Effect of factory carbine barrel length?

[Gardener]

i have noticed that most the Contender barrels are 21 inch long (factory).
the new G2 barrels appear to be 23 inches long.

If this is correct, what is the advantage of one over the other?  Is there an accuracy advantage for a sporter, or might it be more to differentiate between the two separate products?  just wondering which one(s) to try to spend hardearned $ on?
thanks

[BNoz01]

Hey,

At the risk of being too much of a smart alec, I can answer that question with a 100% certaintainty of being correct.  The answer is:  "It depends".

Some calibers will not have any noticeable difference in accuracy or velocity.  Examples include, but are not limited to, pistol calibers.  A 45ACP will not know the difference between 21 inches and 23 inches.

Slower burning powders in rifles cartridges will probably see a minor increase in velocity with the longer barrel length.  I doubt there will be anything concrete as far as accuracy goes, that is not within the normal barrel to barrel accuracy variances.

Personally, I think the new barrel length is just a slight marketing gimick.  Something new to think about in our purchases.  And I love pondering these kinds of decisions.  

B.Noz.

[BNoz01]

What caliber are you pondering for purchase?  That  might greately influence the decision.  And what bullet weights do you intend on shooting?

What I would be checking into is the twist rates for the barrels.  For example, if the new (G2) 223 Rem barrel had a faster twist, say 1 in 9, then I'd take that in heartbeat over the old slower twist barrels.  

B. Noz.

[Gardener]

probably something to mostly live in the gunsafe.  but in order to better quantify, it'd be .223 for hogs; 30-30win for deer; 45-70gov't (to have and to hold?); .22lr for squirrels; .17 hmr cause i ain't never had one, etc.

anyways, consider factory ammo only. i've reloaded for a super14 30-30win with a lee handloader and it was a blast. don't have the time now.

[KN]

If I am seeing correctly the new barrels are straight bull design. I for one like the looks and feel of a bull barrel over a taper in the contender. I think it will be a wonderful improvement.  KN

[Bim]

BNoz01
    Tell me about twist rate please. The faster the rate say 1 in 9" will stabilize larger bullets? Is this right? :? My 22/250 is 1 in 14"  so what grain pill should I be looking to shoot? 40, 50 60? :?

Thanks for any light you may shed.

[BNoz01]

Hey,

Yes, faster twists are needed to stabilize heavier bullets.  In the .223 realm, 1 in 12 and 1 in 14 twists will pretty much stabilize up to about 55 grain bullets.  1 in 9 twist barrels will stabilize up to about 75 grain bullets, depending on bullet make or shape.  And 1 in 8 twist barrels will stabilize the long range 80 grainers.

This is somewhat misleading because it's really a matter of RPM, which decreases as a bullet slows down.  So, shooting a 62 grain bullet out of a 1 in 12 twist barrel may actually stabilize for the first 50 to 100 yards.  But as the bullet slows down, it will become unstable.  At first, accuracy will deteriorate, then the bullet may actually begin to tumble.

Also, there are no hard and fast rules, as bullet design and shape play a major role in what twist is necessary to stabilize it.  That's why some 75 grainers will stabilize in a 1 in 9 twist barrel, while others will require the faster 1 in 8 twist.

Necessary twist rates vary from caliber to caliber.  in .308 caliber, the most common commerical twist rates are 1 in 12 and 1 in 10.  But if you're gonna shoot the long heavy bullets (220 grains), then you may need an even faster twist.

Hope I gave you sufficient insight here.

B. Noz.

[BNoz01]

Hey,

For a 22-250 caliber rifle with a 1 in 14 twist, you are pretty much limited to about 55 grain bullets.  I personally use 52 grain Bergers in my 22-250.  

This is especially important if you are doing long-range precision work.  I'd almost take a bet that most 62+ grain bullets would begin to tumble from a 1 in 14 twist at 350 yards.  Maybe someone can jump in here with personal experience with tumbling bullets from a 22-250 slow twist barrel.

