308 advice for a 1/10 twist barrel.


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chrome_austex
April 15, 2012, 01:25 PM
I picked up a new Rem 700 20" threaded barrel w/ 1 in 10 twist (intended for subsonic suppressed loads?).

Does anyone have any good advice on what bullet weights to try for this faster-than-usual twist?

I've been trying to feed it 155 grain Secnar bullets which I had left over from a previous gun. These were @ 2.830 OAL 'mag-length' over 45.1 grains of IMR 4064, full-len resized, hornady match brass and CCI BR2 primers. Best accuracy is meh with 5 shot groups of 3" at 200y @ 2715 fps and only gets worse with slightly less powder. I'm wondering if I haven't yet found the powder sweet spot or if this gun just dislikes the 155s.

The gun does seem to like Federal Match ammo (168 gr) with 2" groups at 200y @ 2520 fps out of the short 20" barrel.

I notice the Federal Match ammo has R-P stamped brass. Am I giving up anything by using Hornady Match brass? I've also got a little Nosler brass I could try. Up till now all rounds through the gun were full-length resized. My next attempts will be neck sized only now that I have some brass fired through this chamber to work from.

Should I be looking heavier than 168gr ?

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rcmodel
April 15, 2012, 01:41 PM
Must be the bullets.

1/10 is not really "faster-than-usual" twist for a .30 cal rifle.

.30 cal. 1/10 twist has been the standard twist rate since the 30-40 Krag was out service rifle. It continued to be the standard twist rate of the 03 Springfield, and M1 Garand.

When the .308 M14 came along, the twist was changed to 1/12 for reasons unknown to me.

Anyway, your 1/10 .308 should handle any bullet weight from 110 HP to 220 RN just fine.
Finding the one it likes will be the trick.

Was it me?
I'd try some 165-168 range bullets and see what happens.

rc

SlamFire1
April 15, 2012, 01:43 PM
There is no reason why a 1:10 barrel should not shoot all bullet weights, from 125 gr to 220 gr well.

Ninety percent of my rounds are loads with 168's. This bullet is outstanding out to 600 yards though 600 yards is a stretch. I shoot 175's or 190's at 500 or 600 yards.

I have buds who shoot 125's at 200 yards for the lessened recoil, might want to give a few a try.

Ridgerunner665
April 15, 2012, 01:45 PM
When the .308 M14 came along, the twist was changed to 1/12 for reasons unknown to me.



147 grain bullets



Sent from my DROID RAZR MAXX!

Jasper1573
April 15, 2012, 01:56 PM
I have a Rem 700 in 308 w/ 1:11.25 twist and it shoots well out to 800 yards with Sierra 175 match kings. Most of my shooting, though is 300 to 600 yds and the 175s are sub moa if I do my part.

My neighbor has the same rifle you shoot and he loads up Sierra 168s w/ 44 or 45 grains of Varget and his shoots very well at 300 yds.

Recommend you shorten your COAL to around 2.800 and see if that helps.

chrome_austex
April 15, 2012, 02:06 PM
Yeah, I'm going to shorten my COAL to 2.8 and try some 168s next.

thanks guys.

rcmodel
April 15, 2012, 02:06 PM
When the .308 M14 came along, the twist was changed to 1/12 for reasons unknown to me.
147 grain bulletsSeemed to me the Springfield and Garand did pretty darn good with M2 ball 152 grain.

I doubt 5 grains difference necessitated a change in rifling twist anyway.

rc

Coltdriver
April 15, 2012, 03:02 PM
Do a search on optimum charge weight.

If you work up through a series of powder weights you will find the charge weight that is best for your rifle. It is amazing after you try it a few times. I have used it on several rifles including my .308 and the nice thing is the result repeats very nicely.

You may find one or two charge weights that work very well with your rifle. They are not usually the max charges but they can be.

And do go to the trouble of comparing charges against a target that is 200 yards out. 100 yards is not far enough to get good results. It is magic when a group forms at 200 yards.

I also found with my .308 that a 180 grain round nose and a 150 grain partition (both very close to the same length) shot very nicely. The longer bullets like a 165 grain Berger VLD never would group up.

thump_rrr
April 15, 2012, 05:41 PM
I have a Savage 10BA which shoots around 1/2 MOA in perfect conditions if I do my part.
It has a 24" barrel with a 1-10" twist.
I use 180gr Sierra MatchKings with great succuss.
As Coltdriver mentioned use a systematic approach such as optimal charge weight to find the optimal load for the rifle.

I have a couple of additional suggestions.
I would purchase an Over All Length gauge and a bullet comparator.
Instead of using Cartridge Over All Length (COAL) you will be able to measure the distance from your rifling to the base of your cartridge.

You can then try increasing or decreasing the amount of jump for the best accuracy in YOUR rifle. My rifle likes 0.010" of jump or off of the rifling. Other rifles may like being 0.005" jammed into the rifling.

chrome_austex
April 15, 2012, 07:17 PM
I have a bullet comparator now, but I'll be loading for mag length, which is nowhere near the rifling on a Rem 700.

I'll check out OCW, it seems promising. Maybe those 155s will shoot after all.

NCsmitty
April 15, 2012, 09:53 PM
Here's a link to the 6mmbr site, and a bunch of tips for long range shooting, and informative load data for the 308 Win.

http://www.6mmbr.com/308win.html


NCsmitty

REL1203
April 16, 2012, 11:05 AM
I have the same R700 you have it seems, and mine loves 168 and 175s with RL15... Just need to find what your gun likes

chrome_austex
April 25, 2012, 02:06 PM
Ya, after some load development OCW failed to get tight groups for my 155 Scenars, but it looks like the Sierra 168 MKs are winners (2.800 COAL, Hornady match brass, 44.2 grains of 4048, BR2 primers).

With the 168s, my first 14/15 shots fit in a single 0.8" group at 100y, and each one of my four 5-shot groups were <=0.8" as well (all with a fairly powder-dirty barrel). The 168s feel like cheating.

Not bad for a bone-stock Remington barrel and in a flexible Hogue stock.

RyeDaddy
April 26, 2012, 01:03 AM
I've owned several 308's, 1-12", 1-11.25", and 1-10" twist rate. All have handled 110-180 grain bullets of all shapes well. If you're not having luck with the Scenar I would suggest trying the 155 Hornady Amax if that's the weight you like. The AMAX has performed best for me and is for me the most tolerant as far as jump to the lands. I'm using them exclusively out of my 16.5" semi-auto after having tried all kinds. (I can't get the velocity I want from anything heavier with the shorter barrel), the Scenar and Berger VLD also shot well, but the price difference for the same performance at the rate I use up ammo made a difference to me.

If you're into longer range shooting you might try the 175 grain Sierra Matchking, they seem to be the best all around target bullet over a wide range of 308's, and the price isn't too steep. If your Remington won't shoot well with 175 SMK's over Varget(if you have any to try) I don't know what to tell you...

Anyway, for powder with the 155's I have settled on IMR 8208XBR, I tried Varget and H4895 first. Varget and 4064 may be a bit slow for lighter bullets, although with 168 and up they're magic. I found I could get more velocity, better accuracy and less muzzle blast using a faster powder like 8208, due to a more complete burn in my short barrel, your experience with a 20" barrel may vary. Varget is normally my go to powder in 308, but with lighter bullets there are better choices, I mention this because 4064 and Varget are very similar in burn rate.

Anyway, hope this helps. Lots o' luck!

Centurian22
June 20, 2012, 11:01 PM
Tagging this for when I start loading for my .308. Great info thanks!

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