264 Win Mag.....all of a sudden I want one

[Oldtrader3]

Must be the season, even I bought another rifle when I sold my .340 Weatherby! However, I bought 9.3x74. The heck with those prairie scorchers! I will lob one into the vital area.

It is those blasted belted cases that are the problem. The factories never have worried much about head space on belted cases because it is headspaced on the belt, of course which is held to SAAMI tolerance but not the shoulder datum!

 

[Guest]

Tom, the issue of shoulder length (which is not headspace on belted mags) is not critical, and easily addressed with proper die setup for us handloaders. The other piece of the puzzle is that it has little to no effect on case life. Since the cartridge is properly headspaced at the belt, web stretch does not occur. Now, if you push the shoulder back repeatedly, you'll have work hardening issues, but that's got nothing to do with the headspace, either. Again, it's easy to accommodate this with proper die setup.

Now, I'll argue that you don't need a 264WinMag, just because you asked us to. It's purely pedestrian to send 130gr bullets out at 3200fps. You won't get the ultimate satisfaction you're seeking on this course. What you need to do instead is find a good 270Wby, which will send out 130gr bullets at 3400-3500fps, 140s at 3300+, and 150s at better than 3200. That's a real flat-shooting setup right there. And, barrel life is as good as or better than the WinMag. I'd be happy to share load workup info with you at your convenience, of course.

Now, even with Scotty out of pocket, there are those of us who will oblige your wishes and steer you away from certain doom! Enjoy!

 

[FOTIS]

wow.....that was compelling.....

But I am not buying that you're sold! :mrgreen:

 

[woods]

Tom, the issue of shoulder length (which is not headspace on belted mags) is not critical, and easily addressed with proper die setup for us handloaders. The other piece of the puzzle is that it has little to no effect on case life. Since the cartridge is properly headspaced at the belt, web stretch does not occur. Now, if you push the shoulder back repeatedly, you'll have work hardening issues, but that's got nothing to do with the headspace, either. Again, it's easy to accommodate this with proper die setup.

Hey dubyam

Belted cases are the ones best known for case head separations and the main reason is the excessive head clearance (gap between new case shoulder and chamber shoulder). When the case if fired, forward movement of the case in the chamber is stopped by the belt and then the rest of the case forward of the belt has to stretch to reach the shoulder. The ignition and hottest area is happening at the pressure ring just forward of the belt and that brass is stretched and thinned.

There would probably be a point where you could make the head clearance so large that the case head separation would occur on the first firing. Don't know what that point would be, but just for discussion let's say it is .080". With a large head clearance the thinning would be a percentage of the total possible thinning and subsequent total case head separation. Just for discussion let's say that you are 50% of the way toward a case head separation with a head clearance of .041". Now you can reduce further thinning by head spacing on the shoulder but you are working with a case that has diminished strength in the pressure ring area from the initial firing. I have had a case head separation on a 338 win mag on the 6th firing after always sizing fire formed cases by head spacing on the shoulder. IIRC (I'm not at my home computer so no pics no data) that 338 win mag had a head clearance of ~.030".

So to say that the head clearance has no bearing on case life is not entirely correct and I would say that it depends upon how much you are dealing with then how you size. My 6.5 rem mag is a custom rebarrel and has a headspace of ZERO but a head clearance of .017" which is just fine for case life since I do headspace on the shoulder after fireforming. I have read where gunsmiths have even taken the step to put the head clearance within the normal unbelted case specs of .002" to .008" by reaming the chamber to the CASE and not to the SAAMI specs. Their guns and freedom is a beautiful thing.

IMO belted chambers with excessive head clearance make great donor actions for rebarrels.

YMMV

 

[JD338]

Woods,

Great info.

JD338

 

[Oldtrader3]

I always use Forster dies (if possible) for belted cases with carbide neck buttons and set the die to only give about 0.0015 inches headspace of the shoulder datum. Not much that you can do about the intial manufacturers headspace on the shoulder or lack thereof but you can surely make it right from then on.

Also, using good cases like Norma or Lapua can help because they control everything properly to begin with.

 

[Guest]

I'm curious on the source of the info regarding belted mags having the most casehead separations. I've not experienced any (either belted or non-belted) so I can't really speak about it more than theoretically and from observation of others' experience. I don't know that much wall stretch occurs when the shoulder is blown out, though. As I understand it, casehead separation occurs when the case is pushed forward in the chamber, allowing for space in between the head and the bolt. Once that space is there, the case is now expanding outward, gripping the walls of the chamber, and then, after pressure builds enough (to a markedly higher level than it would take to expand the thin case walls outward) the casehead is pushed back against the bolt face and thus the stretching occurs in the web area, as that is strong enough not to expand out to meet the case walls. In a belted case, it seems to me that the case walls would stretch outward and grip the chamber walls, and then the shoulder would be blown out (a la fireforming wildcats) yielding the new case shoulder length, but not stretching the case at or near the belt/web. It seems that the thinner section of the case near the shoulder should stretch outward long before the thicker area near the belt/web. Maybe I'm missing the mark here, but that's what I understand about how brass works in the chamber, under the pressure of the burn.

