50 yard groups

[lppd4]

I have convenient access to our PD range the problem is that it is only 50yds long. So my question is if I can shoot a 1/4" group at 50yds should I expect the same rifle to shoot a 1/2" group at 100yds? Does it work that way? I have access to a range out to 300yds but it is not something I can run over and test a load or the scope on a rifle in an hour or less.

[Absocold]

Yes.

Well, mostly.

The farther the bullet has to fly, the more time there is for external factors to affect it's flight. Wind, heat, spindown, sonic transition, coriolis forces, etc.

A guns accuracy can be gauged at 15 yards. But testing is often done at 100 yards to give the bullet time to show any instability that would affect longer range accuracy and to open up the group enough to be easily measured. If 50 yards is all you have, it's much better than nothing.

[Religious Shooter]

At those ranges (50/100) I'd say generally... roughly... yes.

[ShooterSteve]

The answer is simply yes, but don't get butt hurt when you try the same comparison at 500 yds.

[JonKC]

The answer is simply yes, but don't get butt hurt when you try the same comparison at 500 yds.

Spot on.

Shooting .5 moa at distance is VERY different than 100yds and in.

Sent from my iPhone using Tapatalk

[Wild Gene]

I have a Mossberg that I can shoot great sub MOA groups at 25 and 50 yards, and then at 100 it opens up to about 2", then seems to settle down again out past 300 yards. Heck, I've used it on 10x12" steel out to 700 yards.

I have a GA Precision rifle that just shoots sub MOA pretty much regardless of the distance. Yesterday, I was comparing the different POI of 168 vs 175 SMK's. I had 4 rounds of 175's and one 168 and shot a five round group. The 175's printed a .23" four shot group and the 168 was about .5" below the 175's. Before that, I put five consecutive 175's on a 6" steel gong at 600 yards.

Must have something to do with harmonics and the phase of the moon.

wg

[Absocold]

I have a Mossberg that I can shoot great sub MOA groups at 25 and 50 yards, and then at 100 it opens up to about 2", then seems to settle down again out past 300 yards. Heck, I've used it on 10x12" steel out to 700 yards.

I have a GA Precision rifle that just shoots sub MOA pretty much regardless of the distance. Yesterday, I was comparing the different POI of 168 vs 175 SMK's. I had 4 rounds of 175's and one 168 and shot a five round group. The 175's printed a .23" four shot group and the 168 was about .5" below the 175's. Before that, I put five consecutive 175's on a 6" steel gong at 600 yards.

Must have something to do with harmonics and the phase of the moon.

wg

Bullet yaw is what's causing your groups to get bigger and then smaller again.

Air friction combined with centrifugal force causes yaw. Yaw causes the bullet to spiral. This bullet spiral starts immediately upon leaving the bore, may reach a diameter as large as several inches and then eventually the gyroscopic action of the spinning bullet causes the bullet stop yawing (the bullet "goes to sleep"). Most .223 bullets go to sleep somewhere between 75 and 150 yards depending on bullet weight and velocity. All bullets yaw to some extent or another but the fewer imperfections on the bullet the less it will yaw.

An uneven barrel crown will magnify yaw, a perfect crown will minimize it. Crown quality is probably the difference between your two rifles.

[Wild Gene]

I have a Mossberg that I can shoot great sub MOA groups at 25 and 50 yards, and then at 100 it opens up to about 2", then seems to settle down again out past 300 yards. Heck, I've used it on 10x12" steel out to 700 yards.

I have a GA Precision rifle that just shoots sub MOA pretty much regardless of the distance. Yesterday, I was comparing the different POI of 168 vs 175 SMK's. I had 4 rounds of 175's and one 168 and shot a five round group. The 175's printed a .23" four shot group and the 168 was about .5" below the 175's. Before that, I put five consecutive 175's on a 6" steel gong at 600 yards.

Must have something to do with harmonics and the phase of the moon.

wg

Bullet yaw is what's causing your groups to get bigger and then smaller again.

