Long distance shooting,HELP!

[farmer7]

I have a Remington Sendero 25-06,it always shoots 1/2MOA,out to 300yards anyway,havent tried much further until today.

I decided i wanted to see how i would get on at 600 yards,just for fun. I loaded up some 100 gr ballistic tips over 55 grains H4831 and chronographed them,averaged 3233fps. I then put this into JBM's ballistic calculator: http://www.eskimo.com/~jbm/ballistics/traj_basic/traj_basic.html ,along with the other necessary details such as temp, altitude,air pressure and so on. Zeroed for 100yards bang on,0.45" centre to centre.

I went and set up my target board at 600 yards(measured with my swarovski rangefinder)on the farm. Lay down and wound my scope up 45 clicks like it said printed on the sheet. Fired 5 shots got on the quad to go and see how i got on and to my dismay only 2 had JUST hit the board,about 1 and a half feet low of the bull,3 inches apart.

I just wondered if anyone had any ideas how i was so far out!? There was a very fine drizzle (usually is in Scotland!) would this make a difference? Dont laugh now but the scope is a Simmons 44mag,6.5-20 x 44. I have never had any problems with it,always holds its zero,the adjustments seem to be repeatable, always moves what its supposed to at 100 yards. I checked the instruction book just to make sure it was 1/4" and not 1/8" clicks.

Are the 100gr Ballistic tips capable of grouping at 600 yards? The 2 that did hit hadn't keyholed or anything. Am i expecting too much of the 25/06? I was holding the rifle steady on bags,and never have a problem grouping closer in. I would be greatful of any help or opinions!


Many thanks!!!

 

[YardVarmint]

First I'll be honest and state I have zero experience with the 25-06. I do have a decent amount shooting a Sendero in .300WM at 600yds though.

I've found hot humid air will raise a bullets impact.

So maybe a heavy down ward mist, though colder, may lower it???

 

[farmer7]

Thanks for the reply YardVarmint. Am i right in assuming that the JBM calculator will work out trajectory for my rifle with the necessary info? Its scientific not just guesswork isn't it? I had honestly expected a group pretty near the bull with a 4" spread or so!

 

[ocabj]

Ballistic calculators give you the theoretical trajectory. While the equations and functions to calculate a given trajectory are proven science, practical application may not apply. Just because JBM says I'm going to have a 12MOA drop from my 100 yard zero at 600 yards, doesn't mean that if I dial in 12 MOA on the scope, it's going to just perfectly hit that 600 yard bullseye.

Temperature, barometric pressure, humidity, wind, and even light conditions will affect your zero. That's why you should always verify your zero through live fire. If you plan on shooting at 600 yards, test fire at 600 yards.

As far as the 55gr ballistic tips being able to group at 600 yards, assuming the exact same conditions (wind specifically) for each and every shot in the group, and assuming they are staying supersonic at 600, then there's no reason why they won't group.

 

[jbm]

It's hard to say...

I'll have to agree with pretty much everything that has been said here. It's hard to tell where the error may be without knowing all the inputs.

There are a number of things that come to mind:

1) Is the published BC close to reality?
2) What is the sight height you entered? (Errors here are angular -- worse at longer ranges)
3) I wouldn't think that density error would make more than a few inches of error
4) Is it really 600 yards or 600 meters?

I was shooting my AR-10(T) at 600 yards a couple of weeks ago and with the Hornady A-Max my numbers were right on when shooting at a 10"x17" steel target.

If you want, send me the output of the program (all the inputs are listed as comments in the output so I'll be able to see what you entered) and I'll take a look.

Thanks!

Brad

 

[30Cal]

As the bullet decelerates towards Mach1, several things begin to have a lot of affect on the bullet. So if your computed velocity at 600yds is approaching say 1250-1300fps, you shouldn't be expecting to score a lot of hits.

That said, the ballistic table did its job just fine--it got you on paper. You shouldn't expect it to do more than that. Models are fun, but real data is King.

Ty

 

[Zak Smith]

It should still be over 1800 fps at 600 yards, so that shouldn't be an issue. I agree that data needs confirmation by shooting, but more often than not, and especially to 600-700 yards, most rifles match the computer data within a few inches. In this case he was 18" or about 3 full MOA off, which is a lot.

