Significant 300 Win Mag bullet drop with Reloader 25

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rmark

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Went to the range with a friend yesterday and we were working up a load at 100 yards for his 300 win mag.

Load data
Reloader 25 - 79.1 grains (79.5 gr is alliant book max with a stated velocity of 3050).
Nosler Accubond 180 grain
CCI magnum LR primer
RP brass 2-3x fired
Overall length 3.340”

Rifle data
Tikka T3 stainless with bushnell 4200 3-9 scope.

At 100 yards, it was grouping right at MOA and sighted for bullseye at 100 yards. We moved back to 200 yards and he put the cross hairs on the target, and POI was 6” low below POA at 200 yards (scope was not adjusted at all) . I know from my previous experience with 30-06 is that at most there should be about a 2” drop from 100 yards to 200 yards. We didn’t have enough loads left to put more than about 6-7 shots down range at 200. I even tried one from his rifle and same POI at 6” low.

This substantial drop really has us stumped. I reload for my 300 wsm (180 grain accubond again and IMR 4350) and was ringing 4” steel at 200 no problem (never shot paper), so I’m assuming my bullet drop was much less significant.

Any thoughts? Could it be the temperature sensitivity of Reloader 25 is causing a significant drop in velocity (we do not have a chronograph)??? Hard to believe it would cause a 6” drop from 100 to 200 yards. Or is something else wrong here?
 
rmark said:
Went to the range with a friend yesterday and we were working up a load at 100 yards for his 300 win mag.

Load data
Reloader 25 - 79.1 grains (79.5 gr is alliant book max with a stated velocity of 3050).
Nosler Accubond 180 grain
CCI magnum LR primer
RP brass 2-3x fired
Overall length 3.340”

Rifle data
Tikka T3 stainless with bushnell 4200 3-9 scope.

At 100 yards, it was grouping right at MOA and sighted for bullseye at 100 yards. We moved back to 200 yards and he put the cross hairs on the target, and POI was 6” low below POA at 200 yards (scope was not adjusted at all) . I know from my previous experience with 30-06 is that at most there should be about a 2” drop from 100 yards to 200 yards. We didn’t have enough loads left to put more than about 6-7 shots down range at 200. I even tried one from his rifle and same POI at 6” low.

This substantial drop really has us stumped. I reload for my 300 wsm (180 grain accubond again and IMR 4350) and was ringing 4” steel at 200 no problem (never shot paper), so I’m assuming my bullet drop was much less significant.

Any thoughts? Could it be the temperature sensitivity of Reloader 25 is causing a significant drop in velocity (we do not have a chronograph)??? Hard to believe it would cause a 6” drop from 100 to 200 yards. Or is something else wrong here?
Click to expand...

There is no such thing as a 'velocity' with a certain charge and bullet. All those published values are with test barrels and chambers of specific lengths and so on. It varies a large amount from one firearm to next. Your statements indicate that the velocity is quite a bit lower than you thought it should be. Yes, temperature sensitivity of the powder could be part of the issue, so could the chamber size, neck size, neck tension, barrel length, barrel wear, etc. While you can work this stuff backwards with a good ballistics program recording drop rate at various distances (100, 200, 300, maybe 500m) to determine the muzzle velocity, it is far easier to use a chronograph and measure it.
 
While all of those factors are true, we are still talking about a 300 wm that is showing the trajectory of a weakly loaded 45-70.

Something is up directly related to power factor. Bad batch of powder? By all means check your reloading method, but get the load chronographed.
 
Posts like this are why I think a reliable chronograph is a reloader's good friend. It would help immensely if you knew the velocity you were actually getting as a starting point for figuring out what is happening.
 
I used to try to work up loads without a chrono, and taking the manufacturers data as gospel.

Cannot be done if you are looking to go beyond the usual hunting distance, too many variables.

Chrono purchase time!

Candocad
 
I may be reading your post incorrectly , but i read that your rifle is sighted dead on at 100. If so it will drop by 200. To reach 200 you will need to be sighted a bit higher at 100m.
 
rosebute said:
I may be reading your post incorrectly , but i read that your rifle is sighted dead on at 100. If so it will drop by 200. To reach 200 you will need to be sighted a bit higher at 100m.
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Exactly. 3-4" of the drop showing up at 200 yds is simply due to zeroing the rifle at 100 yds. It should be zeroed approx. 1.5" to 2" high at 100 yds to maximise point blank range for the 300 winmag.

