Author Topic: Bullet drop for each range in rimfire silhouette? (Read 1993 times)

Jason · « **on:** April 15, 2004, 01:36:33 PM »

I'm hoping to get started in rimfire silhouette this coming Sunday (at the shoot at the Machias range in WA, in case anyone else here is). The problem is that I don't have anywhere I can shoot beyond 100yds right now, and I'll have to try to talk the rangemaster on duty on Saturday at my range to let me set up a target at any range other than 25, 50, or 100yds. That's going to make figuring out how many clicks between different distances more of a chore. Does anyone have some bullet drop info they want to share to give me an idea of about how much I'll be looking at changing my scope?

I plan to verify how much my scope actually moves per click (it's a Simmons, so I'm not betting it's exactly 1/4")and if it's reliable on the 25 and 50yd berms, and if the rangemaster lets me I will hopefully be able to set up a portable target frame at the correct distances (except for 100m) using my laser rangefinder. It sure would be a lot easier if I could just combine my scope "per click" numbers and someone's estimated drops to figure out the settings for my scopes. Verifying that calculation would take a whole lot less time than figuring out everything on my own, and would be my only hope if the rangemaster won't let me set out targets at unusual distances.

In case gun/load info is needed for the calculations, the only gun I'll be shooting this time is my custom 10/22 with 20" Green Mountain .920" stainless fluted barrel. I'll be shooting Wolf Match Extra, which I've been quoted muzzle velocities from 1033fps to 1080fps for. If my CZ 452 Varmint, which doesn't have a scope on it right now, qualifies for the sporter class, it will be wearing the Simmons scope for next month's shoot and I'll be acquiring another scope for the 10/22. I'm thinking of a Whitetail Expedition 6-18x42AO for it, as around $150 is my price limit. Any other recommendations?

Thanks in advance for any info you might be to provide. I'd also love to hear any tips you have for a newbie heading to his first shoot.

kahuna · « **Reply #1 on:** April 15, 2004, 03:50:23 PM »

Jason
Elgin Springgay runs those matches they do have a sight in period
from 9:30 to 10:00 in the morning.

nomad · « **Reply #2 on:** April 15, 2004, 06:40:17 PM »

Jason,
Hard to tell someone what settings to use since rifles and scopes vary so much and the height above bore is critical.
If you can't take kahuna's advice and get to the match in time to shoot sighters, try this:
Assuming that you have a standard mount and zero Wolf at 50 yds to be 1/2 moa low, you'll be very close for 40m.
From a good 40m zero:
Come up 2 1/4 moa for 60m.
Come up another 2 1/2 moa (4 3/4 total) for 77m.
Come up another 3 3/4 moa (8 1/2 total) for 100m.
Those settings may not be perfect but they'll get you close.

nomad · « **Reply #3 on:** April 15, 2004, 06:58:45 PM »

And a tip:
After you get your classification this weekend, come to the Conard Bernhardt match in PeEll 24/25 April.
Contact Keith Cairns 360-357-5116.
There's no better way to learn than to hang around very good shooters and the CBC has the highest percentage of master shooters of any match in the country.
(Even I'll be there. If you watch me very carefully you'll see everything that you should NEVER do!)

If you can't come for the weekend to shoot, stop by and watch.

kahuna · « **Reply #4 on:** April 15, 2004, 07:20:50 PM »

Nomad
Talked to keith tonight (thur)he said that he had filled all the relays.

nomad · « **Reply #5 on:** April 15, 2004, 07:29:12 PM »

Kahuna,
That's good news. He was telling me a few days ago that he had a bunch of people who still hadn't gotten the paperwork in. Guess he stirred them up!
Jason,
Don't know how far from PeEll you are but it would be worth a reasonable drive for a newbie just to watch...

Jason · « **Reply #6 on:** April 15, 2004, 09:25:31 PM »

Kahuna,

I talked to Elgin earlier this week. He said I could even show up at 9:00 in the morning just to get acquainted with the place and how things will go. He wasn't clear exactly what the sight-in period would entail, so I would like to be as prepared as possible ahead of time.

Nomad,

Those adjustments are exactly what I was looking for. Thanks!

I live right here by the Machias range, so the Pe Ell shoot is probably at least two and a half, possibly three, hours each way for me. I really do want to learn, but that's a LONG way to drive just to watch. :lol:

nomad · « **Reply #7 on:** April 16, 2004, 03:23:46 AM »

Jason,

Since I don't know how much overall experience you have, a couple of things to keep in mind:

You really need a 'good' 40m zero. The 1/2 moa down from 50 should be close but, if you start off with a poor 40m zero, everything else will just get farther off.

