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Thinking you have to get the bullets damn neart touching the lands. I was doing a little experimenting and had them about .090" off and it was about as good as I have ever done. I also tried others with not quite that far off but a long ways off and it seems to make no discernable difference. I think Charlie B is right, some bullets work better a little farther off the lands than close.
Secant ogives like to be close to the lands. Your twist rate likes heavier bullets so when you put a lighter/shorter bullet you get further away from the lands anyway because of the throat. Are you using a quality reloading manual?
Just a guess...I think it has to do with bearing surfaces, distances between center of gravity and center of pressure and angle of ogive at point of lands. And, of course, bullet run out when in the chamber. I also think Sierra, and maybe Hornady, give up a little BC in order to have a bullet that behaves better off the lands. At least, the few Bergers and Lapuas I have fired (30 cal) needed to be very close to, if not jammed into, the lands, while the Sierras and Hornadys are a little more tolerant.
All just a guess.
My hunting load uses 0.060" off the lands and that was the most accurate (0.264" 130 gr Sierra Game Changers with secant ogive). I don't care so long as the rifle is happy. ;-)
Other bulets like 0.015". My M11 has what I considered a "generous" throat out of the box. But I was willing to do some load development.
I work around what works.
Especially if you plan on using the magazine, like most guys do when hunting.Quote:
Originally Posted by Stumpkiller
twist rate has more to do with length of bullet rather than weight, I was thinkin the opposite until a respected bench shooter showed me the difference
Well i guess since making them fatter wont work, the only choice left is making the heavy ones longer?Quote:
Originally Posted by texken
Everything I shoot (except my gas guns) is jammed .010 into the lands. From 20 on up to 6.8 and a bunch in between.
Got (Had) a friend with a H S Precision that had a 30 caliber with a .090 jump to the lands. Deadly accurate!!
It's up to you to decide what works best for YOU.
I stick to zero free bore on my chambers. I have found that a jam won't show pressure but a jump with the same load will.
It's all a game we keep playing.:cool:
_.
The best discussion I have read came off the Berger Bullet website. They discuss thoroughly why the Secant Ogive behaves versus the Tangent Ogive. Also, test method suggested for optimizing seating depth. Best discussion I have found.
Stock Savage Model 10 in 223 using a "soft jam" on a Hornady 68gr Match bullet. Compared results to recommended published length in Hornady manual and if I seat to manual length I would be .112" off the lands. Loaded to book length, they shoot just fine.
Amazing what works for some won't work for others. I couldn't get the 68 grain Hornady to work in my 223 Axis, 223 Remington or 22-250 Savage. Of course, I swore my Savage Axis would not shoot light bullets but I have them an incredible distance off the lands and they shoot pretty well. So many variables, you could wear out your barrel before you find the ultimate setup.Quote:
Originally Posted by KMW1954
I feel the same way. In my 223 Savage Axis and Model 10 I have so far been through 4 powders and over 1k bullets of the 62 to 69gr weight and still haven't found the optimum. Now I have found a good number that are pretty good but in each group there are some I cannot explain! Seating depth in these guns means very little. If I seated the 62gr out to the lands there would be little to no neck tension as very little of the bullet would be in the case.Quote:
Originally Posted by Mr.Snerdly
I misspoke when I said I tried the 68 grain Hornady in the 22-250. Even I know there is no way that would work. I did try the 60 grain Hornady V Max in all three rifles and it didn't work in any of them and the 68 grain didn't work in either Axis or Remington. The Hornady 52 grain works reasonably well in all three rifles.
I am by no means an expert, and have only been reloading for a couple years, so this is not meant to be argumentative, but rather something to think about. Whenever I hear this discussion about distance from the lands, I always think about Weatherby. They're known for "freebore" (long throats). They do this to keep pressure spikes down in their high performance rounds. Yet, I don't every hear much about Weatherby rifles being inaccurate. They aren't used much in benchrest competition, on the other hand.
Same can be said for my M96 6.5x55 Swede. Long throat, very accurate and they do quite well in Vintage Military competition.
I always thought that Weatherby rifles are meant to hold "minute of Water Buffalo".
If you have a problem with accuracy try the Federal Gold Medal Match or Black Hills match ammo (or the military long range stuff). If you can't get under 1" with those then it might be the rifle. FWIW, Federal and Black Hills use SMK bullets for their match loads (at least they did pre-COVID).
Yeah, these days it is hard to come by.
LOL that may be true of the big bores.Quote:
Originally Posted by RCE1