Barnes > Nosler for BC Inflation? 145 Match Burner 6.5mm

[Mikecr]

What was the atmospheric conditions that Barnes determined LOCAL G1 BC with?
This may need to be accounted for, and something that should always accompany/qualify a BC declaration.

 

[codyadams]

Wonder if a 7 or 7.5 twist would bring that BC up closer to what they quoted?

Or does it not work that way?

I have heard from a few sources that tighter twists can sometimes make a very small increase in bc, but usually not very much if they are already stable or close to stable. However with an applied ballistics tested .340 G7, that really isn't much off of the .349 G7 derived from the barnes assigned G7.

 

[Mikecr]

Being fully stable on muzzle release doesn't increase BC.
It reduces loss in potential with marginal stability.

 

[dblman]

Tried some 145 Match Burners in my 264WM today. Seems Barnes has taken a page out of the old Nosler playbook, and just came up with a BC number by looking at the nearest competitor and adding a few percent...

Rifle = 1:8 twist, 5R, X-Caliber, 24"
Loads between 2995 fps and 3040 fps

LabRadar was used to calculate B.C., with tracking files' maximum distance between 90 and 130 yds. Data culled for fliers, then regressed for near/far distance. Environmentals recorded with Kestrel (Temp/Hum) and iPhone baramoter app (P). This method generally gives VERY good agreement with Berger and Hornady bullets' quoted B.C.s out of a variety of rifles, based on literally hundreds of calculations over the last couple years. It also ALWAYS matches real world drop verifications within my ability to shoot.

Barnes 145 Match Burner results (11 shots)...

Quoted G1 B.C. = 0.703
Calculated G1 B.C. Average = 0.647
% Difference = -8%
Standard Deviation of B.C. = 0.018 (3%)
Extreme Spread of B.C. = 0.062

All in all, we are not impressed. This is reminiscent of Nosler's notorious ABLR B.C. inflation, and worse than any I've measured. The next closest cheater I've measured is actually the 147 ELD-M, with a 4% loss compared to the quoted B.C. I don't get too riled up about that one, as Hornady has consistently matched (± 2%) or even beaten it's quoted B.C.s in every other cartridge I shoot them in.

Frankly, it's not exactly hard to believe the B.C. is inflated. The friggin Berger 156 EOL only quotes a G1 B.C. of 0.679, so how the heck could a bullet 11 grains lighter, without a plastic tip, beat that by 4%? It apparently can't...

I didn't get great groups today (roughly 1 MOA), but I'll reserve judgement on how they shoot, as I was only out to get rough velocity measurements for IMR8133. If I can get them to shoot better, I won't complain about a 0.650 BC in a 145, but it sure irritates me when companies cheat.

Do not have any bc calculating equipment, but I do shoot daily. All 6.5 rifles no a 500 yard range here at home.
The thing I do see is that with 100 or 200 yard zeros I have less drop past 300 yards from my 1:7 twist 6.5 barrels than from either 1:8 or 1:8.5 barrels. These are all 6.5 Creedmore rifles, that's just what I shoot in my old age. This holds true with bullet weights from 125 gr through 155 gr.

 

[264MHC]

Looks like an 8 twist should be sufficient for full bc unless you're at sea level and it's 30 degrees outside then 7.5 is optimal. I've been shooting these at 2850 in 7.5 twist. Not my best load but will usually do .6 moa with occasional flyers. I have weight sorted them but I've read where the BTO measurements aren't consistent so May sort that way before I load more. Been trying to decide if I want more. I saw the $90 for 500 deal. Not sure how they'd do on game. Hollow point is quite a bit smaller than the Bergers and 140 MBs

 

[GSSPatterning]

"LabRadar was used to calculate B.C., with tracking files' maximum distance between 90 and 130 yds"

That statement right there tells me how much you "DONT" understand about calculating BC. All Match Burner and LRX bullets are shot over a six figure$$$ doppler radar to well over 1500 yds. If you take a bullet, any bullet, and measure BC at 100 yds it will differ from the results when shot at 300 yds.

 

[Mikecr]

BC can be calculated at ANY range increment.
Just a matter of measuring lag time from point A to point B, through a given air density.
The lower the drag, the lower the lag, the higher the BC.

 

[GSSPatterning]

Calculated, yes. Calculated accurately, no!

 

[Mikecr]

BC is supposed to be a single number.
It's hard (for me) to say that one derived in extreme is more useful than another.
So, how should it be improved?

 

[ARlife4me]

While I haven't varied any bullets bc , it does irritate the crap out of me when they come out with a new bullet with same weight and different design! Hornady states they use 400 yards to list bc numbers in the m and x line. Nosler's 142ablr originally.710 dropped after the rdf 140 came out. Either fortunately or unfortunately I never use bc numbers for shots. Being honest must be difficult in a bullet world!

 

[QuietTexan]

Frankly, it's not exactly hard to believe the B.C. is inflated.

And yet people still choose what bullets to buy based on the numbers printed on the box Sheeple will always sheep to the next shiny object.

When you can get a 500 box for $166, and they shoot .5MOA, I can deal a bit of an inflated BC. Just adjust BC in your ballistic app with actual drops, and violá.

The 140s have shot fine for me for a long time, better than the barrels they came out of for sure.

338 Dude, Where did you you find the book that the data for the 140 was in?

It's not the reloading manual, it's a separate book of nothing but pages like that:

Ballistic Performance of Rifle Bullets - 3rd Edition - The Science of Accuracy

The Applied Ballistics team compiled performance data for over 724 bullets from 0.172 to 0.510 caliber in this book.

thescienceofaccuracy.com

 

[GSSPatterning]

Depending upon the barrel, twist, environmentals, distance the velocities are taken at BC's numbers will change from shot to shot. Manufactures take an average and publish that number. Someone else comes along, different barrel, environmentals, distances and get a different average BC, if they actually shoot enough to get a decent average. It can change day to day. Be smart. Shoot your long range shots and adjust your BC or velocity to match your impacts. You just might come across to others seeming to know something.

 

[Mikecr]

distance the velocities are taken at BC's numbers will change from shot to shot.

Why?
Provided the distance has not dropped you into transonic, then I don't get how distance is part of calculating lag/drag/BC.

 

[GSSPatterning]

Why?
Provided the distance has not dropped you into transonic, then I don't get how distance is part of calculating lag/drag/BC.

Because through High Speed Photography we see bullets are yawing closer to the muzzle and stabilize as they travel further out, beyond 100 yds. 300 yd BC measurements are much more accurate than 100 yd measurments.