Question for .308 208 amax shooters

[308]

Wanting to try a higher bc bullet for my 308, have used search function but have not located my specific question.

Has anyone tested these at rem 700 mag lengths 2.800 to oh say 2.830 or so, preferably with varget but any testing results would be most appreciated, and with a 12 twist, I live in FL so I'm close to sea level but its hot most of the time and high humidity which helps us get by with a little slower twists than some.

Just wondering if 2500 fps is too much to look for at sane pressures, I know there will be a lot of bullet in the case @ 2.800 but I do so hate to single load. Thanks Joey S aka 308

 

[knight_dive]

Re: Question for .308 208 amax shooters

Check the .308 thread in the reloading depot. IIRC there were a bunch of people loading the 208's.

 

[308]

Re: Question for .308 208 amax shooters

Will do that thanks

 

[Bob 964]

Re: Question for .308 208 amax shooters

I would be concerned that a barrel with a 1:12 twist may not spin a 208 Amax fast enough to effectively stabilize it. I think you might have better success and performance with the 178 Amax.

I shoot the 208 Amax out of a Savage 110FP with a 1:10 twist.

 

[gcoulsey]

Re: Question for .308 208 amax shooters

I have currently shot over 2000 of these with Varget now,
I'm using a 1/10 twist though.

'IF' your 1/12 can stabilise them, I would think you'll be looking at around 2400-2450 maximum fps at mag length before hitting pressure.

For 2500 or faster you'll have to seat them longer and/or change powder to something like viht N550 or RL17.

Viht 550 worked well for me, I got 2530fps but this killed my primer pockets after x4 firings, and I prefer Varget for its temp stability.

YMMV

good luck!

 

[Bob 964]

Re: Question for .308 208 amax shooters

With my Savage (1:10), I can get close to 2500 fps using 43.0 - 43.4 grains of RL 15, and that is close to Alliant's recommended maximum charge weight. Using Alliant's PowerPro 2000 MR, I can reach 2500 fps using about 44.3 grains, and this is nowhere near the recommended maximum charge weight (48.5) for the 208 Amax. At 48.5 grains, I am at or near 2700 fps. You will get greater velocity using the PowerPro 2000 MR powder.

That being said, I suggest you research Don Miller's Twist Rule, (see link) which calculates the spin rate a particular bullet needs to achieve optimal performance. Longer bullets like the 208 Amax (1.532 in.) need more RPM to stabilize than do shorter bullets. Slower twist barrels like the 1:12 will have a harder time spinning a longer bullet sufficiently to achieve optimal performance.

http://bulletin.accurateshooter.com/2008/06/calculating-bullet-rpm-spin-rates-and-stability/

 

[308]

Re: Question for .308 208 amax shooters

I have had very good results with sierra 175s and hornady 178 amaxes over 43.5 varget for about 2720 to 2730 in my 26" schneider barreled 308. They go to 1000 very well, I have 2 friends with ranges to 1000 yds with in 20 minutes driving of me.
I thank you for your responses, I know that the 12 twist will be marginal for the 208s. I guess the only way I will know for sure is to try some. thanks again for your time. JS aka 308

 

[YAOG]

Re: Question for .308 208 amax shooters

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308</div><div class="ubbcode-body">Wanting to try a higher bc bullet for my 308, have used search function but have not located my specific question.

Has anyone tested these at rem 700 mag lengths 2.800 to oh say 2.830 or so, preferably with varget but any testing results would be most appreciated, and with a 12 twist, I live in FL so I'm close to sea level but its hot most of the time and high humidity which helps us get by with a little slower twists than some.

Just wondering if 2500 fps is too much to look for at sane pressures, I know there will be a lot of bullet in the case @ 2.800 but I do so hate to single load. Thanks Joey S aka 308 </div></div>

308,

I tried RL17 in a stock Remington 5R with a 24" barrel and came up just under 2,500fps without serious pressure signs. But it was getting close to showing pressure signs as I started to see some primer flattening with two tenths more powder. That said my range is at 1,400ft. elevation so obviously you will be slower at sea level. But this is a long heavy projectile and even at 2,400fps will remain supersonic and out of the trans-sonic zone to 1,000 yards even at sea level so who cares if you hit 2,500fps or not.

As to the issue of stability check out the JBM Ballistics stability calculator for an excellent proven modern stability calculation method. Based on your data I think you will be in nearely the ideal range as long as you can get 2400fps out of the 208gr A-MAX in your rifle. I had no stability issues in my 1 in 11.25" 5R milspec rifle as predicted by the JBM program.

But try it before you buy them in bulk, some rifles don't like this bullet as well as the Sierras 200gr MatchKing.

HTH!

 

[308]

Re: Question for .308 208 amax shooters

Yaog, I will for sure buy a few and try before I buy a bunch. Did you perhaps give varget a try??? Also what oal did you load at...?

 

[YAOG]

Re: Question for .308 208 amax shooters

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308</div><div class="ubbcode-body">Yaog, I will for sure buy a few and try before I buy a bunch. Did you perhaps give varget a try??? Also what oal did you load at...? </div></div>

308,

Cases were prepped using a Redding Competition bushing die without the expander for a first neck sizing pass followed by a Redding Type S bushing full length sizer without the expader ball cases neck sized to 0.001" neck tension and full length sized to yield 0.001" headspace in my rifle. Cases were trimmed to minimum spec 2.005" and seated to an average COAL of 2.810" but this varies a little bit because I use a Redding Competition bullet seater which seats by ogive height. This is on no neck turn brass.

Nope did not test using Varget as I have given up on Varget. Sure Varget is less temperature sensitive but it is also not a very efficient powder for the .308Win cartridge. IMR4895 and RL17 both give much better velocity and percentage of case fill without having to use an over book max. compressed charge to get good velocity. For a given pressure Varget produces lower velocity than IMR4895 or RL17, 40-80fps slower in my stock action Remington 5R.

HTH!

 

[B3dlam]

Re: Question for .308 208 amax shooters

You can check your stability on JBMs site:
http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

I ran it through for you even if you got it up to 2800 fps your 1:12 barrel will likely only give you a stability factor of 1.099 when you want closer to 1.5.

At 2300 fps a 1:10 barrel gives you a 1.482. As was stated you likely wont be able to stabilize these bullets even at extreme pressures.