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Old November 29, 2013, 12:11 AM   #1
HAMMER1DOWN
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175 SMK's for .308. And 168 SMK load questions

Hey y'all. So I have been loading since I was a tyke with my old man. Took a hiatus due to the service and am getting back into it, and moving into the long range game.
Now for the questions, I have a great load for the 168 SMK's but recently took it out and shot and it was highly eradic at 500, took me 17 shots to get on to the milk jug. Ran the load over a chronograph and it averaged at 2325 fps. I want it to be higher velocity. But don't know what powder to go with to push it to 2600-2700fps.
Now for the 175 grainers, I have a few 5 shot loads worked up and haven't tested them yet. I was just curious about what velocities I should shoot for to be a decent 1200 yard round. What powders to look at trying, and other things to know about that bullet.
I shoot strictly nosler custom brass, wolf primers (don't knock them till you try them). I have a bunch of powders. Also I am shooting a Remington 700 VSM 26" heavy fluted barrel with a 1-12 twist topped by a Leupold MK 4 4.5-14x50 with the TMR reticle.
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Old November 29, 2013, 01:32 AM   #2
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Your not going to get 1200yds out of a 308 unless your at high altitude and 30" barrel . Other may say different but I don't think its going to happen . 168 are not going to make for sure .

Based on your rifle I'd try 155gr Palma smk bullets with Varget , RL-15 , IMR 4064/4320 , Viht N-140 . With any of those you should get too , or close to 2800fps maybe even more and that will get you close to 1200yds at sea level

I'm new-ish to loading so other will know better and have faster loads then I . So far in my reloading I've never cared about velocity . Yes I want want high velocity but I want accuracy more then velocity . I'll take a sub 1/2 moa round with a velocity of 2550 over a 1 moa round at 2700fps .

I think your 2325fps 168gr cartridge is WAY slower then you can get out of that . At that velocity I don't think that 1-12 twist is spinning the bullet enough to stabilize at longer range . I would bet dollars to donuts there's another node you can hit if not two more before the pressure gets to high .

What powder is working well for you ?

Right now I have 3 good 308 loads , All of these are right about 1/2 moa 4 shot groups @ 100yds

40.7gr IMR 4895 pushing 175gr smk 2560fps .6 moa
40.3gr IMR 4064 pushing 178gr A-MAX 2570fps .5 moa and have shot a few .3 moa groups
38.5gr Viht N540 pushing 190gr smk 2345fps . This load is on the low velocity range but has shot sub moa in 9 different rifles .

Powders to try .
Viht N-140 or N-540 if using heavier bullets 190gr or heavier
Varget
IMR 4064 / 4895
RL-15
Winchester 748 or 760
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Old November 29, 2013, 02:01 AM   #3
HAMMER1DOWN
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I have been using a charge of 39.3 grains of IMR 4895 to get groups of less than .5 MOA @ 200 yards. I try not to work under 200 for the simple fact that where I live, anything I want to shoot will generally be well over that.

And to augment to my loadings, I have rarely cared for velocity. I too am a tight group searcher but for that round and what I want it to do I know I can push it faster with the same or better accuracy. The military shoots 175 SMK's at around 2600 - 2750 FPS (depending on source) from their match or "LR" ammunition. I have played around with it in my time as an infantryman and it was pretty darn accurate from our run of the mill M14's.
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Old November 29, 2013, 02:48 AM   #4
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duplicate
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Old November 29, 2013, 02:54 AM   #5
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OK one of are Chrono's is not accurate . I have many notes of me using 175gr smk with IMR 4895 . Most 39.5gr loads are in the 2430fps to 2460fps area . I did have some higher velocity on very hot days . My notes show for me to get in the mid 2300fps the load is 37.5gr to 38gr .

