happyhunter wrote:If your scope is calibrated that each click is 1/4" at 100 meters, set the ballistics calculator to metric. Then you can convert the results to inches by dividing by 2.54. Keep in mind 100 yards is only 91.44 meters so if your scopes turret adjusters are calibrated for 100 meters one click at 100 yards is going to be less than 1/4", assuming the adjusters are accurate.
happyhunter wrote:Is the 1500 fps muzzle velocity measured or a guess?
in2anity wrote:I am trying to calculate the (actual) ballistic arc for 300yd shots with my reduced lead loads through my 30/30. Specifically, the load is a .30cal 165gr RNFP BB with an estimated G1 coefficient of around 0.25, muzzle velocity at an estimated 1500fps, 100yd zero. Here is what the computer spits out:
The rifle has a old Tasco Gold Crown on it which states "1 click 1/4 inch at 100yd", so I interpret that as 1/4moa clicks. Out to 200yd this graph is almost perfect at all ranges from 0 to 200yd. although I never actually adjusted the scope once it was zeroed, I just had a tall portrait target and noted the actual drop at varying distances, both short and long inside 200yd. From experience the scope always seemed pretty accurate at 100yds; 4 clicks = 1 inch.
So I stretched it out to 300m at the range (325yd). Based off the cheat sheet, the estimated come-up in moa for 300m is 25moa, therefore shouldn't it just be 25x4=100 clicks? Well something is very very wrong; the rounds were landing meters low. I wound off all my possible elevation (+ another 40 clicks, so 140 clicks in total from that 100yd zero) and it was still landing a couple of meters low. I can rule out accuracy as I was still able to get it to group at 300m with a massive holdover, but I'm at a loss as to what's failing here... me or the scope?
Any suggestions guys? Are my calculations/assumptions correct?
Gwion wrote:Probably a combination of factors:
Velocity is incorrect
BC is incorrect
Your scope can't handle 25moa of elevation
My bet is it is mainly the third one but your inputs as being guesses will be incorrect. Velocity because it isn't measured. BC because it is with guessed or even if it is listed, those BCs are calculated at average velocities well above what you are starting at; NC is s dynamic thing. Scopes, especially cheap ones, tend not to operate well at the extremities of their range. I'd say 25moa is either right at the edge or actually beyond where your scope will adjust to.
bladeracer wrote:You're using an estimated BC, and guessing your velocity?
bladeracer wrote:Are you at least using a range finder to confirm your ranges?
bladeracer wrote:If you cast them yourself, have you confirmed your bullets do actually weigh 165gn?
bladeracer wrote:When you wind the elevation up 25MoA and shoot at a 100yd target are you grouping 25 inches above your point of aim (assuming you are zeroed at 100yd to begin with)?
in2anity wrote:Gwion wrote:Probably a combination of factors:
Velocity is incorrect
BC is incorrect
Your scope can't handle 25moa of elevation
My bet is it is mainly the third one but your inputs as being guesses will be incorrect. Velocity because it isn't measured. BC because it is with guessed or even if it is listed, those BCs are calculated at average velocities well above what you are starting at; NC is s dynamic thing. Scopes, especially cheap ones, tend not to operate well at the extremities of their range. I'd say 25moa is either right at the edge or actually beyond where your scope will adjust to.
Yeah you're probably right - that's also what I figured. I have my Williams peeps back on now so hopefully they can handle the extremities better I have a long elevation knob on order which has a lot more elevation which should give me plenty of room to move if i need it.
Gwion when it comes to slow, heavy long range lead shooting (for example creedmore 45-70 sort of realm), do the standard g1 charts still apply? I mean, in reality would they just work off actual rather than theoretical? Is bullet stability a factor here?
in2anity wrote:Gwion wrote:Probably a combination of factors:
Velocity is incorrect
BC is incorrect
Your scope can't handle 25moa of elevation
My bet is it is mainly the third one but your inputs as being guesses will be incorrect. Velocity because it isn't measured. BC because it is with guessed or even if it is listed, those BCs are calculated at average velocities well above what you are starting at; NC is s dynamic thing. Scopes, especially cheap ones, tend not to operate well at the extremities of their range. I'd say 25moa is either right at the edge or actually beyond where your scope will adjust to.
