Session to session consistency

rimfiremac

rimfiremac

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I'm noticing a strange trend. In the morning I'll head out for a quick range session and won't be able to print a group better than 1.5" at 200 yards. Then, I'll go out that afternoon, mostly out of frustration, use the same gun, same loads (recently even the same piece of brass shot to shot, reloading on site), and shoot into an inch at 200 yards. I'll have a few good groups, then print a 2-incher that toasts my building confidence. Weather conditions vary, however mostly the 'flyer' that ruins the group is vertical, or vertical and right (even if the wind is prevailing from the right). At shot release, all feels correct, no jerking or pulling I could detect pre-release, and I shoot a lot of rimfire at 100 with capable sticks.

What techniques have you competition/ F-class guys used in the past to iron out those kinks that sneak into your performance session to session?
 
your coffee intake might have some thing to do with it

being in a rush and small groups almost never happen

just having the sun at a different angle messes me up

the air in the morning (colder+denser) then in the afternoon will affect results
 
Welcome to my world.

Seriously.... What constitutes a good group is equivalent to the number of shots you would need to launch in the process of trying to print one score card. In F-Class, that is typically 15 shots plus sighters.

It is what causes the group to head south that provides part of the answer.... if fifteen shots results in a randomly dispersed group in a round pattern well it is either you, your rifle (barrel) or your ammo. You need to isolate which one.

If the group walks from one side to the other in a pattern that is less than .75 MOA -wide linear pattern, it is barrel heat or more likely the wind.

Most grouping problems are shooter related, yet most shooters blame the equipment. If you can shoot a pattern that is less than .5 MOA tall but walks left and right, chances are, your load and your gun are good, you must simply learn to read conditions. If the pattern is more round, it is either you or the load.

Use powders with a good reputation for temperature stability, never rely on factory loads and shoot with a partner.
 
rimfiremac said:
I'm noticing a strange trend. In the morning I'll head out for a quick range session and won't be able to print a group better than 1.5" at 200 yards. Then, I'll go out that afternoon, mostly out of frustration, use the same gun, same loads (recently even the same piece of brass shot to shot, reloading on site), and shoot into an inch at 200 yards. I'll have a few good groups, then print a 2-incher that toasts my building confidence. Weather conditions vary, however mostly the 'flyer' that ruins the group is vertical, or vertical and right (even if the wind is prevailing from the right). At shot release, all feels correct, no jerking or pulling I could detect pre-release, and I shoot a lot of rimfire at 100 with capable sticks.

What techniques have you competition/ F-class guys used in the past to iron out those kinks that sneak into your performance session to session?
Click to expand...

If you KNOW that your shooting has been good and conditions were not a big deal, then look at your rifle and ammo. Load tuning is a huge part of rifle set up and even the best rigs are limited by the ammo you load.

Maybe the bedding is wrong or the ammo not properly set up? Maybe the rifle is simply this inconsistent?

How accurate do you believe this rifle will shoot?

I have done some practising with a rimfire and will do more in the summer. Talk about unforgiving to form and follow through BUT what a great way to learn.

PRACTISE, PRACTISE, PRACTISE, PRACTISE, REPLACE BARREL, PRACTISE, ETC.

Consistent shooting comes from consistent shooting technique and form. There is no other way around it.

But you need to shoot a rifle you KNOW will deliver the bullet where you want IF you do your part.
Jerry
 
What gun are you shooting? Factory gun and barrel or custom barreled job?
Since you've done rimfire, how much centerfire reloading and shooting have you done?
Can you get someone at the range who knows his stuff and look at your gun and technique?
Maybe the gun doesn't fit you properly with cheek weld, trigger letoff, bench technique, etc.

When I shoot bench or F-Class, I can assure I'm comfortable with no strain anywhere. Everything fits and comes together or I'll make it right. If your struggling with anything physical or you mind is not in the right place will have impact on your shooting score.
 
Lejar* makes a very VERY good point: Fit.

Ergonomics is one of the last things considered by far too many shooters, yet it makes all the difference in the world. A gun that feels right, shoots right.
 
I'm running a Savage 10Fp with a home-cut f-class style stock, with cheek piece adjustment. The fit is fantastic actually, I'm absolutely comfortable both off the bench and prone with it. It holds rock steady. Compared to the Tikka T3V I'm also working with, it's a world of difference in comfort. The barrel is stock, but it's turned out the occasional 1/2" one hole group at 200 yards... occasionally.

