Range Report Checking Zero at match Location

[clayne_b]

Hello guys,

I see alot of guys ask if they can check zero before a match....

Lets say I shoot at 4500ft here at home, then go to match at 9000ft, although my drop chars show a different drop at extended ranges at 9k compared to 4k, is that based of the zero I started with or should the rifle be re zeroed at the shooting location.

I am using JBM for building my charts, and have trued a chart for 4500ft and then just change the elevation in the program. to print it off for different elevations and temperatures.

Is this the right way to do this?

any input would be great!

Thanks

 

[Rob01]

Yes always check zero at match location if possible.

I always use JBM and just put in the match elevation/BP/Temps and all my other data for the rifle and load and it's right on.

 

[turbo54]

I'll never ever ever turn down the chance to check zero.

Maybe my rifle sucks, maybe my ammo sucks, maybe it's just me that sucks, but when I zero on location before a match, it's usually off .1 to .3mrad in one direction or another.

 

[Sugarbug]

I'll never ever ever turn down the chance to check zero.

Maybe my rifle sucks, maybe my ammo sucks, maybe it's just me that sucks, but when I zero on location before a match, it's usually off .1 to .3mrad in one direction or another.

Much altitude change?

 

[sjb269]

You could Google a local range that has similar conditions the day before or morning of the match for a quick zero check. Especially if the rifle has been in transit with rough handling. Or if in a rural area, i.e. wide open desert, pull off road and set up a hasty 100 zero target with safe backstop. I sometimes set up the chrono for a couple rounds to verify nothing weird is going on as well. I don't shoot formal comps, but when I travel to my shooting areas to meet others, it's nice to show up zeroed instead of scrambling to get dialed in. Meanwhile, I can observe weather and transfer data from FDAC, whiz wheel, PDA etc. for the expected conditions throughout that day. When I go from 350ft to 7000Ft, I don't get crazy zero shifts, but I have had to add or subtract a couple tenths adj. here and there sometimes.

 

[turbo54]

Much altitude change?

Unfortunately, no...it would be a lot easier to justify/reconcile if there were large altitude changes.

Most all of my shooting is done at ~500-1000ft, and during most of the shooting season, DA is generally from ~1500-2500ft.

That's why I say either my rifle sucks, my ammo sucks, I suck....or some combination of the three, because I generally find my zero is a few tenths off in one direction or another.

 

[Sugarbug]

Unfortunately, no...it would be a lot easier to justify/reconcile if there were large altitude changes.

Most all of my shooting is done at ~500-1000ft, and during most of the shooting season, DA is generally from ~1500-2500ft.

That's why I say either my rifle sucks, my ammo sucks, I suck....or some combination of the three, because I generally find my zero is a few tenths off in one direction or another.

Maybe the earth just spins slower where you live

 

[Tahoe Shark]

You could Google a local range that has similar conditions the day before or morning of the match for a quick zero check. Especially if the rifle has been in transit with rough handling. Or if in a rural area, i.e. wide open desert, pull off road and set up a hasty 100 zero target with safe backstop. I sometimes set up the chrono for a couple rounds to verify nothing weird is going on as well. I don't shoot formal comps, but when I travel to my shooting areas to meet others, it's nice to show up zeroed instead of scrambling to get dialed in. Meanwhile, I can observe weather and transfer data from FDAC, whiz wheel, PDA etc. for the expected conditions throughout that day. When I go from 350ft to 7000Ft, I don't get crazy zero shifts, but I have had to add or subtract a couple tenths adj. here and there sometimes.

I may be misunderstanding your statement that you go from 350 ft to 7000 ft and you sometimes adjust a tenth or so. I shoot normally 600-1000 yds @ 5600 ft and when I go to a match at 170 ft I come up a lot, not just tenths. What am I missing?

 

[sjb269]

Don't know, What are you typically having to adjust to re-zero? Just to make sure... I am talking about 100yd zeros here. Each rifle/scope/ammo combo will have different needs/capabilities. I live at 350ft above sea level and frequently shoot at 7,000 ft. When I confirm zero at elevation I sometimes need to add or subtract a couple tenths of a mil.
Now, drop tables at 7000ft will of course be vastly different than 350ft. But at least I know I am starting out with a good zero. I need all the help I can get when shootin otherwise Ill get my ballz busted by my buddies and a couple tenths off would be just enough to do that.

 

[Bunnypunter]

For the love of all that is holy, check your zero. This bit me in the butt last match. Couldnt figure out why I was shooting low all day. I had zero'd several days before and all was spot on. Match day, low on everything except cold bore shot. Checked after match, 0.3 MRAD low 1t 100yrd. Well guess that solved that. It will be the last time I ever do that again. Show up early, check zero, let gun cool. Just in the event the match has an official coldbore shot.

