i will be shooting exclusively Sellier and bellot ss109... just got e-mail from atlanticfirearms.. and ican get 1/10 or 1/9 or 1/8 barrel twist.... now i know the ammo i will be shooting, and barrel length will be 20"... would you get the 1/9 or the 1/8 for the 62gr. bullet... any advice would be appreciated...please stay off the .223 rem and 5.56 nato... that's been beat to death!!!! it can shoot both... and i know all about black hills 75gr... and all the others... i know the bullets i want and the price is right... just would like recommendations as to 1/9 or 1/8 twist rate for the ss109 62gr. bullet... appreciate it much....

I don't know nearly as much as some here but I would go with the 1/8. Accuracy should not suffer and then you would always have the option of going to longer/heavier bullets.
I shot this S&B out of my colt 1/7 and bushy 1/9 accuracy seemed the same but the velocity extreme spread and standard deviation was much better in the 1/7. I don't kow if this was because of a different barrel manufacturer or the twist rate but it was there.

The 1x9 twist will easily handle most bullet weights, including 69 gr.  SS109 projectiles will be easily stabilized by the 1x9 or faster twists.  You might want to order the 1x8 IF you intend to try some of the newer match bullets heavier than 69 grains.

out of curiosity??? how do 55grain bullets shoot from a 1/8??? i am definatly leaning towards the 1/8... i like cheap ammo also... and S&B has a great rep for both the SS109 and 55 grain... both brass cased boxer... thanks for comments

It depends on what kind of bullets you have .... 55 gr FMJ in general does not give you the optimum accuracy out of a 1x8 barrel.  If this is what you will be shooting mostly I'd recommend getting a 1x9 barrel.

However, 1x8 twist barrel will handle lighter bullets such as the 52 grain Sierra Match King.  I think it has something to do with the curvature design of the bullet.  Many high power shooters use 52 gr SMK for 200 yard match with excellent results out of their DCM barrel (usually 1x8 twist) in no wind condition.  Due to its light weight (hence more sensitive to wind), most high power shooters tend to leave the 52 gr for practice only at 100 yrd or less.  

For actual full course match (200, 300 and 600 yards) many HP shooters like to use the 69 gr, 77 gr and 80 gr Sierra Match king.  The 80 gr is extremely long and will not fit in your magazine.  This is used mostly for shooting 600 yd slow fire prone match.  The accuracy of the 80 gr SMK loaded using an OAL measured specific to a particular barrel is extremely good.  I loaded mine by first measuring the OAL that would allow the bullet to "touch" the rifling, then back it out by 0.010", therefore, the bullet will have roughly 0.010" of free space to "jump" before the rifling bites.  The smaller the "jump", the smaller the variability and the higher the accuracy.  However, you dont want to seat your bullet too long where it touches the rifling.  This may increase your chamber pressure which may lead to other safety issues.  0.010" is usually what most high power shooters use as the acceptable "jump" for the 80 gr bullet.


For "cheap" and "accurate" surplus ammo, I'd recommend the Spanish SS109 from Santa Barbara.  I have personally shot numerous 200 yd high power matches using this ammo (before I started loading my own).  How accurate is it?  Well dont expect to shoot MOA group with this as it is NOT a match quality ammo.  But I have managed to shoot 93-95% scores in high power matches with this ammo.  The downside of this ammo is brittle casing.  Some casing is so brittle that the rim may get ripped by the extractor leaving you with a stucked brass in your chamber.  This happens to me about 3-4 cases out of 1000 rounds or so.  So bring a dowel or cleaning rod to the range with you.

HTH

OZ

 Direct answer is 1:9.

(Get the barrel chrome lined if possible.)

i already have a chrome lined bushy carbine... i am now getting the "broach" cut oly ultramatch... i just wanted to be sure that 1/8 would be ok with the 62gr. SS109 round...so i believe i will go with 1/8 then i can always still go higher, and have my other guns for the real cheap 55gr surplus rds...by the way guys... clearview has S&B 55gr, boxer, brass for $139/500 thanks for the info... still would like to hear what people think of a 1/8 20' barrel would be like shooting the 55 gr.. thanks...

If you want a match barrel ... try to get one finished by John Holliger from White Oak Precision (www.whiteoakprecision.com).  John Holliger is the 2002 National Champion for Service Rifle.  He also hangs out here as Gasgunner.  Check the Competition Forum for details.

I dont know if Oly is the best source for a match barrel.  But I know for real that Holliger's barrel will let you put rounds after rounds into a 12" diameter ring from 600 yards away!  I know this because Holliger has done it over and over again in various matches using the barrel that he cuts and chambers himself.

Your decision to go with 1:8 is a sound one.  This barrel will allow you to use the 80 grain Sierra bullet.  Or, if you want the heavy stuff that still fits in your magazine, go with the 77 grain Sierra Match King.  Recall, GIs were using the 77 gr in Afghanistan out of their 1:7 barrels.  On the other hand, the 1:9 barrel is just not fast enough to stabilize such a heavy bullet.