1/4-1/2MOA but then very poor accuracy at 300

[KevinThomas]

Personal call there, Erik, but I'd sure be hesitant to make the 12 hour drive to either Raton or Perry with ammo I'd only tested at 100 yards, chronographed or not if I had a 1000 yard range available to me to verify things on first. Seen far too many loads that shot well at shorter ranges and fell apart as the distance got stretched a bit.

 

[Erik Cortina]

Personal call there, Erik, but I'd sure be hesitant to make the 12 hour drive to either Raton or Perry with ammo I'd only tested at 100 yards, chronographed or not if I had a 1000 yard range available to me to verify things on first. Seen far too many loads that shot well at shorter ranges and fell apart as the distance got stretched a bit.

I know what you mean, but like I said, I have shot at 100 and then at 1000 to confirm so many times, that now I know what to look for.

 

[6BRinNZ]

Any chance of a picture of the groups? For the 300 group is it one or two that are high causing the overall vertical...i.e. if you took out the flyers would it be ok?

Also where does the bearing surface sit in relation to the neck shoulder junction?

I have seen a .284 shoot .3 at for 7 shots at 200 (plus load development) and go to 3moa at 300 with the bullet into the neck/shoulder. Inconsistency of the donut in the neck/shoulder was the cause...getting the bullet out of the neck/shoulder (re-throating) was the true fix.

 

[BradY]

At longer ranges surely your looking at a better BC bullet than the 120vmax? Why not look at something like the 168VLD?

 

[jmd]

Lots of feedback so forgive me if I miss answering someone. The seating depth in relation to the shoulder isn't an issue. I do load development at 1 & 200 since that is what I have close by. After that, I'll take the best candidate out to check it at 300,400, & 500 since the longer range is a solid 1.5hrs away. I'm no 1000yard shooter & 6-7 is about my max effective range on a good day with the right rifle. This is a first for me so it was troubling. The group was extremely vertical. with one on top of the paper, one in the middle, and one barely touching the bottom. After that they weren't even hitting. I've got a couple of heavier bullet options that I plan to test sometime soon. I also did ask Hornady what their thoughts were. They basically said the jack was falling apart in flight. I'll be sure to let you all know how the heavier bullets do at longer ranges. Oh and those VLD's well I missed the bus when I didn't hoard them in 7mm in the past. They haven't been readily available lately

 

[sailhertoo]

Personal call there, Erik, but I'd sure be hesitant to make the 12 hour drive to either Raton or Perry with ammo I'd only tested at 100 yards, chronographed or not if I had a 1000 yard range available to me to verify things on first. Seen far too many loads that shot well at shorter ranges and fell apart as the distance got stretched a bit.

I know what you mean, but like I said, I have shot at 100 and then at 1000 to confirm so many times, that now I know what to look for.

Would you care to share your 100 yard load development procedure? What do you look for?

I tired of having to confirm at a thousand too.

 

[Erik Cortina]

I shoot consecutive groups 0.5 gr. apart at 100 yards, but once you start shooting, never touch your scope until you are done testing.

I shoot until I find two or three groups that hit the same place vertically on the target in relation to the bulls eye. Also watch you chronograph speed. The speed will not change much for those two or three groups even though the powder charge is different. Then, adjust seating depth to bring them in even closer and then pick the load in the middle of the three. That load will shoot out to 1000 yards.

 

[rcw3]

I am happy to see Erik weighing in on this. For years I have done load work ups for mid and long ranges at 100 yards and clearly the secret of doing it is knowing what to look for. I hear people pooh-pooh working up loads at 100 yards and it just says to me they don't have the necessary critical eye to know what they are seeing in their 100 yard groups.

My general experience is if it doesn't shoot well at 100 yards, its typically not going to shoot well at longer ranges. Correspondingly, if it shoots well at a 100 yards it typically follows out to longer ranges.

I have heard way way too many times that you can't gauge things by 100 yard groups and that at 100 yards a bullet "may not be fully stabilized" - - WHOA - - NOW HOLD ON A SECOND - - - if the bullet is not stable by 100 yards that means it's just bludgeoned through it's first 100 yards of travel chopping and churning up the air it's traveling through and eating up all it's possible B.C. advantage - - what the heck use is that for a long range load and why after it has just done that is it well qualified to miraculously become also a very accurate load???

In any case - that' my "rant" on that topic for today.

Robert

 

[Nomad47]

I have heard - or read somewhere - that the bullet's path can sometimes resemble a corkscrew that "settles" after 200 to 300 yards. I cannot verify that in any way.

Anyway, if Erik and Steve (SleepyGator) say you can develop a 1000 yard load at 100 yards, that is good enough for me.

 

[sailhertoo]

Thank you Erik for the explanation. Good info.


I think there is something to be said about the bullet corkscrewing out to 300 yards before it stabilizes. Look at a spin top on a table. It corkscrews before it stabilizes. But, then again, it don't start out to stable to begin with since you turning it with your fingers. I just don't know.

 

[6BRinNZ]

Thank you Erik for the explanation. Good info.


I think there is something to be said about the bullet corkscrewing out to 300 yards before it stabilizes. Look at a spin top on a table. It corkscrews before it stabilizes. But, then again, it don't start out to stable to begin with since you turning it with your fingers. I just don't know.

