Does your Vudoo shoot high?

[J@50n]

I have a Kidd 22LR classic (i.e. a 10/22 clone) and a Vudoo V-22. Both have 18" barrels. Both have a nearly perfect 25 yard zero. Using the same ammo (I've tried Center-X, Midas+, and Ultramatch) in both rifles, I get nearly the same muzzle velocities. I used Lapua's ballistics app as well as Applied Ballistics to get elevation data for the Lapua ammo. For the Federal ammo, I used trial and error. The ballistics apps both said 2.0 or 2.1 mrad of elevation for 100 yards, depending on the weather, which was correct for the Kidd. With the Vudoo, both still recommend 2.0 or 2.1 mrad, but I find 1.6 or 1.7 to be the correct value.

Am I the only one experiencing this? Does anyone have suggestions as to what it could be?

 

[StrayDog]

Believe the bullet!
Have you chronoed the muzzle velocity?

 

[nesikabay]

With my vudoo shooting center x 50 yard zero. I am 1.6 to 1.7 mills to 100

 

[padom]

Who cares. Zero it and shoot it

 

[hlee]

Scope height difference?

 

[Tiger_Shilone]

Op, it's interesting you get the same FPS velocities for bolt vs. semi auto actions, I don't.

I shoot ARA .22LR BR (I call this match the "Little old man cannon shooting club", as nobody holds a rifle in the tradition sense) and I chrono just about every shot. I've used a variety of rifles over the last few years doing it. The serious competitors at that match make fun of me, asking what new flavor of gun is it going to be this month. I don't care as I'm shooting against myself and proving out theories and equipment. I don't expect to win that game, but I get invaluable data for other matches like NRL22 PRS type matches that I do very well at. At the ARA matches I've shot Anschutzes, Martini MK2, CZ455's, Vudoo 18", PWS, stock ruger 10/22 and various KIDD 10/22s in different barrel lengths and profiles, fixed and switchable barrels. I use a 1 piece rest with roller ball bearing head up front and a teflon roller v block in the back for all rifles.

1 piece rest:


typical ARA set up:


My experience has been a 30-50 FPS difference between a semi-auto 10/22 and a bolt action. That just sounds wrong, but that's what my accumulated data says. I use two different drop values when shooting matches, one for the bolt and one for the semis. Same ammo for both. I make hits on steel at various ranges during matches so the data isn't faulty.

I look at it this way, the semi auto is using energy from the round to cycle the bolt. It needs enough energy to overcome the mass of the bolt and resistance of the spring to cycle it. It's not like an AR gas system where the bullet has to travel a good distance down the barrel before it gets to the gas port and activates the bolt, the 22 blowback system starts to work as soon as ignition happens and is expending energy against both the bullet and bolt instantly. The energy spent against the bolt is going to be a loss of FPS for the bullet velocity. In a bolt action rifle all of the energy gets expended on the bullet only.

That is one factor, another piece of data that I've started to use a lot more is temperature as that also makes a surprisingly large difference in velocity for these .22LR rifles.

 

[J@50n]

@StrayDog
I do trust the bullet, but I want to be able to predict future bullets, which requires an accurate ballistics curve.
I have chronographed both setups...but in different conditions with different chronographs. For the Vudoo, which is the one I care about most at this point, I used a Labradar with an external mic trigger three days ago. I used a Chrony last summer to chronograph the Kidd. The Vudoo was 1071fps on average and the Kidd was in the high 1050s. The Labradar sits right next to the muzzle and measures muzzle velocity. The Chrony sits down range of the rifle and doesn't measure the true muzzle velocity, which accounts for some of the difference.

@nesikabay
My 25 yard zero is effectively zeroed at 50 yards as well, so it sounds like our trajectories are similar. What do you use for ballistics calculations?

@padom
I care; that's why I'm asking. I did zero it, and have been shooting it. When I shoot it in the future, I'd like to be able to predict the drop at various ranges, so I can hit my target.

@hlee
I don't think it would be scope height. The ballistics apps take that into account. And I used the same rings on both, so the height was nearly identical.

