I'm trying to determine whether 6.5x55 sweede will use .257 bullets...and, if not, are all 6.5 mm bullets the same diameter?

The Swede is a .264" bullet user.

No. A 257 bullet should not be used in a 6.5 or .264 bored barrel and certainly a 6.5 bullet should NEVER be used in a .257 bored barrel.

Since the 6.5x55 should have a 0.264" bore diameter, you could shoot 0.257" bullets through it, but the 0.007" difference probably wouldn't seal the barrel, pressure would likely be low(er) and erratic, and accuracy would be "iffy".

Jeff

It`s confusing, 6.5mm is .256" but, the difference in a 6.5 barrel and a .257" barrel is whether the cartridge was designed with a bore measured across the grooves or the lands. The 270 is another, .277" is 7mm.
All 6.5mm designate cartridges use .264" bullets and .257" cartridges use .257" slugs that I`m aware of, although the old 256 Newton also uses 6.5mm bullets despite it`s name.
As I said, it`s confusing at times

its actually 6.71mm for .264

in my past 40 years of handloading experience: For a 6.5mm bore I always use .264 bullets...........257 bore I always use .257 bullets. ......7mm bore I always use .284 bullets....

Close, the 6.5 Carcano is the exception to this rule, it uses a .268 dia bullet. the rest as far as i know, are .264. and confusing is an understatement when it comes to metric/US standard cartridge conversion.

Huh ?

the 6.5mm is .264 except for the carcano cartridge which uses a .268 nope dont do the 257 bullets down a 264 barrel as you wont be happy with the perfomance as your wasting your components.....

the right answer is simple,NO,NEVER,NOWAY!!!

JeffG - Please, please, please! Stop whatever you are doing, buy three reloading manuals, and read the first half of each manual before you take another step! PLEASE! Nosler, Hornady, and Lyman most recent versions are excellent choices!

Then move to the 6.5x55 Swede data section and look at the bullet diameter used in all data testing.

Thanks for all of your considered, and considerate responses...I am not doing anything unsafe, (...famous last words). I was contemplatinging the purchase of a 6.5x55, and was hesitating based on the thought of collecting a whole new bullet selection...did a breif search of bullet diameters, and couldn't determine which one fit.

But again,
Thanks!
Jeff

Ah, okay then. I will err on the side of caution - always! Any reloading manual will list the bullet diameter used with each specific cartridge, .257" and .264" are NOT compatible.

HUH? im confused....

It IS confusing. There are two different diameters that you can talk about with a rifle, bore diameter and land diameter. Take, for example, a standard .30 caliber bullet, it'll measure .308". .308" will be the bore diameter of the barrel it should be shot from. The land diameter, however, will be .300", meaning that each land of the rifling will be .004" tall. Each land of rifling will engarave .004" into the bullet, and with two lands on each side of the bore you can add .300" + .004" + .004" to get .308". Simple, huh? Until the manufacturers started getting cute and basically pulled cartridge names out of their butt. Take the .308 winchester, it uses a .308" bullet, but so does the .300 winchester, .300 weatherby, etc. Oh, and then they decide to make something like the .307 winchester, but .307" isn't a characteristic of either the bore or the land diameter, it has NOTHING to do with anything about that cartridge. So MOST rounds that shoot .308" do get called a .30 cal or .300 something, they go by land diameter, but then you look at the .338 win mag and the bullet actually is a .338" bullet. Take the 404 Jeffrey round vs. a 416 remington magnum, you'd think the 416 was obviously bigger, right? Wrong, the 404 Jeff shoots a .423" bullet while the 416 remington shoots a .416" bullet. Then you get into the metric designations, where a 7mm rem mag shoots a .284" bullet, except .284" is actually 7.21mm. It turns out that they're referencing the land diameter again with the 7mm. Same with the 6.5mm rounds where they shoot a .264" bullet, except .264" is actually 6.7mm, .256" is 6.5mm.

The bottom line is that none of the names mean anything and the only way you can actually tell what bullet they shoot is to look up the specs, either with a reloading manual or online.

Jeff, you need bullets in .264 caliber for the sweede or anything else in 6.5

.257 for things like 25-06, 257 Roberts, etc

CLB

You should give in to temptation and get a 6.5x55. There are lots of good bullets out there but if you want to simplify and economize, just get a box of Hornady 129's and, in the Words of our Esteemed Dober, go forth and fill an ark.

There's a really sweet 6.5x55 Swede in Ruger M77 MkII over in the classifieds right now - go for it!

I've shot a handloaded 257 Roberts round in my 6.5 x 57... there was no worries of pressure problems etc.....accuracy stunk...

tried it for the reason is I like the 117 grain RN bullets from Hornady..

I don't recommend this as a regular practice..

just wish Hornady would make periodical runs of their old 129 and 140 grain Round Noses... or I just happen to find someone who liked me so much they gave me about a 1000 of each, just because I was such a peachy guy..

Selmer,

You need to go ahead and treat yourself to that Ruger. You'll be glad you did.

Best Regards

If it was a real 6.5x57 and not the 257 Roberts necked up and often called 6.5x57, you had a bunch of extra headspace, too.

The 6.5x57 (1.752) has a longer body length than the Roberts(1.728)

The 57mm family has several different body lengths.

http://stevespages.com/page8d.htm

Bruce

Ya know BCP, the rifle was marked 6.5 x 57, and that is what I wanted... it was custom built on a model 70 long action..

but when reloading it, I have to bump the shoulder back with a 257 Body Die before it will chamber...

so maybe the smith just used a 257 Roberts reamer and made me a 6.5 x 257 and just labeled it as my requested 6.5 x 57...

its a good shooter and I've learned to live with that at the reload bench...

I profess tho, that it is my favorite cartridge, as I see it as the most practical all around cartridge out there....
a 6.5 x 55 in more commonly available brass..I neck up 6mm Rem or 257 Roberts..

I also still shoot the 6.5 x 55 and the 260..but if I was parred down to one rifle by the government, the 6.5 x 57 would be the one I kept..