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Thread: BC Question

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    BC Question

    At what point does the bullet's BC really matter? I've read the information on Hornady's site and it seems apparent that it's irrelevant until you pass the approx. 500 yd mark. Is this truly the case?
    Reason I ask is I've seen many guys shooting 140-150 grain bullets out of 300wsm and 300wm. I'm sure it'll kill game, especially with today's bullet construction. I also understand that the game in question should be small (antelope -deer), perhaps short yardage, but will work on large game to, but is not recommended. I know this scenario kills Sectional Density.
    My $0.02 - I think it's more of a fear factor (recoil). But what about accuracy.
    Thanks in advance for indulging me. :-)

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    Interesting question. In terms of drop and wind drift advantages, some where around there. But there is a more important issue to me, when considering LR shooting. Regardless of a bullets BC and velocity, to hit a target at long range, say 500+, you must know your drop and drift, if you don't have your DOPE nailed, odds are you miss regardless of the BC. It is sure easier to correct for less wind drift at long range, vs more, so advantage high BC.

    I see drop corrections as much less of a challenge. Bullets are dropping so fast out there, you have to compensate with any bullet, but with today's great scopes and range finders, that part is relatively easy. The other advantage of very high BC is retained velocity. A given bullet has a velocity window where it is designed to be lethal on game, by design. They vary. A high BC bullet with a low velocity minimum impact velocity, essentially helps extend max range. I'll go so far as to suggest I ignore arbitrary foot pounds rules for lethality on a given type of western ungulate big game and look almost solely to impact velocity being enough for the bullet to perform. Velocity is a big, too big many argue, part in the foot pounds method often used to calculate energy.

    So the way I look at it is this. I pick a bullet that will retain enough velocity to be at least 5-10% above it's minimum velocity to expand at my max range. I ignore drop as I will have to develop my DOPE regardless and as I suggested above, drop is the easy one. I won't shoot far in high wind either. The max range I can easily practice at is 600 yards, so that is my max. Since I hate recoil, I can use a non-magnum to easily be lethal to 600, my 280 shooting a 145 gr. Barnes LRX at 3,013 avg MV fills the bill for me.

    Relative to the light bullet, a hyper fast bullet can be used to flatten trajectory for a bit, then they fall off a cliff due to low BC, really accomplish little a heavier more efficient bullet would do. Out of the same gun, a very fast 150 can recoil very much like a slower 180, in terms of measured recoil, but there is often a difference in felt recoil, pulse, duration and such. Recoil is an issue, one I mitigate with standard cartridges, rifle weight, recoil pads and a properly designed stock, not a light bullet. Individual preference is as important as anything else, where recoil is concerned, in an example like this, I suspect.

    I think you are on the right track with SD. For deer and the like, SD is not a big consideration. For elk, it can be very important unless you are very selective in bullet placement, so for me, good elk bullets begin somewhere around .250 in SD. A 140 grain .284 has a SD of .248, as does a 165 gr .308. In .277 130 gr. = .242 and a 140 = .261, both of which kill elk, with the 140 gaining an edge in penetration due to the SD, all else being equal.

    Accuracy is a push, relative to bullet weight, as far as I know. But it can be easier to be accurate with less wind drift and sometimes less drop. For long range shooting, wind is the real issue in my mind, ergo high BC bullets, which tend to be heavier and very streamlined.

    So it sounds to me like your are well grounded in your opinions, at least according to my opinions...
    Last edited by Tim McCoy; 06-13-2016 at 02:31 PM.

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    Tim,
    I agree with everything you mentioned, or should I say our "like opinions". :-) Thanks again for your knowledgeable insight.
    I'm just trying to understand some folks logic. I wouldn't think a 150grain bullet in a .308 (300mag for example) would be a good fit. I have a 300wm and have always shot 165/180gr.
    As you know, I am currently working with a 162gr SST for my Browning LRH and the accuracy is outstanding, as it the BC and especially the SD.

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    Could be tradition. A 150 gr. In 30 caliber is the traditional deer/antelope load. Could be something else.

    Another path some take is a monolithic bullet, like a Barnes TSX, push it very fast in moderate weight, like a 150 gr. in 30 caliber. The bullet sheds little if any weight, giving penetration like a higher SD "regular" bullet. IMO Barnes X bullets like speed to perform at their best. Standard advice from many, for X bullets, is use the next lighter weight than you normally would.

    The Barnes LRX, like my gun likes, are designed to open at a lower velocity than the regular X bullets, or so the marketing Dept says. Have yet to take any game at LR to test that, but it performs very well at normal ranges, say under 300, on the game we've taken with it so far.

    I did explode a prairie dog at 450, with the 145 LRX, suggesting it expanded. Wish I'd have bet on that shot, first shot hit. I declined more shots as I knew that was not likely to be repeated...

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    I'm relatively new to reloading and shooting at farther than normal distances. I'm thinking everyone worries about high BC mostly for there ability to buck the wind. A range finder can tell you the exact distance, some can even tell you what to dial the scope to for compensation on the distance, angle, baro, and altitude for your specific rifle. But what it can't tell you is what the wind is doing all the way to the target. It's just an educated guess. Some are better at it than others. I saw a video about compensating for wind. It kinda explains how important the wind call is.



    Just my .02 cents and worth the price charged.

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    You will find some great info here: http://precisionrifleblog.com/2015/0...bility-matter/
    He has done Monte Carlo simulations on all kinds of things, I particularly enjoyed his one on accuracy for LR shooting.

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