@Tiger_Shilone
Unless the case leaves the chamber before the bullet leaves the muzzle, the reciprocating bolt shouldn't have much effect on the muzzle velocity. The gas pressure is pushing the Vudoo bolt with just as much force as the Kidd bolt, but in the case of the Vudoo, the entire rifle absorbs that force, because the bolt is locked to the action.
If the case leaves the chamber early, or ruptures, the gas will be able to escape via the chamber, and will stop applying force to the bullet.


Ignoring the Kidd though...with two different ballistics apps, I get elevation data for the Vudoo that is significantly different than what I observe. That's what I'm trying to figure out.
Should I make up a muzzle velocity that fits my prediction? Or would that likely be incorrect at other distances?

 

[StrayDog]

That's some thorough reply, nice.
My 18" kukri gets 1075-1100 for most ammo for 1.7-1.9 mils @100yds.
What's the furthest you've shot for groups?
Maybe do 150, 200, 250, 300 or something to verify your actual drops and then fudge the ballistics #s? Are you using good BCs?
I wouldn't discount the blowback bolt theory.
Either way, you get to shoot your Vudoo more and that's a win win.
I've heard rimfire called the rabbit hole before, we're all mad here.

 

[padom]

@StrayDog
I do trust the bullet, but I want to be able to predict future bullets, which requires an accurate ballistics curve.
I have chronographed both setups...but in different conditions with different chronographs. For the Vudoo, which is the one I care about most at this point, I used a Labradar with an external mic trigger three days ago. I used a Chrony last summer to chronograph the Kidd. The Vudoo was 1071fps on average and the Kidd was in the high 1050s. The Labradar sits right next to the muzzle and measures muzzle velocity. The Chrony sits down range of the rifle and doesn't measure the true muzzle velocity, which accounts for some of the difference.

@nesikabay
My 25 yard zero is effectively zeroed at 50 yards as well, so it sounds like our trajectories are similar. What do you use for ballistics calculations?

@padom
I care; that's why I'm asking. I did zero it, and have been shooting it. When I shoot it in the future, I'd like to be able to predict the drop at various ranges, so I can hit my target.

@hlee
I don't think it would be scope height. The ballistics apps take that into account. And I used the same rings on both, so the height was nearly identical.

@Tiger_Shilone
Unless the case leaves the chamber before the bullet leaves the muzzle, the reciprocating bolt shouldn't have much effect on the muzzle velocity. The gas pressure is pushing the Vudoo bolt with just as much force as the Kidd bolt, but in the case of the Vudoo, the entire rifle absorbs that force, because the bolt is locked to the action.
If the case leaves the chamber early, or ruptures, the gas will be able to escape via the chamber, and will stop applying force to the bullet.


Ignoring the Kidd though...with two different ballistics apps, I get elevation data for the Vudoo that is significantly different than what I observe. That's what I'm trying to figure out.
Should I make up a muzzle velocity that fits my prediction? Or would that likely be incorrect at other distances?

You should care. Individually what each rifle does. You are comparing apples to oranges. 2 different rifles, semi vs bolt, 2 different chronos, at 2 different times, at 2 different distances...

I have multiple 22lr as well. They dont shoot the same ammo the same.

Shoot said ammo in said rifle and record the data. You now have your drops for that combo. Same as any other rifle...

 

[J@50n]

That's some thorough reply, nice.
My 18" kukri gets 1075-1100 for most ammo for 1.7-1.9 mils @100yds.
What's the furthest you've shot for groups?
Maybe do 150, 200, 250, 300 or something to verify your actual drops and then fudge the ballistics #s? Are you using good BCs?
I wouldn't discount the blowback bolt theory.
Either way, you get to shoot your Vudoo more and that's a win win.
I've heard rimfire called the rabbit hole before, we're all mad here.

I've only shot it out to 100 yards. My experience with it so far has been ammo comparisons (my best results were with Eley Tenex, and Lapua Center-X, Midas+, and X-Act--they all get 0.3" to 0.5" groups at 100 yards) and the April NRL22 match.
I didn't shoot it out to 200 yards on Saturday, because it was a bit rainy, and I didn't want to walk out to the 200 yard berm. Also, I made the mistake of taking noobs to the range, who wanted to shoot pistols, so I didn't have much rifle time.
With the Lapua app, I'm using their BCs. With Applied Ballistics, I'm using Brian Litz's data, and their custom drag model for the Center-X round.

