308 Muzzle Velocity with 175gr

[FearlessMagpie]

I'm going to shoot PRS tactical using 308 with 175gr SMK. (24",1:10,planned to shoot 178ELM but found super good deal of SMK)
I searched online and found most people are running it at around 2600fps instead of 2700.

Is there a particular reason for that? I'm not a fun of less than 95% fill ratio
Are they just trying to replicate MK316 or that spot actually works very well?

Thank you

vs

 

[Billl223]

My 308 load was 44.5 Varget, 175 SMK. 2507 FPS

 

[moaorbust]

Probably easy windage. 2650 on my .308 rifle makes it a perfect 1 click per 100 yards out to 1k.

 

[Dogtown]

.308WIN with 175s needs quite a bit of barrel to get above 2700fps, and a lot of folks are running them quite short these days.

 

[FredHammer]

Most people are running it at around 2600fps instead of 2700.

Is there a particular reason for that?

They want their brass to last more than 1-2 firings. 20" 308 loaded for 1K needs 2550fps min to hit 1K with any precision. Black Hills 175 ammo in 20" 308 is more like 2490fps MV. IMR 4064 @42gr got me 2550fps with 175SMK. Lapua brass. I would now look at CFE223 and TAC to get these 175s to 2600fps without undue stressing the brass.

 

[Doom]

20" Rem 700 with 42.2 gr 4064 is around 2500fps. Would be about 2600 fps in a 24" barrel. I will add that the 308 is usually more accurate at milder than maximum pressures. You can pick up a good 75-100 fps with 2000MR but there will a a nice muzzle flash if shooting out of a 20" barrel.

 

[camocorvette]

A soft shooting, accurate 308 will do much better then a fast shooting, high recoil 308 In positional, prop shooting.
Unless your positional fundamentals are 100% I'd go the slower load. I tried my 308 with 155 Palmas and scenars at 2950. They shot nice, but my fundamentals need alot of work on positional shooting. So the recoil induced was not worth it for me.
2500-2600 is perfectly fine if it is accurate.

 

[FearlessMagpie]

A soft shooting, accurate 308 will do much better then a fast shooting, high recoil 308 In positional, prop shooting.
Unless your positional fundamentals are 100% I'd go the slower load. I tried my 308 with 155 Palmas and scenars at 2950. They shot nice, but my fundamentals need alot of work on positional shooting. So the recoil induced was not worth it for me.
2500-2600 is perfectly fine if it is accurate.

Would the 10% difference in recoil(energy) be significant / noticeable ? Thank you

 

[camocorvette]

Would the 10% difference in recoil(energy) be significant / noticeable ? Thank you

This is my opinion only from observation and participation in "PRS". If thats what you want to play. Play to win or don't fret the details and just shoot whatever.

With a 2600 and a 2700 load. The wind difference is .1 @1000. Yeah your drop is 1 mil more. But that's a constant known factor. It's too easy to dial another mil.

If I was you, I'd shoot the best grouping load that is softer shooting. If your doing this for prs.

In prs yes you need energy on long bomb targets. But you don't run into issues until you get to the 6mm's with spoting impacts or shaking the plate. A 308 at 2600 or 2700 is still gonna look like a freight train tracing through the air and hit with enough energy to shake the plate.

I used to chase velocity in everything I shot. I don't any more. I loaded some 75 bthps 2 weeks ago. Shot my groups for load node and forgot to crono it. The best repeatable group is only 2570 out of a 20" barrel after I chrono'd it.

I loaded 1000 of them beacause it shoots great out to 800. I'm just shooting steel and paper. It works fine and the gun recoils less then the 2700 load.

For me it works. For prs I use a dasher because at 22lbs it doesn't move when I shoot correctly.

 

[Thump_rrr]

2625 is where my rifle was most accurate with 175 SMK's.

 

[straightshooter1]

I'm going to shoot PRS tactical using 308 with 175gr SMK. (24",1:10,planned to shoot 178ELM but found super good deal of SMK)
I searched online and found most people are running it at around 2600fps instead of 2700.

Is there a particular reason for that? I'm not a fun of less than 95% fill ratio
Are they just trying to replicate MK316 or that spot actually works very well?

Thank you

View attachment 8255263 vs View attachment 8255265

Maybe this chart will give you some ideas:

 

[bax]

I use 175 SMK and 4064 with Lake City LR brass and 210Ms, velocity around 2610. Recoil is light, accuracy to 800 is good even with my crummy shooting. The difference between 2600 fps and 2700 fps is just math. Even with moving targets beyond 300, it is a minor change in hold - again, it's just math.

 

[nvrpc1]

I'm going to shoot PRS tactical using 308 with 175gr SMK. (24",1:10,planned to shoot 178ELM but found super good deal of SMK)
I searched online and found most people are running it at around 2600fps instead of 2700.

Is there a particular reason for that? I'm not a fun of less than 95% fill ratio
Are they just trying to replicate MK316 or that spot actually works very well?

