270win vs 270wsm

[B rampton Mike]

WOW you guys are getting WAY to technical for me!For the ones who responded that i understood thanks!Brampton Mike

 

[Boomer]

Nope. A more-deeply seated bullet takes up exactly the same extra volume in a pencil-sized case or a tuba-sized case.

The volume of a cylinder (our geometric stand-in for a bullet base) is pi r2 h. 'h' is the amount the bullet sticks into the case, and 'r' is half the diameter of the bullet. Basic math here.

That is only true if the bullet does not extend below the neck of the cartridge or if you could fill the case with powder along the sides of the bullet. The volume below the base of the bullet is decreased when a long bullet extends down into the powder capacity. Let's compare two imaginary bottle neck cartridges of equal volume and equal neck length. One cartridge is 2" long from it's base to it's neck and the other is 1.5" long respectively. It isn't too hard to see that the longer cartridge will have more useable powder volume if a long bullet extends 1" below the neck in both cases. The longer cartridge with more available powder volume will produce a greater velocity with the same type of powder even though the actual case volume is the same. The shorter cartridge, despite the fact that the total volume is the same, will have it's powder charge compressed before the maximum charge for it's volume is reached.

 

[acrashb]

That is only true if [...] or if you could fill the case with powder along the sides of the bullet.

That's fine then, because you can fill the case with powder along the sides of the bullet. When you seat the bullet, powder displaced by the base will flow up along the sides.

 

[Boomer]

That has not been my experience with long heavy for caliber bullets, but if you can figure out how to do it in a bottle neck case good for you. In my experience, once the powder is compressed under the base of the bullet it doesn't allow for more powder to be added, and while it might be possible to get some compression with powder charges up to say 110%, you will never accomplish this with a long bullet whose shank extends below the shoulder of the case.

But lets consider a couple of real life examples. My .308 is chambered so that I can keep the shank of a 200 gr MK from entering the powder capacity of the case. I have clocked velocities approaching 2700 fps with no pressure from a 28" 1:8 barrel. With a 220 gr MK it makes 2400+. Thus by increasing the useable powder capacity I have managed to get .30/06 performance from my .308, but that would not be possible with a factory chambered .308 rifle because the shank of the bullet would by necessity extend deep into the powder capacity of the cartridge.

The .375 Ruger is reputed to outperform the .375 H&H. Yet when loaded with 380 gr bullets seated to the cannelure I was unable to break 2000 fps with the Ruger with either 4350 or 760 while the H&H can make 2200 fps. My long fat .375 Ultra pushes that 380 gr bullet to 2300 with 4350.

The .35 Whelen and the .350 Magnum have very similar case volumes, yet I was never able to match the velocity that was published for the .35 Whelen with 275 gr Speer bullets in my .350 Remington, because when the long bullet was seated so the round would function in the magazine, the useable powder capacity was reduced by the long bullet shank. If I ever get another .350 magnum I will have it built on a long action and have the lead cut long to accomadate long bullets.

 

[acrashb]

That has not been my experience with long heavy for caliber bullets, but if you can figure out how to do it in a bottle neck case good for you.

223, Hornady 75gr #2279 seated to mag length (2.250"), H322. My load fully fills the case but is not compressed. The bullet sticks way into the case.

Stick your finger into a pile of powder. The powder displaces around your finger rather than compressing under it. Works the same with a bullet base.

A long stick powder (e.g. IMR 4895)might want to lock up some rather than flow, but H322 is fine, as is any ball powder (e.g., BL-C(2) and others I've used).

Perhaps the issue here is powder choice.

Certainly if the case was only a bit larger than a bullet the powder might not want to flow up into the small remaining gap. But in a normal case, with the powders I've mentioned, there's enough room to the sides - the .223 is not a short/fat case. The 270 / 270wsm thing should work the same way.

 

[tjhaile]

Ammunition might be a small fraction of the cost of the hunt, but practice is a must for anyone wishing to maintain an acceptable standard of marksmanship. This is where ammo/component cost is a major factor, especially for the casual user who is dependent on factory ammo.

As I see it, the 270 WSM or any other comparable magnum has a number of serious disadvantages over standard chamberings for a gain of a couple hundred fps in muzzle velocity.

Let us not forget that the original poster is looking for a rifle primarily for coyote shooting. As it is, the .270 Winchester is already more than enough rifle for the intended purpose by a considerable margin.

 

[tbell_1]

Why is either .270 a choice for mainly coyote hunting? Don't you know anyone you can sell pelts to? Either .270 will all but ruin any coyote I would think. Why not pick up a .223 or .22-250, then keep saving your change to buy another rifle when the opportunity to hunt anything bigger comes along?

 

[Boomer]

223, Hornady 75gr #2279 seated to mag length (2.250"), H322. My load fully fills the case but is not compressed. The bullet sticks way into the case.

Stick your finger into a pile of powder. The powder displaces around your finger rather than compressing under it. Works the same with a bullet base.

A long stick powder (e.g. IMR 4895)might want to lock up some rather than flow, but H322 is fine, as is any ball powder (e.g., BL-C(2) and others I've used).

Perhaps the issue here is powder choice.

Certainly if the case was only a bit larger than a bullet the powder might not want to flow up into the small remaining gap. But in a normal case, with the powders I've mentioned, there's enough room to the sides - the .223 is not a short/fat case. The 270 / 270wsm thing should work the same way.

Here's a simple test to illustrate the problem with your theory. Take an old fashioned salt shaker, the glass kind so you can see inside, with a screw on cap and sloped sides. This approximates the shape of many rifle cartridges as the salt shaker has a distinct neck, a shoulder , and a tapered body, but allows us to see what is going on inside when a bullet is seated against a powder column. Fill the salt shaker with powder between half and three quarters full. Ball powder, extruded , or flake it matters not which type. Now take a rifle cartridge whose base is just slightly smaller than the mouth of the salt shaker and place the cartridge case head down against the column of powder. This replicates the base of a bullet being seated in a rifle cartridge . Now push down on the rifle cartridge, taking care not to rock it, just straight down pressure. What happens? The powder is confined within the salt shaker and cannot be displaced outward. It will compress until it reaches 100% density under the cartridge head. At that point it will no longer move, and the powder will not displace upwards along the sides of the cartridge.

That is what happens inside a rifle cartridge when we seat a bullet that is longer than many handloaders normally encounter. The useful powder capacity of the cartridge becomes less than the total. If powder was fluid, then what you describe would indeed happen, but there is a difference between solids and liquids and they do not behave the same. If solids behaved under compression the way fluids do, it would be impossible to pack a road-way, the granular material would simply be displaced by the drum of a road packer.

Here's another test you can try, but your hearing will have to be better than mine. Seat a bullet very hard against the powder column and crimp it in place to prevent it from being pushed out, then shake the loaded cartridge beside your ear. If you can hear, or for that matter feel powder shaking in the space between the base of the bullet and the neck of the cartridge, it has obviously not filled that space.