.308Win Reloading Delima - Help

[NC308]

I have found that the 175 smk is not very sensitive to seating depth. My best loads are loaded to 2.800" and 41.7 grs of IMR-4064 in lapua brass and 42.2 grs in Win brass all CCI BR2 primers. This is the military duplicate load that I have shot numerous times to 1000 yards with no issue. Velocity is around 2550 in a 26" 12 twist barrel. Also 43.5 of varget shot about the same for me....
This bullet is by far the easiest bullet I have got to shoot. I will also add that these loads are jumping .160! (longggg throat Remington chamber). So main thing keep seating depth consistent until you get you powder charge close then fine tune with seating depth, then fine tune powder, then tweak seating depth, then again and again it seems like!! Just stop when you are satisfied with the accuracy. You can shoot the barrel out of a gun just chasing that magic load!

 

[J. Gunz]

I shoot 175 smk out of a factory Remington 700 barrel 20" with 1-10 twist. My load are 44 gr varget with an OAL of 2.810 or magazine length. It shoots .48 5 shot groups prone off a bipod. Same load shoots .42 out of a friends accuracy international. Like others have said 44 gr varget is an accuracy node

 

[Rharris]

A few years ago I did something similar to the OP. I just was getting into "accurate shooting" and the required reloading disciplines. I was not fully aware of all the affects of case volume. I learned that lesson first hand. I had worked up a stout (read as over book) load of Varget with the 168 in my Remington 5r, with the bullet just off the lands. Long throat. By my memory, my COAL was 2.96ish. They wouldn't fit in my mag and I got tired of single feeding so I took 50 reloads and "just" pushed the bullets in to 2.8 and went to the range. The first shot locked up the gun, but it held together. I got it open back at my shop with a rubber mallet and a short piece of 2X4. I stuck my nose back in my books and read every post I could find on case volume as it relates to pressure.

Joshb, that is a piece of the puzzle that I have not given the necessary attention. Same thing was pointed out on another forum specific to the FC cases I had used to which I was told that I should consider a lighter/larger capacity case like Lupua. Thanks for confirming that I need to consider this factor.

 

[Rharris]

The 43 grains of Varget what works so well for the 168 gr. SMK is a half grain under the listed maximum charge weight shown in Sierra’s latest manual. That same 43 grains when behind the heavier 175 gr. SMK is 1.3 grains over the listed maximum charge weight and so may well be ‘too hot’ for the heavier bullet. Back down on the charge weight to ‘bout the middle of Sierra’s listings for the 175 gr.SMK. Begin at maybe 38 or 38.3 grains of Varget and work your way back up again, increasing the charge weight using 0.3 grain increments.

Freak, you really blew my mind when you said I was loading over Max! I went back to check the Hodgdon reloading data and it states 45gr is Max. I did find Sierra load data on-line and YOU are right based on their newest info! From now on I am going to consult 3 sources before I commit.

 

[Rharris]

I shoot 175 smk out of a factory Remington 700 barrel 20" with 1-10 twist. My load are 44 gr varget with an OAL of 2.810 or magazine length. It shoots .48 5 shot groups prone off a bipod. Same load shoots .42 out of a friends accuracy international. Like others have said 44 gr varget is an accuracy node

J.Gunz, you have obviously a load that produces solid results. Question: as someone else pointed out the max load in Sierra's new edition states 41.7gr Varget. Are you seeing any over pressure signs loading 44gr? I have always respected published max loads and chrono every new load I try. Example: my 43gr of Varget averaged 2572fps which is in line with spec. Just wondering which data book is correct and could case volume (as mentioned by others) be the variable that I am missing. Thoughts?

 

[joshb]

Freak, you really blew my mind when you said I was loading over Max! I went back to check the Hodgdon reloading data and it states 45gr is Max. I did find Sierra load data on-line and YOU are right based on their newest info! From now on I am going to consult 3 sources before I commit.

