Sighting In a Rifle With a Pencil Barrel

[Formidilosus]

So you don't believe in flyers, bad cheek welds or several other variables that could affect a 10 round string? Do you fire 10 rounds every time you zero or only when developing a load? If 9 shots are in a group(.25) and 1 is .5 away, you're saying you have a .75+ MOA rifle? Just trying to wrap my head around zeroing with 10 round!

I used to work at a place that had acoustic target systems. You may know what those are- but they are target frames linked to a computer system that "catches" the precise point of impact for any rounds fired. They are quite accurate. Anyways, when zeroing and grouping we would ask whether 3 or 5 round groups were enough to get a solid zero and/or see what the system is capable of. Unanimously it would be "of course", and several times it was suggested that even 2 rounds was sufficient. They would say things like- " 3 rounds tests the gun, 5 rounds tests the shooter", etc. once we started shooting we would hear the students say all kinds of things, such as- "flyer, "I pulled it", "bad cheekweld" "a bug was in my eye", "I wasn't in harmony with the earths gravitational pull", etc. for why a round would be out. This was with 3-5 round "groups". Then we would move them to the acoustic were they couldn't see their impacts and miraculously all those excuses went out the window. It would be rare to hear one say that they pulled a shot, etc. Then we'd pull up the "targets" and show them their groups which inevitably would have "flyers", and be virtually identical to their"bad" groups. Usually a lightbulb would go off and they'd get a quizzical look on their face. To which we would explain simple statistical probability and how 3 rounds just doesn't cut it. 3 rounds is like someone telling you well it rained one day last year, and you using that to try and predict the average rain fall for given month. It's virtually useless.


So to answer your question, while bad shots can and do happen, when firing from a bench or prone position using rests, they should be vary rare. If a person is not capable of pressing the trigger 10 times on a row without biting his tongue off, he's not ready for anything except ball and dummy's to cure the flinch. He certainly can't get a good zero, nor will he have any clue what his gun will consistently do. And since human nature is to overestimate ones abilities (and equipment) he will by default come to a false truth.

Using your scenario, I would either say that it is a .75 MOA gun if I was only going to fire one group as there is no way to be certain that it was me, or I would fire a couple more 10 round groups. I do not give excuses for "flyers" nor do I except them.

Given a rifle that's not jacked up if you fire 1 round ten times on the same target, five 3 round groups on the same target, three 5 round groups or one 10 round group with all rounds being counted, you will see that they look identical. The rifle doesn't know what round it's on- it can't say gee this is the 4th round of a five round group I think I'll throw it.

 

[Formidilosus]

I'm not sure if this post just got away from you, or you truly believe what you say. When it comes to rifles, precision and accuracy are two separate things, and need to be addressed as such.

A rifle's precision potential has to do with the group size it can produce; it's accuracy potential is mostly controlled by the sighting system and how well the shooter uses it. Firing a 10 shot group (or 20) to determine a rifle's precision potential is silly and counterproductive. There are too many variables in the real world that would affect a string of fire like that. A heavy benchrest gun, that the shooter has little influence over, could be tested like that, but not a hunting rifle.

With a rifle like the OP is asking about, I would fire several three round groups. Between each group, I would adjust the scope accordingly, and let the barrel cool to ambient temp. I would dry fire while the barrel is cooling to maximize my time at the range. Once I have the zero where I think it should be, I would fire one cold bore shot into the target. That target gets taken down and fired at the next time I'm shooting, with only the first shot of the day. This target will reveal the true precision AND accuracy potential of the shooter and the rifle.

I go through on average a bit more than four barrels a year. Quite a bit of those rounds are normal and lightweight hunting rifles and they all get shot like that. Ironically when overlaying multiple groups on a single target, 1 round a day for multiple days, etc. the groups look suspiciously like a single ten round group, so I just pass the fluff and cut to the chase.


Pleas tell me what variables in the real world would preclude ten presses of the trigger but allow three presses multiple times?

If one is trying to determine a rifles precision then the only way to validate it is to fire a statistically relevant number of rounds.



So between each three rounds (which could have landed anywhere inside if the cone, which is much larger than the 3 round group) you adjust your scope? Ok, but what are you adjusting off of? Those three rounds could have been at the bottom of the cone, at the top, on the right, the left, or maybe though rarely in the center. The point is to move the center of all rounds fired (the cone) over top of the aim point (which is accuracy).

Unless the rifle is needs work (as the gentleman above stated he has) there is no such thing as "cold bore shift" so there's is no reason to dedicate a target for it. If a shooter is using a properly assembled rifle then any shift seen is a either a scope issue (which happens all the time) or just as likely a cold shooter shift.

The concept of grouping and zeroing is the same whether its a Kimber Montana or a 20lb 338L.

 

[dotman]

So your saying barrel temp and amount of fouling in the barrel don't matter? Your barrel is what it is?

 

[Formidilosus]

Yes.

The barrel doesn't know the difference. Unless there is stress in the barrel or bedding heat has very little to do with group size. And if there is stress I absolutely need to know about it. At some point precision will fall off because of fouling but it is SOOOOOO far past what people believe that it is shocking.




