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Real World vs. Calculated trajectory for .22lr

Short-bus

customguncoatings.com
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Minuteman
Apr 13, 2008
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Smithville, MO
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I'm running into some issues that my dope tables aren't jiving with the JBM calculations that i'm using to try to get me close on getting my drop dope out to 300m. I was out recently and was 2MOA off on my 100m starting point. I did check my 50m zero before I went to the longer range area to shoot my steel target at the longer ranges. I was shooting SK standard plus and match. Here are the tables I got before the wind picked up and made hits inconsistent.

50m 0
100m +9.5min
125m +14.75min (Still got a 3/4" group!!)
150m +19.25min

I put the velocity at 1050fps at the muzzle and all the local and current environmental conditions with a BC of .125. JBM has been quite accurate on my .308, and i'm wondering if it's possible that JBM doesn't calculate well at subsonic velocities? What do you guys think?

Branden
 
Re: Real World vs. Calculated trajectory for .22lr

I have found the same thing.... and at 175 with wolf match the computer data was about 2 moa high as well... dont know what software calculated as someone here on the hide gave me the data.
 
Re: Real World vs. Calculated trajectory for .22lr

I have a long weekend this weekend so i'm going to go out super early (long before the wind kicks up) and try to get out to 200 again. I need to order a 20moa base, gotta bug the wife for more toys.

Branden
 
Re: Real World vs. Calculated trajectory for .22lr

How confident are you on the 1050 fps velocity out of your rifle??

I use BC=.135 with Wolf MT and JBM is right on out to 200 yards.

Also, is your scope adjustments correct after that many clicks?

MOAs vs. 1/4" / click??

etc....
 
Re: Real World vs. Calculated trajectory for .22lr

INH is correct, do you know the actual FPS out of your barrel. on a .22lr this will make a BIG difference at extended ranges.

another problem some do not consider, is your scope true to the receiver.
 
Re: Real World vs. Calculated trajectory for .22lr

I don't know for sure that the velocity is correct. I don't own a chrono, however I have a friend that i'll ask if I can borrow his for a few weeks to use with my .308 as well.

The scope is a WOTAC, and i'm confident in it, I haven't personally done a box test on mine, but have read that others have done it, and had successful results. Like I said, i'm going to go out again this weekend to give it a shot again.

I put the .135BC into JBM and modified the velocity until the chart matched (quite closely) my "real world" drop chart. Looks like i'm actually getting right at, or really close to, 1000fps vs. the 1050 claimed. I just got a brick of SK SP today so i'm looking forward to having plenty of ammo to do my tests with and ensure my zero.

Branden
 
Re: Real World vs. Calculated trajectory for .22lr

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body">I don't know for sure that the velocity is correct. I don't own a chrono, however I have a friend that i'll ask if I can borrow his for a few weeks to use with my .308 as well.

The scope is a WOTAC, and i'm confident in it, I haven't personally done a box test on mine, but have read that others have done it, and had successful results. Like I said, i'm going to go out again this weekend to give it a shot again.

I put the .135BC into JBM and modified the velocity until the chart matched (quite closely) my "real world" drop chart. Looks like i'm actually getting right at, or really close to, 1000fps vs. the 1050 claimed. I just got a brick of SK SP today so i'm looking forward to having plenty of ammo to do my tests with and ensure my zero.

Branden </div></div>

What is the length of your barrel?
 
Re: Real World vs. Calculated trajectory for .22lr

Hi Branden,

It may help, I ran your problem through Exbal and got the following based on:
40gns,BC 0.125,59Deg, 78% Humidity, Sight In 50mts.

