6.5x55 Barrel Question

[kbebout]

I am having a new rifle built and need advise on rate of twist of barrel. The rifle is going to be chambered in 6.5x55. Shilen lists a recomended rate of twist of 1:9" for bullets up to 130gr and 1:8" for bullets over 130gr. I will be shooting the 139-140gr bullets in this gun exclusively. Is the Shilen recomendation reliable? Is 1:9" more versitile if I choose to shoot lighter bullets?

Thanks

kbebout

 

[Ogre6br]

HI
FIRST THING – USE EUROPEAN BRASS AS IT’S MADE TO THE CORRECT HEAD SIZE. US Brass is made from 30/06 head size and is smaller than the CIP standard for the brass leading to excessive working of the brass in the head/web area. Not good when you up the pressure to get the most out of the VLD projectiles.
In a strong,not ex mil) action you can run European brass to the same pressure level as a 308-30/06. gives you a few hundred free FPS.

I have had several 6.5x55’s.
Some ex-mil and one custom with a 1:9.5 twist.
GO THE 1:8 TWIST!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
It will do everything you want.
Are you going for a standard 6.5x55 chamber? Bear in mind that the standard chambering is the military chambering with the long throat.

I have also played with a custom chambered 6.5x55 optimised for the 130-142 VLD projectiles and the difference was amazing. Choose you chambering to match your application. You might also want to look at a neck diameter around .290.

There is also a chambering which is a semi Ackley improved made by cleaning out the 6.5x55 match chambering with a 6mm BR Norma reamer to the normal go guage length of the 6.5x55. Maybe even a slight, slight crush fir on standard.
Gives you a 30 degree shoulder that will still feed through the magazine, less case taper but not radical straight sides, less back thrust on the bolt and a good increase in case capacity. In preliminary tests – 130 VLD’s are very close to the 6.5/284 in velocity but with less powder and expected better barrel life.
I am not posting loads here but I started at max 6.5x55 and went up in .2 grains from there using the slower powders for the 6.5x55.

HTH

Later
P

 

[chuckw2]

I just ordered two 6.5 Bbls. From Tim North at Broughton. I also will shoot only 139 or 142 gr.projectiles. Tim said that I needed an 8 twist. Hart told me the same thing.


Chuck

 

[rhino]

Depends on fast your throwing them downrange and what the length of your barrel is 1-9 works fine from what JB's friend does with his 6.5 WSSM. If you push them fast your fine...slow down your FPS and well it might not fly as good.

Of course with a 1-8 it might overstabilize the bullets if you push them too fast.

Some people cut the difference and go 1-8.5 twist...especially the Kreigers.

6.5x55 with a tight chamber and 3100 fps out of a 28 inch tube is possible shooting 139's and 142's.

The key is to use the right powder which is

Reloader 22, VIN N560 or Norma MRP.

Those I have found work the best with a PMC large rifle primer.

RHINOUT!

 

[flatlander]

I've got a Krieger std. Palma 30" 8-twist in 6.5x55 on my Nesika K that was chambered with what JGS calls their match reamer - essentially, it's ground to SAAMI min. specs for the 6.5x55. Through a screw-up of my own, the throat wound up being so short that Lapua 139s & S142MKs were both seated with the boattail/bearing surface junction well below the neck/shoulder junction of the case. Last year, I ordered a separate throating reamer from Dave Kiff at PTG and lengthened the throat enough to get the bullets seated out where they needed to be - and it made quite a difference in accuracy.

I've chrono'd some moly'd 142s at over 3000fps with N560, but wound up with loose primer pockets after one firing with that load. At this point, I'm satisfied with velocities in the 2900fps range - came within one point of shooting my first 'clean' at 1000 with A3100 loads that were just under 2900 last summer, and wound up loosing a single 9 on the last shot for record when, instead of waiting out the pickup in wind, I decided to hold off a bit more.

 

[eskimo1]

That sounds about right, here in Sweden most hunting-rifles are in 1:8" twist. For that caliber i should say.