I suspect if we're seeing relatively more belted failures, the stretching and casehead separations are likely more related to the sloppy headspace cut of the chamber in relation to the belt. That would generate an easy stretching of the area directly in front of the belt, as the belted casehead is pushed backward to meet the bolt face, just like a non-belted casehead. I've done some checking on a rifle I owned in 7mmRemMag, and there was no thinning at the casehead or web despite similar shoulder length clearance to what you've shown above. On both Remington and Hornady cases, the shoulders were just blown out forward, with no stretching. In a couple of the cases, I could still see the crease line visible below where the new shoulder crease was, as a faint "ring" around the case body. That's why I checked for expansion/thinning - because I was scared I'd leave the shoulder and neck of a cartridge in the chamber. Turns out, it was just an artefact as there was no thinning of the case wall anywhere. And I checked a number of cases to be sure.

Anyway, I'm all for learning more about this if I'm wrong, so feel free to help me understand what I'm missing.

 

[FOTIS]

If you neck size only (if at all possible) your CHS issues will indeed be minimized.

 

[tddeangelo]

Wow...interesting discussion that has evolved here.

Of course, this means that whatever I do, someone will think I made a mistake, but.....I make lots of 'em, so I'm used to it!

And there's a big part of me that is saying "eh, screw it......don't really need another cartridge to reload for right now anyway."

I don't mean this to be disrespectful to anyone, but the issues presented are not unique to the 264WM, as near as I can tell. They seem to me to be common to any belted mag, and I already have them on my plate with my 300H&H. And, to a similar degree, with my 30/40 Krag, as rimmed cases headspace on the rim.

So really, the decision of whether I want a 264WM is, based on the above posts, one of whether I want to deal with reloading a belted mag or not. I don't see anything in there that is peculiar to the 264?

And dubyam, until a 270 'Bee appears in a Winchester Model 70, it's a non-starter for me. I don't dislike Weatherby rifles, I just like Winchesters too much to buy anything else, as I know it wouldn't get used by me nearly as much as the Winchesters do.

 

[Oldtrader3]

I don't think that the belt headspace dimension in factory ammo varies much from SAAMI spec. What I do suspect is that case extruders are not using uniform pressures to balloon the case neck properly into the shoulder leaving them a little short in this dimension. Probably to get faster cycle time out of the machine. Then when fired at 55 KSI, the belt seats properly and the case wall just in front of the belt stretches a little to fill the chamber cavity. This condition sets up later incipient head separation if the dimension of stretch is more then about 0.015 inches (I get this number from reading the data and can take no credit for it).

Each additional time that the case is fired the length grows a little and is set back by the dies. The growth of each firing may only be .001/.002 inch if the dies are set properly. If the dies are set to shorten the case more on each sizing, the material comes from that part of the case forward of the belt. That is why separations always seems to be in that location.

All that I can do is insure that I maintain a .0015/.0020 maximum headspace in that datum area. I also neck size about two of every three sizings on belted cases to assure that I am getting maximum length of shoulde datum on nearly each firing. I also often use hot loads for belted cases and throw the cases away every 5-6 reloadings. I have never had a neck separations and have owned many magnums up through .375 Ouch & Ouch.

 

[BK]

This post was obviously a mistake.

j/k.

Wow...interesting discussion that has evolved here.

Of course, this means that whatever I do, someone will think I made a mistake, but.....I make lots of 'em, so I'm used to it!

And there's a big part of me that is saying "eh, screw it......don't really need another cartridge to reload for right now anyway."

I don't mean this to be disrespectful to anyone, but the issues presented are not unique to the 264WM, as near as I can tell. They seem to me to be common to any belted mag, and I already have them on my plate with my 300H&H. And, to a similar degree, with my 30/40 Krag, as rimmed cases headspace on the rim.

So really, the decision of whether I want a 264WM is, based on the above posts, one of whether I want to deal with reloading a belted mag or not. I don't see anything in there that is peculiar to the 264?

And dubyam, until a 270 'Bee appears in a Winchester Model 70, it's a non-starter for me. I don't dislike Weatherby rifles, I just like Winchesters too much to buy anything else, as I know it wouldn't get used by me nearly as much as the Winchesters do.

