I am looking to develop a load for my 22 inch custom .308 that will comfortably get me to 1k. According to my dope to 800 yards, it shoots FGMM 168 at 2800 fps, so my bartlein barrel is pretty fast. I am trying to decide if I should go light and fast, or heavy. Any input?
Range Report 155 lapua or 185 berger for 1k?
- Thread starter glock63
- Start date
I'd seriously question data that put FGMM @ 2800fps, regardless of barrel make. There's 'fast' and then there's 'unlikely'...
Without exact MVs to work with, I'd say the 155s will likely shoot a little flatter; the 185s will likely drift less in the wind. Depends on which is more important to you.
Without exact MVs to work with, I'd say the 155s will likely shoot a little flatter; the 185s will likely drift less in the wind. Depends on which is more important to you.
All I know is 6.8 mils put me on target at 800 last time I shot. Altitude was 1240, temp 16, and humidity 65. According to the shooter program on my phone that puts me right at 2800. I was baffled by it as well.
I try to find the longest and heaviest bullet that my Savage 110FP (24" barrel w/1:10 twist) will effectively stabilize. The 155 Lapua has a length of 1.291"; the Berger 185s range from 1.353" to 1.435". You didn't mention the twist rate of your barrel. If you have a 1:12 twist, your gun may have trouble stabilizing the longer and heavier bullets. If it is 1:10, you should be OK. Dan Miller has developed a formula for calculating the gyroscopic stability of a given round (see link).
http://www.accurateshooter.com/technical-articles/calculating-bullet-rpm-spin-rates-stability/
If you divide a bullet's sectional density by its G7 Ballistics Coefficient, you get a bullet's "form factor" which is a measure of drag and an indicator of how efficiently a bullet flies. The lower the number, the less drag a bullet has and the more efficiently it flies. The Lapua 155 has a form factor of 0.987, which isn't bad (anything below 1.0 is good). The Berger 185 Hybrid has a form factor of 0.959 and the 185 VLD has a form factor of 0.993. So... based on this the longer and heavier Bergers should have less drag and fly more efficiently than the Lapuas.
Having said this, the only way to be sure is to test both in your gun, following generally accepted load development procedures like the OCW or ladder tests. Good luck.
http://www.accurateshooter.com/technical-articles/calculating-bullet-rpm-spin-rates-stability/
If you divide a bullet's sectional density by its G7 Ballistics Coefficient, you get a bullet's "form factor" which is a measure of drag and an indicator of how efficiently a bullet flies. The lower the number, the less drag a bullet has and the more efficiently it flies. The Lapua 155 has a form factor of 0.987, which isn't bad (anything below 1.0 is good). The Berger 185 Hybrid has a form factor of 0.959 and the 185 VLD has a form factor of 0.993. So... based on this the longer and heavier Bergers should have less drag and fly more efficiently than the Lapuas.
Having said this, the only way to be sure is to test both in your gun, following generally accepted load development procedures like the OCW or ladder tests. Good luck.
If your rifle will shoot the 185 hybrid and you can handle the recoil roll with it. Its a great bullet and will most likely have less drift than the 155s at 1000 as Monte has stated already.
Here's a data point:
I just worked up a load for my 308 with the 155 scenars:
Lapua brass, 46.8gr Varget, Tula primer, 2965fps over a magnetospeed chrono, with ES of 6 and SD of 3 for 5 rounds. 26" CBI barrel
Confirmed dope is 8.2mrad to 1000 yards
These things have actually restored my faith in 308.
I just worked up a load for my 308 with the 155 scenars:
Lapua brass, 46.8gr Varget, Tula primer, 2965fps over a magnetospeed chrono, with ES of 6 and SD of 3 for 5 rounds. 26" CBI barrel
Confirmed dope is 8.2mrad to 1000 yards
These things have actually restored my faith in 308.
I chrony'd the 175 7.62 FGMM at an average of 2762 out of my 22 bartlein over a CED M2. Sounds like we are coming up with similar numbers. I think I will work up loads for both bullets and see which I prefer. Thanks for the input everyone.
