I have had my 264 win mag for 20 years now a ruger 77 stainless mark II .It has a habit of splitting the necks and I think I need to try annealing them next time .It did it with a certain bullet and has that funky dual diameter throat in it for factory loads the win and rem 140 gr.I don't shoot these much but I tried some the other day .The nickle plated brass split the necks and the all brass actually blew off a piece of the neck .I am reloading all of them .I never had this problem with other bullets .It is the 140 grain corelocks that cause pressure .I necked down 7 mm rem mag brass because I usually can't find 264 brass .
My other bullet I use has two groves on it and they reduce pressure no problems ever .I need to rethroat this rifle and never use the 140 grain corelocks .That bullet did the same thing in my 6.5 jap and 260 rem way high pressure on a 15 percent below max load .
This rifle is super accurate don't want
To mess it up but it's super picky too .

I’m doubtful that the 140 coreloct is the pressure problem unless they are defective, oversize somehow. That bullet was made for the 264 wm it is said. Not certain that is a fact.
It would be more likely your necked down 7mag brass and thick necks.
Splitting necks and blowing brass off is a brass problem.
I had some problems with a batch of 308 match brass I attempted to make into 260 brass. Just too much brass in the neck. Bought an outside neck reamer and even the pilot would not go in the resized neck as instructions said I should use it. Gave up and bought more 260 brass.
Good luck with your rifle!

I'm with Fury1 on this issue.

Did I read that correctly? You're necking down nickel plated brass?

Any time brass is worked or cut, it hardens. The more it's worked the harder it gets.

Annealing is the answer but I've personally never heard of it for nickel brass and certainly neck turning to thin to the correct thickness is out of the question with nickel.

Zeke

Based on the information presented (and trying to decipher the wording) I too vote for a brass problem. Not just from necking down the 7mm case though, I’ve necked down 7 mm RM brass to .257 Weatherby and had fine case life. To me the nickel plating is likely part of the problem since they have far different elasticities which can induce additional stress. How much neck clearance do the OP’s case necks have? I doubt this is the problem given the usually generous chamber dimensions in Ruger rifles, but it’s possible. Or it could just be a batch of poor brass.

BTW it is certainly possible to turn the plating off the neck (done it) but then why in this instance?

.

I'm guess too of course but that nickel plating doesn't flow like the brass. Even necking up Nickel is an issue.
We have two Hammer forged Ruger Hawkeye 260 barrels here and both chambers are nice and snug.
Whose to say I guess on the OP's rifle but I sure don't think it is the dual diameter 140 CoreLoct bullets.

The symptoms you describe have nothing to do with "pressure".

I was not aware that any of the old "two-diameter" bullets for the .264 were still available, or are you using some very old stock? Have you used a caliber or micrometer to measure the actual diameter of the problem bullets? They should be within .001 of .264", plus or minus. If so, then the bullet is not your problem, which lies elsewhere.

It is certainly possible that 7mm Rem necked down to .264 could result in necks which are excessively thick, but it would be unusual. It could also be that you are necking down previously fired brass that is causing your problem. If fired in a chamber with a somewhat oversized neck then the necks first expand excessively, then when you neck them down they are worked again the other direction, resulting in work-hardening which makes them brittle and subject to cracking/splitting.

I have necked virgin nickel-plated brass down from .308 to .243 without any problem, so I don't think that the fact that some of the brass is nickeled is your problem. However, nickeled brass is subject to the same overworking as unplated brass.

Doughnut being formed at the neck shoulder junction should be on the suspect list until cleared as well. Especially in belted magnum case fired in different chamber I would think.

I have owned and shot two 264WM rifles, which I hand loaded for. I used 264 and necked down 7Mag brass and never experienced premature neck cracking. I wonder if the chamber in your rifle is out of spec. You could have a chamber casting down to measure it to know for certain. Does it shoot factory loaded ammo without cracking? If it does I don't think it is a chamber dimension issue. I no longer own a 264, but I remember after pondering it, that I neck sized the cases because full length sizing seriously over worked the brass. I would advise you to purchase a neck sizing die and try loading and then shooting some of them to see if it solves your cracking problem.

You have a brass problem, not a bullet problem. I wore out the barrel on my old Pre-64 Westerner shooting 140 grain core-lokts, probably 75% of all shots run down that barrel. Never had a single problem. I just rebarrelled with a Krieger barrel and have gone to shooting the 127 grain Barnes LRX with great accuracy, again with no problems. I don’t understand your difficulty in finding new brass, as I’ve bought .264 unfired brass twice in the last year, once at a Cabelas store and once from Midway.

My sense is to buy some new unfired .264 brass and start from scratch. I don’t think you’ll have any problems if you do.

Like Fury01 says above, I used new PPU 264 Win Mag brass I ordered from Grafs today building a load in my new to me pre-64 Westerner 264.

160gr Woodleigh Protected Point Weldcore
67gr RL-33
FED-215 primer
COL 3.275" [15 thou off lands]
VEL 3058 fps

Three went into just over an inch at 100 yards, a little COL and forearm screw tension work and i'll dial em all in under an inch, that's a very serious hunting load for the 264 Win Mags, easy as pie.

