My research and personal experience and seeing hk’s changes over the 34 years I have owned my hk is that at the time of the import restrictions hk was addressing the G-3’s barrel spec to reflect a new use of the platform. A 2-3 MOA military spec accuracy with military ball ammo within the 400 meter iron sight and the 4x optical sight was great for minute of man battlefield use then.
My 911 I think was the start of a change to increase the rifles accurate range to 600 yards by changing the rifling to 1 in 11“ twist and the chambering to 7.62 x 51 instead of .308.
separately the 911 had a barrel shroud added. That increased the political correctness and judging by recent changes may have changed the barrel harmonics.
why do I say this? I recently acquired 2 in the white allegedly hk g-3/91 barrels that have a machined during production “step“ in their forward profile. Fairly obvious to change the barrels harmonics.
i am thinking hk gave or released these particular barrels unofficially as my understanding is that barrels are no longer able to be distributed for military arms from Austria. Part kits yes. No barrels.
if a hk 91 owner wants a MOA or better DMR rifle to 600 yards with 168 grain Sierra HPBT bullets ot to 1000 yards with 169 grain updated Sierra HPBT bullets is to upgrade the barrel.
my understanding is that no one other than hk itself uses the French Albert & Duval cannon barrel steel which hk then adds several proprietary steps during manufacture to basically make a barrel that unless under extended FA use can not be worn out.
so a more accurate barrel and a better trigger is a fix.
unfortunately any non hk barrel would seem to be a normal service life item. 10k? 15k?
so for most owners a barrel swap and at least a trigger specialist’s trigger job would seem to be the way to tighten groups.
lots of reports of 1 1/2 MOA using hand loaded ammo similar to FGMM ammo
denny at WTS told me every hk was capable of MOA with his “set’ trigger(2.5#) and FGMM ammo. Everyone.
so replace the hk barrel and have a service life issue in the far future or keep the almost impossible to wear out hk barrel?
I cannot read the German website for more info but I am pretty certain that they change the barrel and redid the trigger control group.
as far as additional steps hk may have done to add to the cannon barrel life I think they may have cyro treated them with added RF during the process. Probably twice. M1 Abram’s German barrels are reported to be cyro treated during production.
thats why I picked up the 2 step machined forend hk 91 barrels when they showed up.
appear to be 7.62x51 chambered at 1 in 11” twist.
my opinion is that barrel harmomics hold back the rifles accuracy using ball ammo.
possible hk was aware of this and left it in the design so that in FA use the pattern of the bullets would be in a “cone” pattern. not in the same hole?
endless speculation but ways to increase a 91’s accuracy are fairly well known.
easiest are a triggerspecalities trigger and handloads or FGMM ammo in my opinion.
