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Bullet stabilization issues? .300 Norma Mag
- Reloading Depot
- 35 Replies
Yes the twist is incorrect. Most guys are running at least 1:9 and often 1:8 twist. Depending on your density altitude and with enough velocity you might get away with it at high altitude but I assume you are near sea level. It sounds like the 230 grain bullet is as heavy as you are able to stabilize.I just noticed Hornady recommends a minimum twist of 1:8.5" for their 250 grains A-Tip... my barrel is a 1:10". Isn't that the issue?
Is bullet still stable/accurate after it goes subsonic?
- By SIDS01
- ELR - Beyond 1000 Yards
- 30 Replies
These are the error budgets for that 375 with the Velocity spread opened up to 30 fps, the BC spread to 3%, and the precision to 1.0 moa for the Intermediate shooter. The Beginner has 60 fps, 6% BC, and 1.5 moa. This is as much about the reloader as it is the shooter.
Wind is included here as well to provide another sense of scale.
Another huge problem with bum rushing the problem with velocity and BC is most ELR matches require strings of 10+ shots and the match is generally decided at the longest targets which are the last ones shot.
Wind is included here as well to provide another sense of scale.
Another huge problem with bum rushing the problem with velocity and BC is most ELR matches require strings of 10+ shots and the match is generally decided at the longest targets which are the last ones shot.
Wtf is this lone survivor or lone runner stuff about?
- By st1650
- The Bear Pit
- 106 Replies
Chris Kyle also lied about the superdome, he absolutely lied and defamed Jesse Ventura, he lied about his kill count. Oh and shot of a lot of innocent. Oh he also lied about his medal count for some reasons.
Greatest American sniper …
Is bullet still stable/accurate after it goes subsonic?
- By SIDS01
- ELR - Beyond 1000 Yards
- 30 Replies
I put these together to figure out what to work on next for better ELR performance.
It's the error budget for a very competetive 2 mile gun. 375CT, 2950 fps, 400gr Lazer, 15 fps ES for 20 shots, 1.5% BC spread for 20 shots, 0.5 moa. The total vertical spread is the root mean square sum of the 100 yard precision, the velocity spread, and the BC spread. I have a few AB CDM data sheets that are a little lower, but that would be an exceptional gun if that level of performance could be produced on demand every time.
The first thing that should be noticed is 100, 1000, 2000, and 2 miles have very different problems. At 100 yards, precision is all that matters. By 3000 yards, BC variation dominates the problem. Velocity spread is a bigger deal than precision by 2000 yards. My take on it is after a mile, if you're doing the things to minimize Velocity and BC spread, the precision component is pretty much taken care of as a side effect. That is, 1 moa or 0.5 moa just isn't your biggest problem at ELR distances.
If we compare the 2 mile gun to a 6.5CM loaded to the same standards, we see that yes, cartridge does matter.
On the other hand, if we plot the vertical spread against time of flight instead of distance we get this:
They're not really that different from that perspective. 2 mile training ranges are rare and generally distant. 2 mile ammo and barrel life are relatively expensive. The idea that vertical spread scales to TOF can be manipulated for selecting a gun that'll give representative 2 mile training at more accessible ranges.
That perspective also leads to the idea that going after TOF with more velocity and higher BCs is the most obvious way forward. The problem with that is you can't afford to give up a thing on Velocity or BC spread while you do it.
It's the error budget for a very competetive 2 mile gun. 375CT, 2950 fps, 400gr Lazer, 15 fps ES for 20 shots, 1.5% BC spread for 20 shots, 0.5 moa. The total vertical spread is the root mean square sum of the 100 yard precision, the velocity spread, and the BC spread. I have a few AB CDM data sheets that are a little lower, but that would be an exceptional gun if that level of performance could be produced on demand every time.
The first thing that should be noticed is 100, 1000, 2000, and 2 miles have very different problems. At 100 yards, precision is all that matters. By 3000 yards, BC variation dominates the problem. Velocity spread is a bigger deal than precision by 2000 yards. My take on it is after a mile, if you're doing the things to minimize Velocity and BC spread, the precision component is pretty much taken care of as a side effect. That is, 1 moa or 0.5 moa just isn't your biggest problem at ELR distances.
If we compare the 2 mile gun to a 6.5CM loaded to the same standards, we see that yes, cartridge does matter.
On the other hand, if we plot the vertical spread against time of flight instead of distance we get this:
They're not really that different from that perspective. 2 mile training ranges are rare and generally distant. 2 mile ammo and barrel life are relatively expensive. The idea that vertical spread scales to TOF can be manipulated for selecting a gun that'll give representative 2 mile training at more accessible ranges.
That perspective also leads to the idea that going after TOF with more velocity and higher BCs is the most obvious way forward. The problem with that is you can't afford to give up a thing on Velocity or BC spread while you do it.