100mts -9.8", 125mts -19.5", 150mts-32.7", 200mts -70.6", 250mts-95.8", 300mts -199.2"

I use Remington 36gn HP @ 1300FPS and at the same temp etc get:

100mts -6.8", 125mts -13.9", 150mts -23.8", 200mts -53.0",250mts -96.2", 300mts -155.3",

Don't know if it is a help but it is a wet afternoon,

Cheers from Australia,

Regards,

Jeff Gray
 
Re: Real World vs. Calculated trajectory for .22lr

out of my mkII 10 round fps averages:

sk match 1040 fps
depending on environmentals, (temp. and hum., zeroed at 50 yards and using 1/8" adjustment) i'm getting a range of:
2.75"-3" drop or 29-31 clicks at 75 yards
8.25"-9" drop or 63-69 clicks at 100 yards
17.5"-18.25" drop or 108-111 clicks at 125 yards
30.25"-31.5" drop or 154-159 clicks at 150 yards
46.25"-48" drop or 202-210 clicks at 175 yards
66.75-68.75" drop or 256-262 clicks at 200 yards

physically confirmed measurements on paper to 150 yards and relied on ballistics for the rest which matched the # of clicks of adjustment i used in reality.

sk plus 1046 fps

i found sk match a bit more consistant with less flyers (not that there was much with either)so i didn' get too in depth with a chart. p.o.a. was slightly higher than sk match.

oddly enough, SK's wolf "counterparts" had less fps and more drop, which leads me to believe that there is a difference

 
Re: Real World vs. Calculated trajectory for .22lr

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body">21" It's a Savage Mark II BV.

Branden </div></div>

the 21" barrel is likely your problem with velocity and there fore affecting your drop.

take a look at the table below while only a guide you can see the effects of barrel length on .22lr ammo. i believe most ammo is tested with an 18" barrel.

Ruger 77/22; Remington Standard Velocity .22 LR ammunition
Barrel Length/ Velocity
28 1095
26 1107
24 1119
22 1129
20 1138
18 1149
16 1157
14 1149
 
Re: Real World vs. Calculated trajectory for .22lr

DR,

here are two tables that show what will happen when you change the MV by just 50fps.

image-1.jpg


image.jpg


as you can see the difference in POI is 3.36in. at 200 yards with a 100yd zero. and at 300yds the difference in POI is 11.75in with a 100 yd zero. to get repeatable accurate results with the .22lr you MUST know what your ammo is averaging for your MV, and this will most likely change with a different lot # of the same ammo.
 
Re: Real World vs. Calculated trajectory for .22lr

I went and spent a few hours of shooting .22lr at ranges from 50m (zero and group shooting) to 175m (steel swinging target). I was shooting SK Standard plus from a Savage Mark II BV with a Wonder Optics WOTAC 4-14x50 scope. At 50m first thing this morning while the winds were very calm, and in my face I was getting .3-.5" groups. I was shooting in a clean bore. Some of my groups were opening up to 1" but i'd like to attribute that to an imperfect rear bag situation that I didn't remedy. I'm sure the rifle would hold .3" easy if I bagged the front and back instead of bipod front. I moved out to 100 meters with the target box and shot two groups and both were crap. One was over 3" (possible flyer high and left due to changing winds) and the other was 2.5". By the time I was shooting past 50 on the first go the wind was blowing 5-7mph in my face at the shooting line, and at the target the wind from right to left according to the mirage that I was watching through the scope. I wasn't out to get good groups at each range, I was there to get my drop dope so i switched out to my steel swinger at 125m. My previous drop was 14.75min but I was hitting low this time so I had to go up to 15.75min to hit the center of the 4.5" target. While I was shooting I started to notice that when I thought it was calm because the mirage seemed to be going straight up (it was actually coming straight at me) I would touch off the shot, and it would hit a minute, or more low and shortly after that I would feel the breeze on my face. I learned a LOT today about how much wind effects the little .22bullet even when it's a "0 value" wind. If it's at your back, the bullet hits high, face, low.

To make a longer story a little shorter, I did get my target all the way out to 175meters. I was able to get fairly consistent hits on the 4.25" target, but I had to watch the mirage (by 175m the winds were slightly from right to left, I dialed in 1min right but still was hitting upwards of 1min left on some shots. I would love to see how I group at these longer ranges, however I know the only way i'm going to get a decent group is if it's dead still, which means I need to get out there at sunrise (like I tried this morning, but the snooze button got beat up a lot this morning) in my wind sheltered shooting spot to get my group shooting on.

Shooting a .22lr past 50m is challenging, it's quite something else to fire and watch the bullet go downrange through the scope, and wait, wait, wait, hit. wait, wait, ding.

I enjoy this long range .22, I've gone to 250 with my 17hmr, ordering another WOTAC for it on tuesday or so and i'm going to start going out to 300m with it for groups. I don't think i'm going to try for 200m with the .22 unless it's dead calm.

