.308 mag length or single load?

[CharlieHo]

Bought a pound of Varget a whle back to try. Haven't been satisfied with IMR4895 under 168 SMK in my Rem SPS Tac.

Considered trying the ladder method, seems a great savings on components.

I came to the unfortunate realization that I cannot load long enough to get close to the lands without single loading. I can only go ~2.825" and stay in the mag, I need around 2.95" to reach the lands +0.010".

I have a decent enough load I've been using on groundhogs and regular plinking that are mag length,but, I'm always searching for that one hole group.

How many here would abandon the ability to load the mag just to find that perfect load?

I suppose I could just have two differ loads for the same rifle...

 

[azimutha]

Re: .308 mag length or single load?

You can also vary the powder charge and/or try bullets that lend themselves well to seating @ mag length. Out of two Remingtons with factory throats, I've had good luck with the new(ish) Berger hybrid 175gr OTM, for instance.

 

[nfoley]

Re: .308 mag length or single load?

I have a long throat in my remington 700 as well, felt the length I needed to get close to the lands was too impractical. Instead tried different bullets and powders/charges. I tried SMK in 155, 168, and 175 as well as Amax 168. Didn't take too much to get a load I was happy with. Varget worked great for me as a powder choice. I would recommend changing those variables before loading them so long as to make your rifle a single shot.
What kind of accuracy are you now getting, and what is your goal?

 

[Gene Poole]

Re: .308 mag length or single load?

Loading close to the lands is nice if you're a bench-rest shooter, but for practical plinking, you want to find a powder charge that works with your barrel harmonics, then fine-tune it with seating depth. It doesn't so much matter how close you are to the lands as it matters where the bullet exits the barrel with respect to the predominant barrel harmonics. Using OCW, you can find a charge weight that works with your barrel harmonics, then fine-tune it with seating depth. Again, the depth is just a fine-tune. You can be closer or farther from the lands with your seating depth, but it only matters what the end of the barrel is doing in its harmonic cycle when the bullet exits the barrel that determines how it is going to group.

 

[Beef82]

Re: .308 mag length or single load?

Seat to mag length. I've managed a couple ragged hole 3 shot groups that way, and a few four with the fifth 1/4" off. I only tried a few SMKs, the 168 Amax does very well in mine handloaded, even the factory loading, not the superformance.

 

[CharlieHo]

Re: .308 mag length or single load?

Mag length it is then.

I suppose I can still use the ladder method without jamming the lands, just be diligent when adjusting seating depth later on.

FWIW, my goal is 10 shot one hole groups. Isn't that everyone's?

I'm currently getting around 3/4" 5 shot groups, which doesn't look too bad @ 100 yds, but @ 200 yds look terrible. Ten shot groups open up to around 1-1 1/4". I know it's obviously going to double @ 200, but, it still bothers me.

I can get three shot one hole groups with a Daisy Red Rider. I usually shoot at least seven for a group, oftentimes ten, occasionally only five if I'm working with a known good load. Anything less, I believe you're kidding yourself.

Thanks for the thoughts!!

 

[azimutha]

Re: .308 mag length or single load?

I've done ladder tests first varying charge weights (in .3 grain increments) and then tweaking seating depth a few thousandths on either side of OAL for the best load. I found that didn't make a difference, nothing like the change in powder charges.

 

[CanSniper]

Re: .308 mag length or single load?

Seating depth will make a more drastic change the closer you are to the lands. I personally dont mind single feeding my bolt guns, and prefer the added flexibility in the load development. I dont know, can you even get a 168 that long?

 

[Deadshot2]

Re: .308 mag length or single load?

My Remington has a real long jump as well. I've found that longer OAL's actually hurt the accuracy in my gun. By varying the powder charges, varget with 168's and 175's, I was able to find accuracy nodes for each just using 2.800 as an OAL. Using Nosler Custom Comp's and Hornady a-max I have had groups from my 5-R Milspec as small as .190" with the average in the .250-.280" range. (100 yards). Unfortunately, I've found that Varget doesn't like temperature changes.