I'm going to agree with the majority, it's a brass problem. Necking nickel plated brass up or down is a cause for high loss rate, regardless of the cartridge. I did it with some nickel 32-20 Starline brass, taking it to 25-20. It was all that was available in either cartridge at the time and I thought it being nickel would help keep it separate from all my 32-20 brass, which is not nickel. I started with 100 cases and have lost half to split necks and shoulders in less than 3 firings. Needless to say the 25-20 and 32-20 operate at a heck of a lot lower pressure than the 264 WM.

I did neck down some of my brass, 32-20 cases and they work as good today as they did 35 years ago when I first did it.

I deloaded all the 140 grain rem bullets . They had a pressure problem in every gun I shot them in 6.5 jap 264 win mag abc 260 rem .The lapua bullets I shot in my 264 win mag had no problem .I talked to another guy on longrangehuntinf who has 5 264 win mag he said all his 264 split the brass even on new brass .He had to anneal all brass shot in his rifle for every shot or he had split necks too . It has to be those bullets but my 264 win mag has a weird throat in it and will hardly take any bullets I try .I have stuck with the lapua bullets seated super deep and they are the only ones that work right in this rifle and shoot clover leafs .I will rethroat it when it wears far enough out and I already can tell it has worn some .

quote:

Originally posted by dgr416:
I deloaded all the 140 grain rem bullets . They had a pressure problem in every gun I shot them in 6.5 jap 264 win mag abc 260 rem .The lapua bullets I shot in my 264 win mag had no problem .I talked to another guy on longrangehuntinf who has 5 264 win mag he said all his 264 split the brass even on new brass .He had to anneal all brass shot in his rifle for every shot or he had split necks too . It has to be those bullets but my 264 win mag has a weird throat in it and will hardly take any bullets I try .I have stuck with the lapua bullets seated super deep and they are the only ones that work right in this rifle and shoot clover leafs .I will rethroat it when it wears far enough out and I already can tell it has worn some .

Regardless of what you want to believe, you have a different problem than the bullets you’ve been shooting. Have you miked them to check diameter? Something is amiss other than the bullets being 140 grain core lokts. Remington has manufactured millions of those bullets over the years, so if they were the problem other people would have experienced it before you. I’m not aware of anyone who’s ever had a problem with that particular bullet that was greater than not grouping as well as they’d like in some guns. I shot enough Core Lokts down the barrel of my Pre-64 to wear it out and never had a split neck.

I have loaded a lot of the 140 coreloct in my 260’s. No issues at all. Still kill well and shoot fine groups.

I doubt you have an unusual throat in your rifle. If you look at the specs for the 264WM it calls for zero leade (or no throat). This is the way they come if they are to spec.

That being said, I have also never had the problem you indicate with the Remington dual diameter bullet, which was made for the 264 with no leade, hence the dual diameter.

If you need some 264WM brass, shoot me a PM and I can send you a bag of 50 Winchester for $25 shipped. I changed to the PPU stuff because of better consistancy.

I could not even seat a 100 grain .264 bullet in my rifle right .It would seat the 140 gr remington or 140 gr Winchester right at the grove .I tried about 20 differevt bullets and none of them would seat right they hit the rifling in the throat . The regular brass not nickle split and blew the shoulder off the brass.
It was weird the nickle brass had a small split with the 140 gr remington corelocks but but the lapua bullets worked perfict and shot clover leafs at 100 yards and under an inch at 300 yards .I will have to get it rethroated for sure .

If that is an accurate assessment of your rifle, shipping back to the manufacturer is the safe and correct thing to do sir.

Nickel plated brass!

I stopped using them for reloads years ago!

quote:

The regular brass not Nickle split and blew the shoulder off the brass.

Nickel plated brass!

I stopped using them for reloads years ago!

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If it blew the shoulder you could have a headspace problem.

Or as a belted magnum reloader, a technique problem. Still only sure about one portion of this discussion; it’s not a bullet problem.

The 140 gr rem .264 bullets were 2nds from midway .I had problems with them on my 6.5 hap too . They measure .264
.I do think my throat on my rifle is made wrong .It shoots the lapua bullets seated deeply fine .I have to wear them in my 260 rem deep too . It was the brass cases that blew part of the neck and shoulder off not the nickle cases .The nickle ones had a small split in them .The lapua bulkets shot fine in both nickle and brass vases .A friend on long range hunting said if he didn't anneal every case before firing they split .
I had not fired any of these rem 140 gr loads till the other day .I had them loaded with h870 powder and had cases split brass cases with wc867 powder also .I swear it's the bullets but I am going to call ruger and see what they say .I have another one of these stainless ruger 77 stainless 264 win mag unfired .I saw a 257 weatherby do the same thing as my rifle once .I usually only fire those deep seated lapua bullets no problems .I think I have shot at least 200 of the lapua bullets not a single split case or problem . Thats why I think it's these double diameters 264 rem 140 gr.I do know the throat in my rifle needs to be longer .

Every belted magnum factory rifle has a headspace problem for reloaders.

You can lessen this effect by adjusting your die, but you cannot eliminate it.

The reason for this is that every factory belted chambering that I have come across has too much head space.

The ones I chamber here don't have this problem, because every rifle is chambered for minimum headspace.

Years ago I went through countless new brass.

I measured the headspace on all of them.

Selected the one which had the lowest head space.

I use that one for measuring the heads pace on all the belted rifles I chamber.

I also make sure that the bolt closes on it with some pressure.

At the beginning I was worried that some factory ammo might not chamber in them.

Never happened.

And their brass last a long time too.

Non of our rifles will close on a GO gage.