 

[J@50n]

You should care. Individually what each rifle does. You are comparing apples to oranges. 2 different rifles, semi vs bolt, 2 different chronos, at 2 different times, at 2 different distances...

I have multiple 22lr as well. They dont shoot the same ammo the same.

Shoot said ammo in said rifle and record the data. You now have your drops for that combo. Same as any other rifle...

I said I care. You said "who cares?".
I included the Kidd for reference to show that the ballistics data is pretty close for one rifle. I want to get accurate data for my second rifle.

If I just go out and shoot at various distances, I'll know my drops for those distances in that weather. I could guess at distances between the known ones, and I could guess at differing weather conditions. The 10 ring on an NRL 22 3" target is about half an inch. That's an angular size of 0.28 mrad at 50 yards. Past 72 yards it becomes smaller than 0.1 mrad. If my elevation guess is off by 0.1 mrad, my chances of hitting the 10 drop significantly. I bought the Vudoo because I want to hit the 10 every time.

 

[padom]

I said I care. You said "who cares?".
I included the Kidd for reference to show that the ballistics data is pretty close for one rifle. I want to get accurate data for my second rifle.

If I just go out and shoot at various distances, I'll know my drops for those distances in that weather. I could guess at distances between the known ones, and I could guess at differing weather conditions. The 10 ring on an NRL 22 3" target is about half an inch. That's an angular size of 0.28 mrad at 50 yards. Past 72 yards it becomes smaller than 0.1 mrad. If my elevation guess is off by 0.1 mrad, my chances of hitting the 10 drop significantly. I bought the Vudoo because I want to hit the 10 every time.

I said who cares what one rifle does vs the other which is what you posted in your OP. They arent the same. Learn what your ammo does in your vudoo so you can whack 10rings at a gazillion yards in Sahara heat and Siberian winters. You get the point

 

[Tiger_Shilone]

---deleted---- nvm, OP is shooting .3-.5"@100, that is better than I can do. Good luck with your matches OP, groups like that will do very well.

 

[padom]

The bullet doesn't lie. That's what Padom is saying. Throw the chrono back in the truck. I've had rifles doped out to perfect the fps or bc. Then I put a chrono on it and the chrono doesn't match what the bullets actually doing.....so common sense tells me to just adapt my drop charts to match what you see downrange regardless what the chrono is saying.

Exactly. My experience as well

 

[usafa77]

My buddy and my Vudoo's both use Sk Standard and Rifle match. Both zeroed at 50. AB custom curve- 1.7 mils at 100 yds all day. Both 20" barrels. right around 1100 fps as I recall. Seems to be in line with others results. I don't think it's a Vudoo problem.

 

[J@50n]

I'm not saying there's something wrong with the Vudoo. What I'm saying is that the prediction from the ballistics calculator doesn't match the performance of the rifle. I'm wondering if there's something I need to enter differently in the calculator.

 

[Dirtracer151]

Sounds like something is off with your calculator. My dope for my Vudoo at 100yds is 1.7 with a 50yd zero and shooting SK/lapua ammo.

 

[billmeek]

I have a Kidd 22LR classic (i.e. a 10/22 clone) and a Vudoo V-22. Both have 18" barrels. Both have a nearly perfect 25 yard zero. Using the same ammo (I've tried Center-X, Midas+, and Ultramatch) in both rifles, I get nearly the same muzzle velocities.

Just because the muzzle velocities are the same, doesn't imply that they are going to have the same point of impact at longer ranges. Chamber and barrel construction can effect the flight of the bullet. Even similar barrels (i.e. Savage B22 FV-SR and Mark II FV-SR) can have varying ballistic co-efficients when using the same ammo.

Get accurate weather data and use the Labradar to get a series of values from your ammo in the Vudoo. You can then input them into trajectory calculator to get a BC per shot. Average those together and you have a good starting point for your Vudoo.

JBM - Calculations - Trajectory (Simplified)

www.jbmballistics.com

 

[hlee]

I just looked at my drop info for my Kidd. It's 2.0 mil at 100 yards with a 50 yard zero. It's 1.7 at 95 yards. If nothing else, a small error in your range could account for the difference.

