what happens if you work up a load at say 200' but want to shoot it at 6000' the stability going from 1.39 to 1.71. Is this possible of should i just stick to something stable where i am?
marginal stability
- Thread starter twister
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Tagging in cause I've never shot at high elevation. I shoot at lower elevation. So if I'm stabilized at low elevation, it should be more stabilized higher. My situation is probably more desirable than going from a good load at high then going to a lower elevation.
lancetkenyon
Well-Known Member
Depends on if you want to shoot a lot at your current elevation. I would swap bullets myself.
Care to share your info? Like rifle, cartridge, twist rate, bullet choice, etc.?
Care to share your info? Like rifle, cartridge, twist rate, bullet choice, etc.?
its a 6 creedmore twist rate measures 7.75 trying the 115 berger. Im thinking to switch to the 108EOL and call it a day.
The plan would be to use this for antelope in new mexico a good ways from New England. I will have another proven at elevation gun with me.
The plan would be to use this for antelope in new mexico a good ways from New England. I will have another proven at elevation gun with me.
PNWdude67
Well-Known Member
Work up a load that is stable at the lowest elevation you shoot. The 1.5 stability guideline is just that, and when a bullet twist rate combo is at or above it you generally have an easier time working with it. What makes most sense is to have a barrel twist rate that will stabilize the heaviest bullet you would want to load at the lowest elevation. Also, realize density altitude is what ballistic calculators use, and that is not always the same at a given geographical position. For example, on a cold, humid morning at 2000 feet elevation the DA could be -800 feet. Later in the day, if high pressure moves in, the temp rises 30 degrees and humidity drops the DA could rise to 3500'. Extreme example for this to happen in the same day, but it will happen from week to week depending on the weather. This weekend on Sunday we had a DA of 2500' at 2000' elevation and Monday was -450 in the same location. I actually do not have experience with a bullet being marginal at low elevation and stable at 6000' higher to answer your specific question, which is a good question, and probably never will as that is a variable that can be eliminated before a single round is fired through the rifle system. That said, I understand what you may be trying to accomplish if the rifle you want to hunt has a slower twist rate than optimal for the bullet you want to load. If I was faced with this scenario I would find a bullet that is stable for this specific gun.
ShtrRdy
Well-Known Member
1.39 is so close to the 'stable' criteria of 1.4 I would say go with it.
PNWdude67
Well-Known Member
Just saw this after the previous long reply. Ok, YES!! Do try the new 108 berger Elite hunting hybrid. It will be very stable in that rifle. I have been shooting the 109 target version all year in matches. It is super consistent and easy to "tune" so excited to try the new hunting 108 EOL. I have a few 6 Creedmoor barrels and considering this combo for an antelope hunt in Colorado. Also, The 108 ELDM would be money in the 6 Creedmoor 7.75 twist barrel and works very well on game.
What powder are you using? I started with the H4350 and looks only a little behind R16 or 17
Mikecr
Well-Known Member
It won't shoot worse as stability goes up.
1.0 is stable, 1.3 is marginal (which is fine), 1.5 is fully stable, higher than 1.5 is still fully stable (and no more).
Keep in mind that gyroscopic stability rises as the bullet travels down range. This doesn't bail us out of bad stability on muzzle release, but it proves that high to very high Sg doesn't hurt us.
So your calculated Sg at muzzle release is 1.39. Then by 250yds that bullet's Sg will be ~1.71, right there where you're at. By 500yds, that bullet's Sg would be ~2.15.
It isn't hurting you
1.0 is stable, 1.3 is marginal (which is fine), 1.5 is fully stable, higher than 1.5 is still fully stable (and no more).
Keep in mind that gyroscopic stability rises as the bullet travels down range. This doesn't bail us out of bad stability on muzzle release, but it proves that high to very high Sg doesn't hurt us.
So your calculated Sg at muzzle release is 1.39. Then by 250yds that bullet's Sg will be ~1.71, right there where you're at. By 500yds, that bullet's Sg would be ~2.15.
It isn't hurting you
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cohunt
Well-Known Member
extra "stability" often helps a bullet to expand better/faster and also help to keep penetration in a straight line after impact
Mikecr is right. A bullet with a factor >= 1.5 is achieving maximum BC according to Berger.
Mikecr
Well-Known Member
While extra spin might help with terminal ballistics, maybe,, fully stable is just that.
FULLY
FULLY
lancetkenyon
Well-Known Member
Lapua SRP brass
H4350
Fed GM205M
105 Hybrid
I run this combo in my 6CM. From a 24" barrel, I get 3101 w. 42.0gr, and it is crazy accurate, and deadly. Took my NM pronghorn last year at 450-460 yards. Dropped at the shot and never twitched.
Entrance (broke front leg going in)
Bullet was just under skin, blew all the hair off the hide, and ALMOST exited, left a nasty hicky
Mean entrance hole into the body cavity after taking out the front leg
