Is it possible to get a 175 SMK to go 2600FPS

[M ammo]

Is it possible to get a 175 SMK to go 2600FPS

Out of a DPMS LR-308 with an 18 Inch barrel

I’m using Varget but I’m open to another powder if needed.

Looking for a load.

Jim M ammo

[bigbrowndog]

Jim, I'd have to to say..................NO!!! having said that, if you are looking at using it for LR competitions, the 308 is best out to 750ish, and with those parameters there is no reason why a good 155gr. SMK or Lapua, or Berger would not do just fine and reach that velocity. the SMK 155gr, not the Palma, was designed to duplicate the 175gr SMK's ballistic signature but with a lighter bullet.

i got that info straight from a Sierra Rep/Tech, who I trust, and have known for years!!!!!!!!!!!

Trapr

[twodownzero]

Definitely not at any type of safe pressure. I'd have a hard enough time achieving that out of a 24" tube. 2700 out of an 18" is an unreasonable goal.

I run my 155s around 2900 (book max) and they will reach out and touch someone. There is also nothing better than Varget for .308 with heavy bullets. You can try Reloder 15 if you want but Varget is definitely my choice.

[smokshwn]

Definitely not at any type of safe pressure. I'd have a hard enough time achieving that out of a 24" tube. 2700 out of an 18" is an unreasonable goal.

I run my 155s around 2900 (book max) and they will reach out and touch someone. There is also nothing better than Varget for .308 with heavy bullets. You can try Reloder 15 if you want but Varget is definitely my choice.

I have an LR308 that was cut to 18" and both Black Hills 175 and TTI Armory 175 clock 2550 out of it without pressure signs. I am pretty comfortable saying that both factory loadings are well within "safe" pressures.

I haven't done any load development with this rifle yet but I would say it is a safe bet that 50 fps could be had an remain within reasonable safety parameters.

I am planning on using 155's for both my 308's but for grins I guess I will have to try and spit the 175's at 2600.

Edited February 24, 2010 by smokshwn

[Caspian_45]

If you ttry different brass you might come up with less pressure than another brand.

I run RE-15 in my 308 with 26in tube. Remington brass gives me the least pressure signs. I have run the velocity up to 2775 and it showed a lot of pressure.

You mi8ght get to 2600 with the right podwer/brass comb. Trap said it best, go with a lighter bullet.

[smokshwn]

Jim,

Spend some time over on Snipershide in the reloading forums. There are plenty of guys getting 2700 fps from 20" tubes using varget, RL15, IMR4895, etc and a 175gr bullet. 2600 should be easily doable with a little care.

[M ammo]

Thanks for the great info,,

I plan on using The rifle for 3 Gun for the most part, With the wind at the RM3G last year on that Long range stage,, the heavier bullet would have been nice.

Trapr “”””looking at using it for LR competitions””” I’m interested in more info on,, those type of competitions as well…

I looking at the Burris XTR in 7.62 it has the BDC for a 175 SMK at 2600

Right now I’m loading some 150 Rem PSP’s for the under 300 stuff.

And 155 Nosler Comp’s for longer shots.

If I get the Burris and shoot past 500 I was thinking I would just load the ammo to the BDC specs. Just my thinking,,,,

After a bit of a fight getting my loads to run, In my LR-308.. I now use a Redding full leangh Small Base die. And the gun runs fine.

The best group I have shot is .531 at 200 Maybe lucky, last weekend I shot a .971 at 200 with a little wind blowing.

Jim M ammo

[kgunz11]

Thanks for the great info,,

I plan on using The rifle for 3 Gun for the most part, With the wind at the RM3G last year on that Long range stage,, the heavier bullet would have been nice.

Trapr """"looking at using it for LR competitions""" I'm interested in more info on,, those type of competitions as well…

I looking at the Burris XTR in 7.62 it has the BDC for a 175 SMK at 2600

Right now I'm loading some 150 Rem PSP's for the under 300 stuff.

And 155 Nosler Comp's for longer shots.

If I get the Burris and shoot past 500 I was thinking I would just load the ammo to the BDC specs. Just my thinking,,,,

After a bit of a fight getting my loads to run, In my LR-308.. I now use a Redding full leangh Small Base die. And the gun runs fine.

