Igm270 your question is as tough as one being asked by a father having just caught you dating his twin daughters. Well boy which one do you like best?
While the 6.5 cartridges with 30-06 case capacity are paternal twins to the .270 Winchester at reasonable deer hunting ranges, the 6.5x55 as I know it has a couple different faces. The original model is rated at a lower pressure. The new rifles such as the Model 70 Winchester, M98 actions, and Ruger 77 can take advantage of the case capacity. I loaded my Model 96 Swede at the maximum published data. But my deer hunting load consisted of military ammunition which the FMJ was pulled and replaced. These averaged 2550 fps over the Chrony. My full handload consisted of new Winchester Brass, WW primers, and H4831. Velocity average 2600 fps at 15-feet over my Chrony at 6700 foot elevation.
I have read a lot of arguments about loading hotter for the Model 96 but I was happy at that point. Had I been loading for a Winchester Model 70 or a Mark X I would have pushed on.
6.5 fever is one of those things that a doctor cannot cure, unless he gives you money to buy the next 6.5. My brother has it bad and I can only remember some of his 6.5 rifles, 6.5-250-3000, 6.5 x 55, 256 Newton, 6.5-284 Winchester. He also has a couple of 270 rifles.
It was not until late in my deer hunting career that I used Nosler Partitions on deer. I think the focus has always been on the dependable penetration they provide. Two older calibers that I have had satisfaction when using the Nosler Partition is the 6.5x55, 140-grain and the 165-grain in the 300 Savage. It has been my observation that the rapidly opening Nosler Partition creates a lot of damage on entering and then penetrates deep or exits. I like it.
I have played the bullet game with .264 and .277 bullets on the computer. When launched at the same velocity with bullet “A” the .277 wins, with bullet “B” the .264 wins. When the .264 and the same .277 bullet are launch at the same velocity they are next to each other on a shoestring. If I plug the 6.5x55 in at 2550 fps on the same screen it’s performance does not come close to a 6.5 in a -06 capacity case or the 270 Winchester.
When it comes to the care and feeding of the 6.5x55, the 6.5-06, the 6.5 Remington Magnum and the 6.5-284 the bullets cost more, and new brass cost more. You will save some money using -06 brass to make 6.5-06 brass.
Does the 140-grain Nosler PT at 2550 outperform a 150-grain Hornady or a 140-grain Hornady BT out of my rifle. I do not have a good answer based on field trails. I need to shoot a few hundred deer this winter. I have published this before; I shot a buck a couple years ago right behind the front shoulder with one of my .270’s. The bullet hit a rib and created a 3” inch shape entrance hole inside the rib cage, took out a lung, damage another lung, and put a two inch exit hole going out the opposite shoulder. On impact I watched hide ripple along the deer. The deer took off like a bolt of lightning and was quickly out of sight. After looking at the damage I was amazed the deer did not drop on impact.
Defining the deference between two different calibers is an interesting task, at the same time I am playing with paternal triplets. That is three different .270 Winchesters and use different loads in two of the three. One has a slow barrel but has proven itself on deer, or is that why the buck ran after being hit. I keep thinking about buying a 24-inch take off barrel for it to gain back the lose velocity, but why?
The physiology of the critter shot is a major factor in the outcome.
I delivered the 6.5X55 to the son-in-law there are some young granddaughters that have an interest in shooting. Along with it were a few hundred rounds of ammunition. The recoil is lighter than my .270 rifles and they know it is effective because they have seen the buck in the bed of the pickup. They will have to wait for a 270 until I can no longer hunt, or I am pushing up daisies!
Given equal case capacity which one do you think is better?