How important is velocity?

[bgary]

I know lots of folks run their 69s at 2750fps and up.

I've got a load that is very accurate, but runs about 2610fps. I've run test loads through this gun at up to 2750 and not gotten decent but not great results - not bad, but not as good as the one-ragged-hole I get from this one.

Other than the obvious ballistic effects, what am I giving up by running a good load at a lower velocity? Is a hotter load with [slightly] less accuracy "better" than a slower but more-accurate load, all else being equal?

[AlamoShooter]

you did not include the -distance- that your load is very accurate at. you want the bullet to hold its groups past 400 yards.

I don't even care what my 69 & 77 s do at less than 200 yards

The Old school lesson is that the heavy bullets do not stabilize until the reach 180+ yards

my friend can get the same size group at 200 as he can at 300

Edited August 20, 2011 by AlamoShooter

[bgary]

you did not include the -distance- that your load is very accurate at.

Ack, you're right. My home range only goes to 100 yards, so that's the distance I do most of my testing. I have to drive several hours to get to a place where I can shoot out to 300, and so I work up loads at my home range, and then take the "good candidates" for a drive.

That raises an interesting question though: What are the chances that a load which will group well at 100 will *not* group well at 200 or 300? Or, thinking the other way, what are the chances that one of the loads that *doesn't* group well at 100 will somehow group at 200 or more?

I guess what I'm really asking is, how can I best use the results I'm getting at 100 yards to figure out which loads are worth testing further out?

[AlamoShooter]

you did not include the -distance- that your load is very accurate at.

Ack, you're right. My home range only goes to 100 yards, I guess what I'm really asking is, how can I best use the results I'm getting at 100 yards to figure out which loads are worth testing further out?

How to make 100 act like 200 = That not easy to answer , beyond any trick I know.

But you are shooting the bullet just a bit slower than most of us and its working for you. Don't try to fix something that is not broken.

any extra hold over is not important. just punch in the data on a good ballistic program so you know you holds. Vortex Optics .some has a program that is free it will let you enter your data and give you very close results even if your not using a Vortex scope.

And your question about a load shooting good at 200 that will not shoot as good at 100 , I wont even put my longer range loads on paper at 100

There is plenty that I don't know & and some that I think I know , and some that I do know. When your preparing for an event = go with what you know. Work in time and place for adjusting loads months before any events

Edited August 22, 2011 by AlamoShooter

[warpspeed]

Depending on the use, a slower bullet is a good thing ; Less recoil & less barrel wear.

For me, if the load will function 100%, accuracy is first and foremost. I don't care what velocity is as long as the load is safe.

Do a Google search on " Ladder Test ".

[Alaskapopo]

you did not include the -distance- that your load is very accurate at. you want the bullet to hold its groups past 400 yards.

I don't even care what my 69 & 77 s do at less than 200 yards

The Old school lesson is that the heavy bullets do not stabilize until the reach 180+ yards

my friend can get the same size group at 200 as he can at 300

If the bullet were not stable when it left the muzzle it would not be stable magically at 180 yards either. What happends is some bullets retain their accuracy at longer ranges better than others. At least thats my understanding.

Pat

[highxj]

If the bullet were not stable when it left the muzzle it would not be stable magically at 180 yards either. What happends is some bullets retain their accuracy at longer ranges better than others. At least thats my understanding.

Pat

That's not true. In long range circles, it's known as the bullet 'going to sleep'. In other words, bullets will exhibit a degree of instability, or yaw when exiting the muzzle and are more prone to deviation from atmospheric influences. When they 'go to sleep' at some distance down range, the yaw has diminished and the bullet will be more ballistically efficient.

This is not to say that they will somehow magically change course from their original deviation and veer back towards the center of the target like some people seem to claim.

[bgary]

If the bullet were not stable when it left the muzzle it would not be stable magically at 180 yards either. What happends is some bullets retain their accuracy at longer ranges better than others. At least thats my understanding.

