AX 308 180 SMK

[Chanonry]

Ok, I have had an AX for a couple of years. Initially I bought some Hornaday Tap 168gr ammo. I reloaded to a similar load and the groups closed up from a bit less than 3/4 moa to a shade under 1/2. Not off a rest and I am no hot shot so I was happy with that. No fiddling or optimising, just a straight bullet with a load slightly below book max.

 

I changed loads to 180gr SMK with Reloader 17. I am filling the case !

 

What I then found was that I could replicate the tight group with the brake but when I put on the mod the groups opened up to 2 moa ish. I think baffle strike - no evidence of this at all. Clutching at straws maybe its dirty. Good clean. No difference.

 

Ran out of RL17 so I bought some Elcho 17. I went to a pipe range this weekend and I think the technical description is 'crap'. 1 moa at 100m. Lots of vertical very little horizontal. Put the mod on and the group tightened a bit but still not AX standard.

 

This melted my head as I had been reloading for a Sako 75 Varmint for years and groupings did not change with or without a mod and it didn't seem to really care about bullet weight or specific loads. It just shoots. Close to 1/2moa at 100 prone no matter what components. So I had 308 down as real easy to load.

 

There may be a couple of things gong on here that I need to untangle??

 

I find myself having to deal with what sounds like a load my rifle does not like? So I am probably being a bit bullish with the charge weight. The vertical suggests a poor node or variable muzzle velocity ?

 

The precision shift suggests a change in barrel harmonics? But that is counter to my (relatively limited) experience.

 

I think I will have a rake about in the ammo cabinet and see if I have any 168gr heads left so I can go back and reproduce previous results. At the same time I could back off the E17 but it is less than the max load for RL17 so not convinced that is going to take me anywhere I want to go. I didn't think that the step to 180gr would produce a problem, as the Sako never noticed. A learning experience I guess. Pain.

 

Lots of rambling. Thoughts??

 

A

 

 

 

 

[6.5Grendel]

Is the barrel twist fast enough for 180g bullets?

Probably need a 1 in 11 for 180s. I dont know what your ax has.

[gbal]

If you can,duplicate the 168 once good load,if it still is as good....good! If not,something else has changed...

 

Sometimes a rifle just does not like a particular load,or several bullet/powder load combinations.Just change-if you want long range performance-the switch to 180s suggest that-there are other options.

 

Do not assume Sako performance is reliably replicated elsewhere (even,dare it be hinted,in every Sako).

!/2 moa is an entirely reasonable expectation,as you have found,in both rifles. I hope you get it back.

Don't complicate..yet..but consider Vihtavuori powder,maybe Lapua bullets-a well tried combination in 308 (though so are SMKs).

 

gbal

[GeorgeB]

Definitely not a stability problem, the 180 SMK is fully stable in a 1:13 barrel. It was designed for 300m shooting hence the short boat tail.

 

IMO you need a much faster burning powder. You can't get enough RL17 in the case for consistent results.

[dannywayoflife]

I aggree with George Rl17 is great for 200+ grain bullets but very slow for 180's. I'd try something in the RL15, ramshot TAC burn range.