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W.R.Buchanan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote W.R.Buchanan Quote  Post ReplyReply Direct Link To This Post Posted: October 26 2014 at 10:28am
LongBranch:  In Pistols,,, Slower loads always shoot high.  Reason being, that they spend more time in the barrel during Recoil, and thus the muzzle is pointing higher by the time the boolit exits.
 
A similar point could be made for shooting from an unsupported position with a rifle where the gun is rocking you back during recoil thus making the muzzle rise and thus the shot with it. 
 
It would take a movement of about .050 or slightly less than 1/16th " to make a 6" change in the shot at 100 yards.
 
This same phenomenon could be extended to the windage offset.  A rifle with a left hand twist will move the buttstock away from your cheek in recoil which would push the muzzle to the left.
 
This is entirely in the realm of believability.
 
Typically off a rest the slower rounds will shoot lower simply because of the trajectory's decay. 
 
Sounds like Rocket Science, huh?
 
Randy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zed Quote  Post ReplyReply Direct Link To This Post Posted: October 26 2014 at 10:56am
It have read (book not internet) that flexing of the Enfield barrel's is what makes the slow shots impact high and the higher velocity low at shorter distances. It was apparently well known amongst shooters when these rifles were used in long range competitions and the effect was that at longer distances the path's would cross, making the rifle more "accurate at 600 yards than at 200 yards.
 I have seen this personally when chronometering hand loads against the PRVI factory rounds in my No1MkIII*, although I have not seen any lateral deviation caused by the velocity.
If the rifle throw's certain velocities to one side I would first off, get someone else to shoot it and see if they have the same results, then I would be checking out the fit of the fore arm around the barrel and also the contact at the draws etc. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Long branch Quote  Post ReplyReply Direct Link To This Post Posted: October 26 2014 at 11:23am
All rifles do this. The reason being that the bullet has to rise up into the line of sight. The slower bullet has more time to rise before it impacts. This has held true for every surplus rifle I've loaded for. A friend of mine brought me some ammunition he was loading for the wounded warriors project. He didn't have a 303 and wanted me to test it. It was loaded with BLc(2). It was hot stuff (BLc(2) generates higher velocities without overpressure). It shot very low and far right. Now, if you load two different weights and/or types of bullets for the rifle, all that goes out the window. This effect is magnified in pistols because of the recoil characteristics, and so it shows up at shorter ranges.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MaxP Quote  Post ReplyReply Direct Link To This Post Posted: October 26 2014 at 12:09pm
Hmmmm... seems I will have to set some time aside later to address some facts that are either missing or totally wrong here...
Will get back in the next day or two.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote W.R.Buchanan Quote  Post ReplyReply Direct Link To This Post Posted: October 26 2014 at 12:30pm
Max:  it does take a while for responses from DU to get here from there. Clown  Randy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: October 26 2014 at 1:24pm
Its one of those oft quoted & even more frequently misunderstood myths.

I does NOT mean the rifle shoots tighter groups at longer ranges. Just that it disperses less than you'd expect as range increases.

For a long time expert shooter kept the .303 for 1,000 yd shots, but shot the 7.62 out to 650 Yds.

Why?

Well, because the .303 out-shot the 7.62 at that distance. I've heard many theories why  but it just did in My Opinion, I neither know, nor care why if it could get me a higher score "out there" (where matches are won, or lost), then I'll do it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Long branch Quote  Post ReplyReply Direct Link To This Post Posted: October 26 2014 at 1:42pm
That's more a confusion about the term "Minute of angle". If someone says their rifle shoots 2MOA at 100 yards and 1.5MOA at 600 yards, the average person thinks that means 2" @100 and 1.5"@600.

There's also some confusion about the term "accuracy". I was zeroing a rifle at the local range once. Someone watched as I shot a 1" group 4" away from the dot at 100 yards. He said "that rifle don't shoot good. You need ta let somebody look at that."
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 4:35am
They always used to differentiate shooting for group & shooting for score back when i shot with the RAF.
Trying to put them all in the bull was "scoring", but shooting for a group (wherever) was "application". The goal was to be aware of the different way to use sights for the different purposes.
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MaxP Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 4:59am
Ok, got a few minutes, thought I'd start with this old chestnut... as it leads to the rest of the story, probably a good place to start....

quotes from somewhere above....

1. I don't think the type of ammunition would have any effect apart from elevation change; which can be easily compensated for on the rear sight.
2. .... is right on the type of ammo not affecting windage to any large degree.
3. There should be very little if any windage correction necessary between Ammo types.  Differences in ammunition generally result in elevation changes due to differences in Velocity, but that doesn't affect windage
4. My point originally was that the myth of who shoots what was just that, a myth.
5. It never fails that a slower load with the same weight bullet will shoot high (counter-intuitive. I know) and off center.
6. Typically off a rest the slower rounds will shoot lower simply because of the trajectory's decay.


