.308 LAPUA Palma brass

[Bart B.]

https://royalsocietypublishing.org/doi/10.1098/rspl.1901.0052#d1631807e1

The above was published over a century ago.

I have always seen the scope reticle bounce and wiggle on target. Heartbeats expand and contract muscles which moves the bones supporting the rifle. Nobody holds rifles perfectly still. One third MOA is about as small an area us live humans can keep the line of sight inside of.

As the barreled action is held by the stock, any external force on the stock effects the barrel's movement while bullets go through the barrel. Slung up in prone, a free floated barrel will string shots horizontally as the slung arm's elbow is moved sideways.on the ground. Easily observed shooting 22 rimfire ammo at 50 yards.

 

[Unclenick]

There is no position shooting that doesn't affect POI. On the other hand, I assume position shooting does not detune a load. That is, the load that shoots best off the bench in a floating barrel gun will normally be the one the position shooter finds best, regardless of what new recoil moments his position and contact points introduce.

Personally, I've always had a problem with a slippery right shoulder in prone. When I fire the 300-yard rapid-fire prone string in a match, I always have to put about 2 MOA of right windage onto a 30 cal rifle, as the butt of the stock moves slightly to the right when the gun fires. 1 MOA with the AR. I leave that windage in place for prone slow-fire.

For sitting rapid that follows standing offhand, I always have to take two MOA of elevation off. But that applies to all rifles I shoot with a 6:00 hold, so I think it has to do with how my brain handles the greater wobble of the standing offhand position rather than having much to do with recoil moments. I suppose the new rules will let me prove that to myself with an optical sight and a center hold.

 

[hounddawg]

It would be interesting to test with a bipod, shoot 20 rounds from prone and 20 rounds from a bench with a bipod. Then 20 from a rest to see if POI changes.

I need to change my length of pull when adding a jacket it seems and when I removed the jacket my POI went down a full three minutes but it tightened the groups up. I am thinking of ordering a thinner recoil pad and trying the jacket with the pad, easier than hacking off a half inch of stock. I have been rereading Jim Owens books the last couple of weeks and he really stresses having a consistent position.

 

[Bart B.]

It would be interesting to test with a bipod, shoot 20 rounds from prone and 20 rounds from a bench with a bipod. Then 20 from a rest to see if POI changes.

I need to change my length of pull when adding a jacket it seems and when I removed the jacket my POI went down a full three minutes but it tightened the groups up. I am thinking of ordering a thinner recoil pad and trying the jacket with the pad, easier than hacking off a half inch of stock. I have been rereading Jim Owens books the last couple of weeks and he really stresses having a consistent position.

I've shot the same stuff with the rifle on bags atop a bench with rifle held 3 different ways, on one or two bags in prone with and without a sling and slung up in prone with a sling without artificial support. Zeros had a 2 MOA plus horizontal spread, 1 MOA vertical spread.

A friend had tested his rifle clamped in a free recoiling accuracy cradle at 600 yard shooting several 10-shot groups under 1.5 inch: 0.25 MOA. He won the 600 yard prone aggregate at the nationals shooting three 20-shot matches keeping all 60 record shots inside 12 inches

Nobody has put 20 consecutive record shots twice in a row inside 1 MOA with a high power rifle slung up in prone. Last time that was done with a 22 rimfire at 100 yards was about 45 years ago.

 

[Unclenick]

I have been rereading Jim Owens books the last couple of weeks, and he really stresses having a consistent position.

Those books are full of practical advice. I bought a couple of them on Commercial Row long ago, then got the rest when Jim Owen established his web site. I use his sight adjustment strategy in matches. I once started a match in the standing offhand phase by putting three 9's in a row at about 7:00. I didn't touch the sights between them because that's where I called them. Then I remembered Owen's advice to make a half correction, then another half correction if needed. All the rest were 10's and X's. My eye kept calling them at 7:00, but it was just seeing wrong that day, and if I had followed the advice from the git-go, I'd only have dropped one point instead of three in that phase.

The nifty thing about that method is it treats a shooter and shooting system as an amplifier with in-phase feedback that has the potential to oscillate if the gain is one or more (Nyquist's criterion). The feedback is the spotter position and the gain is how far the sights are adjusted to attempt the correction. If that adjustment is 100%, the gain is 1.0, and oscillation ("chasing the spotter") can result. By making less than full correction, the oscillation is damped out.

 

[hounddawg]

I am hoping using his method is going to overcome my biggest obstacle which is centering my groups. Not a whole lot of reloading in his books but he has excellent advice on technique and that is my weak link in the chain

 

[Unclenick]

When you consider service rifle match targets can theoretically be cleaned by a 2 moa (at 600) gun, you realize the shooter's technique is the weak link in most shooting. Making guns mechanically more accurate is almost a separate hobby, though it does a lot for confidence to have a tight-shooting rifle.

 

[hounddawg]

When you consider service rifle match targets can theoretically be cleaned by a 2 moa (at 600) gun, you realize the shooter's technique is the weak link in most shooting. Making guns mechanically more accurate is almost a separate hobby, though it does a lot for confidence to have a tight-shooting rifle.

for F class I think you need to have ammo and a rifle that will shoot .5 MOA 5 shot groups at 100 consistently. Once you start stretching it out the shooters ability comes more and more into play as the distance increases. I used Owens method for zeroing this morning, the wind was negligible at 300 at about 2 - 5 mph from right to left. Moderate mirage. 3 groups of 3 sighters then the last 11 into a seperate target

 

[Unclenick]

Unless you have 1/8" or 1/10" clicks on your sight, that's as close to true zero as you can expect to get. Good shooting!

 

[Bart B.]

for F class I think you need to have ammo and a rifle that will shoot .5 MOA 5 shot groups at 100 consistently.

