.308 Bullet questions

[Riedog]

Let me explain I recently bought a Savage 10FP .308 with the 24” barrel. I am planning on using it as my all around rifle.  When I mean all around I want it to do really really good at the range but am also thinking that if it does good at the range it should also do good on game. In an effort to gain performance I am planning on starting to reload for my rifle so now we reach the questions. #1 do you think there is any real advantage to using say a Sierra 165 gr. SBT game king over using a Sierra 168 gr. HPBT  match king if one was to actually be hunting? #2 I once read that for a bullet to remain stable in flit it needs to be moving at about 2600 feet per second can any one confirm or deny this? #3 IF the 2600 is true then how fast should it be moving from the muzzle in order to maintain this velocity out to 1,000 yards? Well thatÂ’s all for now I guess. Thanks and great site.

[New Hampshire]

I believe I read somewheres, probably the Sierra Manual, that the Match king is not intended to be used for hunting applications.  Yes it is a "Hollow Point" but its inner profile is designed such as to be more conducive to long range paper punching and NOT expanding in game animals.
Brian M.

[Mikey]

Riedog:  New Hampshire is correct about that particular bullet, and any other high powered rifle bullet designated for 'match' or target that comes in a hollowpoint design.  That design is to enhance accuracy not expansion on game.  In addition, hollowpoints are not a good idea in high speed rifle calibers for hunting - they give very poor penetration and often result in hunting failures.  You should select a soft point design for hunting, hence the SBT Game King would be the most appropriate choice.

I've never heard about the 2600'/sec rule and disagree with it.  The 308 I used to shoot would only accurately shoot 180 gn bullets at 2430'/sec and they were good for as far as I could shoot them, so I would disagree with the 2600'/sec rule or thought, or notion or concept, er whatever.

HTH.  Mikey.

[rpseven]

Riedog Sierras are excellent bullets I shoot them all of the time. But I picked up a box of Speer Grand Slam 165 gr. Bullets. I loaded them with 44grs. of IMR 4064 and Fed. 215 primers and they shot real good in my 308. You might give them a try. This was excellent whitetail round for me. Good luck. Robert

[eroyd]

I launch 168 gr sierra match bullets at a moderate 2400 fps and have no problem with accuracy out to 500m's (the furthest I've shot them). From what I've picked up on reading about long range shooting (1000m's) the main thing is to keep the bullet super sonic at target. Not sure why but I think they lose stability going too slow(?).

[Iowegan]

What's missing from your formula is twist rate. How fast you spin the bullet will determine its stability down range. The heavier the bullet, the faster the twist rate must be. That's because the velocity is reduced with heavier bullets.  Most standard factory barrels have a twist rate of 1:10 or 1:12. This will stabilize a bullet up to 200 gr, assuming factory velocities.

The bullet's spin rate slows down with air friction.  Ballistic coefficient (BC) determines how much the spin rate slows. A high BC bullet will maintain its spin a lot further than a bullet with a lower BC. All rifle bullets are heavier at the base than the nose and are naturally unstable. Once the spin slows to a point, the bullet will begin to wobble and then start to tumble.  Of course, the distance where a bullet gets unstable is determined by velocity and spin and has nothing to do with the speed of sound (1150 fps).

Your 165-168 grain bullets should stabilize out to at least 750 yds, maybe more.  The 165-168s have a great BC. I agree with Brian, the hollow point match bullets really suck when it comes to terminal effects. They usually flatten on the surface and don't penetrate far enough to reach vital organs.

[Riedog]

Ok so i can tell you i am using a 1-10 twist on a 24" barrel. The thing is i wont to start shooting long range with the goal of a 1,000 and i am willing to hand load in order to make that hapen but i think as long as i am working htis load up it should be good for game to so............ what bullet wjould youal recument for this task? preferably sierra but not necusaraly...thanks

[snuffy]

Riedog, it's nice to try to make one bullet do everything. Just not possible sometimes. Take a look at my post on the interbond expansion tests here on this category.

The hornady interbond for hunting and the Hornady sst for target. Both have the same high BC. The interbond would be a little too costly for everyday target work.

Notice I tested the 190 match king under the same conditions as the IB and AB. All I found is about 37 grains of the base, the rest was shards of copper and lead. Shooting a game animal with a match king would riddle the carcass with lead and copper.

[jd45]

Reidog,
Your Question #3 has me scratchin my head.......correct me if I'm wrong,but, I don't think it's possible to propel a .30 cal. bullet fast enough at the muzzle in order to have it still traveling at 2600fps at 1000yds (or meters, if that's your preference), if I'm understanding that question right. jd45.

[New Hampshire]

I think I can clear something up here.  Its NOT velocity that stabalizes a bullets, its spin.  As a bullet travels down range its spin, as well as speed, begins to degrade.  Once the spin gets to a point where it is not spinning good enough to stabalize the bullet will begin to wobble.  Velocity determines how far the bullet will reach out and at how fast.  So its a combination of the two that determines preformance.  Now for hunting ranges, you really dont need to worry so much about stabilization at ultra long ranges, speed is usually the determining factor.  However, in long range shooting at paper, stabilization (which translates into your accuracy,) is more important than how fast the bullet is going.....just as long as it gets there  :grin: .
Brian M.

[The Shrink]

Riedog

Sierra's manual explains that the reason they brought out the 168gr GameKing was that people were using the MatchKing bullet for hunting and having blowups.  Not unexpected given that it is a thin shelled hollowpoint bullet!  With the 168gr GameKing people could use the same loads that were successful with the 168gr MatchKing but have a bullet designed for expansion.  