Air friction combined with centrifugal force causes yaw. Yaw causes the bullet to spiral. This bullet spiral starts immediately upon leaving the bore, may reach a diameter as large as several inches and then eventually the gyroscopic action of the spinning bullet causes the bullet stop yawing (the bullet "goes to sleep"). Most .223 bullets go to sleep somewhere between 75 and 150 yards depending on bullet weight and velocity. All bullets yaw to some extent or another but the fewer imperfections on the bullet the less it will yaw.

An uneven barrel crown will magnify yaw, a perfect crown will minimize it. Crown quality is probably the difference between your two rifles.

Any idea where this might generally occur with a .308? What about bullet weight? I suspected the same thing, but had never seen anyone else use the term "yaw". I have flight hours logged and would have never thought of that term! It is perfect. Anyway, yes, Imagine my surprise when I fired an almost one hole 25yard 5 shot group, then moved out to 100 and couldn't get 2 inch, then out to 300-700 and can hit 10x12" steel. Oh well, that is the difference between a $500 and $3500 rifle. I would hope the more expensive one would shoot better.

wg

[1time]

I have a Mossberg that I can shoot great sub MOA groups at 25 and 50 yards, and then at 100 it opens up to about 2", then seems to settle down again out past 300 yards. Heck, I've used it on 10x12" steel out to 700 yards.

I have a GA Precision rifle that just shoots sub MOA pretty much regardless of the distance. Yesterday, I was comparing the different POI of 168 vs 175 SMK's. I had 4 rounds of 175's and one 168 and shot a five round group. The 175's printed a .23" four shot group and the 168 was about .5" below the 175's. Before that, I put five consecutive 175's on a 6" steel gong at 600 yards.

Must have something to do with harmonics and the phase of the moon.

wg

Bullet yaw is what's causing your groups to get bigger and then smaller again.

Air friction combined with centrifugal force causes yaw. Yaw causes the bullet to spiral. This bullet spiral starts immediately upon leaving the bore, may reach a diameter as large as several inches and then eventually the gyroscopic action of the spinning bullet causes the bullet stop yawing (the bullet "goes to sleep"). Most .223 bullets go to sleep somewhere between 75 and 150 yards depending on bullet weight and velocity. All bullets yaw to some extent or another but the fewer imperfections on the bullet the less it will yaw.

An uneven barrel crown will magnify yaw, a perfect crown will minimize it. Crown quality is probably the difference between your two rifles.

This makes as much sense as handgun "stopping power". A bullet may yaw and may straighten out, much like a football. To gain accuracy at distance you would have to believe that the bullet straightens out at the exact same point in flight every time and is effected by external conditions in yaw the same every shot. Once a bullet starts to yaw, it may settle down but it will never better the accuracy it has during yaw.

Rifles may appear to shoot better at distance for any number of reasons. The shooting position may be more repeatable, the cross hair may fit the target better at distance, the shooter may stop trying to see impacts. But a bullet is never more accurate at distance than it is close up.

[Absocold]

Go tell a professional long range competition bench shooter there's no such thing as yaw causing good accuracy at point blank range, then bad accuracy at short range and good accuracy again at medium to long range and that the long-known effect of bullets going to sleep is a myth. Please describe the look he gives you, in as much detail as possible, as well as how it made you feel. I'm just kidding of course, most of those guys look at everyone like they're an idiot, no matter what you have to say. Cheerful bunch for sure. I suppose if I threw away barrels like most people change their socks I'd be grumpy too.

The effect of yaw looks like two cones placed end to end with the big ends touching and a line leading out both ends. The bullet travels in a straight line until exiting the bore, then starts to yaw and spiral, the spiral gets bigger (where the big ends of the cones touch), then gyroscopic effects assert themselves and the spiral gets smaller and then stops. This is where the bullet goes to sleep and is stable for the rest of its flight (at least until sonic transition, but that's a story for another day). Because the yaw is caused by instability, it's not predictable during the yawing. Which means the gun doesn't group well for the short distance where the spiral is the worst.

