Shorty M14 issue

[Sluggo_m14]

Don't open your mind so far that any dumb old idea can get in there, though. From the link you posted:

The link was provided as an example of others experiencing similar phenomena. There could be a variety of factors contributing in variuous magnitudes to create the groupings reported by the OP. The a hole comment was merely an observation, especially concerning how quick individuals cry BS.

 

[Grizzlypeg]

The link was provided as an example of others experiencing similar phenomena. There could be a variety of factors contributing in variuous magnitudes to create the groupings reported by the OP. The a hole comment was merely an observation, especially concerning how quick individuals cry BS.

Yes, the link refers to a shrinking calculated MOA as you go further out.

But does it refer to a shrinking group size, as X man is reporting?

 

[burnaby]

Clearly the Chaos theory at work here. Or black hole theory. Why can't the bullet converge instead of diverge. Anything is possible; we are just tiny humans that knows so little of this universe.

 

[WWIII]

I think Litz is being politically correct and too kind. I think that he said is a nice, scientific way to say, "bulls**t".

Just to be clear, this is exactly what he states:
RE: http://bryanlitz.bravehost.com/EpSwerv.html

“Just to be clear about the conclusions of the modeling: The phenomenon of smaller angular groups at longer ranges was not disproven. The only thing I've shown is that if the phenomenon actually happens, epicyclic swerve is not the cause of it.’’

 

[WWIII]

Enough theory, if you look at Xman's target it appears the bullet holes shot from the 100 & 200 YD ranges are slightly bigger indicating a slight keyholing effect from the projectiles and the 300 YD holes appear more perfectly round - I am going to say this slight keyholing effect is from an unstable projectile and if what Xman says is true this may be the cause of the group phenomenon. The question then would be - is the projectile stabilizing later in flight? - The target holes seem to suggest so. BTW flame away.

Keyholing can be caused for different reasons, but I am going to suggest you (Xman) try to bump up your powder charge a bit if within the safe loading limits and see if this cures your issue, then get back to us.

And FYI:

Definition: Keyhole may be a noun which refers to the hole which a tumbling bullet makes in a target, or it may be an adjective which describes the tumbling which the bullet was doing when it struck the target.
When a conical bullet strikes a surface in any attitude other than truly stabilized flight, that bullet has keyholed. Evidence of keyholing most often comes in the form of oblong holes in a paper target. Sometimes the holes are just a bit longer in one direction, and at other times the bullet will strike the target sideways. See the photo for examples of both.

The causes of keyholing may vary, but in all cases the bullet's flight was not properly stabilized when it struck the target.

In ideal conditions, a conical bullet is given some spin by the rifling in a gun's barrel as it travels through the barrel after being fired. That spin will stabilize the bullet's flight so that its nose is always forward, and it moves through the air in a nice straight manner.

If a gun's rifling is of the wrong twist rate for a particular bullet or velocity, if the rifling was damaged or absent, or if the bullet's diameter doesn't properly match the gun's bore diameter, the bullet is likely to tumble in flight. This results in poor accuracy, unpredictable bullet flight, and unpredictable bullet performance when it reaches the target or game.

Even a properly stabilized bullet may keyhole; this could be caused by it striking an object between the gun and the target.

 

[RememberTheSomme]

http://www.appliedballisticsllc.com/epswerve.html


There are too many closed minded a-holes on the Boards

This is the phenomena that explains a slight tightening of groups, like I mentioned about the No4Mk1(T), where a whole series of dynamics come into play, going from say 1.5MOA at 300 yards to 1.25 MOA at 600 yards. It doesn't account for 8MOA at 100 going to 1 MOA at 300.


Which close minded a-holes were you referring to on the board..........

 

[Sluggo_m14]

Like I said previously -there could be any number of factors that are compounding the effects of nutation, swerve etc. I don't know how or why- I am just curious as to what is happening- There are many references to shrinking MOA on the net with many examples at 100 to 300 yds - thats all I was pointing out but I would like to see the result of shooting this rifle at multiple shorter ranges -25,50,75 .

- The a-holes with a propensity to call someone a liar instead of politely and quietly ignoring that which they don't believe- far too common I think.

 

[Grizzlypeg]

Like I said previously -there could be any number of factors that are compounding the effects of nutation, swerve etc. I don't know how or why- I am just curious as to what is happening- There are many references to shrinking MOA on the net with many examples at 100 to 300 yds - thats all I was pointing out but I would like to see the result of shooting this rifle at multiple shorter ranges -25,50,75 .

- The a-holes with a propensity to call someone a liar instead of politely and quietly ignoring that which they don't believe- far too common I think.

His actual groups are reportedly shrinking as it goes further out. This is radically different from a report of shrinking MoA, which could theoretically occur despite a growing group size.

 

[Sluggo_m14]

His actual groups are reportedly shrinking as it goes further out. This is radically different from a report of shrinking MoA, which could theoretically occur despite a growing group size.

Yeah I know...

