175 SMK and groups

[Sticker]

Hi Gang

I have a little problem,

I have been shooting two types of bullets in my .308 rifle, the 168 grn SMK and the 175 grn SMK

with the 168, my powders are 42.0 of IMR 4895 and 43.5 of Varget. Both loads shoot sub MOA. Usually 4 rounds in one hole and one stray to mess up the group a bit ( another question comming up)

With the 175 I load 43 grns of Varget. Now I do get a really good group now and again, but for every good group, I get a crappy group as well. Always get a decent group with the 168.

My barrel is a 5R 1 in 11.25

Does anybody else have similar problems? Ideas?

Also when you shoot a group, do you shoot 3 or five rounds? I usually shoot 5 rounds, and like I said, 4 in one hole and a small flyer to screw it up.

 

[Obtunded]

Are your results the sum of full load evelopment? (seating depth, powder loads?)

For load development I shoot 3 groups of 3 for each depth and each powder load to be sure. It's sometimes impressive what seating depth a couple of thou one way or the other can do. I figure three rounds (especially if they overlap) is plenty to tell me that the load works.

 

[maynard]

Are you seating these bullets out to the lands or close to it or are you loading to an overall length? The ogive of the 168's and 175's are not the same. Just remember the 168 was designed for 300m ISU shooting back in the 60's and is not the best long range bullet.
I usually like to shoot 10 round groups just because that is usually the number of round fired in a match. I would hate it if the first 3 round touched then the 4th to 10th shot hit 2 MOA out of the group.
3 shot groups are OK for a hunting rifle. 5 shot groups will at least let you find out what doesn't work.

 

[Rohann]

Not sure if this is a factor at all, but when group testing, let 1-2 minutes between shots to let the barrel cool down.

-Rohann

 

[Sticker]

Hi Again

I load to a cartridge OAL of 2.8

175 might be a better long distance bullet in the ballistics charts, but the 168 is more reliable for me at the range at this point and time.

 

[Obtunded]

Hi Again

I load to a cartridge OAL of 2.8

Where is the seating in relation to the lands? I suspect 2.8 is way off the lands in a factory barrel. From my own experience I'd start with 5 thou of jump and work longer from there.

 

[RePete]

I load my 168's to 2.800". I tried all other seating depths, and found that 0.010" off the lads was OK, 0.020" was horrible, 0.030" was good and 2.800" OAL was as good.

I used to use H4895 but am now using RL15.

 

[Obtunded]

I never got 168's to work worth a damned in my gun, but when I went to 178 A-Max's I could not believe the difference, and I soft jam them too. Whooda thunkit...

FWIW I have an OAL of 2.96 with the A-max's...

 

[mpwolf]

How are the pressure signs with 43 gr. of varget behind the 175s? It seems like a really light charge. I'm running 44-44.5 in a really short palma chamber. I know of others running quite a bit more than that. Seating depth doesn't seem to have much effect on the 715's in my experience, but it's worth trying to seat a bit longer.I havn't bothered trying 168s in my rock 11.25 tube, but 175's simply shoot light outs.

 

[prosper]

I've never really had much luck with 168's in general and SMK's in particular, they seem quite picky. What ranges are you shooting at?

 

[Sticker]

How are the pressure signs with 43 gr. of varget behind the 175s? It seems like a really light charge. I'm running 44-44.5 in a really short palma chamber. I know of others running quite a bit more than that. Seating depth doesn't seem to have much effect on the 715's in my experience, but it's worth trying to seat a bit longer.I havn't bothered trying 168s in my rock 11.25 tube, but 175's simply shoot light outs.

Hi

I would be a cautious running more then 43.5 in my barrel. I was getting a squished primers with the 175SMK and groups were worse then they are now. And with 165 SBT I use 44 grns and it's flat enough. Although I keep reading that Varget works better if you push it.

For the other question: 168s shoot great in my barrel, very consistent. I wish the 175 would be so consistent in grouping. I get one group where all five shots can be hidden behing a 5 cent piece, then the next time I try to group I get five individual holes. Always get a cluster with the 168.

I have a box of federal match 175 on order. It will be interesting to see how they shoot in comparison.

I have not had an opportunety to shoot past 300Y

 

[p-17]

Not all rifles like all bullets, even super accurate ones.

I'd recommend that you give the 178 A-MAX a try.

I'd also recommend that you try at least one other powder. I know that Varget is the best overall powder in the .308, but the standard military long-range sniper load uses something like 44.5 grains of Reloder 15 with the Sierra 175. Other powders to try include Vihtavuori N540 and N550.

I'd be shocked if one of these combinations did not work out really well.

Your barrel should be fast enough to stabilize 175-grain match bullets at .308 velocities.

 

[mpwolf]

10-4 on the change weight. Give P17's advice a shot- Reloader-15 definatly has a following. I'm starting to understand just how lucky I was to have the first load I tried produce such good results....