.308WIN Load development for long range *QUESTION*

Evil_Dark

Evil_Dark

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I developed a load for the .308WIN 168gr Hornady Match. My good load giving me sub MOA results (and SD of 10-11 fps) was 40.6gr of IMR-4895, which is really low on the manuals (lower than the minimum on some manuals! Depends on which one I am looking...)
I now switched to Sierra MK 168gr, as they have pretty much the same BC.
I started with the same load, and played around to find this new bullet its particular load. It loks like 40.8gr is working good for it, but as I am starting over again on the load development, am I better to try a hotter load? Is there some real advantages to have hotter load? I know that the velocity will be a tad higher, but will it helps to have a more stable velocity? With 40.8 the grouping is good, 1/2 to 3/4 MOA, but velocity SD is more around 20 at an average of 2630 fps.

Do I better work for a hotter load?

Dark
 
Depends what you want it for... The further you're planning on shooting, the more you benefit from a faster (stable) load in that your round will stay supersonic (hence predictable) further. By my understanding, the 168s aren't great past 600m anyways.
 
You do what's best for you.

Define what "long range" means to you.
Figure out what accuracy is suitable for your needs.
Decide if you are only going to shoot in optimal weather conditions.

Just an FYI, my FTR class 308 pushes a 215gr bullet the same speed you are getting with your 168s.
 
What brass are you using? I'm pushing a 175SMK with 41 gr IMR4895 in Lapua brass (not hot at all). With 168's I was using 43 grains.

Then again if you are happy with the accuracy its all good. You may run into problems past 600 yds with a gently driven 168 SMK though.
 
I went down that road this summer with Berger 175's and 185's. Found lower and upper nodes for both. The upper node was .4-.5 MOA at 2800 FPS for the 175's and 2700 FPS for the 185's. The low node was .3-.4 MOA at 2650 FPS for the 175's and 2580 FPS for the 185's. All in a 24" 5R tube. I was excited for the prospect of a faster accurate load but the hot node was more prone to flyers. It was also tougher on brass. I'm back to the low node now, more accurate, more reliable.
 
J996 said:
What brass are you using? I'm pushing a 175SMK with 41 gr IMR4895 in Lapua brass (not hot at all). With 168's I was using 43 grains.

Then again if you are happy with the accuracy its all good. You may run into problems past 600 yds with a gently driven 168 SMK though.
Click to expand...

I'm using the lapuas brass.

Dark
 
RangerPark said:
I went down that road this summer with Berger 175's and 185's. Found lower and upper nodes for both. The upper node was .4-.5 MOA at 2800 FPS for the 175's and 2700 FPS for the 185's. The low node was .3-.4 MOA at 2650 FPS for the 175's and 2580 FPS for the 185's. All in a 24" 5R tube. I was excited for the prospect of a faster accurate load but the hot node was more prone to flyers. It was also tougher on brass. I'm back to the low node now, more accurate, more reliable.
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I would be inclined to load up a ladder in 0.2 or 0.3 grain increments and chrono the loads to see if you can find the higher velocity node to confirm you're on the low node now. Once this is done, you have 2 load options - I sometimes want to go "low and slow" if I know I'll be taking guests out to the 100 or 200 yard range, but I also have the option of going with the hotter load for longer range, but placing more stress on my equipment and brass.
 
FirearmsEnthusiast said:
I would be inclined to load up a ladder in 0.2 or 0.3 grain increments and chrono the loads to see if you can find the higher velocity node to confirm you're on the low node now. Once this is done, you have 2 load options - I sometimes want to go "low and slow" if I know I'll be taking guests out to the 100 or 200 yard range, but I also have the option of going with the hotter load for longer range, but placing more stress on my equipment and brass.
Click to expand...

This was my conclusion as well. I currently have access to a 300m range so loading hot is of no benefit. Whenever I hit Edson or Rocky Mountain House I'll bring along the hotter load and see which one has the bast results at 600+ yards.
 
RangerPark said:
This was my conclusion as well. I currently have access to a 300m range so loading hot is of no benefit. Whenever I hit Edson or Rocky Mountain House I'll bring along the hotter load and see which one has the bast results at 600+ yards.
Click to expand...

Even at 300 m if it were a windy day, I might reach for the hotter load to minimize lag time / wind effects.
 
Open to suggestions??
Myself, i would sell the smk 168's and start loading 175/185's - they will shoot just as good at your shorter ranges, and be much better when you do decide to stretch it out - trust me, you'll save $$$ doing this as your 168's will give you grief past 600-700yds - wasted shots.
I went to 175 TMK's, and really like them - mild loads shoot great to 1000yds (mild meaning 42.4 4064, 30.5 MOA drop at 1000 in my gun).
Also, my 1000yd groups shrunk dramatically when i put a level on my scope. Scope cant can drive one wacky....
 
rugbydave said:
Depends what you want it for... The further you're planning on shooting, the more you benefit from a faster (stable) load in that your round will stay supersonic (hence predictable) further. By my understanding, the 168s aren't great past 600m anyways.
Click to expand...

