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Shooting & Reloading - Mausers, Big Bores and others >> Rifles
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AussieMike
.300 member


Reged: 01/09/04
Posts: 236
Loc: Southern Tablelands, NSW, Aust...
Same POI with two bullet weights
      #24199 - 15/01/05 03:34 PM

Does anyone have a method to get two loads to shoot to the same point of impact. I'd like to be able to use some of my rifles with a light fast opening bullet for goats/varmints etc and a heavy bullet for pigs and deer?

I've got a 300 Weatherby which shoots 150, 165 and 180gn maximum loads to the same POI and it has some upward pressure on the barrel at the forend tip - could this be the answer?

I know the simple (but expensive) answer is two scopes in QD mounts and the simple but (risky answer) is to count the clicks and adjust the scope. I'd like to be able to just pull a different cartridge out of my pocket and swap, say a 130gn 30-06 Ackley load for a 180gn load.

All suggestions gratefully accepted.

mike

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500Nitro
.450 member


Reged: 06/01/03
Posts: 7244
Loc: Victoria, Australia
Re: Same POI with two bullet weights [Re: AussieMike]
      #24245 - 16/01/05 08:56 AM


Reload all the cases with different powder / bullet weights and shoot them at the range until you find the
combo that works.

It's the only was I know.

500 Nitro

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vapodog
.300 member


Reged: 28/12/04
Posts: 237
Loc: Nebraska USA
Re: Same POI with two bullet weights [Re: AussieMike]
      #24246 - 16/01/05 09:16 AM

In reply to:

it has some upward pressure on the barrel at the forend tip - could this be the answer?



Highly unlikely.....
In reply to:

I know the simple (but expensive) answer is two scopes in QD mounts and the simple but (risky answer) is to count the clicks and adjust the scope


Again.....not as good as they appear.....

The most successful approach I've seen to this and the one I have adopted as it makes real sense to me is to ask....what am I here for?.....if it's cape buffalo then carry ammo for that game and shoot everything with that ammo.
If it's elk.....same thing...Shoot mulies with the elk loads.

The arguement gets thwarted when one says that he'd like to carry 220 grain bullets in his .300 for defence against grizzly.....and it makes sense.....but self defence was never done at 200 yards....it's always at ten yards and the accuracy at that point in time isn't really important.

--------------------

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**DONOTDELETE**





Re: Same POI with two bullet weights [Re: AussieMike]
      #24256 - 16/01/05 01:10 PM

mike

For reasons which escape me it is quite common for calibres with a large case capacity for the bore size to shoot different loads to similar points, as in your 300 Wby.

In good barrels calibres with small case capacities for the bore size usually shoot to very different vertical points.

As 500 Nitro has said it is about tring different powders and in particular different types of powder.

For example in your 30/06 you might try ADI with one bullet and Win 748 or 760 with the other bullet.

Mike

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500Nitro
.450 member


Reged: 06/01/03
Posts: 7244
Loc: Victoria, Australia
Re: Same POI with two bullet weights [Re: Mike375]
      #24301 - 16/01/05 11:00 PM


mike,

as vapodog says, stay away from 2 scopes and rings - more trouble than it's worth.

Re "upward pressure on barrel, I'd get that taken out by a gunsmith. Not good
as POI will change when the barrel heats up.

Just load a few rounds of each bullet weight and go down the range and see where they shoot.
Sight in the gun with your most used load and then try to get the other load shooting to this
point by using different charge weights, bullet seating depth etc etc but ONLY change a ONE thing
at once so you control the variables.

Also, try using ballistic tables to get you as close as can be without multiple visits to the range.

Hope this helps.

500 Nitro

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AussieMike
.300 member


Reged: 01/09/04
Posts: 236
Loc: Southern Tablelands, NSW, Aust...
Re: Same POI with two bullet weights [Re: 500Nitro]
      #24367 - 17/01/05 03:21 PM

I fully float most of my rifles, not because of POI changes when the barrel heats up, in fact a couple of my rifles shoot better groups with upward pressure at the forend tip, but because of changes of POI when the wood takes up or loses moisture eg if rifle stored in Sydney and then taken to the outback where the humidity is low.

I suspect that the two issues are barrel vibration and barrel transit time. Upward pressure could reduce barrel vibration variations between the loads and one would predict that barrel transit time is shorter with a faster powder.

I might try a relatively fast power with the heavier projectile and the slowest possible powder with the lighter projectile as this will increase recoil due to the heavier powder charge.

mike375 may be onto something with his comment about big cases (relative to bore) shooting to the same POI - I've got a 265Win Mag that puts 100gn and 140gn projectiles 2" apart at 110 yards. I might try changing powders etc with it to see if I can get the 140gn up 2-3".

I think I'll stick with ADI powders - I'm tired of working up a load and then finding that the powder has become unavailable.

Thanks to all,

mike

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