On the other hand, the lightweight 40 grainers really show the effects of wind.  The difference between a 40 and 50 grainer with regard to wind is significant from my field experience.  I used to shoot 40 grain Ballistic Tips, until I saw how much less 50+ grainers were blown by the wind.

So, I'd suggest finding a 22-250 bullet that shoots well for you in the 50 to 55 grain weight class.  Then load and shoot that one as much as you can!

B. Noz.

[KN]

Not all 55gr bullets will stabilize with a 1-14 twist either. A freind was trying to shoot a 55gr Blitz king from a 225 winchester and it would keyhole at 50 yds. Sierra told him the bullet profile was too long for a 1-14 and to try the 50gr Blitz king instead. It worked wonderfully.  KN

[quicksdraw45]

Actually stabilizing a bullet is a combination of bullet LENGTH and VELOCITY and twist rate of the barrel. Now of course you wont see a huge difference in the length of 2 bullets of the same weight but i have seen enough to make a difference

[Ladobe]

For what its worth in this thread, Fred at Bullberry believes about the optimum barrel length for Contender carbine's is 20" in full bull profile.    He bases that on balance and stability, lock time and hammer fall more than on velocity.   Since I have a bunch of his barrels in that length, and they all shoot bugholes, I'll have to agree.   The velocity gain or loss because of an inch or two of barrel is insignificant as far as I am concerned.

[Gardener]

At least in "theory" one could swing a shorter barrel in a tree stand a little better.  also walk through the thick spots a little more easily. there's some practicality in such a solution.

the one carbine barrel i have is 21 inch long, and it is very manueverable.
i guess i'll shop for them first, then go the custom or 23inch route.
thanks for the good info.

[Bim]

BNoz01 thanks for the info. I see the light!
Bim

[quicksdraw45]

I have to agree to some degree , I have a 26 inch bull barrel from the factory .The rifle is a little front heavy , But it shoots great groups.

[Iowa Fox]

I have to agree with Ladobe. My first barrel from Fred was a 20 incher. While waiting for it I was a little sceptical. Now I wouldn't have anything else. Shoots great and handles even better.

[BobYoung]

Found the Greenhill formula in a back issue of the American Rifleman and have used it to good effect in choosing muzzleloader bullets.  Never tried it on centerfire smokeless loads.  It doesn't take velocity into account so may be an over-simplification at varmit rifle velocities.  Bullet rate of rotation DOES depend on both velocity and twist rate.  For a given twist, doubling velocity WILL double bullet RPM.   But the higher velocity probably demands faster bullet rotation to achieve stability

The Greenhill formula in words is:

Minimum Twist rate in inches = 150 times (Bullet Diameter in inches squared) divided by the bullet length in inches
or
MinT = 150 *(BD)^2/BL

Where MinT is minimum twist rate
          BD is bullet diameter in inches and (BD)^2 is bullet diameter squared
          BL is bullet length in inches

Therefore if a 210 GR JHC Sierra .44 Mag bullet (of .429" diameter and .675" length) is to be shot, the minimum rate of twist is 1 turn in 40.9 inches.  (used this as an example 'cause it's in my notes)

Turning the formula around algebraically to determine max bullet length for a given twist/bullet diameter results in:

MaxBL = 150 * (BD)^2/Twist

When choosing bullets for a barrel with a given twist, this form is the most useful.  Again, using examples from the muzzleloader world a .50 cal. barrel with 1 turn in 48 inches will handle bullet lengths (MaxBL) up to .78 inches if shooting .50 cal. bullets (BD=.50) or up to .575 inches if shooting saboted .44 Cal. (BD=.429).  This explains why fast twist ML barrels are needed to shoot the heavier (and longer) saboted bullets.

I'm not Greenhill, so don't ask me to defend all this.  But it does seem to work with the smoke poles.  Might be worth runnin' the numbers for .22 cal. to see what falls out.  Keep in mind that even what comes out of a .22-250 eventually slows down to smoke pole velocities.

Hope this helps.
Bob

[BobYoung]

Somehow thought I was replying to the 222 Rem Twist Rate Post.   :oops:

Sorry guys.
Bob