 

[Eznutz]

For the love of all that is holy, check your zero. This bit me in the butt last match. Couldnt figure out why I was shooting low all day. I had zero'd several days before and all was spot on. Match day, low on everything except cold bore shot. Checked after match, 0.3 MRAD low 1t 100yrd. Well guess that solved that. It will be the last time I ever do that again. Show up early, check zero, let gun cool. Just in the event the match has an official coldbore shot.

bpunter has always had that problem and can never rise to the occasion.....

 

[Graham]

A few years ago there was almost never any pre-match zero check. The range was 'cold' until the match started. We were expected to arrive at the match ready for the cold bore shot. If you missed the cold bore it was up to you to make any necessary adjustments on the fly prior to shooting the next stage.

Today, with more people getting involved in the sport, match directors want to make sure that no one has broken equipment and that everyone can hit the backstop. So most of the time there is now an opportunity prior to the match to re-zero at the new location. Usually the zero change is not that much - a tenth or two - but with target sizes getting smaller it matters now like it never did before.

When I zero at sea level here at 40 degrees, then go to New Mexico to shoot at 5500 feet and 105 degrees, I usually have to come down a few tenths. Most of that difference is due to ammo temp and not altitude.

 

[bohem]

At 0 ASL to 12kft ASL the change in impact for a 308 cannot be realized by a correction in the scope until 300-325 yards (depending on bullet, load, etc).

Altitude change has no affect on short range zero, effects showing the difference are not because the bullet is flying differently but it is entirely possible that temp/altitude changes can drastically affect the person pulling the trigger too.

 

[jbailey]

Can parallax change be a cause?

Shot somewhere with the parallax dialed out and then in a new spot, whatever influences parallax has changed, and in the process changed the spot where parallax is dialed out. When we shot again without dialing parallax out again, we have a small change in POI as result.

Not saying I know this to be theory, just putting it out there as an idea.

 

[jbmillard]

Hello guys,

I see alot of guys ask if they can check zero before a match....

Lets say I shoot at 4500ft here at home, then go to match at 9000ft, although my drop chars show a different drop at extended ranges at 9k compared to 4k, is that based of the zero I started with or should the rifle be re zeroed at the shooting location.

I am using JBM for building my charts, and have trued a chart for 4500ft and then just change the elevation in the program. to print it off for different elevations and temperatures.

Is this the right way to do this?

any input would be great!

Thanks

When you zero your rifle, you are setting the angle between the line of sight (centerline of the scope) and the bore. When you go to a different altitude, this doesn't change -- but the drag on the bullet does. This change is very small and most people that use a trajectory calculator probably won't know the difference.

In my opinion, the right way for a calculator to do it is to keep that angle constant (don't recalculate zero at the higher altitude). So you find the angle at the zero conditions and then shoot with that angle at different conditions. You can see the mechanics of it in this article:

JBM - Topics - Elevation

This is what my trajectory card calculators do -- that's why they have two sets of conditions.

The other thing you should take into account is the change in muzzle velocity with the change in temperature. My 0.308 loads are about 2750 at 32 degrees and 2800 at 70 degrees.

Brad

 

[Unknown]

I agree with Graham. As a match director, safety is important, and being able to hit the impact area rather than launching a round over it, and into a town, house, or worse is a bad risk. If there is time between target setup, and start of the match, and someone asks to check zero, I will allow a few fast shots. Three shots should tell where they are hitting, then they can adjust. I don't recall allowing a re-check after that due to time.

The info from the three shots has to date been adequate.

 

[19Scout77]

At 0 ASL to 12kft ASL the change in impact for a 308 cannot be realized by a correction in the scope until 300-325 yards (depending on bullet, load, etc).

Altitude change has no affect on short range zero, effects showing the difference are not because the bullet is flying differently but it is entirely possible that temp/altitude changes can drastically affect the person pulling the trigger too.

Thank god somebody gets it! Right on Josh!

 

[Rob01]

Don't forget possible mechanical changes due to air flight or long drives.

 

[Graham]

Don't forget possible mechanical changes due to air flight or long drives.

Hey... That explains it: My watch does lag a few hours behind when I travel west. LOL!

 

[Rob01]

Hey... That explains it: My watch does lag a few hours behind when I travel west. LOL!

Funny Graham. Was your watch thrown around by baggage monkeys too?

 

[Lowlight]

People who shoot matches are funny and look for all kinds of excuses as to "why" they missed.

We opened up the Demo range this year at the Cup the day before to all competitors to check zero and what not, as well the range was open the entire match.

On the first day of shooting we had wind gusts as high as 45MPH and guys were actually coming back to the zero range to "check their zeroes" at 100 yards...