I wonder at times if it's ammo consistency- I ran five 155 scenars into one hole at 200 a few weeks ago, it blew my mind; then a week later, they go into an inch with five individual holes. Nothing to complain about, but a real head tilter to wonder about what happened over the course of a week (with shooting in between). Same load, same brass, same everything. Some times I wonder if the stars align every now and then such that aiming error and shot dispersion luckily damp each other out on a run of five.

I load with a Lee safety scale and weigh individual charges. I think it might be a suspect, as it runs quirky every so often and needs a nudge to 're-set' balance on the pivot. Other than that, I shoot reloads exclusively and neck size only. I'll vary loads for temperature day to day as well if I'm loading on the bench.
 
Check the bedding, loose scope base AND rings, anything that can move slip or otherwise not be rock solid. Confirm that the stock is not warping due to changes in temp/humidity.

Maybe try another scope?

Then check the scale to ensure it is consistent and repeatable. I loaded on a Lee for years and it worked ok. But it, like all other balance beam scales, has inherent error of +/-0.1gr (some scales have more)

I have yet to shoot a Savage factory barrel that will go under 3/8 min. Most are in the 1/2 to 2/3 min range. So there is no problem getting a 1" group at 200yds one time, then a 1 1/2" group the next. Then a 1/2" group once in a while.

Best way to prove this to yourself is to shoot 3 to 5 groups resting in between THEN look at the average. Same load for all groups. Watch the winds....

One hero group doesn't define the true accuracy of any rifle. Its the average/consistency that we are concerned with.

Good luck....

Jerry
 
Absolutely- one half inch group at 200 makes not a 'quarter minute' rifle.

I'm beginning to realize it's a bit of an obsession. Shoot one rifle that is a quarter minute rifle, and it ruins you for just about everything else. Not that you can't try to convince yourself that the 'magic load' is out there somewhere.
 
I went through some of what you are talking about today. Had some basic load development and went out to fine tune it. Was expecting good things but it just wasn't happening for me today.
 
Got out for a bit of shooting today. Put up 1 flag about 25 yds from the 200yds target. It moved very little during my shooting session BUT the mirage showed a pretty strong gusty wind AT the target.

A piece of target held on by one staple moved quite vigourously in this wind. Dust from the impact moved from fast cross to a lazy 45 deg climb. That is a pretty decent range of wind speeds.

How much did it affect my groups? When I missed the call, it pushed my bullet almost 1" OUT of the group laterally. Had I not been watching the mirage, I would not have seen the wind as the flag didn't move.

The flag was put in a bad place and was in the shadow of a small hill. Just enough that the wind from that direction was being blocked but it was there and it moved that bullet around significantly.

There were a variety of smaller gusts closer to me which I didn't worry about. Could some of this have affected my groups? You bet. Some of it was a tailwind at 45Deg to my firing point. Maybe that gust was still ebbing when I shot and that could cause a bit of vertical?

Doesn't take much to move a bullet 1/4" and that 1/4" looks huge vs a cluster that is 1/2".

It is very rare to have a truly calm day. Put up flags/tape and the more the merrier. Might surprise you at how much the air really moves on a calm day.

Jerry

PS if you really want to see how screwy air can be, get a battery powered bubble blower and set it out on the range on a warm day. Will make you wonder how we can even hit the target let alone in the same hole.

Fun, fun, fun.
 
That's one of the puzzles I've been pondering specifically, Jerry.

Granted there's the constant velocity wind that can be held off for or dialed into. But after that, each gust and thermal spinning down the range will have an effect as well. The theory I have come up with is opposite to yours by one angle, but again, opinions and voodoo.

The sustained wind velocity imparts a constant force on the bullet, yielding a constant lateral acceleration, as well as having some effect on the vertical dispersion of the group due to the spin of the bullet relative to the side the wind is from. The vertical is resultant from a similar effect seen when Tiger crushes a drive (or I hit a wormburner, alternatively) and the golf ball accelerates upwards for a short while, driven by the backspin coupling with the relative airflow. Similarly with a bullet, for a clockwise spin, a wind from the left will cause a rise while a wind from the right will cause a drop. However, those characteristics should stay relatively fixed with a constant wind velocity.

