338 Lapua Load

[Knife Edge]

338 Lapua Load

I cold never get the 285s to do anything with the H1000 or Retumbo in a Sako and 700. I've had great luck with Sierra 250s and 300s in H-1000. 89.5g in the stock 700 and 92 in the TRG. 700 1/4 MOA and TRG 1/4-1/2.

I think the jackets on the 285s are either too thin or too soft and get easily damaged. I have never had Sierra not group, Hornadys 50/50 in various calibers. However, when they group, they group as in the photos above.

[ar15barrels]

I cold never get the 285s to do anything with the H1000 or Retumbo in a Sako and 700. I've had great luck with Sierra 250s and 300s in H-1000. 89.5g in the stock 700 and 92 in the TRG. 700 1/4 MOA and TRG 1/4-1/2.

I think the jackets on the 285s are either too thin or too soft and get easily damaged. I have never had Sierra not group, Hornadys 50/50 in various calibers. However, when they group, they group as in the photos above.

Do your heavy bullet load testing at 200yds.
It's quite common for long bullets not to group well at 100yds and then to group really well at 200yds.
I have seen guns shoot 1.25" groups at 100yds and then 1/2" groups at 200yds, with the exact same ammo within the few minutes that it took to move the target to 200yds.

[diver160651]

338 Lapua Load

Do your heavy bullet load testing at 200yds.

It's quite common for long bullets not to group well at 100yds and then to group really well at 200yds.

I have seen guns shoot 1.25" groups at 100yds and then 1/2" groups at 200yds, with the exact same ammo within the few minutes that it took to move the target to 200yds.

I shoot a lot of 338 can't imagine any of my mags shooting 1.25" at 100y then somehow shooting 1/2" (1/4moa) at 200y.. I shoot a mostly ELR and yes, 338's do tend to (not open up) hold sub MOA better than many other rounds but they never actually create such a drastically "smaller" group as distance increase.

Edited - deleted dup pic

[ar15barrels]

I shoot a lot of 338 can't imagine any of my mags shooting 1.25" at 100y then somehow shooting 1/2" (1/4moa) at 200y..

Shoot enough different barrels and you will eventually run into it.

[diver160651]

338 Lapua Load

My theory is (and only that) that the longer impulse and more recoil of the 338LM is prone to exploit angles and weakness in the shooters recoil management when it comes to repeatability.

I've had several instances were a shooter claims their 338 doesn't group at 100, but claim once the round goes to sleep they do-- only to get behind their gun and find no issue at 100.

Maybe the shooter is shouldering the 338 with more care at 200 or whatever.. But simple physics makes a case against 1.25" at 100 then 2 x further it shrinks to a 60% smaller physical group.





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[ar15barrels]

Maybe the shooter is shouldering the 338 with more care at 200 or whatever.. But simple physics makes a case against 1.25" at 100 then 2 x further it shrinks to a 60% smaller physical group.

I have seen is in other cartridges too, but always with long/heavy-for-caliber bullets.
Litz's book explains the phenomenon of bullets going to sleep.

[diver160651]

338 Lapua Load

I have seen is in other cartridges too, but always with long/heavy-for-caliber bullets.
Litz's book explains the phenomenon of bullets going to sleep.

Oh, maybe your mixing MOA up with inches. And I agree Litz knows what he is talking about; As a side note, I use his custom curves to get reliable results out past transonic and into subsonic distances with a couple of calibers using his Applied Ballistics BT kestrel; it's just amazing.

But the going to sleep theory DOES NOT shrink the physical size of the groups as distance increases. It only make the predicted milliradians or degrees at distant targets open up less than a close range target would predict.

I'll use my 7mag as an example. With 168VLD at 3105fps it out runs many 338s to a mile. It is capable of .25 inch groups (.25MOA) at 100y. With 5-25x scope the .25MOA hold fairly well to 300y with me. But by a mile I am thrilled to hold near a MOA 17.5" (yes some shots are way less) but I am being realistic. Nowhere along the bullet path does the bullet's group deviation get smaller than the .25" as seen at 100 yards and increases to the 17.5" (MOA/.3 Milliradian) at their target in the 1760y example. My 338LM is more of a .5" at 100 with a few sneaking in at the .25" mark. But seems to hold fairly true to the exams above. Maybe less prone to gusts, but it also way harder to shoot.

I think everyone knows the reason ELR distances become impossible to hold the same MOA/milliradians, wind, ES, mirage, and visual aiming references are smaller. In this example we have 1:4+ ratio one can use for ELR predictability.