And remember that some (most!) rifles don't shoot to the exact same point of impact from bags that they do from the shoulder. After you get your basic zero, you need to shoot a few groups on paper at the short line to confirm that you're really starting where you think you are.

tedfl · « **Reply #8 on:** April 16, 2004, 05:30:24 AM »

Jason, here is a program that might also help for future loads
http://www.handloads.com/calc/
Tedfl

Jason · « **Reply #9 on:** April 16, 2004, 06:18:45 AM »

Nomad,

Thanks again. I've shot benchrest before, so I understand about getting a good zero. So far the 10/22 has shot very close to the same POI offhand as it has when held snugly off the bench (free recoil POI is different, of course), which is probably partially due to the thumbhole sporter design of the stock fitting me well for offhand shooting.

Tedfl,

I'll check that program out. I have a few ballistics programs, but I don't have the necessary info for these little rimfire shells like I'm accustomed to having for my centerfire handloads. I need to get around to getting a chronograph so I can just calculate the info myself.

shootingpaul · « **Reply #10 on:** April 16, 2004, 06:29:27 AM »

Hi Jason
Nomad gives you good settings, as to the wolf velocity :

.22 ammo velocity shot out of Anschutz 54?

WOLF      1135
      1077
      1096
      1104
      1100
thats my findings, so the ammo is actually faster, as to the scope maybe you should have a look at bushnell Trophy 6-18 X40, it is exccelent scope and not much off from your 150 bucks

nomad · « **Reply #11 on:** April 16, 2004, 06:36:14 AM »

Jason,

I've just spoken with Keith and he tells me that last year he had several last minute cancellations.
If you have the match weekend available, you might want to call and ask him to put you on the waiting list in case an opening pops up.
IMO it really is the most educational match of the year. (At nationals -- especially at Raton -- you often see conditions play a big part in the outcome. Conditions at PeEll otoh are normally such that it almost always comes down to nothing but the shooter.)

Mongo1 · « **Reply #12 on:** April 16, 2004, 07:24:18 AM »

JBM is one of the best online ballistics sites I have found.

http://www.eskimo.com/~jbm/ballistics/ballistics.html

dwl · « **Reply #13 on:** April 27, 2004, 08:01:00 AM »

Nomad;

I didn't realize it was yourself, but I owe you a Thanks. Went to my first sanctioned match on 4/25 and asked CHunter for some come-ups. What does he give me but:

From a good 40m zero:
Come up 2 1/4 moa for 60m.
Come up another 2 1/2 moa (4 3/4 total) for 77m.
Come up another 3 3/4 moa (8 1/2 total) for 100m.
Those settings may not be perfect but they'll get you close.

They were not exact but they were close! Even with all the missed targets trying to find the proper settings I was able to shoot B Class in the first round and fished AA in the last! Now a proud, immature, middle aged owner of a Green Book.

Still working on organizing the club. We've got targets on order, a supply of rails for frames and requests from another club for a match schedule. Damn, this is fun!

davei · « **Reply #14 on:** April 27, 2004, 04:29:30 PM »

as we were sitting waiting for our relay at the Conard Cup, I asked lucho what the bullet drop would be for smallbore rams on the moon. he calculated it right there on the spot. 1/2" drop at 100 meters. 5 pigs suggested a correction for the temperature drop on the dark side and we were set. just in case anyone was wondering...

(they are both scary smart)

Grasshopper52 · « **Reply #15 on:** April 27, 2004, 07:25:30 PM »

Yes they are Dave,

And you were silly enough to ask, I hope you weren't expecting lucho to not be able to figure it out so quickly!

Just do us all a favor and don't ask either one of them about springs! I had enough of that last year

DanDeMan · « **Reply #16 on:** April 28, 2004, 05:24:50 PM »

DaveI,

You know I've just got to calculate a match 22LR's bullet drop at the Lunar SB Silhouette Range :-D

So, since the acceleration of gravity on the lunar surface is only 1/6 the acceleration on terra firma, that would translate to a lunar gravity induced acceleration on the bullet of about 5.333 ft/sec^2. Given that 100 meters is about 328 ft and the appropriate equation for bullet fall from the acceleration of lunar gravity, in this case the fall of the bullet towards the lunar surface once it exits the muzzle given the barrel is parallel to the lunar surface, is Drop = 1/2at^2. And, the MV of the bullet is 1,200 fps and since there is no drag on the moon the bullet does not slow down, it only takes about 0.2734 seconds for the bullet to hit one of those pesky rams.

So, when the numbers are plugged into the equation we get:

Drop = 1/2(5.333) x 0.2734^2

Or, drop is about 0.1993 ft or about 2.3914 inches at the ram line.

