Tight Barrel 308W

[IanP]

Krieger make 2 barrel diameters available for the 0.300 cal crowd. I came across this recently on the USRifleTeams website and thought it interesting

We only offer the .30 "Tight" caliber barrels up to a 1-12 twist. The reason being, we have seen pressure issues arise when using heavy, long bearing surface bullets in this tight bore/tight groove configuration. We strongly suggest against using bullets heavier than 175 grain, and/or magnum pressure cartridges in any .30 Tight caliber barrels due to the dangers of high pressure and the increased chance of copper fouling.

Thank you,

Krieger Barrels, Inc.

It seems for those of us wanting to use heavy projectiles in F T/R might want to go for the loose barrel version. The tight barrel = 0.298" and the normal barrel is 0.300".

Currently I'm shooting the 308W in its standard form from SARA as a 12T tight barrel but I think I will be opting for the normal 0.300" barrel to provide more options for the future.

IanP

[RAVEN]

Humm interesting Ian this may apply to some of the other calibre we use
RB

[Brad Y]

I have the 0.298bore barrel as well. Shoots ok, I imagine its shooting faster than most due to the decreased size and subsequent higher pressure as Im running the same load the guys who are dominating in WA with their 308's are in regular size barrels.

I have noticed it copper fouls quicker than any other barrel I have used.

Next one will be a 1:12T Maddco in regular bore size.

[IanP]

Bruce just sent me this link on German Salazar's thoughts on this subject http://riflemansjournal.blogspot.com.au ... specs.html

Ian

[bruce moulds]

to the best of my knowledge, tight barrels often shot the old 144 gn military ball better than standard ones.
for some reason, 3 lug actions with floating boltheads were reputed to shoot military ball better as well, hence the development of the omark.
i think bore diameter was reduced, but not groove diameter.
this can encourage bullets to blow up if they are susceptible.
there are tight and standard ( not loose) 6mm barrels as well, and i think the tight ones are reputed to shoot lapua bullets better, while the std shoot sierras better.
we are relying on an old mans memory here, so please bear with.
keep safe,
bruce.

[IanP]

The barrels I got from SARA are tight in both barrel and groove diameter.
All dimensions available here http://www.kriegerbarrels.com/Calibers_ ... wp3390.htm

Tight Barrel dia = 0.298" Groove Dia = 0.3065" (optional 0.3070" or 0.3075")
Normal barrel dia = 0.300" Groove Dia = 0.3080"

Being a F-Open shooter it seems I have a lot more choices than just twist rate when it come to the realms of 308W target barrels. Hope this helps others like me now looking at building a serious F T/R gun to have a think about barrel diameter especially if those heavy 185gr Berger VLDs are on its menu!

Ian

[GregW]

The clue to accuracy with 144 FMJ's was a tight groove diameter. This was because the hard jacketed military bullet wouldn't "upset" in the barrel, and consequently didn't seal properly.

The reason for floating bolt heads was to set headspace as the locking lugs were in the barrel. It also meant cheaper manufacturing. Many interesting "theories" were then invented to justify the process. The Angel 80 had two different bolt head sizes to allow easy change of headspace to accommodate RG ammo in England, which was slightly different.

Greg Warrian.

[bruce moulds]

in the old days, the brits used to call 30 cal barrels 297. e.g. the 297 morris cartridge. and the 276 rigby, which was in fact the 7x57 mauser.
but then some of their so called 7mm cartridges were 0.288 groove.
the 318 w.r. was actually 0.333 or 0.338, not sure.
at least our nomenclature has improved since then.
evidence is appearing that when barrels are so called "shot out" some of them have stretched rather than eroded, to up to several X 0.001, causing the need to seat bullets way out to maintain a relationship with the lands.
tight barrels might be a way of overcoming this, as when they stretch, they would become normal at the breech end, tapering to tight at the muzzle.
those old black mountain barrels were noted for longevity. could this be the reason?
keep safe,
bruce.