Well, maybe not if you're shooting both rifles on the same range.

But as everyone else has said, true the calculation with your real world data and drive on. Keep different data for each rifle and don't sweat it so much. This is supposed to be fun...

For the record, I haven't even put a chrono on my Kidd. I took the mv from the box of ammo and dropped it into JBM ballistics. Printed a chart and headed to a match. I've shot high score 3 consecutive times. Less stress ==> more fun.

 

[45cal4life]

Are you or the ballistics app taking into account the environmental conditions? Station pressure, temp and wind? Using the same ballistic coefficient? Very easy to over look some little setting deep inside the app somewhere when setting up different profiles

 

[MDrimfirerookie]

a lot of other way more wiser people have said, this sounds like an issue with your ballistics app. i would absolutely go with what real world data is giving you and see if there is a truing feature in your app. unfortunately i'm not familiar with either of the apps you are using.

 

[jbell]

Could it be a scope problem: one of the two scopes may not be tracking 100%. Meaning 1 mil may actually be 1.2 or something like that. It’s not uncommon at all and is something that should be tested and accounted for. If it’s repeatable (which it probably will be) you can add that into your ballistic solver as a correction like MV or BC.

If you haven’t measured both scoped you should IMO...

 

[kytrapper]

An Old school observation on the subject :

before everything went high tech.... we were taught to dope ...record and rely on our D.O.P.E... Data Obtained Previous Engagement....and use our lot #

Each rifle ammo combination has its own tendencies. A rifle squeezing more out of a round than predicted is a good thing in my book !!!

just a thought
Charles

 

[Macca]

It may be old school,but still applicable.
I rely on it.

 

[Cofercr]

What BC you using for SK standard plus?

 

[brianf]

Don’t want to derail thread but .3-.5 groups at 100 yards.
If they are not cherry picked send some pics.
Or shoot the 6x5 and send it to jbell.

 

[jbell]

Don’t want to derail thread but .3-.5 groups at 100 yards.
If they are not cherry picked send some pics.
Or shoot the 6x5 and send it to jbell.

Agreed, that is damn solid if it’s repeatable!

By the way I have yet to get a ballistics solver to accurately predict drop with rimfire. It’s always a little off and I have played with BC, and MV quite a bit. I’ll get it dialed in at one distance and it will be off at the next. So I use DOPE.

 

[TIMMYTOY]

Vudoo 20in barrel shooting Lapua Center X 1070 ish 25 zero 50 dead on 75 up 2 Moa 100 up 5.5 moa
216 up 26.5 moa 237 up 31.2 moa 303 up 45.5 moa 50f 66% humidity cloudy day wind head on slightly west to east .

 

[TIMMYTOY]

Funny thing to is my buddy was shooting rpr SK Long Range match and I was shooting Lapua Center X he had to adjust for more drop than I did and the center x are slower. Possible scope? So many factors to consider we didn’t care ! we just kept banging steel out to 300 so cool!

 

[Rumblingdwarf]

This sounds like a scope height issue to me. I have seen .2 mil elevation errors caused by a .2 inch ring height errors in the past. For the record my 16 inch vudoo is 1.8 mil to 100.

 

[Macca]

Zeroed at 50m,it takes me 2.0 mil to get to 100m with 20” vudoo.
That’s been consistent with a Leupold & now a S&B.

 

[jbell]

Funny thing to is my buddy was shooting rpr SK Long Range match and I was shooting Lapua Center X he had to adjust for more drop than I did and the center x are slower. Possible scope? So many factors to consider we didn’t care ! we just kept banging steel out to 300 so cool!

Is your barrel considerably shorter than his? That may account for your shooting Center X faster. Did you try the LR stuff?

 

[10ring1]

This sounds like a scope height issue to me. I have seen .2 mil elevation errors caused by a .2 inch ring height errors in the past. For the record my 16 inch vudoo is 1.8 mil to 100.

Scope height has nothing to do with it. Zero is zero. And same here 1.8 mils to 100 with 50 yd zero

 

[Rumblingdwarf]

Yes but a 25 yard zero with a 2.25 inch scope height and a 25 yard zero with a 1.5 inch scope height will require different elevation to get to the same distance.