The dope that i got was the following;

50 - 0
100 - 9.5min
125 - 15.75min
150 - 19.25min
175 - 25.0min

Even at 150m the subsonic SKSP's were hitting with quite a bit of force. I didn't push the target deep into the ground to have it set up a little higher since the grass and weeds were getting kinda tall in that field. On my 5th shot (which ended up being the 3rd hit) I fired, watched the hit, and watched (and chuckled) the target fall down.

Branden
Branden
 
Re: Real World vs. Calculated trajectory for .22lr

Here's the fly in your ointment:
JBM uses G1 drag function, which is a little off for 22lr roundnose flatbase bullets.

Google Albal, its a ballistics program that was initially developed for airguns, and has proper drag coefficient for 22lr roundnose........

 
Re: Real World vs. Calculated trajectory for .22lr

Actually I googled it for you, its downloadable here:

http://www.stevespages.com/page8b.htm


It may not be as user freindly (can't save stuff, other than as .txt files, and can't bring them back up in the program for tweaking) but has great drag coefficients for 22lr (RA4) through stuff as light as airguns:


 
Re: Real World vs. Calculated trajectory for .22lr

Hey Dust Remover,

Just an idea for you, have you checked your scope "MOA" error. I have a Bushnell elite 6500 2.5-16x50 mil dot. I bought it for my 300 win mag but now use it also with a EGW rail and switch it to my Savage BTVS Mark II.

To test the calibration of the knob(clicks) to moa I took a big paper target backer (22 wide x 24 high) at 100 yards, Drew a plumb line with a level in the middle and put a aiming point about 6" up from the bottom. I then zeroed my scope to 100 yards then fired a 10 shot group at the aim point. I then came up one full turn on my turret cap, 12"MOA" and fired another 10 shot group aiming at the first aim point. I then went right 6 "moa" on the cap then went left another 12 "MOA" with groups.

Here is what I found, 12 "MOA" on the scope now produced group centers 14.5" apart. 14.5"/1.047 = 13.8 MOA

Also the windage groups were about the same error.

I created a calculator spreadsheet on excel to do all the corrections for me and tell me my new scope click numbers, and for example at 200 yards the error of calculated drop to scope come up was almost exactly 2 MOA. At 300 yards this magnifies to almost 5 moa error that I would overshoot the target.

I havent had a chance yet to verify the 300 yard error but the 200 yard correction is right on.

I also tried the same shooting with my 300 win mag and the same scope and got the same come up errors so I'm confident.


If you are interested in a copy of this I can e-mail it to you, just PM me.

Mark
 
Re: Real World vs. Calculated trajectory for .22lr

Strelok is another nice balistic calculator. I have it for my android phone. Has most major common to high end reticles for holdovers as well. I always up the velocity from factory specs by about 5-7% for my 21 3/8" barrel. Best part is its free!!!
 
Re: Real World vs. Calculated trajectory for .22lr

My policy with .22lr has always been to take a roll of paper into the woods, tape it to the side of a tree, and shoot at the same spot (as high up as you can reach to make a dot) from 50 - 500 yards and record results. Sometimes you can wait for a certain wind condition and get a solid group that will give you some good wind data as well. I then go back to the computer and "reverse engineer" the numbers to get what I found in the field (AKA truing). I use Bryan Litz's Applied Ballistics for Android app on my phone to run all calculations (I trust Bryan's #'s). However, I can't use the program's built-in truing feature because the rounds are subsonic around 75 yards, which messes up his software. I believe that he will be fixing this in the next update.

What you have to remember is that as the bullet goes through transsonic flight, it wobbles a little, which makes it less aerodynamic and the B.C. drops. It is also perpetually slowing down, thus the B.C. is further dropping. In high caliber weapons, these effects don't come into play until around 800 yards (for .308 w/ 175 SMK). For .22lr, these conditions pop up around 75 yards. Therefore, to accurately predict the flight path of a .22, the program should look like this (numbers for illustration purposes only):
0-75 yards: B.C. is .140
75 - 120 yds: B.C. is .130
120 - 200 yds: B.C. is .110
etc.