Add gusts into the mix. With a gust, a force is applied to the bullet for an arbitrary duration of time, resulting in a change in the bullet's lateral velocity for the duration of it's trip thereafter. Here's where my opinion varies- I think its the mid range gusts that wreak the most havoc on group size, as the lateral velocity imparted on the bullet by the gust has a chance to have a more dramatic effect on dispersion. I can't wrap my head around a gust in the last 15 yards as having enough effect to move the bullet more than a half caliber distance laterally, unless it was a rockin' gust. The mid range gusts, those I can see imparting a sustained variation in lateral velocity that spreads out a group.

The work I do involves lots of CAD/ FEA analysis, and it takes very little experience with engineering software to realize how convenient it is to have an FEA package. I can't help but think that it would be incredibly cool to model a flight path with random gusts involved to see what sort of dispersion will result.

From my rimfire experience, I've come to realize that the velocity variations are the sole contributor to vertical dispersion, hence my mind can bridge the gap to the lateral factors with relative ease.

Looking forward to getting out next week and playing some more with it-
 
I shoot a Savage LRPV in 6BR and have a similar issue with flyers. To date I have been shooting 3 shot groups and about every 10 shots or so, I get a flyer which is usually high. The gun will print quite a few three shot targets at 100 meters in the 0.1XX" range. I really don't think it is me that is causing the flyers. I've shot quite a bit of rimfire, and you probably know lower quality rimfire ammo has flyers. You get that "I didn't point it there" feel when the hole prints. But that said it could be me. I only shoot for fun, so this is just part of the fun. This season I'm going to have a go at solving the flyer issue, and have quite a long list of things to try. I posted a thread in another forum and got lots of very good suggestions. You may want to give it a read to see if anything looks likely for you. I'll put the link below. I recall toward the end of the thread I summarized the suggestions.

On the most probable list, I've known for some time the bag in my front rest is too hard, and I need to change that. My gut feel is that it is a bullet/seating depth issue. I find the gun is really sensitive to bullets. A Berger 68 Target will print these 0.1XX" groups, while a nearly identical design Berger 62 Target just 6 grains lighter will very consistently print 1.5XX" to 2.1XX" groups.

My current practice in loading is to set up one load to a 0.010" jam (jams seem to work best), and then assume all the rest load to the same jam. This assumes the distance between the ogive and seating die (Forster Ultra Micrometer) cone contact is the same from bullet to bullet. It probably isn't. So one test I plan to do is load all bullets 0.010 or so long, measure each from base to ogive (Hornady bullet comparator), and then use the micrometer seating die to individually seat each bullet to give the same base to ogive dimension that gives a consistent 0.010" jam. I guess testing will tell if that is of any benefit. I also plan to sort bullets by bearing length, so that may reduce the issue some.

So, hope that helps some. I would try different bullets and seating depth combinations, if you have not already. There is an old rule that says 90% of accuracy is determined by the bullet, with the case, primer, and powder only responsible for 10%.

Probable Cause of Flyers
 
Also, have you read the article on tuning the action screw torque on Savages. My gun is now bedded and pretty solid. I plan to try it, but suspect it is not going to have much effect. If the stock is not bedded it may be very effective.

Tuning Savage Action Screws
 
rimfiremac said:
. Here's where my opinion varies- I think its the mid range gusts that wreak the most havoc on group size, -
Click to expand...

The wind that moves the bullet the most has the most affect on your group size :D

Where I shoot, winds can come from all directions in various speeds and intensities. Some times the flags go in opposite direction. And every now and then, because of how the wind flows, you have dead spots that are calm.

So I have given up on rules of thumb and just focus on what area or flag is giving me the most useable information AND what I feel is affecting my end result the most.

Yes, sometimes the info conflicts but that is half the fun.

You have to shoot here to understand that a 25yd area can have a gale flowing through it and most of everything else is quite calm by comparison.

Jerry
 
I've seen when shooting 900meters where flags were blowing 10 - 15 mph from the left at 300 meters, then completely the opposite direction at 700 meters and all the other flags somewhere in between at the same time. I remember shooting dead centre and scoring a perfect V-Bull.

At times is just experience you will learn. There's been many times when you called it right, but the bullet got caught in quick gust just as you fired. No bullseye.
 
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