Bergara Ballistic Calculations / Error

[Orthobill13]

I have used a ballistic calculator before with surprisingly great results. I have used both an app version and different online versions, with a Rem 10/22 with a Kidd barrel and trigger job, zero at 50 yards, went to 100 yards and 200 yards and calculations were basically very close.

I upgraded to a Bergara B14R and so far love it. I zeroed at 50 yards (also have a 20 MOA rail which I had on the 10/22) with a Vortex scope. I am using just standard CSI 22LR, 40 grain, 1070 fps according to the box information. Again, same ammo I used with the 10/22. According to the calculations, my 100 yard MOA should be around 7 give or take on temp etc... I was way high with the Bergara and ended up needing 6 MOA at 100 yards.

To get that calculation in the calculators to be correct, the bullet velocity needed to be more like 1150 fps, not 1070 fps.

Question 1 - would the Bergara be getting that kind of velocity compared to a semi auto like the 10/22?
Question 2 - does adjusting the bullet velocity as the variable to correct real life DOPE findings be the best way to adjust these calculations?
Question 3 - if yes to question 2, could I expect the calculations out to 200 and 300 yards to be accurate?

Thanks for any advice!
Bill

 

[DFOOSKING]

1. Of course a bolt gun can have more velocity for the same load. The semi is using the gas/recoil energy to cycle the gun. Some of the gas/energy goes rearward while some of the gas goes out the front behind the bullet. But you also have things like chamber dimensions, throat dimensions, and "choke" spots in the barrel which also effect the amount pressure built or not built. I'm not gonna say 1150fps is or isn't practical. Too many variables to say. Could be the gun. Could be a combination of errors on your part. How the fuck could I possibly know to predict that. When in doubt....shoot an intermediate distance in between for a handful of shots. See if it is spot on. That'll tell you pretty quick if its right or not.

2. The arguably best way is to chronograph your gun/load and acquire real b.c. numbers from verified sources to start. THEN if necessary, edit/alter those parameters to better match.

I am more of the opinion that if your gonna alter shit.....fuck it. Do whatever works. I don't ever honestly chronograph my loads unless a buddy brings one. Lot to lot (most of the time) they are somewhat the same velocity. So when I swap lots....I verify my 50yds zero and check 100 and 200 yard dope to be sure nothing changed. If the zero moved....likely the 100yd and 200yd is off. Create a new profile with the new lot number notated and roll on.

I also properly zero at verified yardages. I enter a profile with data that is derived to the best of my ability (Google b.c's). Then I get off my ass and shoot multiple groups at multiple yardages. I don't ever wait. I don't need an app at all to guess the dope for 100, 200, and 300 within about +/- 1 mil if I know what the general velocity "should be". I also have a public range with steel at those ranges as well as my own to set up intermediate "test" yardages to see if the supplied dope from the app is holding up. When you've done literally 100's of dope charts this kinda shit is old hat. Oh my dope is spot on at 200yds...let's see if 135 and 160yds is right. They are. Good. Roll on.

And the majority of the time people have issues with apps is they don't actually know how to run their app or they cut corners somewhere. Like guessing yardages or operating on a meters range instead of yards. Or not entering enviromentals, or proper b.c. type and corresponding number. Or entering a sight offset when they weren't supposed to. Or shooting only like 2 rounds at given range to save ammo (buy and bring enough)....the gun may have to warm up or you may have somewhat shanked a shot. Shoot 10 shots at a minimum maintaining the waterline of the plate keeping in mind that at 300yds....you likely have some inherent vertical in your groups. I'd be shocked if you didn't have 2-4 inches of vertical at 300 on a calm rock solid setup.

An app if given the actual correct parameters is fairly reliable. Some apps suck a bit when pressing them out farther (like beyond 250yds) but that might be due to the app is set up at its core to supply centerfire type solutions.... not the solutions that match the dogshit flight characteristics of super duper uber low b.c. rimfire ammo in chaotic winds can potentially exhibit.

3. I think I pretty much answered it above. Go zero it. Shoot at big steel plates that you literally cannot miss with small hit zones painted on. See your "miss" on the steel......make a good correction. Make many multiple hits on the hitzone before you settle on a dope setting for that given yardage. WRITE THAT SHIT DOWN. Then reference the app for the next yardage and repeat. Do your ballistic profile editing AFTER you have ALL THE ACTUALS WROTE DOWN. Use the app to give you "try dope" but it's the actuals we are truly after. You can fingerbang your app to your hearts content at home later. But don't leave the range without accomplishing getting the actuals. That way, if you have problems all the information is there for reference (to include your enviromentals). Then you can ask questions and even provide screenshots of your app and it's 100 times easier to troubleshoot your problems.

This mil based try dope covers a ton of guns/ammos in the typical subsonic flavors. This is not God giving the answer every time.