Ok, please take a minute to absorb this... It is probably the simplest explanation I can find... I will expand on it...

From the moment that trigger is pressed and the firing pin strikes the primer until the bullet leaves the muzzle, a series of many vibrational impulses begin in the rifle, all of which are transmitted to the barrel in various magnitudes. These include such minor things as; the trigger sear releasing the firing pin, the firing pin moving forward, striking the primer, and the cartridge being moved forward. The powder then begins to ignite, and the bullet starts moving forward and engages the rifling. Because of the twist of the rifling, the bullet while it is being propelled forward, begins to spin imparting a small but measurable torque, but more importantly as it traverses the barrel it also sets up a circular vibrational pattern, or arc. The heat of the burning powder along with the pressure wave generated by the expanding gasses start another vibrational pattern that is induced into the barrel. All of these movements cause the barrel to stress and vibrate with a number of different harmonic patterns which if not controlled by some means cause each projectile to leave the muzzle at a slightly different point in the vibrational arc. Some people speak about the "whip" of the barrel, which would imply to some, that the barrel simply vibrates up and down like a buggy whip. Although there are some of the vibrations that are traveling in this direction, the main vibrations are circular. If this were not true, then a 3 shot group from a rifle would always be in a vertical string. This would be because, one would leave at the bottom of the "whipping action", one would leave from the center and one from the upper travel of the "whip". As we all know this seldom occurs, and if it does, it is usually caused by the barrel being under a heavy stress, such as way to much pressure exerted against it, caused by improper bedding, usually of the barrel. Most 3 shot groups you will see will be virtually triangular in shape, this is caused because as the barrel vibrates through its "circular arc" one bullet leaves the muzzle at say 12 o’clock, another at say 4 o’clock and the third at maybe 8 o’clock. The larger the arc of the barrel, the less accurate the rifle will be, and the larger the triangle. As a rule the less mass a barrel has, (the thinner) the more it is affected by the vibrations, this is the reason that a "heavy" barrel seems to shoot more consistently than a sporter barrel, and is also easier to tune.

Ok, so now barrel whip is actually circular in motion. The art (yes, ART) of accurising a rifle is in taming those vibrations. Tame the circular motion. As said above, the tighter the circle the smaller the group. The circular motion varies during each shot. The aim is to have the projectile exiting the barrel during the period where it's motion is at it's smallest arc
You have possibly heard or seen written that the Lee Enfield barrel is tuned for MkVII ammunition, that is a 174gn spitzer projectile exiting the muzzle at 2440 fps. The correct bedding combination of well fitted factory woodwork will dampen the vibrations to the point that the MkVII ammunition is departing the barrel at the point where the muzzle is in it's smallest arc. (they worked all this out over a hundred years ago)

If your ammunition is very accurately hand loaded, then it can improve the results even further because it will be exiting at near the same point of the arc every time so less dependent on having a small arc for accuracy.

Now... add some other ammunition, say a 150gn pill doing 2600fps.
The likelihood that it will cause the exact same vibration pattern and exit at the exact same point in the muzzle's circular motion is not good. In fact it might even be exiting the barrel while it is at it's most violent motion. With ammunition that isn't finely measured, the result will be a noticeably larger group (hey, there's something we've all probably seen in a rimfiree with different ammo, now we know what heavily contributed to it) But if you are using good quality handloads, then you might see it group reasonably well, but print a few inches off to the side because they have all departed the barrel during the time it was at it's furthest off to that side.

If you want proof of all this, just ask any benchrest shooter for a look at his load development targets. He might be shooting for tight group size primarily, but the groups will all be centered on different parts of the target. Once he confirms his tightest group, the sights can be adjusted to bring that load on centre.
If barrel whip were up and down, they would be in line above one another.

To touch on the light load shooting high... There are a couple of possibilities. The pills are exiting at the extreme top of a violent muzzle arc.
The load is so light the powder is spread along the case exposing a large surface on top, and giving a flash over ignition. The pressures that can be produced by such a change to the burn pattern could change the barrel whip and the POI quite drastically.

Now, back to something I have said... these rifles are tuned for MkVII ammunition. If the rifle is in good nic and has not been messed with in the bedding, it should shoot to the sights both windage and elevation with MkVII.
If you or anyone else before you used any other ammo and adjusted the sights because it was way off, it was because the rifle was not tuned for the ammo you used. If it appears to be in good nic but you cannot get it to group (not centre, group) no matter what you use including MkVII, then it's possible the bedding is out as well.

One more favourite of mine...