I'm glad you took my comment in a good way. I thought I might have been too harsh with my comment, but I wanted to get across the fact that reloading can be very dangerous and must be approached with caution. I presented my personal story to let you know you're not the only one to do something "stupid". Understanding what is safe and what is not is paramount. I repeat this thought every time I sit down to put loads together: "You are making an explosive device that you are planning to set off mere inches from your face" Keep that in mind.

 

[J. Gunz]

J.Gunz, you have obviously a load that produces solid results. Question: as someone else pointed out the max load in Sierra's new edition states 41.7gr Varget. Are you seeing any over pressure signs loading 44gr? I have always respected published max loads and chrono every new load I try. Example: my 43gr of Varget averaged 2572fps which is in line with spec. Just wondering which data book is correct and could case volume (as mentioned by others) be the variable that I am missing. Thoughts?

I think your brass case volume is one of the factors as to why a charge could show over pressure signs. I use Winchester brass that has more case volume then, say Lapua. 44 gr of varget in a Winchester case may not show any sign where as in lapua it might, given its smaller case capacity. With this load I don't see any over pressure at all. A factor of that might be my seating depth. Generally the manual will give you a spec that will load safely in most chambers with out an issue. I seat mine out further then that depth, thus decreasing the pressure in the case because it now has more room. You also need to remember that if you have it touching the lands it could also increase pressure signs. For the most part I seat all my bullets at mag length and build my charges up from there. I also primarily use SMk that are very jump tolerant.

 

[J. Gunz]

op,,,shoot a few of the proven loads again and see if they still work well,,,maby your scope went bad or bedding ,,,check action screws,,,etc,,,,Roger

That a good point. I shot some 250 smk that I worked up a couple months ago and know that they shoot 1/2 groups at 100 yards. Well I had taken my scope off for whatever reason and put it back on before shooting. When I got to the range I went to zero the rifle. Well after shooting about 15 rounds getting wild groups. I was furious and decided to pack up and go home. Well whenbdoing that I picked my rifle up and the butt stick of my sako tag 42 fell off. Well I put it back in and tightened the Allen screw back up. Guess what...1/2 groups again. Did the OP state if he has shot that far before? Or has he shot a factory bullet that did better out to that distance? Just to decrease the variable of shooter error?

 

[Rharris]

That a good point. I shot some 250 smk that I worked up a couple months ago and know that they shoot 1/2 groups at 100 yards. Well I had taken my scope off for whatever reason and put it back on before shooting. When I got to the range I went to zero the rifle. Well after shooting about 15 rounds getting wild groups. I was furious and decided to pack up and go home. Well whenbdoing that I picked my rifle up and the butt stick of my sako tag 42 fell off. Well I put it back in and tightened the Allen screw back up. Guess what...1/2 groups again. Did the OP state if he has shot that far before? Or has he shot a factory bullet that did better out to that distance? Just to decrease the variable of shooter error?

J.Gunz - Interesting and my initial thought was to check scope to make sure all was secure and it was. I have shot factory loads out to 600 yards with this rifle that did a good job, but know developing the right loads can show an marked improvement. This was the first time to shoot reloads beyond 100 yards. My first mistake was not shooting known 100 yards that printed 1/4 MOA at 300 to see how they would hold up. Had some 175gr and thought I would begin to develop a heavier bullet for longer distances.

Since my initial post I have picked up a lot of valuable information and appreciate the level of detail that all have provided. I've been reloading for a long time, but this is the first time for rifle which is far different from pistol and shotshell. The science involved is amazing and to be honest, I'm having almost as much fun reloading and prepping cases than shooting! I have just purchased a new scope which I set up this weekend so I'm going back to my 100 yard load to re-validate after I get scope sighted. Once accomplished, I will go to 300 with same load and see where I am and determine what if any changes need to be made. After reading posts, I'm hopeful that I can keep Sierra 168 MK out to 600 before needing to go heavier. At this point 600 is my clubs longest range anyway.

Thanks to all for your help.

 

[Nature Boy]

The best at long distance load for my FN SPR has been 43g of Varget with 175g MKs, Lapua brass, 210M primers and an OAL of 2.800. This load produces 2,650 FPS and single digit SDs. This weekend I was pounding an 18" steel target at 1K with almost boring regularity.