 

[GunTech]

Did you chrono the loads the same day you shot at 600? Keep in mind that temperature can effect velocity. With some powder, it's 1 fps per degree or more. Also, publish BC may not be accurate. Many vendors tend to fudge a little. Sierra is the only bullet maker where I've found the calculated BC to be very accurate.

Also, scopes are typically not accurate in their adjustment. Many use shooters MOA - 1 inch at 100 yards, not true MOA. Also, the actual adjustment can vary quite a bit as the reticle is moved from dead center. Clicks may represent 1 MOA at dead center, but much less are you approach the limits of reticle movement.

Tod

 

[Zak Smith]

It would take a loss of about 350 fps muzzle velocity to require 3 additional MOA at 600 yards with that bullet.

On the BC side, if the MV was accurate, it would take a BC reduction from .393 down to .260 to get an additional 3 MOA of drop.

Splitting the difference, if the BC were actually 0.3 and the MV dropped to 3100, you'd be 3 MOA low.

Definitely "box test" the scope at 100 yards to determine the actual click demarcations.

 

[gimposaurus]

How'd you get a sendero in .25-06, they're only chambered in 7mm rem mag, .300 win mag etc...?

 

[farmer7]

Thanks very much for the replies guys, and 30Cal like Zak says according to the printout it should be doing roundabout 1899fps at that distance so not about to go transonic.

Guntech i did chrono the loads just half an hour before. I also made sure and entered 1/4" clicks to JBM's rather than 1/4 MOA clicks. I wasn't expecting to be on the bull but didn't expect 18" low either! Perhaps it is my scope,although at closer distances i have always found it spot on. I will box test it and see how it fairs.

Jbm are you the owner of the ballistic calculator? Just so you know i have a Steyr in .223 with a Leupold 8.5-25 x 50 and using the software and 55gr v-max's i have nailed hundreds of rabbits out to as far 400 and 520 being my record. Always found it spot on for the .223. I suspect i should maybe get a new scope!

Thanks for your replies chaps. Not many folk round here know much about the technical side of things! Great site!

 

[farmer7]

Gimposaurus I bought my Sendero probably 10 years ago, 25-06 was one of the cals. I know they have a new sendero out now perhaps it is that model you were thinking about??

 

[riddleofsteel]

My 25-06 Sendero purchased over 20 years ago with a Leupold 3.5x10 x 50mm Vari X III. This fine old rifle will shove a 117 grain Hornady at close to 3200 FPS out of its 26" barrel.

With the proper torque on its bedding screws and some cooling time between shots it produced this 1/4 inch ten shot group at 100 yards.

I have fired 1.5" groups at 400 yards on a calm day. The longest deer killing shot to date was 385 measured yards. Longest groundhog killing shot to date was a clean 505 yards.

As far as your problem............I gave up on ballistic computers long ago. In the real world I record the load, temperature, wind, the amount of drop and wind drift, and the scope setting at known distances. Latter when making shots in the field I can compare my notes to try and compensate.
A couple of weekends shooting ground hogs at outrageous distances will teach you more than a lifetime at a ballistics computer. One of the problems is that the MZ varies widely with temperature and that the calculated ballistic coeficent is often very different than the published one. Minor variations in the input formula greatly affect the figures. The longer the distance the greater the variation.
Still if you take your observations from the real world and follow them the variations created by temperature, humidity and bullet lot will still be there but not enough so you will notice them on a buck's shoulder or a ground hog's chest.

The scope can make a huge difference. Get a big board and set your scope to zero at optimum PBR for your bullet weight. On my rifle with a 117 grain Hornady SPBT interlock it is 2.75 inches high at 100 yards. Move the board to the point where your bullet is hitting the bullseye or is at zero. then start moving the board back in 25 or 50 yard increments. Check to see how many clicks on your scope it takes to maintain hitting the zero. It should follow the changes of distance very closely. what you may find is that as you approach the limits of your scopes ajustment range the zero point may "JUMP" suddenly with a click moving the zero either none at all or way to much. My scope moves in consistant clicks from top to bottom on the elevation screw with each click moving the zero up a predictable amount. If yours does not you may have found you problem.