Accuracy vs Speed

[Skelo10]

I've tested several loads for my .308 Rem 700 LTR and I'm pleased with the short range accuracy of 43.7 gr of Varget at 2480 fps. However, this load does not give me the speed to reach 1000 yds before going transonic. It breaks somewhere between 850 and 1000 yds. I recall reading posts of others making it out to 1200 yds or more with the same twist and barrel length. I guess this means I should sacrifice accuracy and increase speed so what speed or loads do others have sucess with at longer range?

.308 Rem 700 LTR
1:12 twist 20" barrel
43.7 gr Varget (2480 fps)
175 gr Sierra HPBT MK

 

[shooter.dm]

Re: Accuracy vs Speed

I shoot 155s they have a better bc than 175 plus they fly better in a 1-12 twist powder is 2000mr at around 2850fps (51 grns) produces 1/4 groups @ 100 yards with REM 700 20in 1-12 twist that will get you past 1k

 

[Kevlars]

Re: Accuracy vs Speed

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Skelo10</div><div class="ubbcode-body">I've tested several loads for my .308 Rem 700 LTR and I'm pleased with the short range accuracy of 43.7 gr of Varget at 2480 fps. However, this load does not give me the speed to reach 1000 yds before going transonic. It breaks somewhere between 850 and 1000 yds. I recall reading posts of others making it out to 1200 yds or more with the same twist and barrel length. I guess this means I should sacrifice accuracy and increase speed so what speed or loads do others have sucess with at longer range?

.308 Rem 700 LTR
1:12 twist 20" barrel
43.7 gr Varget (2480 fps)
175 gr Sierra HPBT MK</div></div>

Do you see any pressure signs? I know I use 44.5 gr of Varget in my 308 with 175SMK and my MV is 2683 and that is more than sufficent to reach out to 1000 YDS.

1:10 Twist
44.5 Varget
175 SMK
Lapua Brass
Federal 210M
Barrel Length= 20 Inches
MV=2683

I would be careful using a lighter bullet as it does have more MV out of the barrel, but it will loose speed much faster and can be tossed around a bit more than the 175gr bullet. It has to do with the mass of the object. I know a lot of guys fixate on MV.

-K

 

[shooter.dm]

Re: Accuracy vs Speed

I do not agree about the lighter bullets the 155 pamilas have way better bc than does the 175 thus retained velocity and fights the wind a lot better than the 175smk even Speer 168 bthp match has a better bc than the 175smk

 

[Supersubes]

Re: Accuracy vs Speed

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevlars</div><div class="ubbcode-body">

I would be careful using a lighter bullet as it does have more MV out of the barrel, but it will loose speed much faster and can be tossed around a bit more than the 175gr bullet. It has to do with the mass of the object. I know a lot of guys fixate on MV.

-K </div></div>

Not according to my software. BC is where it's at. Two bullets with the same BC, same velocity, but different weights fly exactly the same. The heavier bullet hits harder.

The 175 smk has a slightly better G7 BC than the 155 lapuas (.243 vs .236), but the 155 can be pushed much faster. The 155 wins in drop, drift, and energy(which is very close at all ranges). When launched at reasonable velocities that is (26XX vs 28XX fps).

 

[sniperaviator]

Re: Accuracy vs Speed

Speed helps accuracy because given two of the same bullets, the bullet going faster will be less deflected by the wind. And if you are off on your wind call, the faster bullet will be off the target by a lesser amount.

 

[Kevlars]

Re: Accuracy vs Speed

All I can tell you is what I have expienced and at 800 yards and beyond the 155 get squirly at least for me.

-K

 

[shooter.dm]

Re: Accuracy vs Speed

The 1-10 twist your rifle used might not like the 155gr you tried but for a 1-12 they work great

 

[Kevlars]

Re: Accuracy vs Speed

I also have a Remmington 700 XLR with a 1-12 and the same thing. You get a full value 10MPH wind going and the 155 are blowing all over the place for me ... again that is just my experience. And what I have witnessed with others. Now at closer range ... sure .. work great.

 

[Supersubes]

Re: Accuracy vs Speed

If your gun doesnt like 155's there isn't much you can do about that. There is no denying they fly better at normal velocities. The twist rate doesnt matter, both are stable in either twist. The 175 in a ten twist is way over stable, but everyone knows from shooting them in a ten that they work fine.

To the OP: My software says you are just reaching the transonic region at 990yds in a baro of 27.50(about 2000 feet ASL). Is your accuracy just falling apart? Could it be you? Has anybody else tried your rifle at those ranges?

