Ballistic Coefficient Calculator Which Includes Cast Bullets

[Yodogsandman]

I thought that I'd pass along an easy to use calculator I found while trying to figure out a cast bullets BC. No calculator is perfect but, this is pretty good.

http://tmtpages.com/calcbc/calcbc.htm

[OnHoPr]

Thanks and just marking, I always wanted to be able to calculate BCs, especially cast boolit BCs. It really doesn't matter much if your sitting on the feeder, but if you have a low BC boolit like .125 to .225 and the November winds are wanting to blow all the leaves off the trees those 15 mph winds can push a boolit 6 to 8" @ 100 yds. It really starts to matter from 150 to 300 yards. A real nice looking boolit with a decent metplat might be perform great at under 150 yd, but with mid low range BC it can turn not so great at 200 yds. Where as a higher BC boolit would come closer to the intended point of aim, you would just have to alloy your boolit for those speeds of impact to perform well.

[Yodogsandman]

I find that I use different calculators fairly often and have them bookmarked for my own use. I'd like to see a sticky here that would have cast boolit friendly calculator links listed for instant use. Are there any calculator links that other members use that they'd like to add? Here are a few others I've used recently...

Barrel Twist Rates...
http://kwk.us/twist.html

BHN Calculator...
http://www.ajdesigner.com/phphardness/brinell_hardness_number.php#ajscroll

[Blackwater]

Great posts. Thanks! Usually, I just look in the Lyman Cast Bullet manual, and if using a different bullet, just use an estimate based on what they show for the Lyman versions. BC estimates are just that - estimates - and BC usually varies over the flight of the bullet as it loses velocity, which makes all calculations approximations. Still, they can be very useful, like when shooting at longer ranges, in estimating drop so we can at least get the bullets on target when trial shooting them at range. Where longer shots may present themselves, it helps to at least know what's probable, and then fine tune according to what the targets show. Saves time, powder, primers and bullets, and these days, none of those is a very small thing any more. Again, thanks!

[Wayne Smith]

Tom is a long term member here, and he does have some useful software.

[outdoorfan]

I no longer pay much attention to BC estimators and manufacturers numbers as they relate to cast lead bullets, as the limited testing I've done often shows differently.

My testing involves actually shooting flat-nosed bullets (mostly rifle) at extended ranges of 100-350 yards over the chrony. My testing has been limited to .35 caliber designs.

Somewhere in the castboolit archives there is a post by Felix where, if I remember correctly, he said that most cast bullet BC's are going to be in the .18-21 range. Well, anyway, that has been my experience, as well.

I find the pistol bullets in the rifle application to be in the .18-.21 range, and I find the rifle bullets to be .2-.24, for the most part. Certainly, really heavy-for-caliber lead bullets will do better, especially if they're launched at slower speeds. And, of course, BC changes with velocity.

If you have a mid-weight flat-nosed, with a decent meplat (hunting bullet), conventional design at around 1800-2400 fps launch speed, expect anywhere from 300-450 fps loss at 100 yards. Expect another 250-350 fps loss between 100 & 200 yards.

I've found that pushing that bullet another 100 fps at the muzzle only generates about 50 additional fps at 250 or so yards. In other words, I've learned that once the load is reasonably strong, I don't bother for that extra little bit, being that accuracy usually declines, brass life will be often be less, more powder is being burned, and doing so usually magnifies felt recoil which is hard on the shooter.

Just my opinion based upon limited experience with .35 caliber designs. However, I reckon most here haven't tried shooting over the chrony at ranges beyond the muzzle to actually see what's happening.

[OnHoPr]

I think BC plays a very important part in ecksternal ballistics especially while hunting. Now it depends on the actual idiosyncrasy of the hunter. There are many that hunt the thicker woods where long shots may be in one or two alleys around 100 yds, but the most general deer shooting is 30 to 75 yds. BC really doesn't come into play in these incidences. But, when that hunter comes out for lunch and sees a 4 pt 150 yds away on the two track the BC can come into significant play. This site has a lot of lever hunters, so the metplat comes into the general thinking. A debate whether metplat or BC is always pondered upon in the hunting conditions. I don't have any real ecksperience with metplat hitting deer. Though it seems to be very encouraged for hunting and from countless success reports about its effectiveness is very noticed in my eyes. I just have a high consideration for BC. Getting the higher BC to perform or as well as big metplat on deer is a consideration.

Using a known hunting alloy of 50/50 both boolits will mushroom, the the big metplat has the advantage of the initial touch (given similar speeds) of the game animal, where as the higher BC with RN or 2R designs actual mushrooming performance might start on the off side lung. These are split milliseconds, but there is obviously a difference. My idiosyncrasy as a hunter is more open hardwood ridges and flats near the thicker stuff, so ranges can be over 200 yds. I wonder why the CBA Pro, Heavy, and Unrestricted classes usually use boolits like the Lyman 299 with its .377 BC or similar for the 100 and 200 yd ranges. It may have something to do with putting a boolit where you want it to go. Where BC helps is with windage, even though it helps with trajectory most all bullets with accurate barrels, loads, SDs, with just about any boolit after testing can be judged with elevation. Where the BC shines is with the windage and mis calculations of the wind and its direction from muzzle to target.

Take these two ecksamples and put them in the situation stated above with the hunter coming out for lunch and seeing the 4 pt on the logging road 150 yds away.

Lyman 311440 151 gr @ 1800 fps with 10 mph winds @ 150 yds - Vel 1251, Ftlb 524, windage 9.43" now if you are only shooting 2 - 4" groups @ 100 yds this gets eckspanded @ 150 yds

Lyman 311299 200 gr @ 1800 fps with 10 mph winds @ 150 yds - Vel 1520, Ftlb 1025, windage 3.93" now there is another 50 grs to the boolit, but that adds BC. Both loads would be mild and for double the energy and for 59% less wind deflection about 6" would be a more applicable load for that situation. I am not sure if having a bit more metplat will make up the differences when the ribs of a deer are hit especially on a possible raking shot.

[Harter66]

NOE lists the BC on all of their boolit drawings. You know for what it's worth .

[OnHoPr]

http://spoton.nikonsportoptics.com/spoton/spoton.html#:4

Here is a program that may be beneficial to a lot of shooters here. I can't seem to find the other one I had which may have been a bit better and/or similar and not related to Nikon. This one could help though, both with BDC (if Nikon) scopes and regular scopes as well. If you go advanced you could put in the finer details and construe it for your own purposes or details. It states a lot of factory slug BCs. Some of the BCs from cast boolits come close to some slug BCs. Remember that when you use it to really check the height of your scope acksis. For ecksample, (IMPORTANT) if your scope is on a cantilever or See Through mounts, measure the height. Most all calculators come with a default setting of 1.5" for scope sights. If you are using irons you need to lower this data input to about 3/4". With this higher scope mounting position the data or cheat sheet type data that you will acquire will or will/seem like your boolits will shoot flatter and give you a longer pint blank range, which it does. Remember though without really using a chrony, using older worn barrels and shorter slug barrels that there will probably be a 100 - 200 fps reduction in advertised velocities.

[dragon813gt]

NOE lists the BC on all of their boolit drawings. You know for what it's worth .

And you will end up w/ a l different value if you use the calculator linked in the OP. I enter the ones NOE provides into Quickload. And use the calculator for MP molds.