Yeah you're probably right - that's also what I figured. I have my Williams peeps back on now so hopefully they can handle the extremities better I have a long elevation knob on order which has a lot more elevation which should give me plenty of room to move if i need it.
Gwion when it comes to slow, heavy long range lead shooting (for example creedmore 45-70 sort of realm), do the standard g1 charts still apply? I mean, in reality would they just work off actual rather than theoretical? Is bullet stability a factor here?
in2anity wrote:bladeracer wrote:If you cast them yourself, have you confirmed your bullets do actually weigh 165gn?
They are commercial, coated cast lead projectiles, and I have nothing to indicate that they are inconsistent weight. They consistently group inside 2 inches at 100yds, even with long strings of shots.
TheDude wrote:in2anity wrote:Gwion wrote:Probably a combination of factors:
Velocity is incorrect
BC is incorrect
Your scope can't handle 25moa of elevation
My bet is it is mainly the third one but your inputs as being guesses will be incorrect. Velocity because it isn't measured. BC because it is with guessed or even if it is listed, those BCs are calculated at average velocities well above what you are starting at; NC is s dynamic thing. Scopes, especially cheap ones, tend not to operate well at the extremities of their range. I'd say 25moa is either right at the edge or actually beyond where your scope will adjust to.
Yeah you're probably right - that's also what I figured. I have my Williams peeps back on now so hopefully they can handle the extremities better I have a long elevation knob on order which has a lot more elevation which should give me plenty of room to move if i need it.
Gwion when it comes to slow, heavy long range lead shooting (for example creedmore 45-70 sort of realm), do the standard g1 charts still apply? I mean, in reality would they just work off actual rather than theoretical? Is bullet stability a factor here?
The more accuracy in estimating BC, velocity, bullet weight, scope height, elevation/air pressure etc will get you close.
Both mine and my fathers 45/70s (highwall and trapdoor) with black powder and creedmore sights. I plugged in the values into n iphone app. a couple of tweaks to line it up with known settings for 100/200 yards and it got us hits on an 18" steel plate at 575 yards in 3 shots
bladeracer wrote:I don't mean consistency, I mean that the particular alloy will throw different weight bullets from a mould listed as "165gn". The mould "weight" is usually based on either pure lead or a 6% alloy. My Lee .323" 175gn mould for example throws a 178gn pure lead bullet (182gn when lubed and checked), and a 161gn bullet from a very-high tin alloy. Do your 165gn bullets actually weigh 165gn?
TheDude wrote:I plugged in the values into n iphone app. a couple of tweaks to line it up with known settings for 100/200 yards and it got us hits on an 18" steel plate at 575 yards in 3 shots
bladeracer wrote:I just checked and your figures would have a 165gn 0.25 BC bullet at 1500fps dropping subsonic just around the 200yd range.
Try setting targets at 220, 240, 260, 280yds and see if there is a range where accuracy goes out the window due to the bullet going unstable and the BC falls apart.
I think I have a similar problem with the .22LR CCI Copper-22 I tested on Saturday. At 100m they were spraying an area covering about two-feet around the target. Although the 21gn bullet leaves at 1850fps I think it's going transonic after maybe 50-60 meters.
I'm going to shoot groups at 40, 50,60,70 meters and see where they start falling apart.
in2anity wrote:TheDude wrote:in2anity wrote:Gwion wrote:Probably a combination of factors:
Velocity is incorrect
BC is incorrect
Your scope can't handle 25moa of elevation
My bet is it is mainly the third one but your inputs as being guesses will be incorrect. Velocity because it isn't measured. BC because it is with guessed or even if it is listed, those BCs are calculated at average velocities well above what you are starting at; NC is s dynamic thing. Scopes, especially cheap ones, tend not to operate well at the extremities of their range. I'd say 25moa is either right at the edge or actually beyond where your scope will adjust to.
