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Putting The Bullet to Sleep Theory

ContacFrontContacFront Member Posts: 1,113 ✭✭✭✭✭
edited March 2005 in Perry Shooter Competition Shooting and Reloading Forum
Gentlemen,

I am curious how many of you have experience the "Putting the Bullet to Sleep" phenomenon.

I have experience this time after time again with my Savage 10FP 308.

My load:
175gn SMK
44.5gn of Varget using a CCI BR2 Primer in a Federal Gold Medal Case.
Cause is cut to 2.010
OAL of round is 2.80
Fireformed cases neck sized with .337 Redding Die
Gives me a Avg. Vel of 2735 SD: 17 and ES: 25

100 yards groups I would be lucky to get 5 into a 2.0" group.

200 yards groups will be 1.75" inches easily.

300 yard groups will be 1/2MOA, best I've done is put 4 shots in 1 1/4"

Anyone else experience this? I know of a few guys that have this happen to them in their 300 Win Mag. They won't even bother to load test at 100, just start at 300yards on up.



This is my group from today's range session. The entire group measures well under 2.5" at 300. Gives me Sub MOA at that range but can't even get MOA at 100 yards.

3insamehole.jpg
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Comments

  • sandwarriorsandwarrior Member Posts: 5,453 ✭✭✭
    edited November -1
    Contact,

    I've heard of it happening with more than a few people but never had it happen to me. Being of the airplane/aerodynamic world I do not personally see how it could happen that once thrown off it's original course, the unpowered glider(bullet), can return to it's original course without aerodynamic inputs to get it there. The rotation of the bullet will only want to keep the nose in line with the barrel but once drifted, it's path is destined. -my $.02 only...no facts involved.

    We have the second amendment so that all the rest are secure....UNK>
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  • nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    This is not an easy topic to explain to the satisfaction of most shooters. It involves some fairly significant concepts developed through mathmatics. This is a well written thesis on this idea but it is not terrifically difficult to understand. Here is a short introduction with a link below:

    How Do Bullets Fly?

    "The title of this document "How do bullets fly?" seems to be an odd question, and appears to be almost foolish at first sight..
    However, as in many fields of science and technology, studying an apparently simple matter more thoroughly, may bring to light complex and complicated facts. This indeed is the case with regard to the motion of spin-stabilized bullets fired from guns.

    Most people expect that bullets fly nose-forward and remain stable from the muzzle to the target, but this is not necessarily so. For short ranges, most trajectories could be approximated by a straight line, whereas bending of the trajectory must be considered for longer ranges.

    Most firearm experts accept that bullets may tumble when grazing an object or when leaving an intermediate target. However, as it will be outlined, some physical conditions must be fulfilled to guarantee stable flight, and bullets are by no means automatically stable. Causing a bullet to spin endowes it with gyroscopic properties which are very important - but by no means exclusively - in maintaining bullet stability.

    However, from a teacher's point of view, the motion of a spinning gyroscope is one of the most complicated motions with which a student of physics is confronted during lectures on classical mechanics. Although the general motion of gyroscopes can be explained and completely understood only by a thorough mathematical treatment, this introduction makes an attempt to explain the elements of the subject by means of numerous illustrations."

    http://www.nennstiel-ruprecht.de/bullfly/intro.htm#header_introduction
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  • mrbrucemrbruce Member Posts: 3,374
    edited November -1
    My 22/6mm Ackley 3 groove 8 twist shooting 80 gr Sierra and Nosler's
    don't shoot worth a darn at 100 yds, but out at 300 yards it seems to wake up and shoots less than MOA.
    My 9 twist 22/250 Ackley shooting 75 grain Hornady A-max's don't seem to have that problem.
    Often wondered why, and still dont know.

    Gun control is hitting what your aiming at.
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  • JustCJustC Member Posts: 16,056 ✭✭✭
    edited November -1
    long bullets with long bearing surfaces usually show this symptom. The bullet is NOT off course,..it is wobbling like an arrow just as it leaves the bow,..then in short order,..it settles into it's spiral. I have yet to see it with short bullets,..but long VLD pills especially if they are just barely stabilized enough when the twist should realisticaly be tighter.

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • ContacFrontContacFront Member Posts: 1,113 ✭✭✭✭✭
    edited November -1
    I guess I wont worry about it too much as long as she performs out pass 300.

    At 200yards I am still able to drill the X so it won't hurt me too much at the matches. At 300+ the gun really starts to shine.

    JustC,

    You shoot anything in 300 Win? Using 190s? I am finally going to start loading for my buddy's Sako TRG42. Can't wait to see how that high dollar rig shoots.
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  • JustCJustC Member Posts: 16,056 ✭✭✭
    edited November -1
    I have worked with the 165gr NBT and the 178gr A-max in the 300win. I would love to run the heavier pills,..but the 2 pards with the rifles are still all about flat shooting bullets for point blank hunting to 350yds, so they won't let me load them with anything heavier.

    I would suspect a 190-210gr pill to be the way to go. I would think something in the H1000 or RL25 range as well as IMR7828 would make it sing.

    74.0gr RL22 with a 178gr a-max seated about .015" off the lands in a sendero is well under 1/2moa at 100yds with a competent shooter.

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • ContacFrontContacFront Member Posts: 1,113 ✭✭✭✭✭
    edited November -1
    JustC,

    I was thinking 72 - 73gn of RL22 with 190 SMK. A lot of the guys at the match this last Sunday are going that route with great results. I may have to step it up to the 300 win in my next long range rifle. I was able to keep up with them out to 600 yards fine but at 800, 900, and 1K the wind got me bad.

    Shot 30 more points this time around so I am creeping up to mid field now.
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  • gunnut505gunnut505 Member Posts: 10,290 ✭
    edited November -1
    I've had really great success with the Sierra 240gr(#9245) on top of H1000 with CCI LRM primers in my TRG-S, but the G-42 doesn't like the heavier bullets and H1000 combination. It prefers RL-22 and Rem 91/2M primers.
    These loads are in 300Win Mag.; I doubt you could get enough powder in a .308 case to get them to where we shoot at.
    I've also had good luck with those 178gr A-Max bullets and 85 grains of H870 over CCI LRM primers.
    My M77MKII enjoys superb accuracy with 190's down to 165's, but won't shoot the heavyweights any better than the really light pills.

    I've never experienced the wobbly starting bullet phenomenon in my rifles, but I have seen it happen with a muzzle-damaged Super Blackhawk. That thing shot horribly out to about 100yds; then got dime-sized groups at 200 & 250.

    "Qui non est hodie cras minus aptus erit" --OVID
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