The best group I have shot is .531 at 200 Maybe lucky, last weekend I shot a .971 at 200 with a little wind blowing.

Jim M ammo

Why so many different loads? Why not pick one load that works for everything?

The 155's will only shoot inside the 175 when driven fast enough. When you run a shorter bbl you need a little faster powder to get the velocities up before you run out of tube. H4895 will get you more velocity out of an 18" tube every single time when compared to Varget or Re15. Been there done that. Re15 is a little slower and better suited for the heavier .308 bullets. It's also quite temperature sensitive, which is a moot point under 600 yards. Play around on a ballistics calculator and see which bullet wins. You can get the 175 to 2575 reliably and it shoots decent in that velocity range. You can get the 168 to 2700, and you can get the 155 to 2800.

As for loading to match a BDC reticle beyond 500 yards, that is going to get rather pricey. BDC reticles work in one area with one set of atmospheric conditions. If you change altitude, humidity, or temperature, your reticle is no longer accurate. Let's look at the reticle itself... did they use a 175gr bullet? Did they use a G7 drag function or a G1? Where did they create the reticle? Was it 4500' ASL?

There's nothing wrong with getting a reticle with subtensions that are a known measurement. Your BDC reticle is an unknown, and probably not the wisest route. Know your come ups for your rifle at distance and learn to hold using the MOA or Mil marks in the reticle. It's not at all hard to do. Trying to match a load to a BDC reticle beyond 500 yards can be quite hard though.

175 SMK @ 2575 = 16.9 up at 600 with 5.3 of wind

168 SMK @ 2700 = 16.0 up at 600 with 5.7 of wind

155 Palma @ 2800 = 14.8 up at 600 with 5.5 of wind

I had an 18" AR-10 for a while. Tried and tried to make it do something it wasn't meant to do. My shooting begins at 600 yards. Inside of that and I'd just use a 223 with the 77gr SMK. Just my opinion, and probably worth what you paid for it.

[M ammo]

Thanks for the great info,,

I plan on using The rifle for 3 Gun for the most part, With the wind at the RM3G last year on that Long range stage,, the heavier bullet would have been nice.

Trapr """"looking at using it for LR competitions""" I'm interested in more info on,, those type of competitions as well…

I looking at the Burris XTR in 7.62 it has the BDC for a 175 SMK at 2600

Right now I'm loading some 150 Rem PSP's for the under 300 stuff.

And 155 Nosler Comp's for longer shots.

If I get the Burris and shoot past 500 I was thinking I would just load the ammo to the BDC specs. Just my thinking,,,,

After a bit of a fight getting my loads to run, In my LR-308.. I now use a Redding full leangh Small Base die. And the gun runs fine.

The best group I have shot is .531 at 200 Maybe lucky, last weekend I shot a .971 at 200 with a little wind blowing.

Jim M ammo

Why so many different loads? Why not pick one load that works for everything?

The 155's will only shoot inside the 175 when driven fast enough. When you run a shorter bbl you need a little faster powder to get the velocities up before you run out of tube. H4895 will get you more velocity out of an 18" tube every single time when compared to Varget or Re15. Been there done that. Re15 is a little slower and better suited for the heavier .308 bullets. It's also quite temperature sensitive, which is a moot point under 600 yards. Play around on a ballistics calculator and see which bullet wins. You can get the 175 to 2575 reliably and it shoots decent in that velocity range. You can get the 168 to 2700, and you can get the 155 to 2800.

As for loading to match a BDC reticle beyond 500 yards, that is going to get rather pricey. BDC reticles work in one area with one set of atmospheric conditions. If you change altitude, humidity, or temperature, your reticle is no longer accurate. Let's look at the reticle itself... did they use a 175gr bullet? Did they use a G7 drag function or a G1? Where did they create the reticle? Was it 4500' ASL?

There's nothing wrong with getting a reticle with subtensions that are a known measurement. Your BDC reticle is an unknown, and probably not the wisest route. Know your come ups for your rifle at distance and learn to hold using the MOA or Mil marks in the reticle. It's not at all hard to do. Trying to match a load to a BDC reticle beyond 500 yards can be quite hard though.