Wayne the Shrink

[Swamp Fox]

Riedog,

I believe what you are refering to is staying supersonic at 1K.
There are things that happen to a bullet when it goes from supersonic to subsonic that negatively affect accuracy, particularly at long range.

Most shooters who play the 1K game use a little more powder behind the .30 cal bullets than you can put in .308 brass.

[Iowegan]

Just for grins, I fired up my Ballistic Explorer and examined the standard factory loads. All manufacturers list 2700 fps as the muzzle velocity for a 308 using a 168 gr bullet. The bullet goes sub-sonic at 820 yards. It retains 1002 fps velocity at 1000 yds but drops 485 inches (200 yd zero).

I've been in this long range business a long time but never heard about any stability correlation with super sonic vs sub-sonic, not to say it isn't a factor. I've also shot targets out to 1000 yds and it's not an easy chore. First, the gun must shoot 1-MOA groups or better before you even have a chance of hitting the target. Second, you must be able to correctly compensate for wind drift. Third, you need some very good optics, and last, you got to be a hell of a good marksman.

[Larry Gibson]

Riedog

"#1 do you think there is any real advantage to using say a Sierra 165 gr. SBT game king over using a Sierra 168 gr. HPBT  match king if one was to actually be hunting?"

As stated, do not use the 168 MK for hunting as it is not designed for terminal performance on game.  Use the 165 SBT or the 165 HPBT ( a very nice game bullet at .308 velocities) or any of the simular type bullets from the other makers.

 "#2 I once read that for a bullet to remain stable in flit it needs to be moving at about 2600 feet per second can any one confirm or deny this?

Lots of confusion on this question;  What it was supposed to mean is that in order for the 168 MK to stay sonic at 1000 yards a muzzle velocity of 2600 fps was required.  However, that 2600 fps has proved to be too low a figure with the bullet dropping through the speed of sound around 900 yards (800 meters).  Bullets get buffeted badly when coming down through the speed of sound and lose accuracy, some even lose stability and go off into never-never land.  If you really want to shoot 1000 yards with the .308 I suggest you forget the 168 MK and go with the 175 gr MK which was designed for 1000 yard shooting with the .308.  I use it over 45 gr of Varget in W-W cases with WLR primers in my M70 target and it will hold sonic to 1200+ yards.  It is a very accurate load for 1000 yard shooting and runs 2680 fps at the muzzle.  With a 200 yard zero it requires 36 MOA correction for a 1000 yard zero.  The amount of correction required for your rifle will depend on the actual velocity you get from your rifle and the height the scope is mounted above the bore.

" #3 IF the 2600 is true then how fast should it be moving from the muzzle in order to maintain this velocity out to 1,000 yards? Well thatÂ’s all for now I guess. Thanks and great site.[/quote]"

If you read #2 then this is a non-question.

Larry Gibson

[Iowegan]

Just did some more work with Ballistic Explorer. Assuming the speed of sound is 1116 fps at sea level, 72 deg F, and 30% humidity.  A 308 with a 168 gr bullet, BC of .339, would have to be launched at 3100 fps to make it 1000 yds and still be above the speed of sound (1120 fps).

To travel 1000 yds and still retain 2500 fps would require a MV of 6000 fps. Ballistic Explorer won't accept a MV higher than 6000 fps.

[Riedog]

IÂ’m back thanks for all the responses. I have learned a lot and also posed some similar questions to other shooters and found many errors in my ways so the newer game plan is to stay with the VARGET powder but probably try to go to 180 SGK. I now have the fallowing new and wonderful questions LOL. #1 has any one have comments on the bullet weight retention for the 180 SGK? #2 Any brass preference and why? Thanks again

[eroyd]

I understand a lot of shooters use 155 gr sierra palma bullets in 308 for 1000 meter shooting and do very well. I've also seen it suggested that the 168 bullet (in 308) is not a good bullet for 1000m yet 155 or 178gr + are. I can't imagine why? I find this long range bullet performance topic quite interesting, can anyone suggest some good books on the subject? (Tubbs?)

[jd45]

Just my .02, but, I'd suggest Norma brass, because of its more consistent dimensions, such as primer pockets, etc. jd45.
P.S.....be aware, if you're fixin to harvest one o' them steel rams at 1000yds,  they're mighty tough chewin'. (grin!)

[RaySendero]

Just did some more work with Ballistic Explorer. Assuming the speed of sound is 1116 fps at sea level, 72 deg F, and 30% humidity.  A 308 with a 168 gr bullet, BC of .339, would have to be launched at 3100 fps to make it 1000 yds and still be above the speed of sound (1120 fps).

To travel 1000 yds and still retain 2500 fps would require a MV of 6000 fps. Ballistic Explorer won't accept a MV higher than 6000 fps.

Riedog,

I'll  try to add some more info to Iowegan's comments:

Iowegan showed its next to imposable to get a 168 gr bullet out to 1000 yards and keep it supersonic fired from a .308 win.  It just may be possible to do this however with a 190 Match BT.  My ballistic calculator shows a 190 SMK (BC =.525) starting at 2550 FPS might just hold 1175 FPS out to 1000 yards assuming no head wind.  Lots of ifs here - Rate of twist in barrel may not be fast enough to stablize bullet out to there, BC changes with velocity, ect...