 

[0481]

Re: Accuracy vs Speed

I am holding a half assed 6" group at 900 yards with 3" of vertical seperation.
175smk
45gr varget
Win brass
Fed 210m primers

 

[0481]

Re: Accuracy vs Speed

I am holding a half assed 6" group at 900 yards with 3" of vertical seperation.
175smk
45gr varget
Win brass
Fed 210m primers
Mv 2703

 

[CanSniper]

Re: Accuracy vs Speed

If you work up you will most likely find another node with the 175s. I like 45 grns of varget in my 5R. But that is max load so work up carefully. This load runs 2720 from my rifle.

 

[0481]

Re: Accuracy vs Speed

If you look on the front of the varget one pound can it lists 46gr as max load.

 

[Kevlars]

Re: Accuracy vs Speed

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 0481</div><div class="ubbcode-body">If you look on the front of the varget one pound can it lists 46gr as max load.</div></div>

the MAX load differs on who you ask... Lymans says one thing, Sierra says another.

You need to work up the load and look for pressure signs and accuracy.

I currently use 44.5 with SMK 175 and that is the most accurate load for me. Some people use up to 47gns

-K

 

[Okie Gordon]

Re: Accuracy vs Speed

I used an LTR for a couple of years before giving it to my younger brother.
That was far and away the most accurate factory rifle that I ever owned. I actually used it to take my first training at Badlands Tactical Training Facility back in 1999.

Had the same problem you are having. Couldn't get a load to shoot consistently out at 1000 yards. It was fine at 800 and closer. Tried 175 matchkings first. They did outstaning out to about 800 yards. By 1000 yards about every third shot would fly strange and sometimes not even hit the back stop. Tried the 155 palma bullets but they didn't shoot well out of the factory barrel.

About that time I had my first custom barrel done on my other Remington rifle. Had it done to the same length as the LTR because I really like the carry qualities of the shorter barrel length. As I remember it was a Shilen select barrel. That barrel shot both the 175's and the 155's just fine to 1000 yards.

My suspicion is that the factory barrels are just not consistently up to the quality standards required for true long range work. Some people get lucky and get a good barrel and have no problems. Others are like me (and you) and can't get good results.

 

[pdogsbeware]

Re: Accuracy vs Speed

What good is the velocity to reach 1000 if you can't hit shit once it gets there...? Velocity is nice, but I choose accuracy.

As far as the whole "transonic" thing, while there are some bullets (amax? If I recall correctly) that lose stability, there are also alot that don't. Real world results count, so I'd say at least try your most accurate load at 1000 and see what happens. Worst case scenario...you're right back here where you started. Best case...you hit what you're aiming at and no longer have an issue.

 

[Greg Langelius *]

Re: Accuracy vs Speed

The issues I have with velocity are based on copper fouling and throat wear.

I suspect that once bore velocities get up above 2800fps, the copper fouling deposition rate goes up fast. I also suspect that the pressures and heat needed to generate such velocities will have significantly increased wear and tear on the bore's throat area.

The Palma 155gr bullet was an answer to an artificial, arbitrary requirement that Palma Trophy matches be fired using NATO or Qausi-NATO 7.62mm ammunition. At the time the weight spread for various national NATO equivalent loads went as high as 155gr and that weight was chosen for an uber-bullet Palma projectile design, the thinking being that the highest possible weight would have a palpable advantage.

Now, then; in order to get the damned thing to even reach 1000yd supersonic, some arcane strategies evolved. They were based around the triple dictum of Velocity, VELOCITY, <span style="font-style: italic"><span style="font-weight: bold">VELOCITY</span></span>! All else became secondary. The key attributes become long barrels and hot loads.

So, if you don't have A) a long barrel with a twist appropriate to shorter, lighter bullets (i.e 1:13", 1:14", or maybe even longer), and B) a load that comes close to boggling the mind, you're playing at a disadvantage in what's already a pretty fast lane.

IMHO, (and I stress the opinion part) 150/155's are great for distances out to 300, 168's for out to 500 at least, and if you really wanna play out in the boonies, go with the 175.

Otherwise you are dealing in contradictions, and the price involves heavier copper fouling and shorter barrel life.

...And then we hear the, "But..., but...," chorus. Yeah, it can be done. I just prefer a more mundane approach.

My view is, a rifle is a rifle, and not a carbine. A carbine is a fine implement for short and medium ranges. For longer ranges, I consider the <span style="font-style: italic">rifle</span> to be the superior implement. Aw, gee, the balance and 'feel' aren't what we like. Suck it up and move on; the rifle is the tool for distance.

Greg