Forming 264 Win Mags from 7mm Rem Mags

[ScotMc]

7mm Rem Mag to .264 Winnie- No problems that I have encountered, I personally like to graphite my necks inside and out. I also use Imperial sizing die wax on the case body. Use your friends rifle as a test platform for the resized rounds. Just a slight resistance on the bolt when you close it on the resized round.
Leadman is very correct. The Factory ammo uses a 2 diameter J word bullet. If you use regular .264 Bullets , you will be seating them quite deep compared to the factory round.
I have been using surplus H870 and a 140 gr. Accubond in an early Model 700 with a stainless barrel . I found the bullet was cutting into my case space, reducing my powder capacity. I had my rifle throated by a local smith to get the bullet further out of the case. The .264 really spins coyotes good......

[swheeler]

Remington got the 7mm over on Winchester in this case.

Winchester spent quite some time developing the 6.5 round but someone found some of the cases during the development stage and Remington took advantage of it and just necked the cases up to 7mm and introduced their round.
the 6.5 was pretty much dead in the water from minute one at that point.

I think this is just another "old wives tale" because Winchester introduced the 264 Win Mag in 1958 and rifles and ammo were readily available, then 4 years later in 1962 Remington introduced the 7mm Rem Mag. They did indeed just neck up one caliber, it caught on because of better bullet selection and was deemed not such a "barrel burner" in the gun rags of the time. I shoot both cartridges and prefer the 264, loaded to it's full potential with 140 bullet it is capable of taking anything North America offers.

[kiwi]

I have a Ruger 77 in .264 Win fitted with a Douglass barrel it came with 80 loaded rounds in 7mm Rem cases it shoots 140 grain Hornady interlocks into nice little groups
it also came with 100 new Winchester .264 brass I am still using the 7mm brass have not lost any yet so it is not a problem using 7mm Rem cases
I picked up a few 7mm Rem cases to try necking them down one pass through the FL die and job done just as easy as sizing a fired case

[eagle27]

If I were you I wouldn't anneal first, but last. Second....If your sizing down/up 7mm mag brass I would have the rifle right there to use as a gauge. Many of the sizer dies out their just aren't made with case forming in mind.

I do know for a fact I had to remove .030 from a sizer die in order for it to work right, and that was from the bottom of the die. Others not so much, usually around .008-.012 which is common.

So don't expect that the case will be formed when the sizer die bottoms out on the shell holder. I'll bet if you had the rifle right there the bolt wont close, which means removing material from the base of the die until that newly formed case will fit and the bolt closes.

For the record, removing material from the base of a die to remedy tight chambering cases is not the way to go. Most often it is the base of the case that is contained in the shell holder that needs sizing slightly more and removing material from the die mouth does not make a scrap of difference as this part of the case will always be in the shell holder. It is better to carefully grind/sand down the top of the inexpensive shell holder which allows more of the case base to enter the sizing die. Often only a few thou taken off the top of the shell holder is needed.

[Lloyd Smale]

ive made lots of it just running it through the 264 die. Like others I wouldn't fool with annealing. Its easy to do wrong and make your brass dangerous.

[Harter66]

Remove metal from the bottom of a belted magnum die ?????
All of the Mag dies I've had were stepped for the belt . If you need belt or base sizing that far down I would think that there's something amiss .
I have a FL RCBS now but I can say that the Lee wasn't up to the task of moving a shoulder to get 264 from 300 brass . The 275 H&H form die was handy there .

[Smk SHoe]

I agree with eagle27. Always file down the shell holder vs the die. Replacing the shell holder cost 5$ if you bugger it up vs replacing a die. I have filed down a couple of shell holders and all get duracoated blue to remind me they are altered. Works great to get .223 range pickup that last little bit.

For the record, removing material from the base of a die to remedy tight chambering cases is not the way to go. Most often it is the base of the case that is contained in the shell holder that needs sizing slightly more and removing material from the die mouth does not make a scrap of difference as this part of the case will always be in the shell holder. It is better to carefully grind/sand down the top of the inexpensive shell holder which allows more of the case base to enter the sizing die. Often only a few thou taken off the top of the shell holder is needed.