:wink:

nomad · « **Reply #17 on:** April 28, 2004, 06:04:13 PM »

So, given the density of silhouette shooters and the specific gravity of BS -- and using Eley Tenex fired from a Wilja 24.000000000008" Sunberger barrel as the standard -- how far from the top pad of a four foot high rail will a center-struck ram travel before falling to the lunar surface...? :twisted:

"Texas isn't all that flat, but, on a clear day, you can see the back of your own head!" :wink:

DanDeMan · « **Reply #18 on:** April 28, 2004, 06:53:33 PM »

Yo Ernie,

If a SB ram weighs 1 lb and is sitting on a frictionless pad on the lunar surface and it is hit in the center-of-mass, like when a ram goes straight back and then begins to fall as its feet clear the pad, this is an easy problem. Next we assume that the 1,200 fps impact of the 40-grain bullet produces an elastic collision, that is the flattened bullet drops near the rail. One caveat though, there is a small loss of momentum transferred to the ram due to bullet deformation that will lower the result; how far the ram travels from the rail before it hits the lunar surface. Anyway, on to fun with physics.

For an elastic collision the state equation is:

M x V bullet + M x V ram the instant before impact = M x V bullet + M x V ram the instant after the impact

Where M=mass and V=velocity

Since the weight of the bullet is 40/7000 lbs and is traveling at 1,200 fps the instant before impact, the ram weighs 1 lb and is not moving the instant before impact the equation looks like this:

(40/7000 x 1,200) + 0 = 0 + 1 x Ram Velocity

Solving for Ram Velocity we get about 6.86 ft/sec. That means the ram is moving backwards at 6.86 ft/sec just after the bullet impact. Now, since the ram is 4 ft above the lunar surface when it starts falling, it moves backwards for the same amount of time it takes for it to fall. Since the acceleration of lunar gravity is about 5.333 ft/sec^2 we find using the equation distance = 1/2at^2 that the time of fall is about:

Fall distance = 4 ft = ½(5.333) t^2 solving for time we get the fall time of about 1.22 seconds.

When that result is plugged into the equation distance = velocity x time we find that the ram hit the lunar surface about 8.36 ft behind the rail.

Arizona Jake · « **Reply #19 on:** April 29, 2004, 02:14:03 AM »

Dan:

I can only presume you are a fellow engineer! I hope you don't get asked how loud the "clang" produced by the bullet's impact will be.... :cb2:

ajj · « **Reply #20 on:** April 29, 2004, 03:11:37 AM »

This has answered a few questions that have been nagging at me for some time. So, what is the meaning of life?

nomad · « **Reply #21 on:** April 29, 2004, 03:29:48 AM »

While visiting with Keith Cairns after his CBC match last weekend, I noticed a sign on the wall of his machine shop:

"At some point, you have to kill the engineers and start production."

At the time, I thought it was pretty unreasonable...but I'm beginning to come around! :-D

Jake:
Why wouldn't you hear the 'clang'? (Don't give us any of that bull about sound in a vacuum. You always hear the explosion when Picard shoots 'down' Romulan Warbirds!)

AJJ:
A '40'! (One must always strive for the greatest goal, Grasshopper.)

Arizona Jake · « **Reply #22 on:** April 29, 2004, 08:27:14 AM »

Nomad:

Everyone knows that only phasers and photon torpedoes produce sound in vacuum.....

lucho · « **Reply #23 on:** April 29, 2004, 08:44:06 AM »

Hey Dan

I did my calculation on the back of an envelope in my head, so being off by a factor of 4 isn't to bad.

Lucho

DanDeMan · « **Reply #24 on:** April 29, 2004, 09:37:25 AM »

Yo Lucho,

How do you like my new Avatar??? Cool, eh.

If I was going to do a back of the envelope on the line at CBC it would have gone like this. Gravity is about 1/6 the earth so acceleration would also be 1/6. Since typical drop of a 22LR match bullet (MV 1,080 fps) is about 12 MOA over 100 meters, the math is easy. There would been an estimated drop of 2" on the moon at 100 meters.

longgun · « **Reply #25 on:** April 29, 2004, 10:33:29 AM »

Dan, I think I see a flaw in your lunar calculations......... The 40 gr bullet surely would be different in a lunar equation than it would be in earth calculations since less gravity would mean less weight for the said 40 gr bullet. Right? This would probably produce an increase in the velocity of the said bullet in a lunar equation. ( However the momentum might be the same since the bullet weight is down and the velocity is up.) So you may have to put different numbers. If NASA ever does any more lunar exploration perhaps we can get them to include this as one of their experiments....... Don

lucho · « **Reply #26 on:** April 29, 2004, 11:09:00 AM »

Very cool Dan. You must be retired.......

Longgun, on the moon the weight of the bullet is different, but the mass is the same. All the calculations are done with mass.

Weight = mass x acceleration (or g)

It's a subtle difference.

Lucho

ajj · « **Reply #27 on:** April 29, 2004, 11:12:35 AM »

I don't care about the math. Where can I get some of those frictionless pads?

Fivepigs · « **Reply #28 on:** April 30, 2004, 09:50:21 AM »

I've got a set of frictionless pads I'll sell you. I never use them any more -- they're a nuisance in the wind.

ajj · « **Reply #29 on:** May 03, 2004, 02:55:04 AM »

Great, I'll pick 'em up. Wait. How do you pick them up?