Interesting Observation

[ShootDots]

The last (2) 6.5 x 47 barrels I had did not like 140class bullets. Normally, I always try to get the heavies working well. This last barrel REALLY did not like'em! I tried H4350, N160 and N540>> ALL to no avail. So I started on the 123-130 grain projectiles and VOILA!!! My barrel ate them up like candy! Well a good friend of mine (Smoking-Brass on this site) bought a Criterion Barrel in 6.5 x 47 with a .167-8? Can't remember which freebore. He started out with H4350 and a 139 Scenar and promptly shot under 1/3MOA @ 300 yards with very little development. That got me thinking, I had a shorter freebore which may account for my barrels lack of an affinity for the 140class bullets. However, now 1200 rounds later, I thought, "my "freebore" has got to be lengthened by at least 10-15K". So I tried some Berger 140 Hybrids and H4350. I started at 39.5 and worked on 0.2gr increments to 40.5. Well ALL of the loads shot very well BUT at 39.9-40.3 it shot EXTREMELY well. All were under 1" at 300 yards and the 40.1gr load went 9/16 of an inch! These are all 5 shot groups. Additionally, the e.s.'s all stayed 15ft or below, with most at 11 or below!

Needless to say I am beside myself with anticipation of the next 1000 yard competition. We are on our "summer schedule" which is 15 shots for score. In October we will be back to 20 shots for record. Then I will be bringing out the 284 Shehane>>> BUT until then, I will NOT feel "under-gunned" or at some disadvantage to the hoomers, T-Rust me!

 

[jonbearman]

That is indeed an interesting observation as I had a similar problem with a .260 rem shilen that did the same thing.I shot it for awhile with lites because the heavies were not as accurate as I wanted and went back to the heavies to save my lights for competition.It must of moved the freebore out some and it now works better.

 

[ShootDots]

Hey Jon, I would be willing to bet that the shorter freebore would not allow the level of accuracy I demand with the 140's.. It is the ONLY segment of the accuracy equation I could not control, unless I had a throater and / or my own reamer>>>>which will be the next item I get when I need another 6.5 x 47 barrel!

 

[Joe R]

That is an interesting observation, and well worth remembering.

 

[gotcha]

VERY interesting!

 

[CaptainMal]

Not the same thing but I just now am thinking there's a connection.

Have a 260AI that fought me for over 1,000 rds. In frustration I had the throat moved out even more.

It's been shooting great since. I just never made your connection.

 

[ShootDots]

Yes! The more I think about it the more I am convinced that the key on this cartridge (or similar cartridges) to shooting the heavies is to get enough freebore in there to put enough powder in the case to get those "heavies" moving at least 2800f.p.s. without undo pressure, as in using powders in the burn rate vicinity of H4350.. I may be way off base, however, evidently it is not just me experiencing this phenomenon..

 

[searcher]

I think you are right. I have a .223 Remington bolt gun that has a factory barrel and was so tough to clean, I ran Tubb's abrasive bullets through it to mellow out the machine and tool marks. It worked and also changed my freebore ever so slightly. The big plus was the newfound ability to shoot heavier bullets better than it would before. We all know that every barrel is unique and that anything done to a barrel can induce a change in the barrel harmonics. Perhaps just firing several hundred (or thousand) rounds does enough to also change these harmonics...??? It would be interesting to hear a barrel makers take on this.

 

[ShootDots]

It was fascinating to me to see how radically my rifle changed. It did not appear to so much as shoot even reasonably well with the 140 Hybrids I tried when the barrel was new.. Now, as if a new barrel was installed, it LOVES the Hybrids! Believe me, I tried no less than 300 rounds AFTER the barrel was broke in and settled down to get those Hybrids to shoot. They shot NO BETTER than 1.75 inches to well in excess of 2 inches at 300 yards. It did not matter what I did to improve the groups. Then 1200 rounds later, it spits those Hybrids out with about the same precision as my 105 VLD's do in my 6 Dasher! The only variable to change since then is the throat erosion caused by 1200 rounds going down the barrel and moving the throat forward...