 

[Rumblingdwarf]

What BC you using for SK standard plus?

.125 G7 works for me.

 

[Hellbender]

Like jbell, I've never had a ballistics calculator ACCURATELY predict .22LR trajectory. It will get within .1-.2 mil (good enough to ring most steel) but, if you do a ten shot group and find center, it always seems to be off past 150-175 yards or so.

Just look at the different 100 yard DOPE discussed in this thread, it varies from 1.6-2.0 mils ...WAY more than any minor variation in our scope heights and velocity should change.

With .22LR and it's long barrel lag time, the different ways we, as individuals, address the gun (hard hold vs. free recoil, scope parallax adjustment, follow through, etc, etc), it adds endless variations to what we see on target (compared to a fast lock time center fire bolt gun).

I see many of the same things with center fire AR's, with their slow lock time and recoil impulse.

 

[Dthomas3523]

I haven’t looking into the “why” because it doesn’t matter much.

Sk standard plus = 1.9 at 100

Lapua center x = 1.7 at 100


For center X

I don’t even worry with the MV. Just whatever the custom curve velocity inputs. I just shot 25/50/75/100/150/200/250/300

Record the dope. When it doesn’t match up with AB, at whichever range, I put that into the calibrate DSF (since .22 is subsonic).

It then pretty much lined up with it all.

For standard plus, it’s a little different since they don’t have a curve for it. I chrono and tweak bc a bit until most things are close and then I calibrate the dsf as normal.

 

[10ring1]

Yes but a 25 yard zero with a 2.25 inch scope height and a 25 yard zero with a 1.5 inch scope height will require different elevation to get to the same distance.

After you have zero, scope height makes no difference in dial values

 

[Dthomas3523]

After you have zero, scope height makes no difference in dial values

I’m assuming you’re misinterpreting him.

For examples, 300yds with a 2.5” bore height is 13.9mil and 1.5” bore height would be 14.4mil

He’s suggesting the OP has the wrong bore height in his calculator, which would possibly account for why he is seeing a difference in real world vs calculator.

 

[Anderson_A]

After you have zero, scope height makes no difference in dial values

Go into any ballistic app and change your scope height and nothing else and check your dope it will alter your entire curve

Another thing is I noticed the poster stated he used the same rings on both guns so his sight over bore must be the same I have a vudoo and a kidd “classic “ and I have .3” difference between them from centerline of bore to top of pic rail so that could be and error your introducing

I don’t think you can compare a 10/22 to a vudoo nor should you each one is it’s own ballistic profile the way I do it and I use my chrono for checking sd/es and for a STARTING MV I rarely leave it unchanged it usually takes some tweaking and truing mv and bc to get my apps to mirror my dope that’s all everyone is trying to say by believe the bullet make your app match your bullet it dosent work the other way round

 

[JG26_Irish]

Billmeek & KYtrapper both provided good advice. I can offer nothing better. When I was setting up a PRS rimfire rifle, I planned on using Wolf Match Extra since I had been given two bricks of it. I had good ballistic data for it out to 300y. Nonetheless, I took this data to the range and did groups at 50, 100, 150, 200, 250 and 300y just to verify the data. Out past 100y I was seeing significantly more drop than the data on the ballistic curve. We have lots of humidity here and it does make a difference. Changes in altitude will as well.

No problem, just use the real data and tweak the curve until it matches. I shot in both cold and warm-hot weather and recorded the variance. While temperature did make a difference it was close enough to the match venue temps to be negligible. When I arrived at the match range, I came a day early and checked my zero and my ballistic data out to 200y. Made a minor (1 click) adjustment and was good to go. When I ran out of the Wolf a few months later, I figured I would switch to Center-X since it is slightly better in my rifle. That turned out to require much more work than expected. The CX was a little slower and I had to tweak my dope all over again. Now I am looking to swap to a better rifle. Guess what? The two rifles do not shoot to the same POI with the same ammo despite having the same bbl length. Good news is I like to shoot and enjoy the technical side of adjusting the dope for the rifle/ammo/shooter combo.

Irish