Correct C.O.A.L won't fit in the mag..

[Thegreg]

It is usually suggested that the diameter of the bullets seated in the neck is a good starting point ie 308 should be at least 308 thou in the case or better still start at the recommended COL of 2.800 as in your 308 using the OCW or Satterlee method to test.

Personally I have never been able to get my head around the concept of seating the bullet 20 thou or less unless it happens to be a bench rest rifle. Most rifles have as many as four sweet spots, granted the first may well be less than 40 thou but that may be the obvious node to find - against it are two points to consider - will it fit the magazine and now with this long bullet balancing at the end of the case neck you are creating quite an air gap above the powder which can delay ignition by a nano second especially as that air pocket will creep back towards the primer as usually rounds are fired on the horizontal.

I must confess to having a little chuckle when you mentioned 'a massive 175 thou jump' - a chuckle only because my 20 Tac with a custom barrel is 223 back and will group sub .2, my 22.250 at 220 thou and 6.5 at 180 thou - both well less than .5"

Tried to put a couple of scans of other people's rifles I reload for showing these 'massive jumps' but I'm not technical enough to achieve this.

Peter

Thanks for the reply Peter. It is encouraging to hear that bullets don't necessarily need to be be set just off the lands but it's always a variable I've tried to keep tight control of. It does make sense to me that seating a bullet just off the lands will eliminate a lot of potential misalignment that might occur with a jump. When doing testing on my .223 I recorded noticeable differences when seating between .005" & .020" from the lands, so I believe it is influential.

I'm going to try some different heads. See if I can get the seating depth I want while still being able to fit in the mag. Using polymer tips doesn't help me with the length issue so am going to look at hollow points instead.

Point taken about the air gap created by seating further out of the case.

Cheers
Greg

[severnsider]

Greg,
Is it not simply the case that the TMK projectiles are longer/slimmer at the "sharp end" than, say, the equivalent weight SMK and others?
I was put off using them in my .308 as the OAL increased to the extent that they wouldn't fit the mag if powder space was to be preserved. Presumably the same would apply to your .308 too. Is it a Remington by any chance? In other words, if you seat the TMKs to mag length you risk losing case volume and having a compressed load.

[Thegreg]

Greg,
Is it not simply the case that the TMK projectiles are longer/slimmer at the "sharp end" than, say, the equivalent weight SMK and others?
I was put off using them in my .308 as the OAL increased to the extent that they wouldn't fit the mag if powder space was to be preserved. Presumably the same would apply to your .308 too. Is it a Remington by any chance? In other words, if you seat the TMKs to mag length you risk losing case volume and having a compressed load.

That's what I'm hoping. They are a long slender profile and I noticed in the .223 they had a longer C.O.A.L than the equivalent 55gr Hornady AMAX head.

I'm going to try Lapua Scenar's for starters, which I've heard good things about.

The rifle is a Krico 640S, not at all common so very unlikely I'd get feedback from anyone else who owns one on here!

Cheers
Greg

[severnsider]

That's what I'm hoping. They are a long slender profile and I noticed in the .223 they had a longer C.O.A.L than the equivalent 55gr Hornady AMAX head.

I'm going to try Lapua Scenar's for starters, which I've heard good things about.

The rifle is a Krico 640S, not at all common so very unlikely I'd get feedback from anyone else who owns one on here!

Cheers
Greg

The Scenars ought to work, but if you really want to use the TMKs then I think you're going to be stuck with single loading and not using the magazine. As you say, the TMKs will probably give you the same probem in the .223. Good luck!

[simgre]

The ogive of TMKs is set further down the shank. My Redding seating die won’t sit .223s deep enough firvnag length loading.

Roy Wetherby was a great proponent of free bore. He was so convinced of his testing that he was the first manufacturer to guarantee the accuracy of his rifles and all factory offerings had a long leade.

[harry mac]

Forget how far it has to "jump", see how it shoots when loaded to either book length, or just short enough that it fits the mag. You have to work very hard to make a .308 shoot badly.

[kennyc]

Forget how far it has to "jump", see how it shoots when loaded to either book length, or just short enough that it fits the mag. You have to work very hard to make a .308 shoot badly.

I 2nd that if it shoots at 2.800 why bother playing with the length? All you are doing is introducing variables and expending materials and time, of course if you enjoy that then crack on, but IMHO too many people jump straight past the basics and then get into trouble because of the "wisdom of the interweb"