When things dont' go their way a competitor will look to find anything else to blame but themselves.

We no longer have to worry about the safety factor with a 7000 acre ranch we use, but we have found opening up the range is a nice added bonus for the shooters. Expect us to open it up completely next year and reduce the "train up" time to allow for more people to take advantage of the vast open ranch. I personally would be changing my rifle if I put it in a pelican case and flew with it only to find my "zero was off" ... if that bumps your zero, you're equipment needs to be looked at.

 

[Graham]

Was your watch thrown around by baggage monkeys too?

No, but the last time I flew I was pat-searched by TSA when I politely refused the body scanner and asked for a physical search. Having pat-searched people for a living I simply wanted to see whether or not they were properly trained. I won't comment publicly on my findings or on our discussions after the search.

 

[2Shots]

I understand all the arguments for rechecking zero, I have shot enough big matches now to form my own adaptation. I may check my zero but I don't reset my scope anymore. I look and see if i'm within a click or two and leave it alone. I always check my zero at home on that ammo/rifle the week I am going to the match, I don't clean the bore in case we have a "real" cold bore stage. When you arrive the night before and they have the zero range open it's usually low light, the light angle is weird, DA is higher that it is in the morning and unless the actual altitude is way different than at my range I don't want to make a correction that will hinder my chances the next day. I would rather worry about what the DA will be doing the next day and how it will affect my drop. I shot in texas a year ago and checked my zero, good to go. the DA started out at 500 at 7:00 am and was 6000 by 1:00, now that will make a difference! Had a shooting buddy of mine reset his zero the night before a big match, it was a lot like 3 clicks right and 4 up, and this shooter is not one to be sloppy about his settings. Blew the first three stages the next morning until he set his zero back to where it was. Call it superstition if you like but if my zero is on when I leave, unless I drop it from the second floor I ain't moving it.

 

[Rob01]

I personally would be changing my rifle if I put it in a pelican case and flew with it only to find my "zero was off" ... if that bumps your zero, you're equipment needs to be looked at.

True but stranger things have happened. It's just another possible cause.

I have never been off more than about .2 mils when checking zero at any match and I just reset the knobs and go. I wouldn't leave that zero offset on the scope as it just asks for a miss. Some targets are small and .2 mils will be a miss. Trying to remmeber that it's there under stress is also not advisable as it will probably be forgotten.

 

[6.5x47]

Clayne's question, I believe, is based upon a match he and I just attended this past weekend. He and I live and shoot around 4500-4700' elev. The match we shot had us shooting out to 1150 or so yards with the first days elev being around 8,000 and the 2nd days elev at about 9,000'. I didn't check my zero before the match at the 7,200' elev of camp but did check it the day before at 5,700'. All was right with my rifle. At the end of the first day's match, I did some 100 yds shooting for the fun of it and to prove to myself my Gunwerks G7 LRF was working as intended. My hits at 100 were 1/4" high. I then lased the target and it told me to turn down .2 moa. The next 3 hits obliterated the X I was aiming at. On Sunday afternoon, my last COF was a paper target that was at a lased 89 yd, 30 deg down angle, over a make shift fence rail. The G7 told me to turn down .2 moa; I did and put 10 shots into the 10 ring with 6 of them going into the X ring.

The point, proved to me, is to NOT mess with my scopes zero when the match's elev changes but to trust my dope and free my mind of the mental gymnastics otherwise gone through.

Alan

 

[Rob01]

To each his own but if I get a chance to check zero before a match I am taking it and making the proper adjustments if needed. Trust is great but verification is better for the mental part of the game.

 

[6.5x47]

To each his own but if I get a chance to check zero before a match I am taking it and making the proper adjustments if needed. Trust is great but verification is better for the mental part of the game.

I'll clarify. If I get a chance, I'll check to make sure it didn't get knocked out of alignment but won't change a thing if I'm close; 1/4 to 1/2 moa. Like Lowlight said, not quoted, if your rifle's zero is bumped off due to rough handling, might rethink another rifle.

Alan

 

[Rob01]

I'll clarify. If I get a chance, I'll check to make sure it didn't get knocked out of alignment but won't change a thing if I'm close; 1/4 to 1/2 moa. Like Lowlight said, not quoted, if your rifle's zero is bumped off due to rough handling, might rethink another rifle.

Alan

I didn't say just from rough handling. If your rifle was right on when you left home and you go somewhere for a match and check zero and its off then it needs to be rezeroed no matter the reason. You want to live with being a 1/4 MOA off and possibly missing that last kyl target then that's on you. I want my gear as dead nuts on as I can get it when I shoot a match and not afraid to readjust the knobs. When I know the rifle is on then I know where the problem lies when I miss. It's about taking as many variables out of the equation as possible.