30-06 Silvertip Bullet

Its simple and uncomplicated.
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It all depends on who is saying "all you gotta do is etc. etc.".

And then life is much easier on a reloader if he knows how to zero a gage, next come the gage, I understanding reloaders are conditioned to use the term 'head space' at every opportunity so "It's simple and uncomplicated" is not true if they do not understand there is a chance they are using a comparator. Life could be real simple for a reloader if they knew the difference between a head space gage and a comparator.

I do not use a comparator, I do not use a head space gage, I transfer the dimensions of the chamber to the seating die and then zero. I believe the problem starts when forum members try to talk the subject to death.

F. Guffey
 
Perhaps, in my previous post #10, above, I may have been misunderstood.....
I was referring to using a fired, un-sized case, a bullet, and a magic-marker to use as measuring devices only, and not making an actual loaded round of ammo. You want the bullet to be easily, but not accidentally moved for this procedure. The case needs just enough grip on the bullet to hold it from falling out and to scrape the ink off the bullet as it is pushed into the case by the rifling. After you get all the measurements you need, make all the real ammo you want. And yes, if you do this right, you wont ruin the bullet for actual use later. The whole procedure is simple as pie, until misunderstanding and confusion sets in.;)
 
Pathfinder's method works well and is the one I use to find my max COAL to the lands. A wooden Dowell that fits down the bore is helpful. Bullets can stick m in the lands and give a false reading but I do the test and measure 10 or 12 times. This tends to highlight false readings. The magic marker on the bullets let's you know when you are there.
 
It is an aluminum cap. The second groove is only decorative. If you load to the reeded canellure you should be loaded to factory specs. you can generally use the measurements interchangeably with others of similar shape with start charges. The silvertip was designed for heavier game. T h e cap was meant to delay expansion, limit explosive expansion. The extra ring showed that the core was "locked" into place. Since all of that aluminum had to be torn open before full mushrooming happened, the bullet had slowed down to velocity that could prevent over expansion.
 
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I purchased a large bunch of Silvertips bullets once only to discover the crimping groves were somewhat random in distance from the bottom of the bullet. There was quite a bit of difference in some of them. I just had to ignore the grooves and load them all to the same length and they shot just fine.
 
The apparent randomness will be due to different tooling sets making the bullets and having their output combined later. The difference will be there, but it should be within the designers intended range. One advantage to that variation is you can probably sort your bullets by cannelure position, and in that way get those that all came off the same tooling collected together to see if one group is more accurate for you than another, if that matters to you.


Bucksnort,

The SAAMI standard actually calls for a 0.050" range of COL from 2.940" to 3.340". The is a match to the 7 cal ogive radius military FMJ bullet design, which is the standard reference length. With other designs it can be too long and get the bullet too close to the lands, or give the neck inadequate grip on the bearing surface. So, the range is for magazine fit and feed of that standard bullet shape. Pushing a 7 caliber bullet of that military shape deeper in the case than the minimum number will leave a visible gap around the bullet at the case mouth.

If you measure commercial loads, though, you will find the range is not followed for all other bullet shapes. Hornady, for example, gives their shorter 150 grain BT-FMJ a recommended COL of 3.185" in the .30-06. Sierra recommend 3.290" for the 168 grain MatchKing, etc. These bullets have shorter ogive designs with tighter ogive radius than the standard military shape does. If you seated the 150 grain Hornady to 3.340", not only would case have inadequate grip on it, the shorter ogive would be jammed in the lands of some chambers.

The reason for the above is illustrated below. It shows two different bullet designs seated for the same amount of jump to the lands, but with very different resulting COL's:

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So, you don't have Winchester's load data for your obsolete bullet. How do you tell where the manufacturer intended it to be seated? The cannelure. It is there for manufacturing purposes, as the factory loads will be crimped into it, even if you don't crimp. To find the intended COL, seat in two steps. First seat to 3.340", and then look to see which cannelure is still above the case mouth. Seat the bullet deeper until the top edge of that next higher cannelure is getting close to even with the case mouth, sticking up maybe 5 thousandths as if you were going to crimp into it. That's where the maker intended the bullet to go in this cartridge.

Now, that whole business of the maker's intentions disregards how long your individual chamber's throat is. It may be long enough for a 3.340" seating depth with this bullet. It also may not, and if it is too close, commercial load recipes may get higher peak pressure than stated.

For non-varmint hunting and plinking accuracy, I tend to stay with the manufacturer's intended seating depth unless there is reason not to, as it will generally guarantee smooth functioning with fast feeding and that pressures are less far off load data for similar bullet type and shape. The maker chose to put the cannelure where he did because it made the bullet compatible with all chambers it might be used in. It could be shorter than you need in your gun, but that has to be confirmed by measurement and testing.

If you want to avoid finding your throat with that bullet and all that work, stick with the first cannelure that makes the cartridge shorter than SAAMI maximum. If I am after gnat's backside accuracy or just want to see how accurately I can make a particular bullet shoot, then I adjust COL to the individual chamber by trying a range of seating depths.
 
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