# smaller MOA @ 400yds vs. 100yds?



## gunattic (Jan 9, 2005)

I wouldn't believe it if someone told me their rifle shot less moa at 400yds than at 100yds but now that is exactly what happens with one of my rifles. How can this be? Until I saw this, I would have thought hearing it from anyone else it had to be a fluke, but this particular rifle/load definetly prints about the exact same group size at 400yds as it does at 200yds, and the 200yd groups are nearly the same as the 100yd. When I first benched it at 100yds I was ready to sell or trade it because of it's poor accuracy, but after moving the targets to 200yds, then 400yds, there is no way I'll part with this. the rifle is a 7mm stw, winchester laredo lrh, the loads are 139gr hornady's. and it is NOT for sale or trade.


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## Whelen35 (Mar 9, 2004)

I think that a lot of long range shooters refer to the bullets "going to sleep" at ranges longer than 100yds. Or more correctly, the bullet fully stabelizes aster going faster than sound. This also happens when the bullet goes from supersonic to subsonic where the bullet will destabelize a bit at this time. For a true "accuracy load, you need to shooot your loads at all ranges it is likely to be used at. When doing this, you may find a load that looks good at 100yds may not look so good at 200 and 300. Anyway, it sounds like you have a good gun and load, have fun with it.


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## Jiffy (Apr 22, 2005)

hhhhhhuuuuuhhhhhh, I dont understand.....please explain. That does not make any sense....although alot of things dont make sense to me....lol.... sounds like the shooter to me.....once again...I am not taking a shot at ya man I just would like some clarification....thanks guys....latter


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## gunattic (Jan 9, 2005)

I am familiar with the "breaking the sound barrier" effect on the bullets. I've shot a lot of rimfire and am aware about using sub-sonic ammo for target shooting to avoid the effects this has on the stability of the bullet.. so that the bullet neither passes into super-sonic nor falls back into sub-sonic .. outta my 7stw it's traveling to super-sonic in the barrel and not crossing back into sub-sonic until well beyond 400yds so that isn't what is having the effect on the bullet, unless it's the passing into super-sonic alone. Rather, I have to believe that it's a case of the bullet not becoming stable until sometime shortly after or before 100yds. Maybe this instability is instigated by the pass into super-sonic. Either way. had you told me you had a rifle that shot smaller MOA at longer ranges.. until I had this rifle, I never would have believed you.


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## Whelen35 (Mar 9, 2004)

If you spend some time reading about some of the bench rest target shooting, this is talked about in great detail. In several instances, these very specilaized guns will shoot a tighter group at 200yds than at 100yds. Lets say that you have a bullet that is not quite in exact alignment with the bore and the case itself. When fired, it will not quite enter the barrel at an exact paralel angle. After leaving the barrel, it will take some time for the bullet to calm down and re stabalize on its axis. The same thing can happen if you have a heavy side to your bullet jacket, or if you have a small air space in the bullets lead core, or the core to jacket areas. All of these things can make your bullet not quite spin in the right way. It will take a small ammount of time to do this, but when a bullet is traveling at a very high speed, 100yds may not be enough time in flight to do this. I think the term is the bullet goes to sleep and spins on its axis point which may as in these examples would not be in the exact center line of the bullet. There is a machine called the Junkel concentrisity tester Check spellind on that one, but it will test a bullet for inperfections, and in tests that I have read seems to validate this concept. Work with some target bullets that are of a bit more stringent specs, and I would think you will see emen better groups than you have been getting. A super accurate gun is like holding a beautiful worman, you lust after them, and soon no matter what, you want more. Good shooting, it sounds like you have a very good gun, now you are screwed for life always wanting this standard or more. What a great infection this shooting.


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## gunattic (Jan 9, 2005)

whelen, thanks for the replies and jarring my memory, it does seem to me that years ago I read about that same thing.. btw, my standards got set a long time ago with an old bench rem 40x in 308 and then a 788 in 222. After those two I thought accurate rifles were a dime a dozen. ohhh, so young and foolish, the 308 got sold outright and the 222 I think I traded for a #1 or a lh 308 788, guns that printed good but not quite as tight as the 222 or the 40x. shoot, I don't have those rifles today either :roll:


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## Jiffy (Apr 22, 2005)

Very informative, I guess a guy learns something everyday....thanks for the info!!!!!!


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## jeep_guy_4x4 (Apr 11, 2005)

The sound produced by a firearm is principally comprised of three components.

(1) the muzzle blast created by shock waves generated from the sudden expansion of hot propellant gases.
(2) the miniature sonic boom, or crack, produces by a bullet traveling downrange at a velocity above the speed of sound (1,087.5 fps at 32 degrees Fahrenheit at sea level) 
(3) in the case of a semiautomatic or full-auto weapon, there is the mechanical noise produced by the action.

Note. If the projectile travels downrange at subsonic velocity, it will not produce a sonic boom as it passes stationary objects.

Are you loading cartridges that travel less than 1100 fps?

This logic is dificult to comprehend after considering the basic principles of sound...

Perhaps the projectile design has flaws with a muzzle velocity of approximately 3,450 and requires 100 yards to stabilize as suggested.

If this is true I would greatly reconsider its validity as a useful cartridge.


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