Rimfire Bull Barrel Question


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cat_IT_guy
July 23, 2007, 08:02 PM
I a fellow THR member posted the following recently:
There's no benefit to using a bull barrel on a rimfire other than weight.
Is this true? If so, please explain why. So this would mean my .17HMR and .22 with bull barrels are no more accurate than if they had sporter barrels, assuming that both were held completely still?

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R.W.Dale
July 23, 2007, 08:58 PM
. So this would mean my .17HMR and .22 with bull barrels are no more accurate than if they had sporter barrels,

Unless you do enough shooting to get the barrel hot, which takes A LOT of rounds with a rimfire. just cause the barrel is heavy doesn't mean it'll be accurate. I've seen way too many great groups fired through sporter barrels just as I've seen bull barrels that don't shoot worth snot. My CZ 452 american in 17hmr would shoot circles around my buddies bull barreled savage in the same caliber. The barrel profile and harmonics are a VERY small part of the variables to take into account to make a rimfire accurate or not

Rimfire rounds simply do not generate the forces to take advantage of a bull barrel like a centerfire does


So this would mean my .17HMR and .22 with bull barrels are no more accurate than if they had sporter barrels,

you got it! You just end up lugging a heavier rifle through the woods for no reason.

hksw
July 23, 2007, 09:22 PM
IMO, sporter and bull profiled barrels should perform identically or nearly identically given that they are from the same manufacturer when cold, cool, or even warm. (Variations between manufacturers could give an advantage to one barrel over the other no matter the profile.) Where the bull really shines is when the barrel gets hot. The tendency to warp (very minutely) is less with the thicker bull barrel than the thin simply by the amount of material. The more the material (of the same composition) the less the deflection when heated. THere is much more material the warping force has to overcome.

To compare the barrels of one manufacturer of a particular profile against another's of a different profile has, again IMO, very little to do with the profile. It is mainly due to the build of the barrel (chamber dimensions, rifling dimensions and specifications, etc.) It is said that the CZ barrels outshoot a lot of the other manufacturers' barrels because of the bore dimensions. The muzzle end of the bore (being hammer forged) is tighter or just the right dimension as compared to the chamber end. My CZ sporters do outshoot cheaper (i.e., Butler Creek) bull barrels but they also outshoot sporter and semi-heavy barrels from other manufacturers. (A very good inexpensive bull barrel that slightly outshoots my CZ sporter barreled guns are the Green Mountain barrels.) Agains my CZs with heavy barrels (Varmints), the sporters shoot about the same.

Another big factor is ammo selection.

NOOk
July 23, 2007, 10:36 PM
Good thing you came back for a second opinion. HKSW is right on. It helps the barrel lose heat faster and lowers the effect of barrel harmonics. Your barrel 'whips' to a small effect as the blast forces travel down the barrel. See the shooting times guide to accuracy, page 121. ( still on racks in some bigger magazine outlets)

quicktime
July 23, 2007, 11:09 PM
[QUOTE]There's no benefit to using a bull barrel on a rimfire other than weight.

I beleive I weighed in on the other thread but, I will try again on this one. Pardon the long winded rant before it begins. First of all making a rimfire barrel is a whole other animal than making a centerfire barrel. If you think I am blowing smoke call someone that makes both and ask them. Many barrel makers have tried their hand at rimfire and have given up in disgust. Just and FYI Bo Clerke makes most of the 22 lr barrels that you see as drop in units no matter what the label on the package says. All 22 are very finicky when you get down to the accuracy that wins matches and that is why when a small bore target shooter finds a lot of ammo that their gun likes they will do everything they can short of pimping out their significant other to acquire all of that lot. But, that is a long way away from your average shooter who wants to impress his buddies at the range with how good your 22 shoots. A heavy barrels main benefit is the Harmonic dampening ability. As most of you probably know a barrel essentially turns in to a tuning fork when shot. You achieve your best accuracy if you can get your bullet to exit at the crest or trough of the wave of the end of the barrel. It is said that a heavy barrel has a lower frequency than that of a small diameter barrel so the dwell time is longer at the peaks. As for the benefit of cooling I am sure it helps but the stuff I have experience with is target stuff so the rate of fire is slow enough that heat is not a huge concern. So at the end of the day a big barrel is better but your true consistent accuracy comes with ammo testing and harmonic tuning. I have a generic bull barrel on my plinker it shoots fine but the pencil barrel did too. As for the target guns you will never see a small barrel. We try nad cut weight everywhere else just so you can add barrel diameter.

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