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Joined: Mar 2006
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I cannot remember where, but I thought I read an article in the past 3 months where it was stated that the best accuracy is obtained with a muzzle velocity of between 2,750 and 2,950. Is this true?
I ask because I am loading for my .223 and if I can decrease the amount of Varget, I can seat my 69 grain Sierra's a little deeper, which I need to do to get a little better accuracy. I think I can decrease by 3 grains and still get 2,900 fps.
What are your thoughts and comments?
Life is Good....
One trip a week to the range and a family that loves to shoot and hunt.
John
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Joined: Aug 2004
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If I understand your post right, I don't believe it. Saying that there is a universal accuracy-velocity correlation that creates an 'accurate speed' that applies to all cartridges, bullet weights, twists, etc. just doesn't make sense. No way I would take a 257 Wby or 7 STW and throttle it back to 2800 fps expecting it to be an more accurate than it would be at 3400 fps.
So perhaps I mis-understand you.
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Joined: Jan 2006
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It depends on each individuals guns and cartridge being used. But i can say that most of mine shoot the best groups if the load is reduced a few grains down from max.
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Jeese, I guess the benchrest guys who shoot the smallest groups known to man need to slow down their 6 PPC's by about 500 or 600 fps. <img src="/ubbthreads/images/graemlins/blush.gif" alt="" />.
Ya never can tell what powder charge, powder type, primer, velocity, is gonna do what till you try it. Each gun has its favourite diet , ya need to experiment to find it. Some specific cartridge designations tend to like the same things as a rule of thumb. Such cartridges like the 6PPC tend to like 28 to 31 grs of N133 with a 68 gr. flatbase, 1-14 twist at between 3300 and 3500 fps. but not all of them do. There is no rule of thumb as to a velocity that will work across the board on the whole spectrum of cartridges. Youd blow up a 30-30 trying to get to 2800 fps to see if it were more accurate, and it would be pointless loading a 220swift down to 2700fps.
Your .223 might like 2800 fps, mine might not, won't know till you try. It's like feedin a cat, they can be fussy.
Last edited by bushrat; 09/27/06.
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Joined: Aug 2002
Posts: 278
Campfire Member
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The closest thing to this that I've heard is a number of people shooting long range High Power rifle competition seem to be of the opinion that certain cartridges typically shoot best in a certain speed range. Case in point: 6.5-284, around 2950-ish. They can go faster, they can go slower, but most people seem to find their peak accuracy around that speed, plus or minus a bit. Not a hard-n-fast rule, but a lot of prior work and examples that seem to end up right there, time and again. I don't think that particular speed applies to every round, but I think most case/bullet combos probably have a couple similar 'band' that they are happiest in.
Last edited by milanuk; 09/28/06.
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My understanding on the subject. It all boils down to the RPM of the bullet. You need the proper twist rate and velocity to stabalize a bullet. I don't believe there's such a thing as "over stabalization", if you spin a bullet too fast it magnifies the effects of the cant the bullet has leaving the barrel. IIRC Sierra lists the accuracy velocity and the top velocity for each bullet they manufacture. I would think that the bullets are designed around the parameters of the velocity that can be achieved in a given cartridge.
There's two trains of thought when it comes to benchrest (short range). You'll generally see two different accuracy nodes with the 6PPC. The slow node is more accurate than the fast node. The thought is that you give up a slight amount of accuracy by shooting the fast node for the gain of less wind drift. I prefer the slow node. YMMV
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