Home Forums Hunting & Shooting Ask The Gunwriters 6,5-270 vs 6.5-06 vs 6.5x64 Brenneke

I understand the 270 WCF case is longer than that of the 30-06 Springfield, but where does its excess length come from? Is it just the neck that is longer and all the other dimensions are identical? Same headspace?

Are the 6.5-270 and 6.5x64 Brenneke (a CIP cartridge) cases identical and with the same headspace?

Yup....that's exactly right.....the .270 has about .046 longer neck!

I'm not familiar with the 6.5x64 Brenneke so I'll let someone else comment on that one.

It sounds like you want a larger 6.5 case without going magnum, the 6.5 gibbs is your answer.

From what I can gather, the 6.5 Brenneke IS a 6.5-.270, same case length and all.

The 280 Rem does have a slightly longer head space dimension than the 270, 25-06, and 30-06.

A wildcat 6.5-280 would gain you the capacity for a couple extra kernels of your favorite slow burning extruded powder. While the wildcat 6.5-280AI could net you a couple grains of capacity compared to the 6.5-06.

Neither will quite match the internal capacity of the Gibbs cartridge.

Actually the "Handloaders Manual Of Cartridge Conversion" lists the 6.5 Gibbs as having a capacity of 74.41gr of water and the 6.5x.280 Improved as having a capacity of 76.11gr of water.

Loaddata and I concur.

I use RCBS Load 2.88 cartridge designer tool as my reference.

The program does not list either the 6.5 Gibbs or the 6.5-280AI as a reference cartridge. It does, however, allow the user to neck the 280AI down to 6.5 mm and maintain the 40 degree shoulder. It lists the capacity of the altered cartridge as 60.7 gr water to the base of the neck.

The 30 Gibbs necked to 6.5 mm and held to a 35 degree shoulder shows 64.2 gr water capacity to the base of the neck.

Neither measurement takes into account any internal capacity lost as a bullet is seated into the case.

I found it interesting to note that the 6.5-280AI shows 67.0 gr water capacity when filled completely to the top of the neck.

The body length is longer on the 30 Gibbs, the diameter is larger at the shoulder on the 30 Gibbs, than on the 280 AI. Unless Gibbs designed a 6.5mm cartridge which is smaller than his 30 Gibbs, I would suspect a typo in your reference material.

Wouldn't be the first mistake I've found in the book.

The 6.5x280 improved referenced in the book is the RCBS version.

The dimensional data in my book shows many differences between the 6.5 Gibbs and the .30 Gibbs.

I have Wildcat Cartridges Vol II from Wolfe pub. It shows that the 270 Gibbs is simply the 30 Gibbs necked down. Same distance to shoulder and same diameter at shoulder.

The volume also has one article on the 6.5 Gibbs. It does not give dimensional data, but does show a photograph which seems to indicate neck and shoulder geometry to match that of the 270 Gibbs.

Can you list here distance to shoulder and diameter of the shoulder on the 6.5 Gibbs?

Those measurements on the 270 and 30 Gibbs are 2.145 inches to the shoulder, diameter .453 to .455 at the shoulder, and a shoulder angle of 35 degrees.

As I remember, the 280 RCBS improved has less than 40 degree shoulder angle and has slightly less internal capacity than the Ackly version. Please correct me if I am wrong about that.

Like I said, this "Handloaders Manual....." has been known to be wrong from time to time.

The listed length to the shoulder is 2.195"
Diameter at shoulder .449
Shoulder angle of 29.08*
Neck length of .270

Now, my newest book on wildcats is "Wildcat Cartridges" by Fred Zeglin (published by none other than our old friend Oldman1942!)
There is a whole chapter on Rocky Gibbs and his cartridges.
The dimensions for the 6.5 Gibbs given in this book are as follows.
2.1672" to the shoulder.
.4420" diameter at shoulder.
35* shoulder angle.
Case capacity is listed as 70.00gr even.

I think I would tend to believe the Zeglin book more at this point.

As to the 6.5x280 RCBS Improved the shoulder angle is listed at 33.99*
Length to shoulder at 2.02
Diameter of shoulder at .443
Case capacity of 76.11gr of water.

I do not like cases with radical designs, like the Gibbs, or even like the AI. Also, the basic '06 case provides with enough capacity for my needs.

Now, between the 6.5-270 and the 6.5-06 I prefer the first one, as you need to work the brass less when sizing it down than with the '06, and both parent cases are equally common and easy to find.

In my mind, their rival would be the 6.5-284 but, again, its design is a bit "radical" for my taste. Also, chambering it in a short action which would consitute an advantage, limits its overall length even with the mediunm weight bullets, and if I were to go for a standard length action I would rather stay with the .270 0r '06 case.

You mentioned the 280 Remington has slightly more capacity but I do not believe it will make any difference, its cases are far less common, and they require more sizing down to 6.5mm than the 270s.

One last question, if I may, the 6,5x64 and the 7x64 are both identical cases except for the neck diameter?

Thanks to all that contribute.

BBerg

As far as where the extra length on the 270 case comes from--- the way i understand it is that when winchester started making brass for the 270 they started out with the same amount of brass as with the 06 case. They kept the neck wall thickness the same so the extra brass formed a longer neck.

With the 6.5-06, making brass doesn't get much simpler than running 25-06 brass in the 6.5-06 sizing die. 25-06 brass isn't too hard to find.

There is one basic flaw in the logic of making 6.5-06 brass from 25-06.

If one also owns a .25-06, and it has a slightly oversize neck... Then the possiblity ALWAYS exists that one may accidentally chamber a 6.5/06 round in the .25-06 with potentially disasterous results. That is NOT a chance I'm willing to take...

Which is why when I built both of my 6.5's, I specified 6.5x64 Brenneke! Besides, one never knows when the rilfe may ultimately belong to someone else...

Yes, headspace dimensions are identical. I load my brass with standard 6.5/06 dies.

GH