A good barrel and good bullets minimizes the effect and is rarely a big enough problem to be noticeable by anyone who considers 1 MOA as good shooting. But when it's bad, it's perplexing as hell to the uninitiated. Good groups close up, bad groups a bit farther out, good groups even farther out. It's just weird.

The US Navy Iowa Class battleships 16" guns were calibrated at a test range after their upgrade in the 1980's. With microwave tracking the shells were shown to have great galloping yaw over the first mile that then settled down and gave better than 3/4 MOA accuracy at 19 miles.

[Chills1994]

[1time]

If a bullet goes off course due to yaw, precession, nutation or hitting a branch, nothing is going to bring it back onto target, even if it becomes more stable. It is not a guided system. Once off course, it is always at least that much off course. I can see the group appearing larger if the bullet hits paper in yaw because the hole left will be bigger because the bullet did not fly straight through and left a bigger hole.

If a rifle shoots better at distance than up close, parallax, reticle matching the target or poor shooting form is to blame.

[Chills1994]

[Absocold]

Computer plots are no substitute for measured and recorded effects. Whether you call it yaw, precession, nutation, Magus Effect, precession, epicyclic motion, damping theory or active/sleeping, the phenomenon of bullets grouping better at longer range than at short range is well known among precision shooters and artillery techs. But, like any debate, there are three camps. Those who say it's impossible, those who say it is possible and those who have seen it themselves.

http://www.bergerbullets.com/information/

It has been reported that the VLD bullets don’t group as well at 100 yards but get better as the bullet “goes to sleep” at further ranges.

Some calibers, because of bullet shape/length, are more susceptible to the phenomenon than others. Google "bullet goes to sleep 7mm" for page after page of argument between those that say it's impossible and those that say it's absolutely happening to them.

Since I've personally measured the effect on several rifles no matter who was shooting them, seen lots of corkscrewing vapor trails at the 1,000 yard line and seen it in naval gunfire tracking (can't blame that on the nut behind the gun!), I'm not really interested in arguing about it. But you guys can knock yourselves out until the mods step in. I'm going shooting.

[Tom S.]

50 yard groups are great for comparing .22 rimfire but that's all. High caliber bullets take time to settle into their axis - as noted by Absocold when he mentioned yaw. Some bullets, depending on weight, velocity, rate of twist and bullet construction may never get out of the yaw stage. Bullets also re-enter this state as velocity drops off. Again, this is impacted on by several variables, While working the pits at 1,000 yard matches in the 60's, I remember seeing several keyholes in targets, caused by bullets either yawing or even tumbling. Well over 100 years ago, a person by the name of Dr. Mann did some interesting studies on bullets and what effects their flight. His experiments were fascinating and included spacing targets along a 100 yard path that was enclosed to prevent windage, and taking a barrel and chopping inches off to see the effect. He even tried seating bullets in the lands and using shells to fire them He wrote about it all in a book appropriately titled The Bullet's Path. Long since out of print and somewhat difficult to read, it's still extremely interesting to those studying ballistics, and was later reprinted, complete with notes written in the margins by Harry Pope, one of the most renowned rifle and barrel makers of the time. You can still find used copies or even buy it in Kindle form from Amazon. The sad news is Dr. Mann continued his work long after the book was published and was working on a follow up when he died, His widow, angry with all the time he spent on the project instead of with her and his family, burned the manuscript and all his notes. What a tragedy.

[jkrispies]

Interesting discussion!

I'd like to point out that you need to be extra careful about sighting the gun in at 50 yards: most scopes are designed to shoot at 100'+. Shooting at less than that distance can create some "false inaccuracy" that is in fact an optics parallax issue that's separate from the actual accuracy of the gun.

[Wild Gene]

Interesting discussion!

I'd like to point out that you need to be extra careful about sighting the gun in at 50 yards: most scopes are designed to shoot at 100'+. Shooting at less than that distance can create some "false inaccuracy" that is in fact an optics parallax issue that's separate from the actual accuracy of the gun.