175 SMK @ 2575 = 16.9 up at 600 with 5.3 of wind

168 SMK @ 2700 = 16.0 up at 600 with 5.7 of wind

155 Palma @ 2800 = 14.8 up at 600 with 5.5 of wind

I had an 18" AR-10 for a while. Tried and tried to make it do something it wasn't meant to do. My shooting begins at 600 yards. Inside of that and I'd just use a 223 with the 77gr SMK. Just my opinion, and probably worth what you paid for it.

All good advice,, thank you,,

Why not one bullet,,?? cost,, no need to piss away a match bullet on targets under 300 in a 3 gun match.. I'm shooting the LaRue match, and might shoot out to 500 for that,,If I make it to the RM3G this year, that will be the other time.

My chances to shoot past 500-600 are very limited.

but I would like to have a good chance to hit something,, if I were to give it a try.

Jim M ammo

[steel1212]

So what would the cost difference be between your hoser loaded ammo and the long range stuff for just that match? I use MG 55 FMJBT because we don't shoot out past 200 yards around here. If I was to shoot some of these bigger matches I would buy a K or so of some really good bullets to shoot out at distances with. Your talking what may be 50 bucks or less for a bullet swap for a match?

Edited February 24, 2010 by steel1212

[M ammo]

So what would the cost difference be between your hoser loaded ammo and the long range stuff for just that match? I use MG 55 FMJBT because we don't shoot out past 200 yards around here. If I was to shoot some of these bigger matches I would buy a K or so of some really good bullets to shoot out at distances with. Your talking what may be 50 bucks or less for a bullet swap for a match?

I'll have to look them up and do the math,, again,, I do like the 155's they will probably do eveything I want them to do.

I still have a scope with a BDC on my mind.... I would just have to load them to match as well as I could,, I know I can get them pretty close.

Jim M ammo

[smokshwn]

I think you are putting too much stock in the BDC reticle.

You only have to get close with the loading to match the reticle as there will be many variables on any given day.

Also when you start to factor in all the variable conditions the reticle will have a margin of error anyway.

You could easily just find a load that your happy with and then shoot it at the corresponding BDC distances and adjust from there.

[twodownzero]

Thanks for the great info,,

I plan on using The rifle for 3 Gun for the most part, With the wind at the RM3G last year on that Long range stage,, the heavier bullet would have been nice.

Trapr """"looking at using it for LR competitions""" I'm interested in more info on,, those type of competitions as well…

I looking at the Burris XTR in 7.62 it has the BDC for a 175 SMK at 2600

Right now I'm loading some 150 Rem PSP's for the under 300 stuff.

And 155 Nosler Comp's for longer shots.

If I get the Burris and shoot past 500 I was thinking I would just load the ammo to the BDC specs. Just my thinking,,,,

After a bit of a fight getting my loads to run, In my LR-308.. I now use a Redding full leangh Small Base die. And the gun runs fine.

The best group I have shot is .531 at 200 Maybe lucky, last weekend I shot a .971 at 200 with a little wind blowing.

Jim M ammo

Why so many different loads? Why not pick one load that works for everything?

The 155's will only shoot inside the 175 when driven fast enough. When you run a shorter bbl you need a little faster powder to get the velocities up before you run out of tube. H4895 will get you more velocity out of an 18" tube every single time when compared to Varget or Re15. Been there done that. Re15 is a little slower and better suited for the heavier .308 bullets. It's also quite temperature sensitive, which is a moot point under 600 yards. Play around on a ballistics calculator and see which bullet wins. You can get the 175 to 2575 reliably and it shoots decent in that velocity range. You can get the 168 to 2700, and you can get the 155 to 2800.

As for loading to match a BDC reticle beyond 500 yards, that is going to get rather pricey. BDC reticles work in one area with one set of atmospheric conditions. If you change altitude, humidity, or temperature, your reticle is no longer accurate. Let's look at the reticle itself... did they use a 175gr bullet? Did they use a G7 drag function or a G1? Where did they create the reticle? Was it 4500' ASL?