 

[Guest]

To be clear, I neck size everything except my 30-30WCF and my 243Win, and only then because they are lever and semi-auto, respectively. About every third or fourth firing, I have to push the shoulder back on my neck sized cases. This is for everything from 8x57 and 30-06 to my 270 and 300 'bees.

Charlie, I'm curious as to whether or not the same pressure to blow the shoulder out during manufacturing would then lead to a lot of undersized cases in the non-belted group, and provide for similar issues, ahead of the non-belted web area?

Tom - all I can tell you is, there are some Win70s factory chambered in 270'bee. I've seen one or two in my time. I like my Mark Vs though, so I never felt compelled to go find one. A quick search of gunbroker and gunsamerica turned up exactly none, but Cabela's recently had one in their gun library (though it is now sold) and apparently someone here on the Nosler forums owns one:

viewtopic.php?p=67303

They were apparently available in both pre-64 and late-model (1990's production) guns, so keep an eye peeled and you might get lucky.

 

[Oldtrader3]

Dubyam, this is just my take (and that is all it is) and that is the belt on the magnum case assures more stretch at the base, near the belt, since it grabs the wall later as the brass is a little thicker there than up front. Also, the brass is more likely to be annealed at the front end and harder at the back end for greater tensile strength where it needs it. So if the case is .030 short, the final stretch comes at the rear and thins the brass at the worst place for case integrity.

I just have to believe that the front pushes forward first. This is just based on 50 years of watching, shooting, doing engineering studies on lots of mechanics and a technical eye for seeing things. I could be all wet on this but don't think so. Plus at Mach 4 gas expansion, it all happens so fast that who knows?

 

[Guest]

I understand the softer, thinner brass sections expanding first. But if the case is headspaced properly on the belt, it seems to me the case head and web section would not have sufficient rooms to move about to create stretching. If the softer portions of the case move first, it seems the forward shoulder should, due to proper headspacing (on the belt) the manner of movement should simply be assumption of the shape of the forward section of the chamber, via a balloon like expansion causing minor thinning in the shoulder and neck joint areas, though not appreciable, I'd suspect, as the case shoulder simply "rolls forward." If I understand correctly, brass is going to stretch to conform to the chamber at something like 7-10kpsi. It seems the shoulder area would simply balloon forward under this light pressure, as the case walls begin to grip the sides of the chamber. If the chamber is properly headspaced on the belt, the ability for the rearward portion of the case to have any room in which to stretch should be within tolerance and thus near zero, relatively speaking. Certainly a tiny amount of headspace tolerance could exist, but it is no more than any rimmed or rimless (non-belted) case. Unless a handloader repeatedly over-re-sizes the brass, there should be no problem. It would be the same for a 30-06 if one were using minimum spec dies and a max spec chamber, or maybe not even as much.

All this theory is nice to chat about, but I'm with you - I'm not entirely sure what happens at Mach 4. I can tell you I've not experienced any issues and I've fired a lot of belted mag brass, including a significant amount in a terribly out of spec, long shouldered 7mmRemMag. I wish I had a bandsaw so I could section one of the cases to show what I've been able to measure with a feeler and dial gauge. The case walls on that old 7Mag brass are just as smoothly flowed from web to thin neck brass as the day they were created, I believe.

 

[Oldtrader3]

The only other issue that I can think of is the vector of the web adjacent and forward of the belt having to expand outward as well as forward. adding another movement component. Somebody needs to do a high speed camera movie of all this.

On non belted cases, there are studies showing that the cases are pushed forward by the firing pin and expand to fill the chamber, then lastly stretch the entire wall to fill the viod left by the firing pin. That is why nonbelted cases have fewer head separations IMHO. Which BTW is worth nothing.

Edited to answer Dubyam's question about non belted cases.

 

[woods]

You may be right about a lot of this dubyam, and good thoughts and info from Oldtrader et. al.

Here is the pic of the case head separation I had

and all that I have heard of happen at the "pressure ring" just forward of the belt where the solid case head opens up to the powder column space

And this is the point that influences me to believe that the case starts stretching at the pressure ring before there is significant pressure in the shoulder/neck area; on several of these reports about a TYPICAL case head separation on a belted case, there was also a report of an indentation at the case body/shoulder junction

which after several discussions on different forums, the most credible explanation is that the gases escaped from the case head separation and made their way forward to exit out the bore (path of least resistance). This leads me to believe that in the microseconds after ignition, the case expands just in front of the belt and starts pushing brass forward toward the shoulder, the superheated brass at that location is easily thinned and with no backing at the datum line, the brass thins to separation. Of course there are several questions which are not answered such as why the dent does not show up elsewhere, is it superheating the brass that is the culprit or some other mechanism, etc. etc.

