Long bullet Phenomenon

[Luke45]

I heard the other day from an old time benchrest shooter that long skinny bullets like 140 gr 6.5 berger may be less accurate at 100 yards than 300 yards plus because the bullet is not fully stabilized at close range and has to "get it's legs under it" . Is this true or complete BS? It doesn't make sense to me. I have a 6.5 that is having accuracy problems and wondering if I'm shooting myself in te foot doing load development at 100 yards.

[Rick_W]

It does happen.

[cvx444]

It has also happened with long / heavy (75-80 grains) bullets in the 223.

Another factor may be rifling twist that is slightly on the slow side. Any way similar size groups have been noted at 100 yards and 300 yards with long / heavy for caliber bullets. Of course it depends on what you call good.

What is your twist and have you verified it?
Cooler, low humidity days need slightly more twist to stabilize. Higher altitudes require less twist. If you are on the edge it may make a difference.

[Luke45]

It has also happened with long / heavy (75-80 grains) bullets in the 223.

Another factor may be rifling twist that is slightly on the slow side. Any way similar size groups have been noted at 100 yards and 300 yards with long / heavy for caliber bullets. Of course it depends on what you call good.

What is your twist and have you verified it?
Cooler, low humidity days need slightly more twist to stabilize. Higher altitudes require less twist. If you are on the edge it may make a difference.

Yes it is a 1-8 twist 6.5x284 and it shoots about 1-1.5" groups at 100 yards and I shoot 140 gr bullets out of it. No matter what I do , seating depth ect it won't shoot better than 1" at 100. Yards. You would suggest shooting it at 300 to check? If it keeps same groups at 300 yards I will be Moore than happy!!

[Maztech89]

It isn't going to shoot great at 300 if it doesn't at 100. You have other places to look for your accuracy IMO.

[missed]

Same here the 53 grain smk flat base will make one hole at 100 yards but the 70-80 grain bullets im lucky to keep them in a 1" group at 100 in my 22-250. But I move back to 400 and the 80's will bug hole there.

[Luke45]

It isn't going to shoot great at 300 if it doesn't at 100. You have other places to look for your accuracy IMO.

That was my thought as well. but now ive heard from more than a few people now saying that a bad group at 100 yards with a long heavy for caliber bullet is not necessarily a bad thing. ill try it out at 300 this weekend and let you know

[stoky]

I thought I was seeing this with 175gr BTs in a 7 mag. Figured it must be a loose nut behind the trigger. :p

[chukarmandoo]

This could help. http://forum.snipershide.com/snipers-hide-reloading/44763-hand-loading-long-range-4-powderin.html
I have never shot a good group at a longer range if I did not shoot a good group at 100 but that's just me. Another thing, just a thought, is parallax?
I think barrel harmonics effect the longer bullets more than shorter flat based bullets.

[82boy]

I heard the other day from an old time benchrest shooter that long skinny bullets like 140 gr 6.5 berger may be less accurate at 100 yards than 300 yards plus because the bullet is not fully stabilized at close range and has to "get it's legs under it" . Is this true or complete BS? It doesn't make sense to me. I have a 6.5 that is having accuracy problems and wondering if I'm shooting myself in te foot doing load development at 100 yards.

I am not a ballistician, nor do I play one on TV. There is a basic accepted theory on this, and it is called "bullet yaw." Basically the bullets is spinning, but not fully stabilized. This is common for VLD style bullets. http://www.youtube.com/watch?v=4pF8W5liSRc
Brian Litz, is a known expert on this issues.

The thing is I have seen funny things, some barrels and calibers stabilize bullets very quickly, and some don't. It may also be that the yaw is consistent, and the bullet follows the same path over and over, fooling me thinking that it is stable. I have had a few barrels where I could get .200 and smaller 5 shoot 100 yard groups with long VLD bullets. It may be that some barrels may have issues keeping the yaw consistent, and causing shots to go unpredictable all over target. Generally I would not pick this style of bullet for 100 yard use, but in sighting in times I may print a group or two for amusement. I have also done this over periods of time, as I have changed scopes on a fairly regular basis, and shot groups over the life span of the barrel. The thing I have found out is a barrel that does well in the early stages will continue to do so through out its life.