To answer an earlier question as to whether I always for ten rounds- not always. The first thing I won't to so with a rifle is determine the validity of the system, that is rifle, bedding, barrel, scope, bases, rings and ammo. The first step is to insure that there is no underlying issues (ignoring load work up). Fire 1 round, adjust from the point of impact (POI) which should adjust the next shot very close to point of aim (POA) and then fire 10 rounds. That gives me a place to start. A known benchmark. With normal hunting rifles anything between 1-1.5 MOA for ten I adjust to center the group, fire ten more to confirm a POI/POA zero and then get off the bench/bipod. Periodically (read- every time the gun is fired at the range) I check zero. Depending on what the gun groups and what scope is mounted will determine how many rounds to fire. If it is a hunting rifle that averages 1.5moa for ten rounds and there is a regular scope mounted on it then I might feel that 5-10 rounds are needed to see a shift. If it's a competition rifle or dedicated LR gun with a solid scope (read- Nightforce) that consistently averages significantly less than 1 MOA for 10 rounds, than maybe 1 round is sufficient to check zero.



When in doubt- shoot. They're made for it.

 

[Broz]

Different strokes! I am sticking to my 3 to 5 groups of 3 with cool time.

And fwiw, I have called a bad brake of the trigger many times before the bullet got to the target on distant shots. I have a decent ability for follow through and often see the last visual as the trigger breaks.

Reguards
Jeff

 

[unm1136]

Different strokes! I am sticking to my 3 to 5 groups of 3 with cool time.

And fwiw, I have called a bad brake of the trigger many times before the bullet got to the target on distant shots. I have a decent ability for follow through and often see the last visual as the trigger breaks.

Reguards
Jeff

Follow through and the ability to "call the shot" is incredibly important. BUT it requires absolute honesty... a trait our society is sorely lacking, and takes tons of ammo; you have to miss a lot and know it as you deal with recoil. It took me about 8,000 rounds through my AR with both eyes open before I could reliably call my shots. Of course, I am incredibly dense and slow to pick up on things that are clearly apparent to most normal people.

I fully agree that many fliers are shooter caused, despite the common belief that they cannot be accounted for but by blaming equipment. But sometimes the equipment is not up to snuff. I have not delved into the statistics of rifle precision. But I do know that defining the accuracy and precision of your rig by what you can produce with it, gained by empirical evidence is probably the "A" solution to the problem. I cannot shoot up to the capability most of my guns, and that tells me where I need to focus on making improvements. To quote Col. Cooper "it is the singer, not the song."

pat

 

[wpwarren]

My .300 mag with a medium contour barrel behaves very predictably with all of the loads and the factory ammo I have shot through it. The First 5 shots fit in a group just over 1" after the barrel is fouled it settles down to the groups that I can expect from a certain load. My current hunting load shoots about .75" groups whether those be 3 or 5 shot groups when I do my part. I also put up 5 targets. The first is a fouler target which I fire the first 5 shots at. I then fire one shot at each target before starting again at the 1st target. After 25 shots the accuracy starts to drop off again and I clean the gun before starting the process over. I haven't had problems with my zero shifting so that isn't a major concern to me, but the barrel does get hot pretty quick if I don't take a break between shots.

To try to prolong the live of my barrel I usually intentionally slow my shooting down. I take a shot through my chronograph. Record the velocity in the spreadsheet that I keep track of all of my reloading data. Check the atmospheric data and note the changing atmospheric conditions in the spread sheet. I also inspect each piece of brass. This takes about 1 minute. I then take my next shot working my way through all 5 targets with the above steps in between each shot. After this I take a longer break and go down to the target where I mark each shot with a 1 for the first shot of the group. I also usually put some rounds through other guns during this break. Either a magazine or 2 through one of my .22s or some patterning shots through a shotgun or some rounds through another rifle. Firing 25 shots usually takes me a couple of hours, but I have lots of fun and end up with a lot of good temperature and velocity data.

 

[GKPrice]

I go through on average a bit more than four barrels a year. Quite a bit of those rounds are normal and lightweight hunting rifles and they all get shot like that. Ironically when overlaying multiple groups on a single target, 1 round a day for multiple days, etc. the groups look suspiciously like a single ten round group, so I just pass the fluff and cut to the chase.


Pleas tell me what variables in the real world would preclude ten presses of the trigger but allow three presses multiple times?

If one is trying to determine a rifles precision then the only way to validate it is to fire a statistically relevant number of rounds.



So between each three rounds (which could have landed anywhere inside if the cone, which is much larger than the 3 round group) you adjust your scope? Ok, but what are you adjusting off of? Those three rounds could have been at the bottom of the cone, at the top, on the right, the left, or maybe though rarely in the center. The point is to move the center of all rounds fired (the cone) over top of the aim point (which is accuracy).

Unless the rifle is needs work (as the gentleman above stated he has) there is no such thing as "cold bore shift" so there's is no reason to dedicate a target for it. If a shooter is using a properly assembled rifle then any shift seen is a either a scope issue (which happens all the time) or just as likely a cold shooter shift.

The concept of grouping and zeroing is the same whether its a Kimber Montana or a 20lb 338L.

this whole "debate" appears to be an article Jim Carmichael wrote some years ago that has gone terribly awry