We may never know with absolute certainty since very sophisticated testing equipment would have to be used to even get a idea of what is happening.

Now that I have my records, the head clearance on that 338 win mag was .027". On all of the belted mags I have reloaded for the headspace is within normal range varying from 0.000" to 0.008" (difficult to measure but I have worked out a method) and the head clearance is from .017" to the aforementioned .041" with most landing around .020"

 

[Oldtrader3]

I bet that the dent is right adjacent to the hole for the gas to escape the action?

This got pretty controversial and that was not my intention. My intentions are always to find deeper knowledge of the subject at hand, not to create controversy.

 

[Guest]

I certainly didn't take this as controversy, Charlie. I am always trying to learn about this hobby. A lot of stuff can be learned through direct observation - how to size cases, seat bullets, use a powder funnel without spilling, etc. - but the stuff that happens after you insert a round in the chamber is not directly observable, and though I've been loading for 20+yrs and shooting for about 40yrs, I still don't know all there is to know about it. I relish the chance to see where others have experience I do not, and especially to see photos and hear the full stories behind them.

As far as the dent, Woods, I've heard (and cannot verify) that dents like that, with no visible powder residue, may actually be caused by the rapid evacuation of gases at the point of case separation causing a significant negative pressure locally within the chamber, resulting in the indentation you show in your picture. I can't speak to whether or not the guys who have postulated that theory are geniuses or jacklegs, but it's at least something else to consider. Any time I've had powder gases get between the case and the chamber wall I've had black soot as a result. The lack of soot in your pictures tells me there may be some other force at work rather than combustion between the case and chamber wall. But, again, I'm not an expert. Perhaps you cleaned that case prior to the photo? Or perhaps there are other factors at play.

Keep the discussion coming, for sure, guys. I am eating up the new knowledge and expansion of my thoughts regarding loading and brass care. One can never know too much nor be too careful in implementing it when handloading!

 

[woods]

No controversy for sure, amiable discussion in which no one is assumed to be correct but are all collecting facts that may connect dots later

The case was not cleaned and no explanation for no soot marks. Soot does appear often when the neck doesn't seal quickly but that may be part unburned powder and smoke. If it were at the pressure ring then unburned powder may be less prevalent. IIRC, there was a little smoke type of deposit at the separation. IOW, not soot which has to be wiped off with a solvent and rag and is black but rather light gray surface deposit like fine ash.

The case shot, ejected (I do it gently in order to catch fired case) and then fell apart in my hand. Oddly enough this is often what happens or at least what I have heard described by others.

IMO the stretching is more prevalent in belted cases because the forward movement of the case in the chamber is stopped by the belt and the case then has too much expansion left to fill the chamber. On an unbelted case the headspace has to be more regulated because if you have too much headspace the primer will back out of the case completely or be severely flattened. The manufacturers of guns and brass know this and don't really care about us reloaders. They expect the case to fire once and then you buy new.

Picture this in my custom chamber that has ZERO headspace (bolt closes and the case head is tight to the bolt face held there by the belt) but has .017" of head clearance; when the primer ignites the case must expand to the entire chamber dimensions, there is not much outward case body expansion but significant movement of the shoulder forward is necessary, pressure builds from the primer/powder interface at the pressure ring, where is the brass going to stretch? In the relatively colder powder areas closer to the neck or the action area at the pressure ring?

We know for certain that the pressure ring is where case separations normally occur (there are some anomalies for sure but they may have a different explanation). The pressure ring is where the thinning occurs. After this all else is theory (someone may know for certain but I don't). To me the most likely explanation is that the brass is initially stetched there at the pressure ring.

 

[killdeernow]

I love these topics and the replies and everyone seems to be professional and respectful in this forum. I don't post much, but I lurk ALL THE TIME.

I will say this--My first gun was a 264 Win Mag (moment of silence) that my father left for me. I started reloading with this cartridge. Long story short, I blew it up. I'm talking BOOM!! It had nothing to do with headspace, brass, dies, caliber, etc. It had to do with an inexperienced moron who never reloaded before, who didn't have a CPU at the time so there was an information vacuum. I had brass in my neck, face, hands, arms, etc.

Anyway, it took me years on the range with my 30-06 to stop flinching. I worked my way up to a 338 Win Mag shooting 225 grain bullets and stopped flinching. I think I’m good now…

Now, it's mid October 2012 and I own all brand new reloading equipment because I'm taking the leap again.

My point to all of this???

Keep it going fellas. The more info, the better. Hopefully I won't be wearing parts of my 338 Win Mag when I go to the range!!

Take care and safe shooting,