Excessive bullet drop

[belly-deep]

Good grief. Slow ammo is not common. Ammo manufactures test their ammo with long (26") match grade barrels (i.e. tight throats). Actual velocity is almost always short of published data (i.e. on the box).

I own a chronograph and shoot quite a bit. Don't need you telling me not to believe my own eyes.

 

[deflave]

I'd re-shoot with the same ammo to confirm it wasn't operator error (happens to the best of us), bring along another type of ammo to compare bullet drop. If you're still seeing 20" of drop then move onto the scope/bases, bedding, etc.

Hope you get it worked out, sounds like a neat old gun.

Bedding changes the trajectory of a bullet?




Travis

 

[deflave]

I own a chronograph and shoot quite a bit. Don't need you telling me not to believe my own eyes.

Since you own a chronograph and shoot so much could you please list the factory ammo that you've found to be 800-1,000fps slower than advertised?

That'd be some good info to have for those of us that don't shoot much.




Travis

 

[jzeck2]

You are losing speed somewhere, could be the ammo could be the gun. I agree with using a chronograph.

 

[mtmiller]

You're not helping my lust for a GAP...

Kilt any critters with it yet?

Deer, lopes and yotes.

 

[belly-deep]

Since you own a chronograph and shoot so much could you please list the factory ammo that you've found to be 800-1,000fps slower than advertised?

That'd be some good info to have for those of us that don't shoot much.




Travis

Haven't seen any that slow but I've clocked federal, Remington, and Winchester loads up to 300 fps below advertised velocity

 

[RobG]

heading out to the Livingston range with hopes of not returning embarrassed... Anyone with a chrono is welcome to show up.

 

[deflave]

Aim at the right diamond this time! Grin...

If I was close by I'd meet ya.



Travis

 

[Gr8bawana]

Haven't seen any that slow but I've clocked federal, Remington, and Winchester loads up to 300 fps below advertised velocity

I seriously doubt even 300 fps slower would produce a 20 inch drop. Most ammo manufacuturers test ammo from a 26 inch barrel. So if fired from a 20 or 22 inch barrel they are going to be slower.

 

[deflave]

I seriously doubt even 300 fps slower would produce a 20 inch drop.

It wouldn't.




Travis

 

[belly-deep]

I seriously doubt even 300 fps slower would produce a 20 inch drop. Most ammo manufacuturers test ammo from a 26 inch barrel. So if fired from a 20 or 22 inch barrel they are going to be slower.

Never said it would

 

[RobG]

Well a couple things.
1) I checked with the rangefinder: the distance is 329 yards, not 300 yards.
2) I checked the poi at 200 yards. It was -3.5", not 1.5"
When you run these numbers a 20" drop @329 yds isn't so unreasonable.

I changed the zero to 200 yds and the poi was -12". My calculator shows -8.2" @300 yds, -14.9" @350 yds... So -12" @329 yds sounds reasonable.

And here's the kicker... after the 300 yds shots I rechecked 200 yards and I was 1.5" high! Arg! This was a new box of the same ammo, but that is quite a bit of variation, so I think some things on the rifle might be moving too.

So, in addition to the target being farther away and the scope not zeroed at 200 yards (the main issues), I think either the scope is moving or the barrel is moving when it gets hot. The stock is fairly tight on the barrel so maybe I could sand away the high spots.

 

[Gr8bawana]

Your ammo is not the problem. Sounds like a scope problem. Either in the mounting or the scope itself. Perhaps whatever holds crosshair adjustments is broken internally.
You could try mounting a known good scope from another rifle and see if the results are the same.

 

[deflave]

Sounds like your range is set to meters and not yards. It also sounds like there is nothing wrong with your setup at all. To include the ammo.

Set up a milk jug @ 100, 200, and 300. Aim dead on at the first two, hold 5" high on the last one. They'll all blow up and you'll feel better.

Then drink beer.



Travis

 

[deflave]

Your ammo is not the problem. Sounds like a scope problem. Either in the mounting or the scope itself. Perhaps whatever holds crosshair adjustments is broken internally.
You could try mounting a known good scope from another rifle and see if the results are the same.

I wish my broken scopes worked as well as his.




Travis

 

[RobG]

Sounds like your range is set to meters and not yards.

LOL, you made me look, but nope, wrong again; it was set to yards. However, I like the way you think so if I ever have a circuit problem expect a call

PS: 329 yards is 300 meters so now I understand why they put the target there.

It also sounds like there is nothing wrong with your setup at all. To include the ammo.

Set up a milk jug @ 100, 200, and 300. Aim dead on at the first two, hold 5" high on the last one. They'll all blow up and you'll feel better.

I think the POI is moving a little, but it might be human factors too... after 15 shots of 180 gr without a pad a guy gets to flinching. Instead of a milk jug I'll try it on an elk to keep the streak going on grandpa's gun. I'm not going to shoot much past 200 where I'll be at anyway.

 

[deflave]

Rob,

I mean each yardage line is in meters at your range.

Did you use your rangefinder @ the 200 as well?



Travis

 

[RobG]

Rob,

I mean each yardage line is in meters at your range.

Did you use your rangefinder @ the 200 as well?

Yeah you nailed it with the 300 meter range observation. That didn't click until you said it. The 200 yard target was pretty close, I think 204 yards. They had another berm a little farther out which must be the 200 meter (219 yard) setup.

 

[deflave]

Well 200 meters would have you about 1 MOAish low so that's why I guessed it.

Either way, I don't think there's a thing wrong with your rig. Factor in the box of 180's fired, ball-parked velocities, elevations, etc and I still think you're in there like swimwear.

Good luck out there.


Travis

 

[RobG]

You need to darken the circle in the diamond. It helps alot. That's 3 too. mtmuley

Well if we are showing off groups where we miss the bull's eye, I might as well highjack my own thread...