Decidiing which calibre

[Lee308]

Hiyas,
I will soon be up for a barrel change for my mod12 Savage and was thinking about maybe changing calibres. The rifle is currently used for a 1000 to 1200 yard competition and I'm using 208g Amax projectiles in .308win. more often than not the wind is fairly howling at the range I shoot at and the Amax projectiles seem to go reasonably well however using a load of just over 49g of powder the barrel gets a good workout.
Do the 6.5's and 7mm's stand up to the wind very well and if so which would be the better to handle the wind, secondly which is the easiest on barrels and finally if I were to change calibres which one would be the easiest to change over to as far as the action and bolt are concerned. Ideally a necked down .308 case would be good but not sure what sort of barrel life to expect.
The other way I was thinking of going was to change up to a 30 06 but this would mean a new rifle but I don't know if the 30 06 has much benefit over the .308 other than a larger case capacity.
I would be interested to read your opinions
Thanks :-\

 

[jonbearman]

Have you won with the .308? If so why not go for a good aftermarket barrel.Stay with the .308 or you will end up with 6.5x284 which is a great long range cartridge Or maybe one of the wsm cartridges which will burn out barrels quicker than your current caliber.Just something to think about.If you go to articles on our home page and look up some of the articles on long range shooting.

 

[Lee308]

Hi Jon,
Never won a match although I have had some very good shoots with the .308. the long range shooting is still quite new to me and my skills need refining somewhat to get to the stage of winning matches. That just comes down to practice and coaching I'm afraid and that's not a bad thing the more practice the better. I was basically just wondering if there was a better round as having read a lot about 6.5's and 7mm. On taking up your suggestion and reading the articles on the home page I am steering towards the 7x284. My biggest quandary is the effect of the wind on these smaller rounds and if the barrel life is as good or better than what I'm getting with the 308 (approx 3000rnds).

 

[RDavies]

So you are shooting Matchrifle/long range F class events. You have 2 choices. Now that Match Rifle Australia has brought in F/TR class, you could get a 10" twist 32" long 308 barrel and shoot 185-210gn bullets out of a long throated 308. To get to 1200 or even 1500 yds you will need to push the 308 pretty hard with a hot load of N550.
The other way would be to switch to F Class open and use a 284. The 284 will be better in the wind and is effective even at 1500yd shoots with low pressure loads. Same bolt face, easy to find cases and dies, 3000 rounds before rechamber.

Or you could try a 280AI which will get you maximum velocity from a 7mm on a 308 size bolt face, should get you 2950 fps with 180gn Bergers.

 

[Lee308]

Ahhhhh at the meeting in March they were going to give it a go (F/TR) have they got it sorted now have they.hmm thought I would of taken a bit longer to get going. There's something else to think about
Good to see about the .284 and barrel life though that is pretty much the same as what I'm getting now with the .308 and better in the wind can only be a good thing down here in Tassie.
Cheers for the info.

 

[jlmurphy]

I have a Model 12 and have a 6mmBR and .300 Win Mag barrels. The Win Mag requires a different bolt head and firing pin, but pushes the .208 A Max at 2900 easily with H 1000. I have had good luck at long range competitions. The straight .284 Win. would be a good choice also.

 

[Lee308]

Thanks for the replies,
After reading quite a few articles on different calibers, talking to a few people that use the calibers in the same competition that I'll be moving into and weighing up pros and cons for each I've settled on 7mm x .284. The only thing now is to choose what brand of barrel and if its to be fluted or non fluted.
Thanks again for the replies.

 

[Laurie]

308RUG, you won't go far wrong with the .284 Win, although its external ballistics performance is a couple of hundred fps down on the 7mm short magnums that dominate GB F Class (and it looks like the US F Class team will adopt 7mm Rem SAUM, although understandably nobody is saying anything at this stage two years shy of the next F Class World Championship round). What you lose in ballistic performance compared to the magnums, you gain in barrel life - but it will still be considerably less than .308W.

Some people prefer the 'improved' .284 Shehane which gives another 100 fps, its performance falling between what is now usually referred to as the 'straight 284' and the short 7mm magnums, and has a reputation for exceptional accuracy. It suffers a big downside IMO of nobody producing off the shelf dies so far, so expensive custom jobs are needed.

Your basic question though - about small calibre bullet performance in the wind - suggests you're unsure about basic bullet performance. Can I suggest buying a copy of Bryan Litz's book Applied Ballistics for Long Range Shooting, the enlarged 2nd edition having just gone on sale? This is a mine of information for the long-range rifleman and contains tested ballistic values for around 200 long-range match and sporting bullets in all calibres from .22 to .338 as well as a G7 BC based PC ballistics program on a CD-ROM. This allows you to compare the wind drift at 1,000yd for a 180gn 7mm VLD against that of the 0.308" 208gn A-Max at 2,700 fps for instance (the former FAR superior) in a couple of minutes as well as explaining how ballistics work in a practical sense. Bryan is Berger Bullets' ballistician, a top American Fullbore Rifle shooter and member of the US Palma Rifle team, so when the book's title says Applied, that's exactly what the information contained inside is.

 

[Lee308]

Hiya Laurie,
Yep ya hit the nail on the head.One might say that I'm ballistic-ally challenged. Although I have been loading for a few years now I have pretty much been limited to one or two projectiles simply for the fact the shooting comps I was shooting in were projectile specific and once I had found the projectile that worked the best, I stuck with it. The idea of trying different weights and makes is still quite new to me. Over the last 12 months I have been reading quite a few articles some of them written by Brian Litz, on ballistics and how it all works however for all the reading I have done and questions I have asked my knowledge of the subject barely scratches the surface of the topic. There are a few books on my wish list relating to the subject and the one you mentioned is up there near the top. I guess that the lack of knowledge and the want for it is a lot of the reason why I find the F-Open class very appealing, along with the longer ranges as associated with Match rifle shooting.
Thanks for the suggestion.