Ballistics for 100 yd zero:
View attachment 158284


Ballistics sighted 2" high at 100 yds.
View attachment 158286
 
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NRA American Hunter
Going the Distance
https://www.americanhunter.org/articles/2012/12/10/going-the-distance/

"With a 200-yard zero the .300 Winchester’s bullet will be about 3 inches below the line of sight at 250 yards. So from zero to 250 yards the bullet is never more than 1.86 inches above or 3 inches below the line of sight. On big game this means you can hold on the center of the chest and you will hit the kill zone if you do your job. Even at 300 yards the bullet is only 7.3 inches below the line of sight. If you hold slightly high, but still on the critter—on hair not air—you will hit vitals."

Your being punished for not buying a .270 Winchester, the worlds best non-belted magnum...............:evil:

I sighted my .270 2 inches high at 100 yards and got the same trajectory as above with less powder burned and far less kick. :stirthepot2:
 
According to the 100 yard zero charts above, if my velocity was the same as listed (and it’s not), I should only be 2.9” low at 200 yards, but the problem is the actual drop is a full 6”+. So my dilemma is more with the “why aren’t we closer to the drops listed in these charts”. The load is within 0.4 grains of alliants max load for that bullet/powder combo, so in a perfect world I should be getting near that velocity (and closer to the bullet drop listed in the chart above) or just a slight deviation from there. If I run that 180gr accubond bullet and muzzle velocity of 2300fps (which is incredibly slow for 300WM) with a 100 zero I get a drop of 6” at 200 yards, which is what we’re seeing on paper.

So does that mean (and I understand without a chrono we’re talking hypothetical) I’m getting in the neighbourhood of 2300 actual FPS, well below the approx 3000FPS it should be?
 
rmark said:
According to the 100 yard zero charts above, if my velocity was the same as listed (and it’s not), I should only be 2.9” low at 200 yards, but the problem is the actual drop is a full 6”+. So my dilemma is more with the “why aren’t we closer to the drops listed in these charts”. The load is within 0.4 grains of alliants max load for that bullet/powder combo, so in a perfect world I should be getting near that velocity (and closer to the bullet drop listed in the chart above) or just a slight deviation from there. If I run that 180gr accubond bullet and muzzle velocity of 2300fps (which is incredibly slow for 300WM) with a 100 zero I get a drop of 6” at 200 yards, which is what we’re seeing on paper.

So does that mean (and I understand without a chrono we’re talking hypothetical) I’m getting in the neighbourhood of 2300 actual FPS, well below the approx 3000FPS it should be?
Click to expand...

Not necessarily. You didn't say how many shots you fired at 200 yds or what the group size was. Any combination of sighting error, accuracy, and velocity could give you that result.

For instance if you are actually sighted in 0.5" low at 100 yds it might make an inch or more difference in drop at 200 yds. If the accuracy of your rifle/ammo is 1.5MOA, then that's 3" spread at 200 yds. If the velocity is 150 fps slower than expected that could add another inch difference. If the range is actually 210 yds, then that also would account for some of the drop. If sighting error is 1/2 moa, that would be 1" error at 200 yds.

Having not been there makes it impossible for anyone to say exactly what happened. It's judgement call for you - how certain are you of the variables? If you know the rifle was dead on bullseye at 100yds, that the ammo is accurate in that rifle, and you shot enough rounds to represent the rifle/ammo accurately - then you can start to question the velocity.
 
I had a similar experience, a long time ago. Turned out my balance bean was out one notch. 5 grains low on the powder charge.

Pull a round to make sure you have what you thought you had.

Did you try again at 100? Maybe the elevation knob got turned?
 
jethunter said:
In the interests of a fair comparison and all that - you were using 180gr bullets in your .270, right?
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Sorry but that doesn't make any sense....you can't use the same bullet weight in the 270 which is 2 calibres down.
A 180 in a 300wm would be like something more like a 140 maybe 150 in a 270....Then again it is really an apple and oranges thing...
 
Canuck525 said:
Sorry but that doesn't make any sense....you can't use the same bullet weight in the 270 which is 2 calibres down.
A 180 in a 300wm would be like something more like a 140 maybe 150 in a 270....Then again it is really an apple and oranges thing...
Click to expand...

In a hunting rifle, bullet weight does matter and that's the point. If it was only about ballistics, then the 243 is just as good as a 270, and a 22-250 is better than both. And yet a 22-250 wouldn't be my first choice for a moose hunt.
 
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