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308w sst advice

11 Apr 2015
@ 03:00 am (GMT)

john feyereisn

I have a savage mod 11 varmint barrel in 308 that shows a very strong liking to varget and 150 nosler ballistic tips. what i found suprising was not the accuracy, but what i did find it interesting how accurate it was with a very wide range of seating depths and charge weights. The ssts i have shot in both 165 and 150gr weights are good, but not quite as good as the balistic tips so far and i would like to tinker with it to improve the ssts. I have a genral range of charge weights that seems to show slight prefrence with the ssts, but would like to revisit exact charge weights and seating deapths.
I also just bought a cronograph, so what to do with this info is new to me. Should i start my attempt at improving it with seating deapths or start by fine tuning powder charge or swaping different primers? Will seating deapths affect velocity standard deviations?

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11 Apr 2015
@ 03:31 am (GMT)

john feyereisn

Re: 308w sst advice
I forgot to mention that one reason i would like to revisit seating deapth is that looking back i may have started a little on the close side at about .015 off the lands. I am planning to back them off a bit more. Has anyone noticed a prefrence as far as seating deapth with this particular bullet?
11 Apr 2015
@ 03:37 am (GMT)

Mike Neeson

Re: 308w sst advice
Hi John, try reading this thread. It might help.
http://www.ballisticstudies.com/Resources/Discussion+Forums/x_forum/18/thread/4756.html

In regard to seating depth, the 308w normally has a long throat so one is normally limited to the magazine length - although I'm not sure on the magazine length in the savage. My magazine is 72mm, so I load to COAL of 71mm for optimum feeding. Please read COAL article by Nathan...
http://www.ballisticstudies.com/Knowledgebase/Determining+COAL.html

Hope this helps.
11 Apr 2015
@ 05:46 am (GMT)

john feyereisn

Re: 308w sst advice
I would have to look at my notes to find the coal measurements but with these bullets in this rifle, i will hit the lands before i will run out of magazine length.
One other interesting comment that someone on savageshooters.com mentioned that had the same model as i do was that he had found that the throat was not as shallow as he thought, it was just tight clearance and when pushing a bullet out of the case towards the rifling, that it felt like the bullet was touching the rifling when it was not, it was just in a bore that was on the tight side. I have no idea how he determined that or if he was a reliable source of information, but I suppose he cant be wrong, ot was on the phone nternet afterall!
11 Apr 2015
@ 05:53 am (GMT)

Mike Neeson

Re: 308w sst advice
The key part to the COAL length article is to provide full neck support to the projectile to achieve good concentricity. The 308 was designed to have a good jump to the rifling to act as an expansion chamber for better velocity/pressure curve.
11 Apr 2015
@ 04:01 pm (GMT)

Bryan Webster

Re: 308w sst advice
It is also possible the sst bullets are not what the barrel likes.
I found (my surprise) the 168 and 178 grain Hornady A-Max bullets were a
significant improvement in precision in my .308. I did not bother too much about trying to seat close to the lands, allowing magazine length to guide my efforts, but found 3/8 inch 5 shot groups to be just fine with COAL of 2.80 in my Remington 700P LTR with heavy 20 inch barrel.
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