I even have a 10 shot sting I shot on 10/2/13 using 24" barrel = 1.1 moa
37gr IMR-4895
175gr smk
WCC-06 case trimmed 2.004
Win LR primer
OAL 2.790
Ammo temp 76* - barrel temp 78*
Ave velocity 2332fps , ES 37.77 , SD 12.18



I should add this group was shot when my rifle was not shooting well . I was having some stock and action screw problems . I believe those 2 to the right are do to my action issues . at least that's what I'm tellig my self

I also have a 39.5gr load getting close to 2500fps when the temp out side was 98* . My ammo temp was 94* when I started that string . ( 4 shots ) That was on 10/6/13

At what temps are you shooting in ?

Next time you go out have somebody else shoot one of there confirmed loads through your chrono and see if it's accurate , I'll do the same
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Old November 29, 2013, 06:15 AM   #6
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1200 yards is doable with a 308,but your pushing it using a 168 or 175 gn bullets.
In FTR I was shooting 155 Palma Hybred's. As for the 168 and 175's

42.3 gn RL-15
GM210M primers
175 SMK's

43.2 gn RL-15
GM210M Primers
168 SMK's

175 SMK's are probably the most common weight bullet used in 1000 yard matches. Your talking 200 yards more,but thats a lot of extra drop there.
Both loads I have listed will get you into the mid 2600's with no pressure signs.

Another load was 43.5 for the 175's,but you gave up some accuracy with it. Also for what it's worth-GM210M primers are the choice of long range shooters of 308's. I my self have never tried Wolf,but keep hearing good things about them.
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Old November 29, 2013, 09:15 AM   #7
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Well right now in Montana, the temps are hovering around the forties to higher 20's. The day I shot it was -10 f* with the wind. I have had a buddy shoot his .300 over my chrony to verify and it's pretty darn close to what he gets normally.
Also I am not against giving up a little accuracy for a better velocity as long as it doesn't spread over 3/4 MOA. I am still a one hole kinda guy
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Old November 29, 2013, 10:08 AM   #8
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After re reading your post I have to go with Metal god here. 1/12 twist,not sure on the 175's. Shooting the 155 Palma's or the Hybrid you should get 2800 or better. If ( big if ) you can get your hands on some RL-15 give that a try.
Speed does not mean accuracy.
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Old November 29, 2013, 10:36 AM   #9
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Having worn out a few 1:12 twist 7.62 NATO 24" barrels shooting bullet weights from 147 to 190 grains scoring well and winning some matches with them, it's my opinion that those bullet weights for bullets will drive pins (they're smaller than tacks) with the right load in good barrels 26" long. Many others have done the same thing.

Powders, many extruded (stick?) ones are suitable for the .308 Win in a 26" barrel for good accuracy. I'd not even try any ball powder if best accuracy's your objective. Too many top ranked competitors tried it over the years and none of it produced the consistant, excellent accuracy levels as extruded powders. Much consternation among competitors prevailed when Winchester put ball powder in M118 Match ammo while they operated Lake City Army Ammo Plant; it did not shoot all that well accuracy wise. Use powders from the following link:

http://www.hodgdon.com/burn-rate.html

... with a burning speed between that of numbers 77 through 100. Slower powders for heavier bullets, faster ones for lighter ones. Favorites in the heyday of .308's in various competition disciplines were IMR4895 or Varget for the 150 grain ones, IMR4064 for the 168 through 180's and IMR 4320 for the 180's and 190's.

If accuracy's important at very long ranges, muzzle velocity numbers have to be a concern. Not the average speed bullets leave at but the spread of the velocities. A 50 fps spread in muzzle velocity from a .308 will cause a 1/10th inch/MOA vertical shot spread on paper at 100 yards. At 1000 yards, the vertical spread will be 20 inches; 2 MOA. Slower bullets drop more than faster ones.
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Old November 29, 2013, 10:44 AM   #10
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Bart- Interesting reading. I see you did not mention RL-15?. As from what I see and ask at the meets now RL-15 is the most common powder used in 308 matches now. Running from 150's to the 175 gn bullets. It is also a very very good powder to use in my 6MMBR too
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Old November 29, 2013, 11:21 AM   #11
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4runnerman, I didn't specifically mention RL-15 'cause it wasn't around "back then" but it is in my range of powders. I know it's often used these days but forgot that when writing up my post. Some of the VV powders are also popular these days, especially with the 155's. My bad, your good.

