POI at distances longer than 300 yards

[ElkHunter11]

I went to the range this weekend and shot out to 400 yards. I have my rifle zeroed at 200 yards and am shooting 1 MOA at that distance (slightly to the left of bullseye by about 0.5". At 300 yards, my poi is a little to the left (by about 1.5" of my point of aim). However, at 400 yards my poi is about 4" to the left of my point of aim. There was a slight breeze, maybe 5 mph. Question is, why does my POI at a distance longer than 300 yards change so dramatically to the left? Could it be that my slight left poi at 200 yards opens up at longer distance? Any advice is greatly appreciated! I'm somewhat new to longer range shooting as most my shots in the past have been under 250 yds.

 

[engelwood]

Small POI adjustments at shorter ranges will be exponential at longer ranges. Start by shooting out at 600 or so, with no wind to be a factor, and zero your left and right at that point. Then when you back down to 200 you will see that you are very close to bullseye. This is why I feel that people shooting at 100 yards and then having a misconceived confidence that their gun will be true out to longer ranges is scary as the miss will open up at longer ranges. If you feel good with left/right at distance you will feel confident with it at closer ranges versus vice versa. Just my .02

 

[BuzzH]

You could be canting your rifle, or the scope is not aligned properly.

I used to have the same problem...mainly due to not properly mounting the scope from the get-go.

Wheeler level level is your friend.

 

[sbhooper]

Good advice. It could be a combo of the breeze, your trigger squeeze and failure to hold the rifle level-which is very hard to tell without a level on the scope. When the distance is stretched out, it really amplifies whatever issue there may be in your equipment/procedures.

 

[Southwind]

You are loosing steam quite a bit more from 300-400, look at the drop at 300 compared to 400 yards. Depending on what you are shooting it's around 2 1/2 times. Little things start to matter a lot at longer distances. Rifle cant, trigger weight, follow through etc. but even at 4" that is still 1 moa at 400.

 

[ElkHunter11]

Thanks for the advice, all. I will check into the scope level and give it another try. I'll also test out starting out at longer distance and bringing it down to 200 to see what that does.

 

[bowhuntmontana]

You could be canting your rifle, or the scope is not aligned properly.

I used to have the same problem...mainly due to not properly mounting the scope from the get-go.

Wheeler level level is your friend.

This. I also recently aligned my scope using a string and plumb bob method. Leveled the rifle and adjusted the scope. I had previously used the wheeler level, level, level, but found the plumb bob to be more effective. Turns out my top turret cap is not perfectly level. Once that was taken care of, I also added a scope level to watch for canting. Helped a lot.

 

[ElkHunter11]

My gun is a Browning X-bolt .300 win mag and is right handed. I however am left eye dominant and shoot left handed. The X-bolt has a little cant in the stock for right handed shooters; I wonder if that could be an issue that I need to compensate for. I will keep an eye out for that as well next range visit.

 

[coppermushroom]

Good suggestions above - one other potential...is your barrel the same temperature (cold)? My POI is good until I run 5-6 consecutive shots through my 300, at which point it drifts consistently 4" left at 450 yards. I will never run 5 shots that fast in real world hunting so it does not bother me but rather an observation. Cold barrel and she shoots straight at 450.

 

[MKotur325]

What are you running out of that .300? Slug, weight, FPS? What direction was the wind from? My ballistic calculator shows 3.8" of wind drift for a full value 5mph wind from right to left at 400yds for a 180gr Nosler AB at 3150FPS I based this on 1500' elevation, which s. Also, same conditions it lists 2.1" drift at 300yds. If you are 4" left at 400 and were about 1.5" left at 300 that sounds like a 5mph wind to me. Wind drift is based on the time of flight, and the impact grows over time.

None of this is to diminish the advice above. Make sure that your scope is square to your barrel, and you are not canting the rifle.

 

[Deleted member 20812]

You could be canting your rifle, or the scope is not aligned properly.

I used to have the same problem...mainly due to not properly mounting the scope from the get-go.

Wheeler level level is your friend.

Canting was my first thought also. It doesn't have to be much to affect things at longer ranges.