A I 338 MAG MADE IN 2006
CAN ANYONE TELL ME WHAT IS THE TWIST RATE IS ,I HAVE BEEN TOLD 1-8, 1-11 ,1-10---THE PLACE I GOT IT FROM CANT HELP----[:(]
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3DFUEL,
Not enough information.
Are you asking about an Accuracy International rifle? Or is this an Ackley Improved chamber?
The fastest determination is to use a cleaning jag with a slightly tight fitting patch on a cleaning rod with a ball bearing handle. Mark the rod where you start it in the bore, mark the handle with a line on top. Push the rod in one complete turn and mark the rod with a twist of tape. Measure between the two pieces of tape for the twist.
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THE RIFLE IS AN ACCURACY INTERNATIONAL, NOT A ACKLEY IMPROVED[;)] 0 -
3DFUEL,
The .338 Lapua Magnum usually is the 1:11" twist according to the folks at Accuracy International.
Other barrels can be gotten which have twist rates ranging from 1:9.5" to 1:12". I haven't made any 1:8" yet...
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THANKS FOR THE INFO,DO THE BRITS USE THE 1-8 IN THEIR RIFLES? 0 -
3DFUEL,
The British are rare birds sometimes when it comes to their military developments. Currently, AI is fielding their Super Magnum (L115A1) with the 1:8" twist for the military. This supposedly addresses some of the physics behind the widely varying theaters, sea-level to the mountains of Afghanistan, by supplying a little more rotational velocity.
The newest VLD bullets are only 300 grains and can be stabilized with a 1:12" twist when the muzzle velocity and pressure are at maximum. However, some discrepancies are noticed at extended ranges so the decision was made to increase the twist rate in favor of higher rotational velocity as a 'just in case' factor. This will also allow for slightly longer bullets to be developed in the future.
When we step up into the highly specialized mono-metallic Match bullets from Lutz Moeller and Gerard Schultz, the required twist rates necessarily run in the 1:7" and 1:6.5" and with specialized land shapes and can also include gain twist rifling. The bullets range from 2.157" to 2.260" in length as compared the the 1.730" of the Sierra 300 grain MK. Theses SP bullets utilized drive bands instead of the typical full contact of the jacketed Match bullets. While these may be esoteric examples of extreme design, The LM-105 set records and won the biggest long range sniper competition in the world, twice. Unfortunately the barrels were running about $900.00 each just for the blank.
As it stands right now, I'm using a 1:9.5" twist with Bartlein's standard 5R rifling form. I have a second barrel that uses the gain twist principle which starts at 1:10.5" and runs to 1:9.5" at the muzzle. Neither has demonstrated any significant advantage over the other but the testing is still young.
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