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6.5 X 55 Bullet question
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<marcus>
posted
I have a new Tikka rifle in 6.5 X 55. It has a 1 in 9 twist. I have been working with 125 gr. Nosler partitions and 47 gr. of IMR 4831. At 100 yds the bullets group at about 1.3 inches. At 200 yds, it groups UNDER 0.5 inches. Can someone explain why the bullets group better at 200 than 100 ? Also, my gun shoots the partitions far better than ballistic tips. Is this due to using a boattail vs. a flat base ? Also, if anyone has great success with any of the Sierra bullets, I would like to hear from you. Thanks to all for your help.
 
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<AKI>
posted
Marcus. How many shots per group? Three shot groups can be less than satisfactory when searching for a good load. A very small group might be (is usually) chans alone. I have shot a .15" with my 458 WinMag and Hornady 500gr SP... Large threeshotters on the other hand are useful as a good load should keep not only three but five or ten bullets within a "small" area. BTW I love Tikkas AKI
 
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Gerard
one of us
posted Hide Post
Markus,
The better result with the partition bullets is because they are shorter than the ballistic tips and better suited to the twist of the rifle. Nothing to do with boat tail or flat base. Go to a shorter (lighter) ballistic tip if it is available and try them for group. Have you actually measured the twist or did someone tell you it is one in nine? It sounds like the twist might be slower.

------------------
Gerard Schultz
GS Custom Bullets

 
Posts: 2848 | Registered: 12 August 2002Reply With Quote
<Peter>
posted
I have had excellent results with the Sierra 140 gr. MK's in my Rem 700 6.5 x 55. I have no idea what the twist is, but the 140's are clearly better than the Sierra 120's.
Peter.
 
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<Scott H>
posted
Marcus,
If you were shooting 140 grain bullets, I would bet bullet yaw was the reason. But since you aren't, my guess is your scopes parallax is better adjusted for 200 yards.
 
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<OKShooter>
posted
Scope parallax would be my guess as well. Overstabilization can cause a certain amount of precession, but I've never seen it result in that much difference between the two ranges.

I have a Remingtom M700 long action that I rebarrelled with a 1-8 twist Douglas Premium barrel chambered for the 6.5x55mm Swede. It shoots 120, 129, 140, and 160 gr. bullets very well, with the 140 gr. Sierra SBT being outstanding -- albeit at a pressure level way above the 51,000 psi SAAMI average of the Swede.

 
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<Daryl Elder>
posted
I have a Tikka in 6.5x55 and I shot one hole groups @ 100yds w/Sierra 120gr.BTHP and H450.The number of shots didn't matter as they all went into the same hole. Unfortunately I can't get H450 anymore.
 
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<Royce Gladden>
posted
My Ruger M77 in 6.5 Swede has a 1:8 twist.
Is this twist rate best for stabilising 125
or 140 grain bullets? Or is there any sig-
nificant difference between the two? I'd
like to try reloading the 125 grain Nosler
Partition for the Ruger. What handloads and
powders seem to work best for that particular
bullet? I've had excellent results shooting
the Hornady Light Magnum 129 grain bullet in
that rifle but they are a little pricey.

Regards, Royce

 
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<OKShooter>
posted
You will probably have the best results using propellants in the range of H4350 to RL-19. I haven't done a lot of testing with the 125 gr. Nosler Partition, but RL-19 has done the best for me so far. I suggest a starting load of around 44 grs. and work up to accuracy from that.
 
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<Made in Sweden>
posted
quote:
Originally posted by OKShooter:
You will probably have the best results using propellants in the range of H4350 to RL-19. I haven't done a lot of testing with the 125 gr. Nosler Partition, but RL-19 has done the best for me so far. I suggest a starting load of around 44 grs. and work up to accuracy from that.


I�d say you have a simple matter of bullet stabilization over a longer distance. This is quite well known phenomena in sniper-circles. It means that the bullet has got to much velocity to stabilize before a certain distance is covered. A normal huntingbullet is optimally stabilized at around 600 to 1000 yards. I have noticed the phenomena in my Ruger Varmint in 243 wich will shoot 3/4" at 100 meters and still group 1" at 200 meters.
/Peter

 
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