For F class, I think you need to have ammo and a rifle that will shoot sub .5 MOA 5 shot test groups at competition ranges consistently. Doesn't matter what it shoots at 100 yards.

Groups for a given load don't have the same subtended angle at all ranges. Variables causing this include bullet velocity, departure angle and BC along with atmospheric conditions. You may need one charge weight for closer ranges and another for further ranges. Or a tuner set for each range with one load.

 

[hounddawg]

I'd be willing to bet that it is more this shooters ability to hold a .5 MOA than the rifles ability to shoot .5 MOA as yardage increases. Just speaking for myself, others may be shooting gods that are only held back by the ammo and rifle

I say that becasue recently one of the club members was selling one of his rifles, a high end custom built rifle. In his hands the rifle shot .5 or below out to 800, when I shot it my groups were not much better than my garage builds. I did fall in love with that Shehane tracker stock though and plan on retrofitting at least one of my rifles with one soon

 

[Bart B.]

I'd bet most F class competitive shooters can easily hold inside 2/10ths MOA and less than 10% will hold well inside 1/10th MOA. The rifle is artificially supported and heartbeats won't cause much LOS wiggle at all.

Conventional prone competitors using slings can hold inside 1/2 MOA when the wind isn't buffeting them around.

 

[hounddawg]

I'd bet most F class competitive shooters can easily hold inside 2/10ths MOA and less than 10% will hold well inside 1/10th MOA. The rifle is artificially supported and heartbeats won't cause much LOS wiggle at all.

And I will bet you are wrong, this isn't five or ten shot short range benchrest

In F class anyone who can shoot 1 minute of angle 100% of the time would get a perfect 200 score every target, the ten ring on the @300, 600, and 1000 is 1 MOA. F class at 800 yards uses the 1000 yard target so the ten ring is 10 inches or 1.25 MOA.

2019 mid range national championship

winner had a 1794 aggregate. Six shots out of 180 were outside one MOA. 61 were outside .5 MOA. 10th place guy dropped a average of 5 shots out of ever 60 outside 1 MOA. A far cry from your claims of .2 hold and wind calling

I smell a strong odor of bovine organic fertilizer

 

[Bart B.]

The hold area I'm referring to is where the point of aim is. Not the size of shot hole groups.

 

[hounddawg]

The hold area I'm referring to is where the point of aim is.

and how did you measure the point of aim to come to that conclusion ?

I suggest you read Jim Owen's book Sight Alignment , Trigger Pull and the Big Lie. Pay attention to Chapter 9. Page 143 to be specific where he describes a marksman with a 6 minute hold being able to keep his shots within a 36 inch circle at 600 yards

Using Owen's definition my own ability is a .5 MOA hold @100, 3/4 MOA hold at 300, 1 MOA hold @600, and a 1.5 MOA hold at 800 judging by my average group sizes. I am below average compared to the top F class shooters who have 1 MOA or less holds out to 1000

 

[Bart B.]

and how did you measure the point of aim to come to that conclusion ?

If the scope's reticle (the point of aim) wiggles around inside a 5 inch diameter area on a target 1000 yards downrange while you're slung up in prone without artificial support, your hold area is a half MOA.

 

[Unclenick]

A distinction has to be drawn between your ability to hold a sight picture (what I believe Bart is referring to) and your ability to get the shots to place that tightly on an actual target, especially at long range where wind, gun and ammunition limitations, bullet drop and even bullet-to-bullet variation all have effects you are challenged to resolve at 100 yards. You can prove your hold by shooting at 100 yards with a load suited to that range to eliminate those variables. When things are going well, shooting knots or sometimes bugholes at that shorter range isn't wildly uncommon, and I think we've all experienced that when our gun and loads were working well together. This article describes a fellow who apparently can do it consistently. Most benchrest competitors hold sight pictures at that level of precision regularly. I don't know how close to that F-class shooters, specifically, do on hold, but don't see why they should be too much worse and Froggy shows they don't have to be worse.

I recall in Mid Tompkins's Long Range Firing School he told us 1000 yard wind changes faster than you can dial in adjustments finer than about half-moa, so he felt having sights with adjustments finer than that was pointless. If he picked up on a quarter moa shift by watching where the other competitor's spotters came up, he used Kentucky windage rather than sight settings to correct for it. And he was talking about Palma rifles with open sights. So, small moa numbers are discernible to the eye and, in the case of Tompkins, for one, even possible to correct hold for, though position and trigger control and equipment and ammunition that are all solid as a rock all have to be present for the shooter to be up to the task of getting the bullet where he wants it.

 

[hounddawg]

my rule of thumb is groups on windless cloudy days at 100 show what the rifle/ammo is capable of with me behind it. Group sizes at 600 and farther with wind and mirage show what the flaws in my environment reading and hold. When the group sizes at 800 and 1000 are the same size as the group sizes at 100 I am squeezing everything I can from that rifle/ammo and it is time to upgrade the rifle/ammo. If they are larger I need to improve my technique

 

[Bart B.]

If groups at 100 yards are averaging half an inch, they won't be that size further downrange.

Muzzle velocity spread causes groups to change their angular size with range. A 50 fps spread from a 308 Win can cause a 1/10th MOA vertical spread at 100 yards. At 1000 yards, it's 2 MOA. This assumes there's no compensation for velocity spread by the barrel vertical vibration shooting slower bullets at greater angles to the line of sight than faster ones.

 

[Bart B.]

When the group sizes at 800 and 1000 are the same size as the group sizes at 100 I am squeezing everything I can from that rifle/ammo and it is time to upgrade the rifle/ammo. If they are larger I need to improve my technique

There's a flaw in this reasoning. Groups are never the same extreme spread dimension in inches at all ranges for a given barrel profile. Nor subtend the same angle.