308>> 155 gr+Varget Befuddlement

[Qc_BearHunter]

.75 MOA for 5 shots from a factory rifle is VERY VERY VERY good. Everyone seems to shot .5 MOA or better but they show us only their best groups shot when the moon is straight in line with Aquarius.

I have 2 new winchester model 70 and they cratters primers like that with anything i put into them. Sometimes it's not a pressure affair but somtething to do with the firing pin hole and the firing pin herself.

My only question is did you check your case lenght?


Keep reloading..

 

[notsorichguy]

Don't give up!

I usually hit a "wall" when doing inital load development! I generally give it a bit of a break, and try again a week or 2 later....

Your groups are decent, that load is good enough to hunt with.

I find Fed primers seem to 'crater' a bit more than other manufacturers offerings, but as long as the primers is not pierced I don't worry about it, it's when they start to flatten out I start to pay attention.

Cheers!

 

[rimfiremac]

Bearhunter- that's some very welcome news- the notion that it may be the tolerancing on the firing pin hole is most likely, I suspect, but trusting it is the stretch I'm battling with. Thanks for letting me know you've seen the same- its a big help.

I'll give it a go next week again for some 'verification' testing-

I'm not actually going to quite reloading- all kidding aside, it's a ton of fun and quite interesting- some days though, boy it gets the gears going trying to figure out what's going on.

Thxagain-

 

[rnbra-shooter]

Rimfiremac, your photos are interesting. They show moderate to strong cratering about to the degree one would expect), increasing with increasing powder charges. Except for your highest charge of 46.0, which seems to be less cratered; perhaps due to slightly different camera angle?

They look very similar to the primers on my ammo fired from my M70-based target rifle (my primer strikes are even off-centre in the exact same way that yours are! ;-)

46.0 grains of Varget with a 155 is a good, full-power load. It's probably safe in most rifles, but it should be worked up to. It might even be too hot, given the right set of complicating factors (e.g. heavier brass, such as Federal or Lapua; bullets with longer bearing surface, such as the Lapua 155; an unusually "quick" lot of Varget, etc).

Having said that, 46 grains of Varget, in a Winchester case, with a Sierra #2155 seated to more or less magazine length (2.800"), works well in both my target rifles, and also in others' rifles too. It is presently the best load I have for Sierra 155s. It is a nice hot load (a bit over 3000fps in a 30" barrel), and even with (carefully-) thrown powder charges it has good-enough SDs for 1000 yard competition shooting.

Using magnum primers was unlikely to have been causing you problems. While magnum primers are not necessary for .308W's with easy-to-list stick powders, they seldom cause any harm (and sometimes are a useful thing to try, when trying to refine a load).

Your 200 yard 5-shot group is really great. In my M70-based target rifle (match barrel, bedded stock, 25X scope, fired BR-style) most of my 5-shot 100-yard groups are 0.55"-0.60" - i.e. hardly any better than what you have achieved. If that group is typical (heck, if 5-shot honest 1-MOA groups are typical), you have a really good-shooting rifle.

While Federal brass might be (relatively speaking) "crap" compared to Winchester, Lapua, Norma etc, if you have it I would use it, and without any qualms. Brass quality is one of the less important factors to making good ammo. Using a good bullet, with a correct charge of powder, loaded straight, in a good barrel and chamber, are all more important accuracy factors than brass quality.

As a matter of fact, if you continue to be able to shoot groups like the one you have posted, you are showing that everything is working just fine.