In the 338LM, it is common for a .75 MOA gun at 100y maintain far less than the 1:4+ MOA/milliradians ratio out to that same ELR distance. This is were the going to sleep therapy seems to work. But it is important to note, that the .75" 100 yard group, is not going to shrink in physical size. It will only expand, just in some cases not as much as we would predict.

I hope that makes sense. To complicate matters, no point in time are the same and the shooter is the biggest variable. All that said, I still don't buy it when shooters are not properly managing the recoil and trigger brake, then claiming they get amazing tiny groups at distance; yet can't hold MOA at the test range; especially when someone else can squeeze off groups smaller on their own gun.


Jt

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[ar15barrels]

In MOA, the groups measured 1.2 at 100yds and 0.24 at 207yds.
I'm not arguing a justification for it.
I'm only saying that I have observed it on several occasions.
There are many factors that influence group sizes.

Oh, maybe your mixing MOA up with inches. And I agree Litz knows what he is talking about; As a side note, I use his custom curves to get reliable results out past transonic and into subsonic distances with a couple of calibers using his Applied Ballistics BT kestrel; it's just amazing.

But the going to sleep theory DOES NOT shrink the physical size of the groups as distance increases. It only make the predicted milliradians or degrees at distant targets open up less than a close range target would predict.

I'll use my 7mag as an example. With 168VLD at 3105fps it out runs many 338s to a mile. It is capable of .25 inch groups (.25MOA) at 100y. With 5-25x scope the .25MOA hold fairly well to 300y with me. But by a mile I am thrilled to hold near a MOA 17.5" (yes some shots are way less) but I am being realistic. Nowhere along the bullet path does the bullet's group deviation get smaller than the .25" as seen at 100 yards and increases to the 17.5" (MOA/.3 Milliradian) at their target in the 1760y example. My 338LM is more of a .5" at 100 with a few sneaking in at the .25" mark. But seems to hold fairly true to the exams above. Maybe less prone to gusts, but it also way harder to shoot.

I think everyone knows the reason ELR distances become impossible to hold the same MOA/milliradians, wind, ES, mirage, and visual aiming references are smaller. In this example we have 1:4+ ratio one can use for ELR predictability.

In the 338LM, it is common for a .75 MOA gun at 100y maintain far less than the 1:4+ MOA/milliradians ratio out to that same ELR distance. This is were the going to sleep therapy seems to work. But it is important to note, that the .75" 100 yard group, is not going to shrink in physical size. It will only expand, just in some cases not as much as we would predict.

I hope that makes sense. To complicate matters, no point in time are the same and the shooter is the biggest variable. All that said, I still don't buy it when shooters are not properly managing the recoil and trigger brake, then claiming they get amazing tiny groups at distance; yet can't hold MOA at the test range; especially when someone else can squeeze off groups smaller on their own gun.


Jt

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[JMP]

I have seen is in other cartridges too, but always with long/heavy-for-caliber bullets.
Litz's book explains the phenomenon of bullets going to sleep.

I would be interested in understanding this phenomenon, if you have a link to the reading material. For me, there is no intuitive explanation off the top of my head as larger groups tend to expand with further distance, so it would see to indicate a slight error in trajectory, which extrapolates to a larger error with more distance rather than correct itself.

I have personally not observed this. However, I can give an example where a similar result ensues. At 500 yards, I shoot .338LM at 5x magnification in order to spot my shot since there's a fair recoil and the bullet doesn't slow much. At 500 yards and 5x magnification, I can easily hit a target of 1 MOA (~5"). However, at 100 yards, I cannot shoot 1 MOA at only 5x magnification (~1").

Hence, a very similar situation happens to be due to optics. At 100 yards, I need big magnification to shoot the best group to ensure precise point of aim. So, the "pinching" of the target at further distances can help reduce the angle of error.

[ar15barrels]

I would be interested in understanding this phenomenon, if you have a link to the reading material.

http://store.appliedballisticsllc.com/ProductDetails.asp?ProductCode=0001

[diver160651]

[QUOTE=JMP;14399902]I would be interested in understanding this phenomenon, if you have a link to the reading material. ]


Quote


Brian is fairly active in the Hide if your interested ... Be forewarned, if the guys on the hide see to much misplaced bravado they can get a bit ... Well funny


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[jcat]

j-cat,

I bought some 308 brass from you a few months back.
You didn't tell me to change my name then.

Mine makes sense, since they are my initials.

JCat