I have also see barrels that will spray VLD bullets all over the place at 100 yards, shoot smaller groups out further. So just because it doesn't shoot well at 100 yards doesn't mean the gun is not in tune, or that it will not shoot good out further. with hat said I have seen barrels that could not keep 5 shoot at 100 yards under 1 1/2, shoot 2 inch area groups at 600 yards. Barrel harmonics has nothing to do with this, as barrel harmonics, deal with tuning of the load.

Something else which is a miss conception; is that a boat tailed bullet will not stabilize under 200 yards. This is a total wash. I often wonder if this was not started because most VLD bullets have boat tails. It is the design of the front of the bullet, not the back of the bullet. Many 100-200 yard Benchrest shooters have gone to using Boat tailed bullets. The have found that they work very well. there is different thoughts on how to optimize them, but many like to drive them hard, and it work for them.

For the most part the "Old Benchrest Shooter" has told you right. Generally speaking a long pointed VLD style bullet is designed for long range, and is not best suited for 100-300 yard shooting. But there is some exceptions to the rules, sometimes it is possible to get a consistent good accuracy out of these bullets at short range.

[Stockrex]

The thing I have found out is a barrel that does well in the early stages will continue to do so through out its life..


Patrick,
What are the common features of these barrels? like twist rate? length....

I read on benchrest that going slower sometimes yields better accuracy also.
So less yaw with slower speed?

[82boy]

Patrick,
What are the common features of these barrels? like twist rate? length....

I read on benchrest that going slower sometimes yields better accuracy also.
So less yaw with slower speed?

Well most VLD bullets have a heavier weight to them, so they are better suited for faster twist barrels. My experience lies with 6mm, and for long range shooting a 1 in 8 twist barrel , with 105-108 gr VLD bullets. Length depends on personal preference, but there is a point to where a barrel is longer than the burn rate of the powder, and friction sets in , and causes the bullet to slow down. It is because of this I tend to favor shorter barrels.

What you have read on Benchrest central about going with slower twist would relate to using bullets designed for 100-300 yard shooting. These bullets are usually short, and are fully stabilize before they leave the muzzle of the barrel. (Unlike the long pointed VLD style bullets the OP is refereeing to.) So these bullets do not see the bullet yaw factor that they longer VLD bullets suffer from. They choose slower twist barrels because they have a bullet picked out, and they want to be on the edge of where that bullet is gyroscopically stabilized. (usually 68 gr 6mm bullets using a 1 in 14 twist or 112-118 gr 30 cal bullets using a 1 in 17 twist.) This is done so that the torque of the barrel has less affect on the moving things out of shape, (Sand bags and such) and makes the rifle return to battery quicker. Guns designed for long range that utilize longer VLD bullets are usually much heavier, and disturb things less, so they are easy to return to battery. With these 100-300 yard gun using slower twist they usually use short barrels because they are under strict weight limits.

[Luke45]

I am not a ballistician, nor do I play one on TV. There is a basic accepted theory on this, and it is called "bullet yaw." Basically the bullets is spinning, but not fully stabilized. This is common for VLD style bullets. http://www.youtube.com/watch?v=4pF8W5liSRc
Brian Litz, is a known expert on this issues.

The thing is I have seen funny things, some barrels and calibers stabilize bullets very quickly, and some don't. It may also be that the yaw is consistent, and the bullet follows the same path over and over, fooling me thinking that it is stable. I have had a few barrels where I could get .200 and smaller 5 shoot 100 yard groups with long VLD bullets. It may be that some barrels may have issues keeping the yaw consistent, and causing shots to go unpredictable all over target. Generally I would not pick this style of bullet for 100 yard use, but in sighting in times I may print a group or two for amusement. I have also done this over periods of time, as I have changed scopes on a fairly regular basis, and shot groups over the life span of the barrel. The thing I have found out is a barrel that does well in the early stages will continue to do so through out its life.

I have also see barrels that will spray VLD bullets all over the place at 100 yards, shoot smaller groups out further. So just because it doesn't shoot well at 100 yards doesn't mean the gun is not in tune, or that it will not shoot good out further. with hat said I have seen barrels that could not keep 5 shoot at 100 yards under 1 1/2, shoot 2 inch area groups at 600 yards. Barrel harmonics has nothing to do with this, as barrel harmonics, deal with tuning of the load.

