Which Bullet - .308 at 1,000

[TonyR]

In my own .308 GA Precision Hospitaller which was throated for the Sierra 175MK to be fed using AI magazines with a max COL of 2.885 the Hybrids were to deep in the case to get the velocity I wanted before showing pressure signs. The 185 BTLR was a better choice for me. In a rifle that is throated longer initially and to be single loaded it would be able to use the longer length of the Hybrids and their slightly higher BC to better advantage.
There's no way out of it if you plan to use the Hybrids you'll need to chose a longer freebore for them and single load or else you'll have to settle for less velocity than you might like.

In your current .308 using the Sierra 175's do yourself a favor and buy a box of the Berger Tactical 175 OTM bullets. I did not change anything else in my load just switched bullets and my groups shrank noticeably. This bullet is a real sleeper. I've shot some very small groups at our ranges 822 maximum yardage.

Danny

Danny.
According to Berger, the 185LRBT needs a 1:12 while the Hybrid is supposed to need a 1:11. Have you found that the Hybrid needs a 1:11?
Thanks

 

[dreever]

Tony,

My Bartlein barrel is an 11 twist so I've had no problem there. So I don't know if a 12 twist will work or not.

Danny

 

[Laurie]

Tony,

the 185 Hybrid is 1.435" long and has an Sg factor of 1.18 in Miller at 2,800 fps in standard conditions from a 1-12" twist rate. My experience is that you can get away with 1.18, or even slightly lower values. I'm assuming you're using a quality barrel where 1-12" really means 1-12" of course.

It would be marginal in freezing air, at sea level in a high pressure weather pattern, so as always stability is affected by when and where you're shooting.

I first tried the 1.35" length 185gn BTLR in a 1-13.5" Bartlein where the Sg was calculated as 1.11 in the Miller spreadsheet at 59-deg. It shot a storm at 100yd off the bench in autumn / early winter, temperatures in the high 40s to mid 50s, 0.15-0.3" 5-shot groups. Unfortunately, that opened out 1-2-MOA plus at 800yds a few weeks later in colder weather, somewhere in the high 30s. I don't know if it was the range increase, or in my view more likely, the temperature drop that caused the fall-off. The rifle was rebarrelled that winter, so I never got the chance to try the bullet at long range with the 1-13.5" job in warmer conditions.

These episodes were on an upland range and we get more low pressure than high pressure systems in the UK. Going to Bisley at this time of year sees our F/TR loads hit a full 1-MOA lower at 1,000yd than back home.

 

[TonyR]

I guess it would be worth loading up a few and giving them a try. We generally shoot in warmer temps and/or higher altitudes than what you are describing however, I have certainly been surprised by some of the extreme conditions we see sometimes.