 

[searcher]

WOW!

 

[Cassidy]

Your increased freebore observation with over 1200 rounds impact is impressive. I've been struggling with my 6.5x47 for months now trying to get it to shoot with N540 with the bullet placed at touchpoint + .002 (which was the best seating depth on my last tune starting at minus 0.020 from touchpoint), so far without much success. I just got some H4350 and have Berger 130 gr, 120 gr and Scenar 123 gr bullets to try with it. Your observation suggests to me that I should try the H4350 with maybe the Berger 130gr starting the tune with the bullet seated considerably deeper in the case, maybe 0.030 back from the touchpoint and moving up (out from the cae) in 0.003 increments. Is this approach consistent with your observation.

 

[DennisH]

The last (2) 6.5 x 47 barrels I had did not like 140class bullets.

I can just about state the same senerio. My 6.5x47 loves 120 smk's and 123 Scenars. It will shoot .200 or less groups (when I do my job) @ 100 yards and shoots 3/4 moa @ 600. I just couldn't get the 139, 140, or 142's to shoot like the lighter ones.

Interesting post

 

[glockaholic]

Ben, Very interesting information. What twist is your 6.5? Also did Omar do the work? I'm having him re-barrel mine in 6.5x47. ....Carl

 

[ShootDots]

Your increased freebore observation with over 1200 rounds impact is impressive. I've been struggling with my 6.5x47 for months now trying to get it to shoot with N540 with the bullet placed at touchpoint + .002 (which was the best seating depth on my last tune starting at minus 0.020 from touchpoint), so far without much success. I just got some H4350 and have Berger 130 gr, 120 gr and Scenar 123 gr bullets to try with it. Your observation suggests to me that I should try the H4350 with maybe the Berger 130gr starting the tune with the bullet seated considerably deeper in the case, maybe 0.030 back from the touchpoint and moving up (out from the cae) in 0.003 increments. Is this approach consistent with your observation.

It has been my experience with virtually every VLD I have shot, that VLD's prefer to be "set" into the lands somewhere close to 10-12K IN... H4350 could very well be a GREAT powder for the 130Berger VLD's, however, methinks that either RL-15 or Varget may be the better choice. Once you get to the 136 (New Scenar Bullet) and above realm, I would opt for H4350.. The ONLY thing I am postulating here is that in order to shoot the "heavies" with any degree of accuracy and get the velocity you desire without undue pressure, you need slower powders (H4350 / RL-17 / VV N550) and enough of it in the case to MOVE those heavy weights.. A generous amount of freebore is apparently the answer to the 6.5 x 47 "dilemma" of problematic accuracy with the 140 class of bullets. Please don't read more into it than that..

 

[ShootDots]

Ben, Very interesting information. What twist is your 6.5? Also did Omar do the work? I'm having him re-barrel mine in 6.5x47. ....Carl

Yes Omar did the work... I have a 1-8 Krieger that is 28" long. My best guess is that now I am having about (hard to tell exactly) a 175freebore from throat erosion..

 

[glockaholic]

Well I bought a bunch of 130gr VLDs and a 100 140s. Well see if mine has the same results. I told Omar that mine HAS to shoot better than Ben's......LOL

 

[ShootDots]

Well Carl, Omar's "buildability" if you will, is as good as some of the "better rifle builders" out there. If you want your rifle to shoot better than mine, all you need to do is make excellent loads and yours will shoot better>>> because I am NOT the greatest shot on this terra firma! LOL!!! You will do just fine!

 

[Syncrowave]

... 1200 rounds later, I thought, "my "freebore" has got to be lengthened by at least 10-15K". So I tried some Berger 140 Hybrids and H4350. I started at 39.5 and worked on 0.2gr increments to 40.5. Well ALL of the loads shot very well BUT at 39.9-40.3 it shot EXTREMELY well. All were under 1" at 300 yards and the 40.1gr load went 9/16 of an inch! These are all 5 shot groups. Additionally, the e.s.'s all stayed 15ft or below, with most at 11 or below!

That *is* interesting. Thanks for the report.