 

[WWIII]

Yo nay sayer’s... address the 100 & 200 yard holes in the target that indicate slight keyholing and unstable bullet flight and the perfectly round 300 yard holes that indicate stable bullet flight. Also notice the 100 yard holes are slightly more keyholed than the 200 yard holes indicating a progressive stabilizing of the bullets at further distances. These holes directly correspond with Xmans claim of very poor accuracy @ 1 & 200 Yds and MOA accuracy at 300 Yards.

As I mentioned in a earlier post Xman maybe first check your FS and see if the bullets are tipping it somewhere creating the keyholing and also check the muzzle crown for nicks or peening that may also be the cause of the keyholing, if these are good try bumping up your powder charge in increments and see if this cures the keyholing, other less likely possibilities are bullets or barrel out of spec.

 

[Norton]

I don’t really see distinct key holing myself, in a couple of the #3–100yard strikes they look just fine, perhaps the others are just paper rips, I don’t know what to think.
The whole thing just seems to goes against the laws of physics to me.

 

[JeremyR]

Any updates Xman?

 

[enefgee]

How about varying the charge a little - assuming that you're not at max add a couple of tenths, or drop a couple of tenths? Also, is the charge relatively filling the case, uneven or incomplete burning can cause erratic behaviour, also I'm assuming the bullet's aren't mic'ing under size? I don't know, I'm more or less guessing but I've seen some intersting video of gyroscopically stabilized objects that lose their stability and the results are far from predictable. It doesn't seem unreasonable that an unstabilized bullet would generate different impact points as a result of precession and nutation.

PS - I don't think anyone would show up here reporting something that is causing them issues without them actually having those issues, and to suggest otherwise is slightly absurd. When dealing with shooting, there are more things that can happen than the experience of any one person can define.

 

[sikwhiskey]

Also maybe try another shooter with factory ammo in your rifle?
And please, for the love of all things orderly start with 100m, then 200m then 300m and lable your hits 1 for 100m 2 for 200m... and aim at the same point the whole time, no holdovers.

I had an optics problem that had me scratching my head and wasting ammo trying to figure it out. Once I took a step back, had a coffee and set out a clear plan of attack, I found the problem.

Create a controlled environment and you'll figure this out.

Exactly, eliminate the variables. Don't use holdovers , Same point of aim at all distances at the same target, same hold, same magnificatiion. If that doesn't work. Try a different scope. I would bet my mother in law its the scope.
Was the Op switching magnifications at different ranges and using hold overs?

 

[Lost...again]

Thank God for the innernet eh...........If this had been a discussion in a Bar there would have been teeth on the floor
But what a wealth of knowledge you guys have, and free to all

THANKS.

Be nice if Xman gives an update to a truly weird phenomena
Sometimes we dont always get to hear what we want, dont be offended......lifes too short and SHOOTING is too much fun

 

[LordEvilPepper]

His actual groups are reportedly shrinking as it goes further out. This is radically different from a report of shrinking MoA, which could theoretically occur despite a growing group size.

radicly differnat then reporting shrinking moa... how so?

1MOA at 100 is 1 inch, 200 is 2 inch 300 3 inch group

If the moa shrinks as the rounds travels further and stabalizes... potentialy so does the grouping if the change is rapid enough

in the video you see the round go from a wild 2 MOA at 100 to sub moa at 200
AKA a 2 inch group at 100 to a 1 inch group at 200... wow like magic! At its peak the bullet is out by 6 moa! now what if Xmans bullets took longer to stab then the VLDs, from his groupings its finaly coming into its true flight path between the 150 and 300 meters instead of between 60 and 150 like in the video.

 

[Grizzlypeg]

radicly differnat then reporting shrinking moa... how so?

Why? Because for the group size to shrink, some force has to draw them back to centre. These are bullets, not boomarangs. How does an unstable bullet remember where it came from? and reverse its course back to centre? Inertia tends to keep a moving body on its same path.

For the MOA to shrink, it only takes a group size that fails to further expand, or that while it continues to expand, it doesn't do so at the earlier rate. If you double the distance, but don't quite double the group size, the MOA goes down. This doesn't suggest the bullets returned to point of aim. This phenomena could be accounted for by a bullet that stabilizes and deceases its rate of randomness of direction as it moves further out. But it will never return to the point of aim, except by luck, gravity or the coriolis effect.

 

[Norton]

^^^^^
Exactly.
How can a projectile sailing along at plus 1000 fps at x degree angle from center curve its way back to center without striking something.
The only thing that comes to mind are the Kennedy assassination bullets

 

[zupermann]

Truly weird result/phenomenom. I know that it can take a bullet a small distance to "go to sleep"--think of it like those old toy tops that spun crazily when first released and then stabilized themselves on their axis. I've never heard of such a drastic difference however--8 moa then 1-2 moa.
Is the muzzle crown okay/undamaged?

 

[Tikka223]

If all the shorts were taken with optics I would say that this could be a parallax issue (is the parallax is actually set for 300 and thus is off for 100). But if the group sizes are replicated while shooting with irons and with a different shooter then this really is weird. I don't have much experience with irons but I will say that your eyes can play some games sometimes. Maybe the 100m target is actually too big and thus you're not forcing yourself to "aim small".

My two cents