50-0

100-2

200-7

300-14

This is just usually good enough to be on paper/steel near the bull given no wind. That's it. If you're a MOA guy just multiply it by 3.438 to have a MOA based solution.

 

[Orthobill13]

Thank you very much for all of the info!!! I moved recently, and lost my "at home range" where I could shoot distances up to 200 yards to test. Now I am trying to calculate yardages to get me close before I go out and find a new range to test.

Thanks!

 

[oneshot.onehit]

If the app you are using has worked well in he past then you can trust it for other rifle profiles.

One thing I would do after you have checked all your inputs as far as making sure they were correct is too tweak the BC of the bullet, every barrel distorts the bullet differently from another due to the lands or groves being slightly different when cut. Also you are runnning sub sonic so adjusting the BC is more effective then tweaking the speed at this point. Adjust the BC value higher or up if your impacts hit higher then what the program requires and if for some folks that hit low you lower then what the BC value.

In your case if you tweak the BC up until it calls for the correct elevation at 100 the curve will still be very close for 60 or 80.

Osoh
JH

 

[1911Shootist]

You've got a big enough velocity discrepancy that I think you've got error elsewhere. CCI SV will have some fliers, so it's even more important to use large sample sizes with that ammo.

1. Make sure your zero is perfect. 10+ rounds. I'll sometimes do 1 shot at each cross hair on a target to make sure I can see the mean radius of each hole.
2. Make sure all your inputs are correct into the solver. Gun measurements, twist rate, environmentals (also watch for station vs corrected pressure).
3. Use large sample sizes at whatever distance you're trying to calibrate your data to. 10+ shots. If the weather is less than ideal, wait until is better.
4. Try to find an accurate chrono (Magnetospeed or Garmin) to use to measure an actual MV.
5. Changing MV will change the whole curve. Changing BC will have a minimal effect at ~150 yards and in, and have a greater effect at longer ranges - the inflection point will vary slightly, but is typically around 200 yards for match ammo if I recall correctly.

Every time I've been in your position - the errors have been on me, not the solver.

 

[DownhillFromHere]

Lots of good information above.

Condensing some main points, maybe adding a couple:

• Velocities printed on ammo boxes may as well be pulled out of your backside. While they're fine for getting started in absence of a chronograph, they are essentially useless as input for a ballistic calculator.
• The Bullet Speaks. As Dfoosking says, you MUST write down ACTUAL RESULTS observed on paper targets at different ranges as far out as you might conceivably shoot. Include environmental conditions - temperature, humidity, barometric pressure. Your goal is to have your calculator reflect the ACTUAL OBSERVED trajectory of your rounds.
• You MUST have accurate yardages. A .22 has a trajectory more like a mortar than a rifle. At anything over 100 yards, a measurement error of only a few feet introduces significant error. For example, next weekend I'm shooting a little match scored on number of hits on 8/6/4-inch plates at 300 yards. At my "home range," the steel on the 300-yard berm is actually 295 yards from my favored bench. I need .4 mils or 1.2 MOA additional elevation needed for the additional 15 feet to 300 - almost half the width of the largest plate,
• Ballistic Coefficient (BC) - the other main calculator variable in addition to velocity - of .22LR bullets is a little fuzzy, ranging from ~.132 to .172 (G1). Once you have your range/elevation/environment written down, you might experiment with adjusting velocity out to 200ish yards and BC at 250+ to get your calculator curve to match your observed curve.
• Ammo quality. Your Bergara can take advantage of better ammo than CCI SV. I have a few bricks of CCI SV out of a case I bought cheap a few years ago and find it useful for positional practice out to 100 yards, but it simply cannot hang with even lower-tier "serious" ammo like SK Standard+, let alone better SKUs like Lapua Center-X or Eley Match. The very best SKUs like Lapua X-Act, Eley TenX, RWS R50, etc... I'll take my lot-tested Center-X over a random brick of X-Act.
• In my experience, it's fairly straightforward to get your calculator to match observed data out to 250-300 yards. Past that, the inherent limitations of the .22LR cartridge coupled with environmental influences make that alignment more difficult. For the "long gong" match I mentioned above, hits on an 8-inch or even 6-inch plate are reasonably doable in calm conditions. Add a gusty/puffy/switchy wind... yeah, Lady Luck be with you.

Enjoy the .22 journey. It's a far different beast than centerfire.

 

[Orthobill13]

Thanks All. As an update, I am borrowing a Garmin tomorrow and will verify muzzle velocity with same ammo in both riffles. That will be very interesting and get me one step further.

 

[DownhillFromHere]

Thanks All. As an update, I am borrowing a Garmin tomorrow and will verify muzzle velocity with same ammo in both riffles. That will be very interesting and get me one step further.

I'll be curious as to what you learn. I have a couple of predictions...