Thank you

View attachment 8255263 vs View attachment 8255265

What sofware tool did you use to make these two charts. I need to make one for each 308 rilfes I have for both FGMM and my own home loads. Please advise ASAP. Thanks

 

[memilanuk]

JBM - Calculations

www.jbmballistics.com

Scroll down to the range cards section.

 

[jLorenzo]

Maybe this chart will give you some ideas:

View attachment 8255992

Some of these loads for the 175 seem pretty hot, I would be careful and work up for sure. I have never shot 44.6gr of Varget under a 175 in a bolt gun, let alone a gas gun.

 

[Dogtown]

45gr Varget with 175 SMKs was my go to in an SR90...about 20 years ago.

Edit: on second thought, twenty years ago I was a bit more naive about pressure.

 

[straightshooter1]

Some of these loads for the 175 seem pretty hot, I would be careful and work up for sure. I have never shot 44.6gr of Varget under a 175 in a bolt gun, let alone a gas gun.

You're right, some of these loads are indeed "hot" and one should always be cautious and work up to "hot" loads since every gun is different in they way it can handle the ignition.

 

[stello1001]

So, for reference, I'll list some info below of factory ammo I tried in my FN SPR with custom 22" barrel and some more testing with an FN PBR with its factory 24" barrel.

SPR 22"
American marksman 175 - 2703 FPS
PRIME Ammo 175 - 2538 FPS

PBR 24"
FGMM 168 - 2643 FPS
Norma Match 175 - 2592 FPS

I had multiple rifles that day and a bunch of different loads to test that I was going back and forth between rifles. When I got home, I realized I didn't test the same type ammo across both my 308s. It would have probably been good to see what difference it made.

Anyhow, the 22" had the highest speed with the American marksman ammo.

 

[JerkyFreak]

I get extractor marks on Lapua brass shooting 180gr Hornady Interlocs, Norma Oryx at 2580 fps. This using a Tikka .308 with a stock 24" barrel. Getting above 2600 with 175gr bullets seem close to the limit to me. Wonder what the Quickload calculations show?

 

[straightshooter1]

I get extractor marks on Lapua brass shooting 180gr Hornady Interlocs, Norma Oryx at 2580 fps. This using a Tikka .308 with a stock 24" barrel. Getting above 2600 with 175gr bullets seem close to the limit to me. Wonder what the Quickload calculations show?

When I use Varget (these days I'm mostly just using AR-Comp) 43.4 grs giving me a hair over 2700 fps where the sweet spot is for my rifle, having a 26" 1:8 heavy Krieger barrel. It's right at what QL says is max SAAMI pressure and I don't get any pressure signs. Here's the QL data I have for that (keeping in mind the burn rate for my lot of Varget has been adjusted to match my chrono data):

 

[wvfarrier]

I believe Shellshock is releasing Nas3 cases in 308 next month which "should" allow most of us 308'ers to push the heavies quite a bit faster.

 

[straightshooter1]

I believe Shellshock is releasing Nas3 cases in 308 next month which "should" allow most of us 308'ers to push the heavies quite a bit faster.

Interesting that they're using the case design like Sig produces for their 277 Fury Hybrid cartridges.

277 SIG FURY, 150GR HYBRID HUNTER

Featuring NOSLER Accubond Bonded Core Bullets.

www.sigsauer.com

1,000 5.56x45mm Cases | Shell Shock Technologies

1,000 new unprimed NAS3 5.56x45mm cartridge cases. Shell Shock’s NAS3 cases: Up to 50% lighter than brass cases Offer greater lubricity and will not abrade, clog, foul, wear-out or damage breach and ejector mechanisms. Offer greater corrosion resistance, tensile strength, and elasticity than...

shellshocktechnologies.com

 

[918v]

Just because you can push a bullet faster doesn’t mean it’s going to be accurate. And if you load to excessive pressure you’ll eventually damage the bolt lugs.

 

[Thump_rrr]

I shot 4,600 175gr SMK's in the neighborhood of 2625fps in a 24" barrel using 42.2gr of Varget.
This was done with 200pcs of Lapua brass.
I bought another 200pcs when I replaced the barrel.
Accuracy with the factory Savage barrel was around 0.6moa.

 

[jpjulian]

My M1A load uses 41.0 of IMR4895 for 2520 fps with LC Match cases and 175SMK's. Accurate and perfect function. No bolt gun numbers since I sold off my 40-X.

 

[diggler1833]

I still run 42.7gr Varget under a 175 SMK. It isn't all that "hot"... it just matches the velocity for the 41.75gr 4064 load. The only thing I load the 175 SMK for is an M24.

I will add that depending on what brass you're using, you can certainly get into pressure quickly loading the .308. That standard Lake City brass is thick... as in I popped a couple primers at only about a grain over starting. 43.0gr IMR 4064 gets me up to the bottom of the neck, and just allows me to seat a 150gr flat base hunting bullet (150gr Interlock) for my pig gun. Again, this is with LC brass. You go with another brass manufacturer and you might be able to fit a lot more powder in there.