That's not true. In long range circles, it's known as the bullet 'going to sleep'. In other words, bullets will exhibit a degree of instability, or yaw when exiting the muzzle and are more prone to deviation from atmospheric influences. When they 'go to sleep' at some distance down range, the yaw has diminished and the bullet will be more ballistically efficient.

This is not to say that they will somehow magically change course from their original deviation and veer back towards the center of the target like some people seem to claim.

Okay, so... help me understand this.... I "get" that if a load produces a 1/2-MOA group at 100 yards, there's a good chance that it'll produce sub-MOA accuracy at 200, 300 and beyond.... there's also a chance that it'll "open up" at some distance, but at least it is worth testing further. So far, so good?

My question is... if a load *doesn't* produce a good group at 100, let's say it "patterns" over 1-1/2 inches... is there anything about this stabilization issue that would have a chance at making this load magically produce a sub-MOA group somewhere downrange? I've, so far, assumed that if a load doesn't produce a good group at 100, it won't produce a good group at longer distances, so I've been throwing those loads out. Is that a mistake?

Edited to add: I'm working up 69gr loads for an 18", 1:8 barrel if that makes any differnce in the "stabilization" equation...

Edited October 30, 2011 by jakers

[MarkCO]

This is a good thread to read... http://www.brianenos.com/forums/index.php?showtopic=124136&hl=nutation&st=0

[bgary]

This is a good thread to read... http://www.brianenos.com/forums/index.php?showtopic=124136&hl=nutation&st=0

Have done. Especially this part:

Yaw, Precession and Nutation also affect accuracy and the "cone" and "cylinder" of the accuracy. Bullet weight definately has an affect on these variables. For a 55 grain .223, the initial cone ends at about 60 yards and the cylinder ends at about 320 yards @ STP. 69 grain .223 slugs almost double the cylinder length. The heavier the bullet (regardless of BC) the longer the cylinder.

That *was* my understanding until I read things like this:

I wont even put my longer range loads on paper at 100

Made me wonder if my 69gr loads were "in the cylinder" at 100 (and would stay good at 200 and beyond), or if they were "still in the cone" at 100, and might open up considerably before moving into the cylinder.

I guess, overall, that latter bit has me questioning the validity of using 100-yard groups as a way of "weeding out" good loads for further testing at distance. I don't want to spend the time to find loads that group well at 100 if those results won't really mean anything when I take the "good ones" to test at longer ranges. If the 100 yard groups aren't meaningful... is there a way of knowing what distance a given load/caliber/bullet/BC will go into "the cylinder"?

Edited October 30, 2011 by jakers

[highxj]

Mark and jakers, I read that thread and it almost made my head explode, lol.

I do most of my testing at 100 yards for a couple of reasons. One, the conditions in SE Wyoming are very rarely conducive to meaningful load testing at long range. It's almost *always* windy, and even with wind flags it's just guesswork.

Second, if a load shoots well at a hundred, chances are it will do well at longer distances. But if it does not do well at 100 yards, things are only going to get worse at longer range. Once a bullet has left the muzzle and begun deviating from it's intended path due to yaw/tipoff or whatever, nothing in the world will make it *stop* on that deviated path and suddenly start traveling parallel to the bore again. The bullet doesn't know where it's supposed to go....so how could a gun that shoots a 1 inch group at a 100 yards shoot a 1 inch group at 2 or 300? The bullet "going to sleep" and flying straighter does not allow for that, as it has already started on its deviated path early on in it's flight.

I've read many times people saying that their rifle/load will shoot groups just as tight at 200 yards as it does at 100, and I never could quite get my head around that....it's all angles. I've never personally seen it and never experienced it. The only explanation I can come up with is parallax/optics/shooting conditions or something of that nature.

As you can probably tell, I'm not a ballistician or an engineer, but this is what makes sense to me.