Bryan Litz's applied ballistics does allow the shooter to input data like this to get more accurate outputs, but I've never had the equipment to gather that kind of info, so again, I just let the bullet do the talking, and then try to trick the ballistic solvers into closely duplicating field data. (P.S. - When you do trick the ballistic computers into duplicating field data, jot down how you did it [i.e. what you had to change muzzle velocity and B.C. to], so you can do it in the field when conditions are different)

Here are some of my field results. Hopefully these numbers can help you find what you're looking for.

Test Rifle: Ruger 10/22 w/ Green Mountain .920" diam bull barrel. 17.5" length, 1/16" twist rate, stainless steel.

Condtions: Zeroed at 50 yds (in same conditions as testing was done). Temp: 45 deg. F; Altitude: 3100 ft. (Barometric Pressure, Density Altitude, and humidity unknown as I didn't have a kestrel at the time
frown.gif


Test Ammo: Remington Gold Bullet (Bulk 550 rnds/box)
Accuracy: ~ 2 MOA (This ammo likes warm weather and can shoot 1 MOA as far as 300 yards when the temp is 70 degrees or higher)

Muzzle Velocities: High: 1198 fps; Low: 1076 fps; Avg: 1145 fps

Drop (Inches)
75 yds -2.5"
100 yds -6"
125 yds -11"
150 yds -19.5"
175 yds -29.5"
200 yds -44.5"
225 yds -59"
250 yds -77"
275 yds -96"
300 yds -120"

Max Range:

Remington Gold Bullet will begin to tumble between 280 - 300 yards in the conditions described above. At that range, it is still adequately accurate to hit a milk jug and is usually 2 for 3 or better on Gatorade Bottles (the fat ones) if the shooter does everything right in 7-10 mph winds. Once the bullet begins to tumble, the wind will make it very unpredictable. However, if there is no wind (0 - 2.5 mph) the weapon can be employed accurately to 350 yds in these conditions.

With the temperature down in the teens (15 degrees F), the bullet exits the barrel substantially slower and has only been found effective out to 140 yds with light winds. After that, nothing good happens. Remington Gold Bullet is very temp sensitive (sorry, no M.V.s recorded yet)

In 98 degree days with high Tennessee humidity (98% easily) at 5,000 feet altitude; I've engaged IDPA targets at 500 yards with Remington Gold bullet. Drop at that distance was 480" (91.75 MOA). In a 5-7 mph wind, we were achieving 2 hits for every 5 shots.

In order to get a similar ballistic table out of my program, I have to set the Barometric Pressure to 25.75; B.C. of the bullet to .140 (G1 Scale) and muzzle velocity to 1190 fps. While I'm almost certain those values aren't correct, they get my calculator to match my field data, so who cares!?

Other interesting field data that you might find useful:

I've found that Winchester M-22 bulk ammo is more consistent at longer ranges than Remington Gold bullet, and only slightly more expensive. It has an average M.V. of 1255 fps and a B.C. of .145 in the same rifle as described above. The projectile is 40 gr. as opposed to the Remington Gold Bullet, which is 36 gr. Both ammos shoot the same zero at 50 yards.

Field Relative Zeroes:

If zeroed for Remington Gold Bullet and/or Winchester M-22 at 50 yds:

Blazer will hit about .75" low @ 50 yds. Ballistics are comparable to Remington Gold Bullet

Eley Tenex will hit 1.6" low @ 50 yds. It is subsonic, so I like to switch to it when I need to make a suppressed shot. It's also stupid accurate (.25 MOA), so I switch to it when somebody bets me I can't hit something at the range (won a couple bucks hitting flies and thumbtacks off the backboard at 50 yds this way). When they see you shooting Gold Bullet, make you a bet, and then you switch to Eley Tenex, adjust the rifle to new zero, and then hit the period at the end of their sentence, you've earned your prize!

GE American Eagle Match will hit 1" low @ 50 yds. It is also subsonic (not sure if they even make it any more) and groups about .6" @ 50 yards, so it's my intermediate match/suppressed ammo.

I sincerely hope that somebody finds all this useful, because that's about 3 years of field data in a nutshell.
 
Re: Real World vs. Calculated trajectory for .22lr

I sure did, thank you!