Most of the time, when you are shooting this far, the scope will have a parallax adjustment for that very reason. You can really tell when you don't adjust it correctly too!

Today I was playing with a new load shooting groups with my 308. I had four rounds that went .27" on center, then for some reason played with the adjustment and put one more over to the side, opening the group up to about .49"OC. It could have been adjustment, or I could have just pulled it. Anyway, the parallax adjustment on this particular scope goes from about 30 yards out to infinity and really makes a difference if you don't adjust it, at least for me. There are a lot of guys that shoot way better than I do, and may not need to adjust their scope as often, but I know I sure have to.

wg

[RWF]

my head hurts!

[Stlhead]

Be a good little bullet and go to sleep now.

[jkrispies]

Interesting discussion!

I'd like to point out that you need to be extra careful about sighting the gun in at 50 yards: most scopes are designed to shoot at 100'+. Shooting at less than that distance can create some "false inaccuracy" that is in fact an optics parallax issue that's separate from the actual accuracy of the gun.

Most of the time, when you are shooting this far, the scope will have a parallax adjustment for that very reason. You can really tell when you don't adjust it correctly too!

Today I was playing with a new load shooting groups with my 308. I had four rounds that went .27" on center, then for some reason played with the adjustment and put one more over to the side, opening the group up to about .49"OC. It could have been adjustment, or I could have just pulled it. Anyway, the parallax adjustment on this particular scope goes from about 30 yards out to infinity and really makes a difference...

wg

Absolutely-- just not sure if the OP has a scope with adjustable ranging for parallax.

[mlmiller1]

I dont know about yaw or real ballistics but I was trying out some loads one day. At 100, I had several very decent groups. I decided the middle load with decent groups(quarter cover 5rd group) was my choice. Moved to 200 & was basically just shooting up my test stuff & shot a 5 round group you could cover with a quarter. Was not the middle charge but a little more powder. All other charge weight groups opened up substantially. Bullet sleep? Yaw? Luck? Who knows but that is my accuracy load for that particular AR 15. I think there is something to this bullet settling stuff.

[dauntedfuture]

50yds will provide you little to know information for load development. you MIGHT be able to get some informaiton about bullet A vs B dont dont count on much more. Much of the time your inside a scopes paralax at 50. You can see if your rifle will stabilise a bullet or if it comes apart from spinning too fast. You can also measure velocity, ES and SD. In general 2x range = 2x the group plus a little more. As range increases group sizes open up a little. This is why its so "easy" to shoot .2 groups at 100 yds and very hard to shoot a 2" at 1K

[Wild Gene]

This is another reply, but worth consideration. If you are developing loads at 50 yards, you really need to take SD into consideration of potential performance at farther distances. I'm not sure if everything I've said is properly stated, but I do know that a 50fps variation in muzzle velocity makes a huge difference at 1,000 yards:

"If load #1 fired MOA or less groups, it would be a better bet for Long Range shooting, over load 6, depending on the bullet's BC. I would kick out loads with an SD or 20 or more of those options (without even considering extreme spread).

Run the Dope charts for a bullet traveling 2600 fps and the same bullet traveling 2650fps and look at the 1,000 yard column. I took some generic figures and there was an almost 20" difference in point of impact. You might have a load that shoots sub MOA at 100, and out past 600 that has such an extreme spread in velocity or high SD that once you get out a ways they are less than satisfactory.

SD is using all the rounds in a string checked while ES is only using 2 rounds so your odds are better using SD for calculation of expected average performance verses ES which gives you more of a possible performance (possible, but not probable).

Just for fun, throw in the BC's when considering what you are going to use, because as you know, doping the wind is the real fight in this game.

Anyway, if 1 MOA is 10" at 1,000 yards and it is measured from the center of your aiming point you have a 5"+/- in any direction. If you have a 50fps difference in velocity at 1,000 yards that works out to 20" (10"+/- up or down) So you are doubling (statistician's feel free to correct this) your decrease in accuracy."

wg