Something else which is a miss conception; is that a boat tailed bullet will not stabilize under 200 yards. This is a total wash. I often wonder if this was not started because most VLD bullets have boat tails. It is the design of the front of the bullet, not the back of the bullet. Many 100-200 yard Benchrest shooters have gone to using Boat tailed bullets. The have found that they work very well. there is different thoughts on how to optimize them, but many like to drive them hard, and it work for them.

For the most part the "Old Benchrest Shooter" has told you right. Generally speaking a long pointed VLD style bullet is designed for long range, and is not best suited for 100-300 yard shooting. But there is some exceptions to the rules, sometimes it is possible to get a consistent good accuracy out of these bullets at short range.

thnak you for the information. great stuff, really appreciate it

[eddiesindian]

It isn't going to shoot great at 300 if it doesn't at 100. You have other places to look for your accuracy IMO.

bingo.
if its tight at 100, its tighter at longer distances... (common sense).... consistant 1/4 patterns at 100 is the seed for planting hits long range.

[Luke45]

bingo.
if its tight at 100, its tighter at longer distances... (common sense).... consistant 1/4 patterns at 100 is the seed for planting hits long range.

I would have agreed with you two days ago, but In the case of heavy and long for caliber bullets I do not. Pitch and yaw of long bullets at close range makes sense now

[eddiesindian]

In 308, Im sending 150/168/175 SMK with various powders from 100 out to 1100 (so far)...After extensive load development on all weights and 2 rigs, (for me) without a dought....the nice and tight method @ 100 has proven itself. Ive learned what speeds/weights does what with which ever barrel. Ive also learned not to over think it. Kinda like when your feeling ill and find yourself searching the web for knowledge and then convencing yourself that youve got every dam ailment that you read up on.
What works for some may not work for others.
I had everybody and there mother telling me I was full of crap for using 150,s out to distance, same with the 168,s
The altitude Im at works wonders.
I guess its like everything else....you gotta go out and give it a go. Spend a hole lotta time/money developing that ever elusive/perfect/consistant/accurate round. sometmes your spot on....others?....ya wish you,d of just stayed home, but it is what it is....hell of an addiction a?:(

[Luke45]

In 308, Im sending 150/168/175 SMK with various powders from 100 out to 1100 (so far)...After extensive load development on all weights and 2 rigs, (for me) without a dought....the nice and tight method @ 100 has proven itself. Ive learned what speeds/weights does what with which ever barrel. Ive also learned not to over think it. Kinda like when your feeling ill and find yourself searching the web for knowledge and then convencing yourself that youve got every dam ailment that you read up on.
What works for some may not work for others.
I had everybody and there mother telling me I was full of crap for using 150,s out to distance, same with the 168,s
The altitude Im at works wonders.
I guess its like everything else....you gotta go out and give it a go. Spend a hole lotta time/money developing that ever elusive/perfect/consistant/accurate round. sometmes your spot on....others?....ya wish you,d of just stayed home, but it is what it is....hell of an addiction a?:(

Yes it is a hell of an adiction. and i have had similar results as you with regular wieght bullets. But VLD heavy bullets like a 140 gr 6.5 and a 180 gr 7mmm and a 230 30 cal, ect is what im curious about

[eddiesindian]

roger that:
were always inquisitive................it never ends

[1.618]

It isn't going to shoot great at 300 if it doesn't at 100. You have other places to look for your accuracy IMO.

+1

If they're not grouping at 100, they sure aren't going to group better at 300. Group size increases with increased range, but the groups size doesn't increase linearally; it increases parabolically. In other words 1" at 100 yards doesn't necessarily mean 3" at 300 yards...it will usually be greater than 3" at 300 yards due to the influence of other factors (wind, etc) that increase exponentially rather than geometrically.

Long boat-tail bullets tend to yaw more than shorter, flat-base bullets, at least initially, until they "go to sleep" ... which means that at shorter ranges (before they stabilize or "go to sleep"), they can make elongated holes in the paper target (almost like keyholing but not quite to that degree). I suspect that is what your friend is thinking of. The group size will still be small at shorter ranges ... but the individual bullet holes will be larger, due to the oscillation / yaw in the aft part of the bullet, if that makes any sense.

[yobuck]

i think youd find that virtualy "all" long range target shooters and hunters are using target or target "type" bullets.
you will also find they are more concerned over mid range accuracy than short range accuracy.