From memory I think Brian Litz states the cork screw is within the diameter of the bullet, i.e. not enough of an issue for it to translate on paper as the big issue that everyone talks about. He does go on to suggest other more likely possibilities where a load shoots better further out. Interestingly I don't think he goes as far as to say it can't happen - just there are more likely explanations.

I'm not a ballistician so I can only regurgitate what is written - my best advice is to get hold of Brians books - well written and the language is converted from "ballisticians" to "laymans" very well.

 

[jmd]

I'll have to check that out at some point. I don't understand the physics of it. I guess I don't understand how a bullet can suddenly stabilize. Is it that the bullet has reached its magical velocity & RPM combo that it likes? Air resistance and gravity is all you have. I just don't see either one taking a bullet that isn't flying true, and straightening it out at longer distances.

 

[CatShooter]

Thank you Erik for the explanation. Good info.


I think there is something to be said about the bullet corkscrewing out to 300 yards before it stabilizes. Look at a spin top on a table. It corkscrews before it stabilizes. But, then again, it don't start out to stable to begin with since you turning it with your fingers. I just don't know.

The nature of bullets, and the laws of physics, prevent them from "stabilizing" if they are corkscrewing, yawing or precessing. Once they go off, they can never come back on axis or the original path...

Not "my opinion", just plain physics.

Anyone that argues otherwise, has no understanding of the dynamics of bullet movements.

 

[BoydAllen]

It has been a while, but I believe that most of the descriptions of how bullets fly that I have read indicated that bullets start out with some yaw, that results in a sort of spiral flight path as the point of the bullet moves in a small circle, and that over time, and consequent distance, that yaw, and the spiraling may diminish to what has been termed its "yaw of repose" with the axis of symmetry at a fraction of an angle to the line of flight, and the point no longer making small circles. Here is an example of one explanation that I have previously seen.
http://www.nennstiel-ruprecht.de/bullfly/stab.htm#header_stability
In other sources, I have read of tests with bullets being shot through multiple targets that verify this motion. Perhaps I am not understanding what you are saying, and because of that have given examples that do not apply. In the past, when I have read, and participated in online discussions, various posters would write something like "it's physics" with no reference provided. I found, and still do find this less than convincing, without some sort of reference. Perhaps you can correct my reading of your post, and furnish a reference, so that I can better understand your point.
Boyd

 

[Trapper243]

From memory I think Brian Litz states the cork screw is within the diameter of the bullet, i.e. not enough of an issue for it to translate on paper as the big issue that everyone talks about. He does go on to suggest other more likely possibilities where a load shoots better further out. Interestingly I don't think he goes as far as to say it can't happen - just there are more likely explanations.

[/quote]

I can agree with that. Working up a new load the other day at 100, 5 shots were holding close to .5 MOA . I backed up to 400 and ran two 5 shot groups that were in the .3s. Almost no vertical at all. I repeated this the next day with almost similar results. I suppose it could be some strange phenomena, but my guess is that I don't concentrate, or execute a shot as well at close range. To verify, I put a friend behind the same rifle at 100 at it went .3s.

 

[Erik Cortina]

From memory I think Brian Litz states the cork screw is within the diameter of the bullet, i.e. not enough of an issue for it to translate on paper as the big issue that everyone talks about. He does go on to suggest other more likely possibilities where a load shoots better further out. Interestingly I don't think he goes as far as to say it can't happen - just there are more likely explanations.

I can agree with that. Working up a new load the other day at 100, 5 shots were holding close to .5 MOA . I backed up to 400 and ran two 5 shot groups that were in the .3s. Almost no vertical at all. I repeated this the next day with almost similar results. I suppose it could be some strange phenomena, but my guess is that I don't concentrate, or execute a shot as well at close range. To verify, I put a friend behind the same rifle at 100 at it went .3s.
[/quote]

Trapper, by "in the .3's", you mean inches or MOA?

 

[savageshooter86]

ok been following this thread for a few. Few shooting guys have this question someone may can answer. Same thing but reverse. If you develop a load at 600 and it shoots 1/2 MOA vertical but take it to 100 yard line and it won't shoot anything better than 1 MOA? Seems like it would shoot smaller at 100 than at 600 ???

 

[Erik Cortina]

ok been following this thread for a few. Few shooting guys have this question someone may can answer. Same thing but reverse. If you develop a load at 600 and it shoots 1/2 MOA vertical but take it to 100 yard line and it won't shoot anything better than 1 MOA? Seems like it would shoot smaller at 100 than at 600 ???

This is a little different, and the reason I no longer do ladder tests.
The reason for that is that during barrel rise, the slower bullets leave the barrel when it is higher, and faster bullets leave the barrel while it is lower, and at some point the slower bullets will drop and meet the faster bullets trajectory and this create a small group. The problem is that they are only accurate at that distance +-

Hope that makes sense.

 

[savageshooter86]

Making some sense here. Well I didn't do a ladder test at 600. I shot 10 shot group. Then took same load to 100 yard and it won't shoot. So in this case would I not worry what it is doing at 100-200 yards since it shoots good at 600 and I won't shoot it any less than that?

 

[Erik Cortina]

Making some sense here. Well I didn't do a ladder test at 600. I shot 10 shot group. Then took same load to 100 yard and it won't shoot. So in this case would I not worry what it is doing at 100-200 yards since it shoots good at 600 and I won't shoot it any less than that?

If you only shoot at 600, then don't worry about it.