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I have a CZ 550 American 6.5x55 with a CZ stated barrel twist ratio of 1.86. I recently started hand loading. I'm getting exceptional accuracy with Berger 130 grain Hunting VLD's but am having trouble finding an accurate load using 140 grain Sierra GameKings. The only factory ammo I've used is the PRVI 139 grain bullets and they were very accurate. I read somewhere that you need a 1:8 twist to stabilize 140 grain bullets. Is that pretty much true or is it hit or miss with 140 grainers in a 1:9 twist? Will some rifles not stabilize 140 grains period and then some rifles stabilize some 140 grain bullets but not stabilize others?
Last edited by cdb; 04/30/14.
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Normally the game kings will stabilize in a nine. I believe they are actually a bit shorter than the 130 vld's; are they not? Keep in mind, it is the length of the bullet and, to a certain extent, it's shape which will determine whether or not it will work in a given twist. Sometimes, Sierra boattails just don't shoot well in rifles with a long, tapered throat such as that which is standard on 6.5x55's. GD
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Keep in mind, it is the length of the bullet and, to a certain extent, it's shape which will determine whether or not it will work in a given twist. +1 I have a CZ 550 American in 6.5x55 and it stabilized the 140g GK just fine. If you are able to stabilize a 130g VLD then you should have no problems stabilizing a 140g GameKing. An inaccurate load does not mean it isn't getting stabilized, it just means it's shooting poorly in your rifle.
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The GameKings are definitely shorter than the Bergers. I'll try some different powders when I can find them. All I have tried is IMR 4831 and 4350. I'm fixing to get some Norma MRP and will try it.
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Length of bullets bearing surface is part of the mix too.
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I load 48 gr of h4831 in mine a and the 140gr Sierra GK. They shoot about 3/4 " groups at100 yards. 130 gr AB's do better
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I've shot 100, 120, 123, 130, 140 and 155 in my Swede. I found the 120-123's seem to perform the best with regards to group size and velocity. Mine was a dog with 140's. I guess it depends on what you want to do with it though. Just something to think about if you are mulling over twist and bullets.
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I've shot 100, 120, 123, 130, 140 and 155 in my Swede. I found the 120-123's seem to perform the best with regards to group size and velocity. Mine was a dog with 140's. I guess it depends on what you want to do with it though. Just something to think about if you are mulling over twist and bullets.
I was just curious mostly. I'm not in to twirling turrets and if the GameKings don't work out I'm happy with the Bergers. I also don't paper punch, my 6.5x55 is for deer and hogs.
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One thing to keep in mind is that actual twist may deviate from nominal twist. Just because it says it is 1:8.6 doesn't mean that your specific barrel isn't really a 1:9.5.
The other thing to remember is that its really about bullet length and RPM, so a lower velocity cartridge might not stabilize a specific bullet but a faster one might.
Are you sure its a stability issue and not simple inaccuracy? Some barrels don't like some bullets, stability be damned. Those very same bullets might work fine 200 fps slower in a slower twist in another gun, they just aren't compatible with yours. Every component you're working with might be really very accurate ... but not when used together in your specific gun.
Tom
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One thing to keep in mind is that actual twist may deviate from nominal twist. Just because it says it is 1:8.6 doesn't mean that your specific barrel isn't really a 1:9.5.
The other thing to remember is that its really about bullet length and RPM, so a lower velocity cartridge might not stabilize a specific bullet but a faster one might.
Are you sure its a stability issue and not simple inaccuracy? Some barrels don't like some bullets, stability be damned. Those very same bullets might work fine 200 fps slower in a slower twist in another gun, they just aren't compatible with yours. Every component you're working with might be really very accurate ... but not when used together in your specific gun.
Tom It could easily be inaccuracy.
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cdb,
I have not tried it, but I hear H1000 powder is *magic* in the 6.5x55. Maybe you ought to try it. My Ruger shoots fine with either H4831 or H4350 so I have no dog in this hunt.
I hope and pray you find a load you like with a bullet you like.
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Harrumph!!!
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If you can find some RL19 that might work for you. My old Tikka T3 Swede that was s'posed to be a an 8 twist tube, loved it with 120 SGK's, 130/129 NAB-SST's and Speer/Hornady 140's.
Ron
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I have a 6.5X55 that really likes H4350 and almost every 120 - 140gr. fed to it. Lapua brass, Winchester primers, H4350, almost any/every 120-140. I have not shot anything lighter nor heavier.
139s and 140s shoot great.
HOWEVER ! I'm shooting an 8 twist. So that may not be much help to you.
Jim
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My 70FWT shoots 120 and 129 grain bullets very well with either 7828 or R19. Playing with 140s has always seemed a bit hit-or-miss perhaps partly due to trying to get SSTs to shoot well. My better loads with them have been mild loads of I4350 (which kind of defeats the purpose of their sleek profile). Recently I found some 140 Interlocks and decided to try them with H414. THat seems to be a good pairing and hopefully it will also work with other 140s - although I the Interlock is perfectly fine for most of what I use the 6point5 Swede for anyway. Admittedly the M70 spins bullets a bit faster than your rifle, but perhaps it offers a clue .
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My Swede likes H4350 the best with the 120's. R19 worked well too, but velocity fell off. It liked H4831 with the 130's and 140's. It was a laser with 100gr ballistic tips over R15.
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I attempting a work up with the 100g Ballistic Tip but mine hasn't liked it so far. Admitedly, I don't have optimal powders for it. I've tried H4895, Ramshot Hunter, and H4350. H4985 didn't appear to want to group. Hunter showed promise, but doesn't seem consistently repeatable. H4350 is still under review.
I wish powder still existed on retailers shelves around here. Primers have come back into stock for the most part. Bullets are about 50-60% stocked. But powder? As mythical as unicorns and fairies...
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The stop at the local Sportsmans Warehouse last Friday showed 4 1-lb jugs of H50BMG and nothing else. Mom & Pop shops don't fare much better.
Powder is a distant memory around here.
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That is the issue for me - finding different powders to try.
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I recently got a Midsouth catalog. I flipped through the pages and looked at all the powder and primers we used to be able to buy. Sad that a mere 5 years ago was the good old days.
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