Good info on long range loads for the .308:

http://riflemansjournal.blogspot.com...pet-loads.html

http://riflemansjournal.blogspot.com...-308-load.html
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Old November 29, 2013, 11:56 AM   #12
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QuickLoad ballistics tells me that you need 2,800fps at the muzzle to stay supersonic at 1,200 yards.

Asking what loads/powders would give me that from 26" while staying at/under 62,000psi and 107% fill (beginning compression) give me this:



This is reasonable for the theoretical answer.
Bart can give empirical data.
The rifle will tell you if its accurate enough.


DO NOT LOAD FROM THIS DATA DIRECTLY
Work up from lower loads and use a chronograph

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Old November 29, 2013, 12:46 PM   #13
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mehavey- Would that change with RL-15?. Wondering because someone else in here said you need a MV of 2830 to stay SS at 1200 yards. Actually it was 1 mile I was looking for. I did strech my 308 out to a mile,but results left a lot to be desired

Bart-- You are a fountain if info. Did not mean to make it sound bad. Sorry if I did. Was just curious about RL-15. It is my go to powder for many different loads. Just can't seem to find it any more. I think it is like the unique equivalent powder for rifles. It just works in anything.
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Old November 29, 2013, 12:57 PM   #14
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QL thinks that 45.5gr RL-15 would reach 2800 -- but for a pressure of 62,250psi w/ the default settings. In other words it's borderline until you actually begin workup w/ a chrono and watching the brass reeeeeeal carefully. (And then you're going to be vulnerable to temperature effects on the powder). At this point, borderline become crapshoot.

Any actual/practical difference between 2800 and 2830 is going to get lost in the vagueries of altitude, moisture, facing/tailing wind, weather-related barometric pressure, etc., etc., etc.
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Old November 29, 2013, 01:12 PM   #15
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One way to estimate what powder might be best for accuracy for a given cartridge is the velocity change for each 1/10th grain change in charge weight. I've used Sierra's manuals with 100 fps increments of muzzle velocity noting the charge weight change for each powders. Some powders require several tenths of a grain more/less for a 100 fps change than others. Those with the least fps change per tenth of a grain are often the ones favored for best accuracy.

Here's an example page from Accurateshooter for the 7-08 Rem:

http://accurateshooter.net/pix/sierra708.pdf
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Old November 29, 2013, 01:18 PM   #16
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I have not worked with 4895 in some time.
My 28" .308 gave
175 SMK + 44 gr Varget = 2654 fps
175 SMK + 45 gr Varget = 2701 fps. Book MAXIMUM, hard on brass in my rifle.

155 Scenar + 46 gr Varget = 2916 fps.

But that was in May in the South, I don't shoot in subzero or even subfreezing weather.
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Old November 29, 2013, 03:45 PM   #17
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Yes- Best I could get was 2710 with the 175's and I was starting to show pressure signs so we ended that shooting session. Since then I have backed all my loads down to mid range and seen the accuracy come up a lot. I did like the 155 Palma Hybrid's , but wind is a issue with them at 1000 yards much more than the 175's. Not to mention the cost too.