Why it should,nt be good past 600Y? My 168 are getting out at, let say 2600 fps, so in my Ballisitic calculator, I 'm still a bit above the speed of sound at 800Y... I' shooting at 500Y every weeks, and I have a sub MOA accuracy at this distance. I know that when the bullet is'nt stabilisez anymore the group opens drastically. But this short? Not sure...

I'm aware of the benefits of heavier bullets (BTHP or VLD or ELD), so I will begin to play with these really soon. I definetly want to shoot at 1000Y this year!

Dark
 
Evil_Dark said:
Why it should,nt be good past 600Y? My 168 are getting out at, let say 2600 fps, so in my Ballisitic calculator, I 'm still a bit above the speed of sound at 800Y... I' shooting at 500Y every weeks, and I have a sub MOA accuracy at this distance. I know that when the bullet is'nt stabilisez anymore the group opens drastically. But this short? Not sure...

I'm aware of the benefits of heavier bullets (BTHP or VLD or ELD), so I will begin to play with these really soon. I definetly want to shoot at 1000Y this year!

Dark
Click to expand...

Conventional wisdom sems to suggest that 168 gr projectiles just aren't that great past 600m(or maybe it's 800m?). In any case, for long range, it seems the way to go is either a 155gr pushed real fast or a 175+gr. I shoot 168gr BTHPs(40.3gr Benchmark, CCI 200s, Fed brass, mv: 2629) out of my M14 but have never shot it past 475 yards but I'm gonna take it up to my long range spot sometime soon to see how it does out to 830 and 870. I shoot 178gr AMAX (43.0gr Varget, CCI BR2 primers, PRVI brass, mv: 2540fps) out of my Rem 700 .308 and it stays sub MOA out to 870 yards. Have also shot it as far as 1274 in a match.
 
If you are limited by twist, I'd do the 155 or 175-178gr over Varget or whatever.

Perhaps try to get the best BC bullet that your barrel will shoot accurately and with low SD up towards highest achievable velocity.

I believe you will see the 168 SMKs "knuckle ball" on you sometimes somewhere after about 700m or so. I really like them in my 700 but they don't seem to do well in transition to subsonic.
 
Heavier is definitely better. If you read on the subject you might come across the saying "Friends don't let friends shoot 168's to 1000 yards". Don't worry about your twist rate. I was getting excellent results with Berger 185 Juggernauts on a 1:12" twist. I'm now using a 1:11.25" twist and the 185's are just as great. 175 Sierra TMK is a very good bullet but I did get slightly better results from the Berger 175 Target. Budget Shooter Supply can get TMK's in 500. Mystic Precision can hok you up with bulk Berger orders. Guys that have success with 155's usually push them very fast, over 3000 fps, out of 30" barrels. There seems to be a no man's land for 168's, if they don't work as well as you want you definitely have other options.
 
manitou210 said:
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The best shooters in north America maybe in world
longrange shooters Use Varget and 185 gr or 200 gr bullets, 155 & 175 gr SMK are very old school and don't cut it today
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Yeah, I'd agree with that for sure. I'd be transitioning to 185s except that I'll be shooting my .308 in Limited class in the matches I shoot next season and we're limited(haha) to 175s...
 
Evil_Dark said:
I developed a load for the .308WIN 168gr Hornady Match. My good load giving me sub MOA results (and SD of 10-11 fps) was 40.6gr of IMR-4895, which is really low on the manuals (lower than the minimum on some manuals! Depends on which one I am looking...)
I now switched to Sierra MK 168gr, as they have pretty much the same BC.
I started with the same load, and played around to find this new bullet its particular load. It loks like 40.8gr is working good for it, but as I am starting over again on the load development, am I better to try a hotter load? Is there some real advantages to have hotter load? I know that the velocity will be a tad higher, but will it helps to have a more stable velocity? With 40.8 the grouping is good, 1/2 to 3/4 MOA, but velocity SD is more around 20 at an average of 2630 fps.

Do I better work for a hotter load?
Click to expand...

My thoughts are that a sweet spot is defined by velocity and that should be your target velocity for a new bullet of the same weight or heavier. If you go for higher velocity you will have to start ladder testing again to see if you have room to get to the next load.

Berger has made it very easy to identify long distance performers with their Form Factor. See chart below. Lower is better, green is good, red is bad. The chart shows why 6.5 and 7 mm are popular long distance calibers. In 30 cal, if you don't want to go up into the 200 grain+ range, or don't have the twist for it, I think I would try the 185 grain Hybrid Target, if you have a 10" twist to handle it.

Form-factor-2016-1-1.jpg
 
168Amax going ~2680 will make it out to 600m no problem and should be able to get to 800m without issue.

Beyond that you likely need something heavier.

As someone else mentioned 168Amax perform better than 168 SMK past 600
 
Got myself some 175gr Hornady A-Max, and ordered 208gr ELD Hornady. So I will test these, I think my 1:10 is suitable for the 208gr. I will try to have the highest velocity possible with the 208gr without having over-pressure signs, as it promise to have very nice capabilities at long range.

Dark
 
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