Interestingly, it's not my most accurate load at 100 yards, producing 5 shot groups between 0.6-0.7 MOA. My most accurate at that distance has been 168g VLDs, 44g of Varget and netting 5 shot groups in the 0.3 MOA range. For some reason though, that load doesn't hold up at longer distances. At 500 yards its 2 MOA at best and it's really hit or miss at 1k

 

[boltgunluvr]

Well, just when I thought I was headed down the right road. Here's the problem - I have been working up 100 yard loads for .308 and settled on Sierra 168gr MK, 43gr Varget, CCI 200 with a .005" jump. .....................

Like another poster said, stay with the 168 SMK and load to mag length or 2.8-2.810 COAL. SMKs love to jump. You won't go wrong with Varget or IMR4064. What twist do you have?

 

[Robert405]

You might also consider your trigger...sometimes what looks good at 100 can be exaggerated as you move to longer ranges...

That is usually the hardest part to accept!

 

[GrimmRuper]

I have or had the same gun, my best load was with IMR-4064, 175 SMK, Lapua cases, anywhere between .013"-.018" jump. I want to say it was 43.2gr but not sure.
168's won't stay stable after 300ish yards.
Water fill case sorting. Usually shot 8-10 X's with that formula at 600yards, and I ain't that good a shooter.

That's my formula, switched the 308 barrel out for a LRI 6.5 creedmoor, in load dev now. If you ever need a barrel for your .308 let me know mine only has "just barely" visible vice marks on it trying to get that damn barrel nut off, LOL.

 

[Comrade Terry]

168's won't stay stable after 300ish yards.

I don't know why you say that. I've had excellent results with 168 TMKs at 600 yards. Like five rounds at <1.5" worth of success.

 

[Ggmac]

I have or had the same gun, my best load was with IMR-4064, 175 SMK, Lapua cases, anywhere between .013"-.018" jump. I want to say it was 43.2gr but not sure.
168's won't stay stable after 300ish yards.
Water fill case sorting. Usually shot 8-10 X's with that formula at 600yards, and I ain't that good a shooter.

That's my formula, switched the 308 barrel out for a LRI 6.5 creedmoor, in load dev now. If you ever need a barrel for your .308 let me know mine only has "just barely" visible vice marks on it trying to get that damn barrel nut off, LOL.

168 not stable after 300 yds ?????? Maybe , but it's way after 300 yds , like 500-600 yds AFTER .

 

[spclark]

168 not stable after 300 yds ?????? Maybe , but it's way after 300 yds , like 500-600 yds AFTER .

Sierra designed their 168SMK for 300 meter shooting competition. Farther than that it's a €rap$hoot if they work or not. There are so many fine 308 mid-weight bullets out there that can do better (2156'd be my choice out to 600 - 1,000 yds) 168's ought to be collecting dust on the shelf.

 

[284winner]

Was hoping that Eric would weigh in on this conversation. He seems to have a pretty good fix on the 308. I'm no expert by no means but 175s did exactly the same in mine. Went to the 168s and suddenly, perfection. Never heard the 168s were not designed for 600 yards tho. In fact, I heard just the opposite. At 1000 they are inferior to the 175s is what I've read. At 600, they were said to be as good as the 175 depending on some variables. Hard to argue with the bullet Smith's at Sierra tho. At any rate, my experience mirrored the OPs. Sticking with the 168s and they do shoot lights out at 600 in my gun.

 

[Ggmac]

Sierra designed their 168SMK for 300 meter shooting competition. Farther than that it's a €rap$hoot if they work or not. There are so many fine 308 mid-weight bullets out there that can do better (2156'd be my choice out to 600 - 1,000 yds) 168's ought to be collecting dust on the shelf.

Yes , but unstable , no .
Unstable is a byproduct of velocity and twist . Personally I liked the 155 , which was designed , well for Palma shooting , but there are still better bullets .

 

[spclark]

http://forum.accurateshooter.com/threads/168-vs-175-vs-180.3898316/