There's nothing wrong with getting a reticle with subtensions that are a known measurement. Your BDC reticle is an unknown, and probably not the wisest route. Know your come ups for your rifle at distance and learn to hold using the MOA or Mil marks in the reticle. It's not at all hard to do. Trying to match a load to a BDC reticle beyond 500 yards can be quite hard though.

175 SMK @ 2575 = 16.9 up at 600 with 5.3 of wind

168 SMK @ 2700 = 16.0 up at 600 with 5.7 of wind

155 Palma @ 2800 = 14.8 up at 600 with 5.5 of wind

I had an 18" AR-10 for a while. Tried and tried to make it do something it wasn't meant to do. My shooting begins at 600 yards. Inside of that and I'd just use a 223 with the 77gr SMK. Just my opinion, and probably worth what you paid for it.

All of that would make sense if not for the new 155 grain bullets, which have essentially the same ballistic coefficient as 175s and the capability of being launched 200 FPS faster to boot.

The 155 grain Lapua Scenar or Sierra Palma (PN 2156) will shoot circles around the 175.

People don't want to admit it, but the 175 grain Sierra was obsolete the day that these bullets hit the market.

Now if they can figure out a way to make a 175 grain bullet that has a G1 BC of .520 or more, the discussion may change. I highly doubt such a bullet would be short enough to fit in even the longest .308 magazines without being seated so short that it eats up too much case capacity, though.

My experience with Varget in .223 has not verified your "faster powder" argument, either. I have not found a powder that will push 62 grain bullets faster in any length barrel than Varget. Perhaps I haven't pushed the pressure envelope far enough with the faster burning powders I've tried, but my experience is that Varget will even push 55s faster than enough H335 to make for some pretty shiny ejector marks and not-quite-flat primers, which is where I stopped (well beyond any modern book max, but 20 years ago a load like this was common in a loading manual, because I have one).

Perhaps your experience with .308 doesn't parallel with my experience in .223, but I can honestly say that the powder which produced the most velocity in a 20" also produced the max velocity in a 16", of course with more blast and noise. That powder, of the ones I've tried, was Varget, and Varget is (I believe anyway) the slowest burning powder I've used in .223. I suspect that all of the powder was burned before 16" of barrel length and so it didn't matter. Perhaps the same is not true of a .308 with its larger powder capacity.

I do find it interesting on how we all load, chrono, and shoot, and result in different conclusions given (essentially) the same controls and variables.

[kgunz11]

I have not loaded for the 223 as much as I have the 308, but lets try to get a fair comparison here. Due to bore diameter and case volume, a 308 with an 18" bbl is akin to a 223 with a 12" barrel.

Muzzle velocity is directly affected by pressure built up in the chamber and bore. In a short barrel, you need to utilize that minimum length of bore to build up that pressure quickly so it can efficiently be utilized. A faster burning powder lets you achieve this with full powder burn. A slow powder will throw a flame out the muzzle due to powder not being burned. If you shoot a can, it's not uncommon to shake unburnt kernels out of the can after shooting if you're powder is not optimized for your barrel length.

In an 18" 308, H4895 will provide more MV than Varget with equal chamber pressure because you have complete powder burn which develops optimal pressure through the entire length of the barrel. With a longer barrel, this relationship changes because the Varget continues to burn further down the barrel which continues to build pressure.

You can always get more velocity out of a longer barrel than a shorter barrel.

You can have more efficiency out of a shorter barrel using a more optimized powder.

62gr bullets in a 223 are a medium weight bullet, as the 168 is in the 308.

I'd wager I can send a 52gr bullet faster out of an M4 length bbl (14.5") with a faster burning powder than you can with Varget.

Don't get me wrong, I LOVE Varget, but in my 20" 308 HD Rifle I use H4895 for F class shooting at 600 yards with the 155's. Varget can't beat it. In my 26" 308 for 1000 yard and UKD shooting, I use the VLD's with Varget. H4895 can't match the Varget in the longer barrel, and I'm using the same bullets/brass/primer in both guns. Your mileage may vary, this is just information I have collected with my limited reloading and shooting.

[twodownzero]

I understand the theoretical basis for what you're saying (shorter barrel needs faster powder because it doesn't have room to burn the slower one), but my (empirical) experience in .223 has shown that not to be the case.