Back to the OP. I don't know how good a 1/12 twist will work with the 175's. Probebly will, You just have to try and see what happens. Lot's of if's come into play at 1200 yards. I am still learning to dope the wind at that range myself. It's not easy to do. Bullet drop is big time at 1000 yards,must be off the wall at 1200. Do you have the scope to do it?. I mean enough adjustment or 20 moa bases?. I guess if I was in your shoes and wanting to go 1200 yards, I would be working on the 155's.
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Old November 29, 2013, 04:23 PM   #18
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For those concerned about 175's shooting accurate from .308 Win 1:12 twist barrels, note the M118 match round for 7.62 NATO M14NM's 1:12 twist 22" barrel won matches and set records at 1000 yards with its 172-gr. FMJBT bullet; both bullets have near identical BC's and form factors. Replacing the M118's bullet with a Sierra 180 HPMK, it won more matches and set more records from those same 1:12 twist 22" barrels; twas the favorite long range load for the US Army Team.
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Old November 29, 2013, 08:44 PM   #19
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For my part , when it comes to the 1-12 twist . I was only thinking it may be to slow because of the velocity he is/was shooting . I ran the numbers through a twist calc and it shows the 168gr smk at 2330fps though a 1-12 twist 26" barrel should be fine .

Now that the twist rate is off the table , at least for me for now I'm thinking temp and the powder being consistent at those temps . I must admit my knowledge of powders and how well they do at different temps is poor . I do know that some do much better then others . My point is if you use a powder that does not do well with temp changes or has large velocity shifts do to temp change . That would make your vertical accuracy go south real quick . I'm thinking if you chrono your load at 65* at 2330 but shoot two weeks later at 20* your velocity could drop some if not a lot and that would throw your DOPE/ballistic tables off and may explain why hitting that milk jug was so difficult .

Others will know better and of what others powders may work best but I hear Varget is consistent at different temps and IMR 8208 xbr
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Old November 29, 2013, 10:38 PM   #20
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I've shot 1000-yard matches at 95*F as well as 24*F with the same rifle and load, all at the same rifle range. Only difference I noticed is I had to come up on the sight about 1 MOA for colder powder and thicker air. No change in accuracy.
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Old November 29, 2013, 10:49 PM   #21
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Y'all are awesome, the wealth of knowledge on this forum is exquisite. I probably won't go to the 155's because wind in these parts is horrendous. I shoot heavy bullets in all my rifles except the .223 which gets a 40 grain. But that is just for varmints/predators. I am going to spend a lot of time at the bench and the range to get things all ready and situated for when I really start trying to hammer the long range targets
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Old November 30, 2013, 01:47 AM   #22
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oops sorry , Yeah that's what I meant just said it wrong . I should have said at different temps you can get vertical POI shifts at longer ranges . Your not going to notice it at 100 yards or so. The accuracy should be the same at all distances.
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Old November 30, 2013, 02:18 AM   #23
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HAMMER1DOWN:

Quote:
I probably won't go to the 155's because wind in these parts is horrendous
155 lapua Scenar BC= 508

175 Sierra MK BC= 505

Just so you know....
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Old November 30, 2013, 02:58 AM   #24
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Because I've never shot 1k or shot the 155 palma bullets I'll ask this .

When using a Ballistic calc I see how a 175gr smk bullet does better in the wind then a 155gr palma smk bullet when all that can be the same is . The problem I see is you can't get the 175gr smk to the same velocities as the 155 palma mk . When you plug in the likely velocities you will get with both . The wind drift for the 155 is less with the 175 having more drop .

Is that or this accurate ?

175gr smk muzzle velocity 2700fps 10mph full value wind
Range---Velocity---Energy---Trajectory---Wind Drift
yards-----(fps)----(ft.-lb.)------(in)---------(in)
1000-----1252------610-----..-377.5--------95.8

155gr palma smk muzzle velocity 2850fps 10mph full value wind
Range---Velocity---Energy---Trajectory---Wind Drift
yards----(fps)-----(ft.-lb.)------(in)---------(in)
1000-----1333------611-----..-332.4--------88.5
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Old November 30, 2013, 06:15 AM   #25
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With that small of a difference in wind drift, I'd pick the load that shot most accurate at 1000. That's more important than a 10% difference in wind drift.

With that 1:12 twist 26" barrel, I'd bet it would shoot 175's more accurate at long range than 155's, especially if it doesn't have a 4 groove barrel.
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