• With CCI SV in your Bergara, I would expect your Extreme Spread / Standard Deviation (ES/SD) values to be in the 45+/15+ range for 10 or more shots (lower is better, of course; any long-string ES below 30 is good for a .22 and 20-25 is as good as it gets), and that 1070fps velocity on the box may be fairly close to actuality (there's a temperature dependency too).
• While I have precisely zero real-world data for autoloading .22s, I would expect velocity to be lower and ES/SD values to be higher with the Ruger.

I'd like to know what you learn. In your original post, you mentioned that you expected a 1070fps velocity and a 50-yard zero to yield a 7 MOA elevation for 100 yards. Not sure how you derived that; the rule of thumb I knew before getting way too deep into rimfire was a 6-inch (or 6MOA) dialed elevation from a 50-yard zero. This tracks with the various bolt-rifle/ammo profiles I have in my calculator for ammo in the 1070-1085fps range; I do have one lot of old Wolf Match Target that requires that 7+ MOA elevation - but its velocity is down around 1030fps.

Make sure your rifle info in your calculator is correct - Scope height above bore (measured center of scope tube at turrets to center of bore) especially. Make sure your reticle is plumb through the bore and the reticle is plumb to gravity when you shoot. The dwell time on a .22LR is almost 3x a centerfire round, so careful shot break and followthrough are critical.

 

[Orthobill13]

Hello All - I borrowed a Garmin Chronograph (amazing technology btw) and shot 10 rounds through both the Bergara B14r and Ruger 10/22. It was on my lunch hour and 32 degrees, or I would have shot more.

I am pleasantly surprised at how well the Bergara handles the CCI Std load. Box says 1070 fps. I found in the 10 shots this data: Min 1055, Max 1081, Avg 1064. Ext Sprd of 26 and SD of 8.3. Really happy with that.

Ruger 10/22 performed as expected, meaning worse: Min 964, Max 1034, Avg 1007, Ext Sprd 69.9 and SD of 20.2.

Knowing this information, I have used 2 different ballistic calculators. One online version called Shooterscalculator.com and the other is an app on my iPhone called Chairgun Elite +. I have measured my scope center to be 1.9 inches above bore center, and double checked all of the other variables. Shooterscalculator.com estimates 6.94 MOA for 100 yard shot, and Chairgun Elite + estimates 7.1. So both calculators are within .2 MOA of each other.

My real world experience was that I only needed 6 MOA, not 7. If I use my now known MV of 1063, I need to adjust the BC from .125 to .350 to get the correct 6 MOA.

Someone asked how I got to 7 MOA. I will attach a couple of screenshots from the online calculator.

Any further thoughts or do I just say the Bergara needs BC of .35 and call it good?

 

[Orthobill13]

Also, just so I can be a 100% nerd.... Here is example of a good group at 50 yards and a group at 100 yards after I found the correct 6 MOA. On the 100 yard, I believe the one shot to the left was my bad... but very pleased with the other 4.

 

[1911Shootist]

That 50 yard target would indicate your zero is off. 0.26" @ 50y = ~0.5 moa at 100y, which would be half your error alone.

Are you 100% sure the target is 100 yards from your shooting position, and that your zero board is 50 yards?

Correct your zero first, but also verify ranges are spot on.

 

[DFOOSKING]

What is the scope? Wonder if you have some scope tracking error.

I assume you have all the enviromentals accounted for in the app.

Either way, it is what it is. 6 - 6.5 moa is the solution for your setup.

There's no way the b.c. is in the .3xx's......its gonna be in the .105 to .185 range likely. Your ammo doesn't have 3 times better b.c. than the average. Just sayin'....

The same ammo in two guns with two different average speeds will mean two somewhat different b.c.'s

B.C. is a function of speed. The faster of the two will have somewhat higher (better) b.c.

 

[DownhillFromHere]

My real world experience was that I only needed 6 MOA, not 7. If I use my now known MV of 1063, I need to adjust the BC from .125 to .350 to get the correct 6 MOA.....

Any further thoughts or do I just say the Bergara needs BC of .35 and call it good?

With a 50-yard zero and goal of truing your calculator at 100 yards, adjust your velocity. With a BC of .35, you will get elevation solutions far too low at longer ranges. And yes, you should have an accurate velocity from the Garmin - but the bullet speaks. You have to adjust ("true") your calculator to what the bullet is actually doing.

Attached is the drop table for CCI SV in my Vudoo. Velocity is trued to 1086, BC .123 ( BC set per CCI SV data from Strelok Pro). Note the 300-yard elevation is 47.8 MOA. If I change BC to .35, calculator returns 38.8 MOA elevation.

True your calculator by changing velocity out to 200 yards, using .123 BC. As 1911shootist said, you MUST be sure your distances are correct.

 

[Orthobill13]

Thanks all! Will do