On that note has anyone tried IMR-8208BR? According to the "press" it's supposed to be less temperature sensitive than Varget with similar loaading weights.

 

[jagged77]

Re: .308 mag length or single load?

CHarlieHo, its a factory Remington so lets me honest you are going to be lucky to get it to shoot 10 shot half MOA groups every time out. That's not to say it never will but realistically if you are demanding that level of accuracy go and have a word with GAP or one of the other reputable smiths here.

Seating 168 SMK's at 2.82" COAL has produced the most accurate results for me in my SPS Tac, however its a slow load - 43grains N140 doing just under 2500 FPS.

 

[targaflorio]

Re: .308 mag length or single load?

Seating the bullet out long also increases case capacity, which may allow you to use more powder. Most advice I get is to stay with SAAMI spec, mag length, etc., and the 308 is a great cartridge for shooting well without being finicky about bullet jump. (btw Bryan Litz wrote a good article arguing that most of us are shooting 30 caliber bullets that are too light.) My throat is short, so I'm at the lands running mag length now, but I'm seating my 300 win mag long and going with bigger bullets. I don't mind feeding the rounds. Most of my shooting is stationary, prone.

 

[2clicks]

Re: .308 mag length or single load?

100 yrds

I've had gap put a sure fire brake on my sps 20" .308 barrel traded out the floppy hogue stock for a McMillan. You can see the 8 shot group is decent I never could get this from the factory setup so... I think it was worth the effort. I load at 2.800 oal every time no time for jackin around with long seating unless its with 80 gr223.

44 grs varget 168 amax win brass & win primers.

It's a little slow about 2550 I'm going up .5 hopefully it will match my M3 turrets then.
One thing I love IMR4895 there's no doubt in my mind I could get the same results with that powder. Only reason I used Varget is cause my buddy gave me his #1 he couldn't get to shoot I don't think he tried hard enough...

As with all powders in this category Rl15, IMR4895, win 748, varget they will all shoot as good as the next some are just more or less affected by temp.
Just one guys experience Ymmv....

 

[nfoley]

Re: .308 mag length or single load?

that's some fine shooting 2clicks!!

 

[hamstur]

Re: .308 mag length or single load?

IMR4895 behind 168BTHP has become my go-to general load after growing dissatisfied with Varget. Varget works great for me for customized loads behind 175s. Just wanted to verify it has nothing to do with your process...and not intending to insult you in case you're an experienced loader, but:

- What's your recipe? Charge, brass & primers.
- What dies?
- Measuring each charge?

FWIW ... my go-to above is Win brass, 2.005 trim, 168 BTHP, 43.5 IMR4895, GM210M primer, 2.820 COL. Full prep using Redding Type S either direct neckdown with 330 bushing, or two-step 0.337 to 0.330.

 

[2clicks]

Re: .308 mag length or single load?

Fwiw my favorite 4895 load....
I realize its not a smk bullet though

168 Amax
43 grs IMR 4895
Winchester brass & primers
2.800 oal
Brass tuned up to include pockets uniformed and deburred

Near zero vertical on 600 yrd ladder test out of my 700p haven't tried it in this 20" .308 yet It's next on the to do list.

 

[hamstur]

Re: .308 mag length or single load?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 2clicks</div><div class="ubbcode-body">
Near zero vertical on 600 yrd ladder test out of my 700p haven't tried it in this 20" .308 yet It's next on the to do list. </div></div>

Hey 2clicks, just in case it helps, the extra 0.5gr for me came from performance out of two 20" 1:11 twist rifles (Sako TRG and Tikka Scout). My 23" 1:11.25 ideal range was 43.0 to 43.6. Since 43.5 was in the range, I decided it was close enough to make my 'general' load.