6.5-270 Gunwriters Cartridge

[Rich Coyle]

I love your post, Quiet.

 

[shortgrass]

I like the idea, but if a guy has .270win cases and is going through the process, why not just blow it out to;

6.5-280ai?

Because there is .050" difference between the .270 case and the .280 case from base to shoulder? It was designed that way to prevent 280 from chambering in a 270 with its smaller bore. The .270 case won't fire in a 280ai chamber unless held against the bolt face somehow,,,, with the extractor or by jamming the bullet. .050" is a lot of stretch, length wise, for a brass case. Use .280 cases for any 280ai variant (.25/280ai, 6.5/280ai, 270/280ai??, straight .280ai, 30/280ai, or any others). There were many cartridge cases Ackley did not improve. Propellant selection then was not what it is today, and only a few Improved cartridges showed any "promise'. Today, we seem to call any cartridge that can be blown out at the shoulder with a 40*, using the 'parent' brass to do so, "Ackley Improved". It has been many years since I read "Handbook for Shooters and Reloaders", by P.O. Ackley,,, but it is a worthwhile read (2 books) if it can be found. It forms the basis of what we call today "Ackley Improved". No need to re-invent the wheel, especially if it's more complicated way of doing so. Years ago there was a popular wildcat where the .270 or .30/06 case was necked to 7mm, creating the 7mm/06 (.270 and /06 use the same headspace gages). That was pre .280 Rem, 7mmExpress Rem. Depending on throat length and barrel wear, a 7mm/06 cartridge might be forced into a 270 Win chamber with not so good results. At one time in the past RCBS made their own version of the .280ai, but it had a 30* shoulder. The .280 Rem case was the basis for that cartridge. Today it is common to see shoulder angles of 30* and 35*.

 

[Wild Monkey]

So what are you achieving that the 6.5-06 isn't, or I guess the 6.5-06ai? I'd imagine if you put those cases side by side you wouldn't be able to tell which is which. Half decent chance they'd chamber in either other's chamber and within a tenth of a grain in powder capacity, it'd matter more who is making the brass and thickness.
In fact are you sure you're not just exploring another way to get 6.5-06 brass?

According to my very non scientific math this Cartridge provides somewhere in the neighborhood of 71 Grains total Volume. If one was to design it as a 40 degree shoulder they would have even more if that's what you're after. I drew up that illustration from memory, as noted earlier you can make the chamber with whatever shoulder angle & width you desire. Oh, and just to set the record straight if the 6.5-06 went full retail and I could buy a rifle at Academy along with box ammo, you can bet your biscuits I'd already own one. You see, I have 270 brass and 6.5mm Bullets and now with Browning offering a fast twist 270 I'm leaning even more towards the 6.5mm. This must be some type of mental wildcat illness I suspect.//

 

[Wild Monkey]

Folks are having a mental block with the entire Ackley Improved thing, RCBS did have one or more 30 degree shoulder dies they used to sell. Remember, Otto's 1st wildcat was in fact a 28 Degree shoulder, not a 40, and he made a two separate short magnum wildcats with 25 degree shoulders I believe. This should help many understand. Otto is famous for "improving" narrow factory chamberings by converting them to 40 degree shoulders, but he did many different designs. It's unfortunate for everyone involved to think only "Ackley Improved" 40 degree cartridges exist and anything else is not worthy or worth pursuing or whatever. In fact it's happened far more that most realize a new cartridge was designed with a 30 degree shoulder for instance and manufacturers changed it and instead used the same old shoulder like in the case of the 243. Can you imagine? the Creedmoor would never have seen the light of day if the 243 were produced with the 30 degree shoulder from the start. None of this has anything to do with the initial topic, but to have to sit here and defend a cartridge because it's not an Ackley or the latest and greatest PRC is Preposterous.

 

[timo308]

I stumbled across an Article published online years ago regarding a 6.5mm-270 Improved based off the 264 Win Mag Full length sizing die. They apparently used a combination of Reamers to accomplish the chamber. I don't recall which 08 Case they used for the shoulder design regarding angle and exact width. This Wildcat offers ample capacity for today's high BC bullets & the new long boat tail all copper hunters.
View attachment 481159

I had to build one of these for the nephew of one of my regular customers. His brother had stumbled across one of these in a model 70 classic with a stainless Douglas premium Barrel and his son decided that he wanted one just like dad's. Only difference was that I used a faster twist rate in the son's rifle. Was fairly easy to chamber for just using a .270 Win ran in to set the 2.246 dimension then a 25-06 to finish out the body of the chamber followed by a necking/throating reamer set up to mimic the 6.5 creed. According the the dad the 'so called' great claim to fame was that you got the 26-06 case without having to buy the 26-06 reamer or any expensive custom dies. I explained him that I was pretty sure that now days the 26-06 dies could be had for the same price as the 270 and 264 Win mag dies.
It is basically identical to the 26-06 standard cartridge which I also had a reamer for, but he chose not to go in that direction.