308 Win: Most Accurate Starting Loads, 110 gr Bullets

[haskins02]

I have a Browning X-bolt, .308, 1:12 inch twist. Since most of my .308 shooting for the foreseeable future will be informal paper punching at 100 yards, while sitting at a bench, I plan to reload lower recoiling, lower cost, lower wear and tear, yet accurate loads suitable for this purpose.

My plan is to load 110 grain Sierra Varminter bullets and use a “starting load” that results in a MV of around 2,900 fps, while maintaining very good accuracy. I figure the extra cost and slightly more recoil of heavier weight match bullets is not worth it, considering that I do not have a match rifle, and because I have read that the 110 grain Varminter can be extremely accurate when range is limited.

My question is which powders and powder weight do you recommend I try that have the best chance of being most accurate for a 110 grain bullet with a MV of around 2,900 fps, out to 100 yards? Here are the options I am considering:

H 4895: 44 to 47 gr.
IMR 4895: 44 to 47 gr.
IMR 4064: 45 to 46 gr.
IMR 4198: 35 to 37 gr.
IMR 3031: 42 to 45 gr.
Reloader 7: 36 to 38 gr
AA 2015: 40 to 42 gr.

Of course, it may boil down to whatever powder I can find! Any suggestions are appreciated. Thanks.

Greg

 

[Kernel]

I think you're on the right track with 2015 and 3031. W748 and H335 might be better yet. IMO that's the sweet spot for 110gr bullets in the .308. On the slow side, H4895 is as far as I would go. RL-7 and 4198 are too fast for best results.

Your target velocity of 2900 fps is still pretty fast. Certainly, out of the realm of a true "reduced load" necessitating the faster powders you might try if you where looking for a sub 2000fps load.

110gr bullets are stubby. I'd load them out as far as I could, while still keeping enough neck tension.

 

[haskins02]

Thanks for responding Kernel. My Hornady manual shows starting loads at 2,700 for 110 grainers, going up to 3,200 fps. My Lee manual shows MVs up to 3,300 fps, so 2,900 is kind of middle of the road.

I did some more analysis on the subject. Based on my Lee Modern Reloading, 2nd Ed, I identified the following for each powder I listed: A) relative burn ranking, B) volume of one grain of the powder (cc), and C) how much each load (I took average grains) would fill up the useful volume of a .308 case (3.43 cc) based on a percentage. The results are below

Faster Powders:
IMR 4198: 35 to 37 gr. 49th, .07920, 2.85 cc, 83%
A-XMR 2015: 40 to 42 gr. 50th, .07300, 2.99 cc, 87%
Reloader 7: 36 to 38 gr, 51th, .07280, 2.69 cc, 78%
IMR 3031: 42 to 45 gr. 52th, .07620, 3.31 cc, 96%

Slower Powders:
H 4895: 44 to 47 gr. -60th, .07280, 3.31 cc, 97%
IMR 4895: 44 to 47 gr. 62th, .07280, 3.31 cc, 97%
IMR 4064: 45 to 46 gr. 63th, .07450, 4.43 cc, 1.29% (compressed)

While the faster powders may be better based on the smaller bullet weight (110 gr at 2900 fps), the slower powders seem better at filling the case, resulting in more consistent burning. So I stumped as to what is more important: faster burning or a more completely filled case. While all will “work”, what I am after is which will like result in the best accuracy. I don’t have the time or money to try each one. And besides, I can’t find ANY large rifle primers, let alone most of these powders, on the Internet! Thanks again for any further ideas.

Greg

 

[kelbro]

H4895 works very well with that bullet in two of my 308s. One match barrel and one sporter barrel. Deer don't like it either

 

[haskins02]

Kelbro, I read that H4895 is considered an all around powder, including reduced loads, even though it seems a little slow for 110 gainers. How many grains of that powder are you using? What kind of accuracy are you getting? You really shooting deer with it?

Greg

 

[kelbro]

H4895 works well for several calibers that I load for. The best accuracy for me came between the middle and top of the range (which is most often the case). You would need to work up the load in your own rifle.

Works fine for neckshots on Texas whitetail does. If I was hunting some of the larger midwest deer, I would use more lead and NOT a 'varmint' bullet.

 

[haskins02]

Thanks kelbro.

 

[Kernel]

Greg,

Light bullets, slow powders, and compressed loads -- doesn't sound like a good tree to go barking up.

Otherwise, I like your analysis. I bet you're a technician or some kind of engineer. Finding an ideal powder is THE Holy Grail of handloading. Everything else, like determining charge weights, or bullet seating depth, is just a process. Discovering that ideal powder is usually treated as an art form -- trail and error, asking around, using what works, reading the tea leafs in reloading manuals, luck, shooting hundreds of rounds, working up countless loads over weeks and months, etc.

This gets results, but it's less than scientific and can be time consuming. Worse yet, the methods aren't always repeatable for other bullet/cartridge combinations. There is a better approach. 50 years ago Homer S. Powley developed a series of simple equations for calculating an ideal powder "index" (aka speed or quickness). It's applicable to any rifle cartridge and bullet combination.

Powley's methods bare up pretty well, even today, when compare to more modern and mathematically sophisticated commercial software products like Load-From-A-Disk and QuickLOAD. Back in the (pre home computer) day, Powley sold his computer as a cardboard slide rule device. I've got one. It's the height of 1960's reloading geekness. Basically, the powder index is a function of bullet weight, bore diameter & volume, and effective case capacity.

Here's a link to someone's free online Powley Computer, it's kinda clunky, but it works (I have my own stand alone spreadsheet version that I wrote myself):

http://kwk.us/powley.html

http://web.archive.org/web/20041126...allisticsonline.com/ballistics/imrpowder.html

All said, Homer's index is still just a guideline. Getting to a great load still requires bench time. I use it sort of like a fish finder. It let's you focus on the sweet spots and keeps you from wasting time on empty holes. It's still up to you to catch the fish.