Sure they can be made to shoot well but with Iron sights or even Red Dot sights this is about as good as it gets

Could not be further from the truth. The sights have nothing to do with the accuracy (as long as they work) You can stick a rifle in an Enfield Rest and fire ten shot groups all day and get the best accuracy possible without even looking along the barrel. It's only when you add the human element that the rifle is not capable of it's best.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote W.R.Buchanan Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 9:05am
MaxP: Great research above and that is a very good description of what happens when a shot is fired.
In defense of my comment.
Sure they can be made to shoot well but with Iron sights or even Red Dot sights this is about as good as it gets.     
I was referring to AR's in that sentence, and with those sighting systems 3-4MOA IS about as good as it gets in the real world.  And that is good enough for the intended purpose of the weapon.

Could not be further from the truth. The sights have nothing to do with the accuracy (as long as they work) You can stick a rifle in an Enfield Rest and fire ten shot groups all day and get the best accuracy possible without even looking along the barrel. It's only when you add the human element that the rifle is not capable of it's best. 
 
I agree with most all of what you say, however you are talking about "mechanical accuracy" not "field accuracy."
 
Most of us shoot while actually holding the gun. (Bench rest shooters aside) Thus the Human Element always affects the guns accuracy. If you were able to shoot from an Enfield Rest all the time there would be no need for sights.
 
Being able to index the sights to the target the same way everytime is what defines Field Accuracy , and the sights are the interface between the person and the gun, However no matter how accurate the rifle is mechanically, the level of precision of the sighting system and your ability to use that system will limit that accuracy in the field. 
 
Certain types of sighting systems are simply more accurate than others, everybody can agree with this point I'm sure.
 
If you have a gun that shoots .5 MOA and you install a Red Dot Sight with a 3 MOA dot the best you will see is about 3 MOA, unless you figure out a way to index that dot on the target in the exact same place every time.  We usually do this by indexing the dot at the 9 O'clock position on the outside edge of the target spot using the edge of the dot.
 
If you try to center the dot on the target the best you will shoot is 3MOA. There is no specific indexing point.  A Red Dot sighting system is more about Speed of Target acquisition than High Precision Shot Placement.  Conversely a High Power Target Scope allows you to precisely index the crosshairs on a specific point on the target and better use the inherent accuracy of the gun..
 
If you don't include the man in the equation the rifles mechanical accuracy means nothing as a gun can't shoot itself.
 
Randy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 9:29am
Also true, My rifle shoots to POA & makes consistent 1 3/4" groups for 10 rounds at 100 yds. I wish I did!Cry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Zed Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 10:54am
Max P, thank you very much for taking the time to explain that. It does make sense and will probably help improve my understanding when trying different loads.  At present I have 2x.303's that I reload for. I have only been using 174gr Spitzer type Sierra orgives and in my No4 rifle I aimed to get the velocity as close to 2440 ft/sec. At this speed it seems to work very well; it requires 39,3 grains of Tubal3000 in this rifle.
 However with the No1 rifle which is a more recent purchase I've found that the same load is too fast and grouping much larger than the factory PRVI rounds that I bought to compare. (PRVI chrono at 2380 ft/sec in this rifle).
Obviously different powder in the PRVI so difficult to compare, but the bullet weight is the same.
I have more testing to do on this rifle; but have found that 37,4 grains of Tubal 3000 shoots similar groups to the PRVI at a speed of around 2415ft/sec. 
I am going to try a slightly slower powder in this rifle as I believe the Tubal 3000 is maybe a bit to hot for the thinner No1 barrel. I see were that experiment leads. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Long branch Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 2:20pm
Tubal3000. That's a Nobel Sport powder right? I hear good things about it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 25-5 Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 3:16pm
My Enfield Rifle No. 4 Mk2 is about 2.5 minutes to the right at 200 yards.  I found this on Ebay along with similar tools for other Enfields.  It's $25.00  What do you think?
 
I reloaded with .311 174 gr Sierra Match Kings HPBT and Hornady .3105 174 gr FMJBT.
Windage results were almost the same for both bullets.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote W.R.Buchanan Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 3:51pm
25-5 I saw that one before I made mine.  That one has to have the Sight Protector Removed to work.
 
It also needs to be Deburred.  Which one looks better?  Mine is $10 more but you'll save that much not having to buy band aids after you use it.
 
Also are you talking 2.5" or 2.5 MOA?   At 200 yards 2.5 MOA would be 5"
 
Randy
 
 
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 25-5 Quote  Post ReplyReply Direct Link To This Post Posted: October 27 2014 at 4:13pm
MOA.  Somehow I didn't realize you had them for sale.  I suppose I didn't read everything.  So much about the ammo etc.  At 100 yds I would just use a bit of left Kentucky windage and plunk em in, but at 200 it's more difficult.
Yes, I would like one of yours.  Let me know what you need.
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