I do have some H4895. I should run that same test in 3 different length .223 barrels and see what the results are.

If what you say about an 18" .308 being like a 12" .223 barrel, the assertion that a faster powder should be necessary may be correct. I've only tested 20" and 16" .223 barrels. My .308 is a 24".

[kgunz11]

I'd be interested in your results so please share. Considering the 223 and the 308 share many of the same powders, also keep in mind the bore diameter, bullet weight, and case volume. Case volume and powder charge are reduced by almost 50% in the 223 as compared to the larger 308.

[bigbrowndog]

Jim, since you are simply looking for a 3 gun load, there really is NO!!!!! need to subject yourself to the recoil impulse of a 175gr bullet. I shoot the SMK 155 Palma and really have no need for any other bullet, for my precision loads. However I am actually looking at going to the 135 SMK, in an effort to reduce the recoil impulse, and lower the mid range trajectory. I push my bullets at what most would consider low velocity considering the max. velocity capable with that bullet weight, but the trajectory is flat enough and accuracy is good enough, and the load is very easy to shoot and recover from.

I think you have fallen into the trap, that so many others have fallen into,.............You are too concerned with one or two targets in a match made up of a hundred or more. The extended distance targets, exist once or twice in a match, and do not deserve the bulk of your attention, you should be focused on the normal long range, mid range and hoser distance targets, that make up the match. You should know where to aim at them to increase your chances of hitting them, but do not spend too much time on them. As for wind effect, I have NEVER had to aim off of a target left or right because of wind, with a .223 much less a .308.

Trapr

[kgunz11]

Hey Trapr, I have a guy here locally shooting the 125gr ballistic tips at 3400fps using H322. Should be a pretty flat shooting load that would be great out to 400 or 500 yards.

[bigbrowndog]

I thought about the 125NBT, 3400 fps is way faster than i need to push it, I'd be happy with 2900 or 3000. for 3 gun my preference for trajectory is a mid range high point of 6" max, with a 250ish yard zero, and then click up or flip the aperture for 350ish. So I can still hold 6 oclock on plates and hit all the way to 300, its easy to crawl into a plate and actually be 1 to 3 inches into it without realizing it, so even with 10" plates you should still be able to get a hit if that happens.

trapr

Edited February 25, 2010 by bigbrowndog

[Religious Shooter]

This thread shouldn't be in Precision Rifle.

[bigbrowndog]

lets not start talking about what should and shouldn't be here!!!

trapr

[benelli2]

"One time at Band Camp"............

[bigbrowndog]

shouldn't that read,........."one time at the pre party"???????????

trapr

[M ammo]

I thought about the 125NBT, 3400 fps is way faster than i need to push it, I'd be happy with 2900 or 3000. for 3 gun my preference for trajectory is a mid range high point of 6" max, with a 250ish yard zero, and then click up or flip the aperture for 350ish. So I can still hold 6 oclock on plates and hit all the way to 300, its easy to crawl into a plate and actually be 1 to 3 inches into it without realizing it, so even with 10" plates you should still be able to get a hit if that happens.

trapr

I guess I'm just thinking,,, out loud in this thread..

trapr,,, your right,, and the 155's will do what I need them to do,,, even if I try and play past 500.. Up at Sheldons.. I was getting,, head hits on their LaRue size target,at 500,. I looked up the BC on the the 155SMK and the NOS Custom Comp 155.. they were the same,, I didn't look up the Palma,, right now I have the Nos 155 going 2648 with a 200Yd zero They work for me, I don't know what the LaRue match will bring this year,, range wise,, but I will be ready.

I have 100 175 SMK's I have RL-15,, Varget and 4895,, I will do some tests to see what I can get them to do,, Just so I will know,,

Jim M ammo

[HiCapMag]

Lots of good advice here.

I have always wondered how the 110 gr vmax would work as a three gun load in Heavy Metal. I have read of a number of people that get excellent accuracy out of 1-10 to 1-12 barrels and I wouod think the recoil would be greatly reduced compared to 155-175 bullets. Maybe not a good load at long range, but worth an experiment.