I do not know what the BC on these bullets will measure as, I am no ballistician, but am interested to see the results. I only know what number I plugged into exbal that works pretty well. I have not compensated for downslope of the areas where I am shooting and am not sure whether that will increase or decrease the number I am using. If Bryan wants some of these bullets for testing while his are on order I can send him some and he can replace them or I will sell them to him for what I paid.
I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.
I'll take you up on that. I'll need about 50 rounds for the tests I have planned. I'm happy to pay the going rate + shipping. Please email me (BSL135@yahoo.com) with your address to send a check.
As James mentioned, I'll be doing some detailed testing and analysis of these bullets including 6 Degree Of Freedom (6-DOF) simulation.
My hypothesis is that perhaps the bullets are flying with a nose high orientation causing them to generate some lift, and that's why they're able to shoot so flat. I know that conventional bullets don't fly like this, as they hit precisely where they're expected to based on a BC derived from time of flight. My thinking is that perhaps the large aluminum tips make a difference. If this is the case, the 6-DOF model will reveal the presence of lift, and explain why/how the bullets are able to shoot so flat. If this proves out, it will cause a challenge for modeling the performance of these bullets with conventional programs. The actual BC will not be 1.1, although it appears so based on drop. So what BC should a shooter use who wants to calculate performance? If you use 1.1 you might get the drop right, but you'll be way over estimating retained velocity, energy, and every other trajectory metric except drop.
If this is so, it's actually a good problem to have because the bullet is shooting flatter than a conventional bullet. Even if it challenges traditional calculation methods, the bottom line is the bullet may have enhanced performance.
If this lift hypothesis proves out, it can explain how James' drop observations are accurate, and that the bullet doesn't actually have a BC of 1.1 (even if the drop tests suggest it does).
This is an interesting learning opportunity. As I stated in the outset, my interest is purely scientific. If these bullets have a genuinely unique performance enhancing attribute, then I'm as excited about it as the next guy. I'm especially eager to understand WHY. Simply shrugging my shoulders and accepting a magic form factor of 0.301 without an explanation just doesn't sit will with me.
It will take a while, but I'll keep this thread appraised of my progress and report on my findings when complete.
I am going to be testing both the longer 280s and the longer 300s on the drop board shortly. If your theory is correct what is your prediction for the flights of these two longer bullets with respect to the 265s using the hypothetical theory?
Will it have a higher indicated BC, a lower indicated BC or, basically the same BC. The reason I ask is to see if the hypothetical holds true for the larger and longer projectiles.
I personally do not think it is the Aluminum tips or the rebated boat tails due to the fact that the Generation I versions (both had the same Aluminum tips and rebated boat tails) followed the G1 profiles with consitent predictability.
We measured them and compared them to Sierras and developed some rules of thumb for BC versus length (in a given diameter) and the anticipated BC was within .002 of what we calculated and predicted for both the 265s and the 280s. This was also the case in the Gen I .30s as well..... Although we missed the 180 BC by .005.
The big change between Gen I (12S) and Gen II is the nose profile and it is much more radical on the Gen II (15S). For the same weight bullet, we lost about .090" of bearing surface.
Looking forward to your prediction.
Last edited by Lightvarmint; 04-08-2009 at 04:26 PM.