[MarkCO]

highxj, I can assure you it works, however, it is not worth getting wrapped up around the axle about. If your load works and gives you confidence, then it works. I have had a few loads that were "more accurate" on paper, but I went with another load due to confidence. Then again, the 2nd best grouping rifle I have ever shoot at 100 yards was with an Ultralight hunting rifle in .338-06 (.28"). When I touch that rifle, I "feel" like I can hit anything inside 500 yards with ease...that is better than chasing load development for me.

I have had .223 loads shoot 1.5" at 100 yards that also shoot 2" at 300 yards and 3" at 500 yards. I would normally not be happy with 1.5 MOA, but it is really a .7 MOA load at distance...things that make you go hhmmm.

[ksmirk]

I have 2 loads that print awesome at 100 yards all the way out to 1K with the 308 and 500 with the 223, they are not fast but they shoot well! I can figure out my drops so I don't mind a load that is a little slower than everyone else cause I know when I touch the trigger I know (ok 80% of the time) where that bullet is going to impact. It boils down to do ya want to hit something with a slow bullet or miss at ubber velocity? I'd rather talk about hits over telling someone I have a load shooting xxxx fps

My 284 Win with the 162 A-Max has a terrible group at 100 yards (1" - 1 1/4") but it will print 2" at 200 yards and keep MOA all the way out to 500 (furthest I've got to shoot it) so as for bullets going to sleep, I used to call BS but the more I mess with the VLD bullets I tend to agree with what is being said. Later,

Kirk

[P.E. Kelley]

Benchrest Forum

Things repeated often enough do not become facts...only factoids.

I too have heard about the mystical "sleeping bullet" I never paid much attention to it as I am not a bench-rester,

but the link referenced above are!

Patrick

Hope it's OK to cut and paste one of the more telling points from the linked forum page...

Quote Originally Posted by Old Gunner View Post

In some cases initial yaw isn't overcome till some distance down range, then groups at farther out will be tighter in terms of MOA than groupings at closer ranges.

I must point out that this is unproven conjecture. No one including the folks at Aberdeen have ever documented groups getting smaller with yardage. Looks good on paper, ain't true in real life.

Myself and many others have shot through yaw cards, three of the folks here on this board have tried it over acoustic targets, I've built and wired my range specifically to test this over the long-term but my buddy moved away with his Oehler 43 and I've been too cheap to buy another.......but in the end NOBODY ever to the best of my knowledge has documented groups converging with distance. (and yes I do understand the assertion)

The pic in McCoy of the bullet "converging on it's flight path" has caused a lot of unfounded rumor! It does "stand to reason" that if a person were to shoot enough groups through two targets sooner or later you'd luck into one which converges..... but so far no one ever has.

Unless you or someone would care to share a cite and enlighten me??? I'm all ears. Anecdotal reports of the thousands of folks who can shoot better groups further out need not apply. I'm talking SAME GROUP.

re the convergence of flight paths compensating for different launch angles, I agree that this is true, and documented/explained quite thoroughly, good call. This BTW can be documented on a 300yd range using only yaw cards, pretty easy to test if you've got accurate enough equipment.

[dauntedfuture]

For the most part, most of the sleeping bullet myth/ fact stuff relates to shooting VLD bullets. These long heavy bullets are more prone to "not shooting well close" but still shooting well at ranges. David Tubb posted some results on a long ago forgotten forum or atricle and he noted that his groups opened up little from 100-400 or 500 and then started opening up more at ranges. I have not experienced this in any of my highpower or long range guns. They shoot 80-82g .224 & 142 6.5mm bullets well at 100-600+

[jdknotts1]

I had a similar experience with a 6mm-284. The rifle was my father's before he passed. He was upset with his rifle because he couldn't get it to shoot anything under 2" @100yds. I messed with it a bit and shot 1.5"@100 with 85gr hpbt. I did ALOT OF WORK getting it to shoot that well. Couldn't understand it. One day I had the rifle with me at a longer range and shot it at 300yds..... Whoa was I surprised. Shot 2.5"@300 consistently. Never was able to figure it out. Strange, very strange.