a bad move, period. Referencing BC's to the G1 standard results in the highest possible numeric BC, it's also the poorest matching profile. To those who are interested in a useful BC that will enable them to hit targets at long range, G7 makes more sense.
Sierra at least offers the multiple BC's. This approach addresses the problem, but it's more cumbersome and is technically not as good of a solution as a G7 BC.

Another reason some of the companies may be reluctant to change is because using the velocity dependent G1 BC allows them to claim a whole range of BC's that technically aren't wrong, but may only be valid for a particular flight speed, usually high speed. In other words, it allows more slop, and it allows them to 'cheat' toward a higher number without being technically wrong. This might be a convenient and clever marketing trick, but <span style="text-decoration: underline">it doesn't help shooters hit targets!</span>

Another reason is that maybe they're just afraid of change. They may not want to confuse the shooting public by throwing out two numbers, giving the shooter the chance to use the wrong one in a calculation and getting a way wrong answer. I can see this point, and it is a challenge of the paradigm shift. You're always going to have growing pains when you change the way things have always been done, but it doesn't mean you shouldn't do it.

And a final reason for being reluctant to move to G7 referenced BC's is because not all ballistics programs are capable of using them. The list of 'G7 capable' programs is growing, but there are a lot of shooters who won't want to buy another program just to use a different BC, when the program they have works pretty ok with G1's.

So some of the above reasons are good, others aren't. I think the G7 paradigm shift has begun with the more serious, technical shooters who are able to observe the advantage directly. Eventually over time, it will trickle down to the mainstream. Somewhere along the line, the other major bullet makers may get comfortable with the idea and start providing G7 BCs, but I think this will take some time.

-Bryan

 

[tikkafan]

Re: FULLBORE Bullet Article

Consumers want better quality information. The business that figures that out wins.

I would like to second the motion on a 6.5mm article.

Thanks Bryan.

 

[Grand]

Re: FULLBORE Bullet Article

Bryan: Nice article. The Berger 155g's I tested were super-uniform and shot excellent.

How about an article on .224 bullets in the 68-80g range? I working up loads for my AR and published B.C.'s are all over the board.

 

[flyboy]

Re: FULLBORE Bullet Article

Tag.