Barrel length

pjifl · Post by **pjifl** » Sat Jul 07, 2007 7:53 am

Following on from the thread under F Standard rules - bipods - which got onto barrel length, maybe some general discussion on barrel length would be interesting.

Its different of course for different calibers. Always a compromise. And we are influenced significantly by our background and perceived needs. Like short range shooters instinctively think short barrels are 'right' but long range shooters think in terms of long barrels. No one is 'right' and the ideal is still evolving because of changing projectiles, powder, shot range, etc.

What do others use ! Both for FS and FO. And why ?

I start off smaller caliber barrels quite long - in my opinion too long - but mainly so they can be shortened and rechambered successfully at least once.

Peter Smith.

Post by **Guest** » Sat Jul 07, 2007 8:53 am

An interesting subject Peter.
Many years ago when I was shooting FB I rarely missed a Queens in Melbourne at the Williamstown Range which is about 10ft above sea level.
Without exception we would need to elevate some 4 or 5 moa at 900 yards above that required at Castlemaine ( 900 ft elevation) . This was a progressive increase in elevation from about 500yds. These were the days of ADI ammo and 26" barrels.
This is why today I would not start with any barrel less than 30", but as I said all barrels are different. eg we found MAB barrels inherently slow compared with Tobler, and Maddco falling in between.
Around central Vic we can quite happily reach 1000yds with a moderate load that will give you an average speed of 2870 ft/sec but down at SL that needs to be 2930 min. That 60ft/sec is a full grain of 08 and depending upon the case AND the batch of powder is sometimes not achievable ( safely )
I agree that there is not a " right " barrel length nor is there a " right " load, but there is a " right " speed which has to be determined by your particular needs. This " right " speed is a combination of barrel length and load and will vary from place to place, and with extreme temperature variations.
These sorts of variations are probably more noticable on FO targets than FS targets. FS shooters tend to be more complacent due to the larger target, and accept the variations as a matter of course, and probably without question as to what is causing these variations.
A little digression there, but it is all ultimately tied up to barrel length.
Barry

Post by **AlanF** » Sat Jul 07, 2007 10:01 am

I'd suggest that barrel life, or at least throat life is a point in favour of longer barrels. A longer barrel will allow slower (and usually cooler burning) powder to be used to achieve the same velocity.

Alan

Matt P · Post by **Matt P** » Sat Jul 07, 2007 8:30 pm

When I started using the 6BR I had a 30" barrel fitted thinking (hoping to reach the CLAIMED 2950-3000FPS) it would get me close to 2950fps, anyway after lots of load development and several different powders the fastest accurate load I could get was 2850, which worked out great, then @ 2000 rounds I had it rechambered and barrel length went back to 27", I thought I would loose around 75-100 fps, using the same powder charge I had 2830fps.
The only advantage in some calibers is the ability to rechamber.
Slightly off topic but about what velocity should I see using 43.7 gr of 2206 with 155SMK in 308 (tight Border 30" long).

Matt P

daj · Post by **daj** » Sat Jul 07, 2007 9:12 pm

Matt,

With an OAL of 2.8", 155 SMK over 43.7gn 2206, 30" tube -> 2833fps (QuickLoad)

pjifl · Post by **pjifl** » Sat Jul 07, 2007 10:30 pm

One of my 6.5 barrels which was 30 inch is now about 26 inch. Have not used it much in its new length but all indications are that it is very accurate. It was always a good accurate barrel. Real testing is still months away but I will let others know how it performs. Of course the critical speed at 1000y is not a real issue here since a 6.5 is supersonic out to around 1500 y.

On the topic of FS/TR, 1000yd and velocity, I wonder if the new Dwyer projectile being used by the Palma team will find its way down to TR and FS. It has a sharper ogive (secant) and is about 2 minutes higher on the target I believe. If so, this may have some impact on the necessity (or perceived necessity) of 30 inch barrels.

Peter Smith.

pjifl · Post by **pjifl** » Sat Jul 07, 2007 10:36 pm

43.7 of 2206 behind 155 SMK's in a tighter barrel in my opinion may go up to or over 2900. But there is really only one way to be sure. I know in some of the tighter Toblers in the past this was so.

My choice would be Dyers over SMK's these days. They are a very well made bullet.

Peter Smith.

Post by **Guest** » Sun Jul 08, 2007 8:47 am

Matt,
Would be supprised if you don't reach 2950 in that barrel with that load.
I have a 28" maddco 4 groove fired 5000 rds reaches 2920 with 43.5 06 or 44.5 06H easily makes 1000yds.
46gn 08 in a 3groove " loose " maddco gets me to 2930. I know barrels and powder vary but like I said 2950 is not unreasonable.
I agree with Peter's statement--Dyers over Sierra's. Too much variation in Seating depth with Sierra's, Dyers dont vary.
Barry

RDavies · Post by **RDavies** » Sun Jul 29, 2007 9:07 pm

I like a 30" barrel, then after it gets a bit worn, I get it cut down to 27-28" with a new throat. All of my barrels have shot best after there first rechamber. What I kind of think, but am no expert, is that the 1st few 1000 shots lap the barrel and maybe the erosion, causes the barel to be slightly wider, maybe only .0001" or so at the chamber end and stay at the same dimension up towards the muzzle. Who knows.

As for the new Dyer bullets, are they available to the general public yet? If so, who has them?