Yeah you're probably right - that's also what I figured. I have my Williams peeps back on now so hopefully they can handle the extremities better I have a long elevation knob on order which has a lot more elevation which should give me plenty of room to move if i need it.
Gwion when it comes to slow, heavy long range lead shooting (for example creedmore 45-70 sort of realm), do the standard g1 charts still apply? I mean, in reality would they just work off actual rather than theoretical? Is bullet stability a factor here?
The more accuracy in estimating BC, velocity, bullet weight, scope height, elevation/air pressure etc will get you close.
Both mine and my fathers 45/70s (highwall and trapdoor) with black powder and creedmore sights. I plugged in the values into n iphone app. a couple of tweaks to line it up with known settings for 100/200 yards and it got us hits on an 18" steel plate at 575 yards in 3 shots
Was that with cast lead projectiles, or modern projectiles/loads?
TheDude wrote:Home cast 525grain projectiles over 68 grains of 2F black powder
Gamerancher wrote:Fat (45 cal) heavy (500gr + ) slow moving ( sub 1500f/s M.V ) round nosed lead bullets retain stability like you wouldn't believe. We shoot these out to 1000+yards and it is very rare to see one keyhole a paper target. I shoot a .45-90 CPA Stevens that has a 1 in 18 twist barrel (tight by black-powder standards) and it is sometimes hard to find the holes as they go through so straight. B.C's on low velocity bullets are more in relation to the centre of gravity of the bullet rather than shape. Blunt "Creedmoor" style bullets with good diameter /length ratio have better B.C's than bullets with a long tapered nose/point.
Gamerancher wrote:As a "for instance" load/trajectory scenario, I load 170gr cast bullets in my .30/30's with 17gr of 2207 which is giving me a M.V of around 16/1700 f/s.
Shooting this load at lever action silhouette targets just using the standard barrel sights on a 20" barreled Winchester '94, I use the first notch for the chickens @ 50m, up one notch for pigs @ 100m, up another notch for turkeys @ 150m, up one more notch (top one) for 200m rams.
This load takes down the rams no problem which means it has more energy @ 200m than a .243W shooting 105gr bullets has @ 500m, as the .243W doesn't take down the same rams at that distance.
Gamerancher wrote:I only use the .30-30 for the lever gun silhouette, reduced loads are a lot more pleasant to shoot, especially at the end of a match when you've put around 100 shots down range for the day. Less recoil also tends to give me better accuracy as the rifle is not beating you up all day and your follow through is more consistent. These rifles only weigh 6 to 7 lbs. I shoot lead bullets as I cast my own which keeps the cost of shooting down to buggery.
With regards accuracy, you have to remember these rifles were designed around black-powder loading's ( velocities ) of the day.
As for the argument for flatter trajectory, I don't think going up three notches on a barrel sight from 50 to 200m is too bad. I can't remember off the top of my head how much it is with the Williams sights on the other ones. I had a mate bring his rifle out to the farm with factory rounds ( Federal) and was able to hit the 200m target at the fist notch on the standard sights.Sort of debunks the old theory that .30-30's are "only a 100 yard round".
I've watched and shot beside others who go with the "load her up and don't adjust" theory, let's just say I'm glad it's them and not me shooting their rifles. They also tend to be the ones with the rifles that break down or have to constantly be tightening action screws. ( Marlins are bad for this). Not having a dig at yours, just what happens on the line. Lever guns have lots of moving parts held together with small screws holding by just a couple of threads. They may have improved barrel steel to handle modern pressures but they're still built on the same basic action.
<<Genesis93>> wrote:So.... this thread is now 2 pages long..... just wondering if anyone has suggested the 'ballistic arc'... is known as the 'trajectory'.... just sayyin.