# Case head separation



## KineKilla (Jan 28, 2011)

Went and did some shooting today. I have always shot my 7mm brass 4 times and scrapped it. Never have I had case head separation before in this rifle with this load. Some of these were being shot for their 4th time, others only 3.

It wasn't terribly hot out, load is mild and has always shot excellent in this rifle. Brass is mixed brand.

What would cause this? Would I have excessive head spacing suddenly? Know a good gunsmith still doing business during the Coronageddon?

X-Bolt Stainless, 7mm mag. 61g RL-22, 160 Accubond, Fed GM215M primers.

Rifle shot fine and showed no signs of a problem. Didn't even notice until I got home and started looking at the brass. Primers don't look too flattened and no strange marks on the case bases.

I have a bear hunt in 19 days and need this rifle to be trustworthy.
















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## APD (Nov 16, 2008)

is there any commonality in the brass that did split vs the ones that didn't?

any weight or volume measurements to compare between them?

were these new casing when you got them or once fired prior to your 3 or 4 loadings? 


i have shot some loads that can share brass but never mixed them. i have a preference for nosler or norma brass in my 7mm rem mag. if i had a bear hunt coming up i'd certainly invest in some shiny new brass to limit my variables. at the vary least look into some nosler trophy grade factory loads in your preferred weight. mine shoots the 160AB very well. you can shoot and reload those or just use them for the hunt if they work for your rifle.


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## APD (Nov 16, 2008)

another thing to think about....

are you bumping the shoulder or full length resizing? you could be pushing too far.


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## KineKilla (Jan 28, 2011)

Full length sizing then trimming to SAAMI minimum length is my standard practice.

Mostly Hornady brass new out of the bag...a few pieces of Winchester among the split ones. All were first shot in this rifle. 

All of them split or were close enough to it that I would have spotted it during pre-load inspection. I can easily check the specs on these fired cases but don't know what I'd be looking for. I would expect their weights to vary as they have burnt powder in them. Possibly could find some with varying lengths.

I found a smith that will check rifle headspacing and I may need to invest in a neck sizing die set. I haven't had a lot of luck using a FL die to only size necks...never feel like I have it adjusted correctly.

Strange that the primers aren't extremely flat, the bolt wasn't hard to lift, etc. I was dialing and hitting milk jugs at 350 pretty easily.

Of all the rounds I already have loaded (+/- 40), about half are going on their 2nd firing the others are new brass not yet fired for thier first time.

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## BPturkeys (Sep 13, 2007)

Given your history with this rifle and load I suggest that you have a problem with some of your brass, not the rifle or the load. I highly doubt that your rifle would all of a sudden develop a headspace problem. Do as APD suggests and start over with some new brass. I have never loaded 7mm Mag so I have no suggestions, but it has been my experience that mixed brass, or any mixed components for that matter, always ends in mixed results.


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## KineKilla (Jan 28, 2011)

I tend to agree BP.

The confusing part to me is that these pieces of brass have all undergone that same treatment and are just now showing the issue. If it's an excessive case stretch issue (which it obviously is) then why did it not show up on the 2nd firing or 3rd in the case of the ones with a 3 on them or even the first?

As anyone that reloads can imagine, it bothers me. I've shot hundred of rounds through this rifle using this same load and reloading process...seems unlikely that all of the "weak" brass showed up all at the same time on the same day.


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## Critter (Mar 20, 2010)

RL22 is a little bit more temperature sensitive than a lot of other powders. When I use it I like to build up my loads in July so that I am usually safe the rest of the year. 

Your problem could be a number of factors coming all together at one time to cause your problems


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## APD (Nov 16, 2008)

KineKilla said:


> I tend to agree BP.
> 
> The confusing part to me is that these pieces of brass have all undergone that same treatment and are just now showing the issue. If it's an excessive case stretch issue (which it obviously is) then why did it not show up on the 2nd firing or 3rd in the case of the ones with a 3 on them or even the first?


think of it like bending a thin wire and then bending it back in place. yes, it's straight again but the metal is fatigued. do it a few more times and it may break.

personally, i'd start with fresh brass and neck size until you need to FL. i've had brass in my 7mm go well past 5 loadings. primer pockets are my typical reason for rejecting. now my 270 wsm eats the primer pockets when i'm using cheap brass. 2-3 loads max. they also split necks too frequently unless annealed.

as of the last season i've started to purchase factory loads and i've been very surprised at the accuracy and reasonably low SD. i mentioned earlier but the nosler trophy grade 160 accubond would likely meet or exceed your expectations. my 7mm has a tight chamber and fast barrel so it exceeds the fps on the box by about 150. it also is precise with that loading. 3 shot groups cloverleaf and occasionally bug hole. not bad for factory ammo.


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## KineKilla (Jan 28, 2011)

When sizing the necks only, do you guys chamber an empty (neck sized) case to see if you are having difficult bolt closure prior to proceeding with fully loading? 

I guess I'm uncertain on how/when you determine your brass is due for a FL sizing. Certainly you don't go through the full reloading process to then find out your bolt won't easily close and have to pull the bullet, powder, etc. to resize.

Anyone know a good smith in Salt Lake or UT County that is still working during this time?
Also, what neck sizing dies are preferred? Forster ones are discontinued so that seems to leave Hornady or RCBS as my options.


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## Critter (Mar 20, 2010)

Any and all rounds that I use for hunting get full length resized. I will also test them in the chamber of the rifle that I am using before I go hunting after they are loaded to make sure that they chamber easily. 

If I am just neck sizing I adjust the sizing dies a little at a time and check the empty case in the rifle that I plan on shooting it out of. I will continue to do this until the bolt closes with just a slight bit of effort. I'll then lock down the die and run a few cases through it and check each and every case to make sure that it will chamber with a little bit of effort before I start loading the rest of the cases.


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## waspocrew (Nov 26, 2011)

Get yourself a Lee collet neck sizing die. They work great. Typically I’ll neck size 2-3 times, then need to bump the shoulder back .002”. Your case separation is likely due to setting the shoulder back too much. 

Also, people will bring up problems hunting with neck sized brass. I do it all the time and have never ran into an issue. Check to make sure your ammo cycles through your rifle and you’re set.


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## APD (Nov 16, 2008)

same here. 2-3 loads until i need to bump the shoulder. adjust your die a little at a time until you can see all the neck is sized and you barely kiss the shoulder.

but again, buy new brass today and start fresh. no need to ruin a good hunt or rifle with brass that's already weak.


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## Al Hansen (Sep 7, 2007)

We have this problem with a wildcat we shoot. Some times it shows up on the fith or sixth loading and on some brass on the 2nd or 3rd. You can check your brass by using a paper clip that is straightened out and put a stubby L shape at one end . Put the L shape end down the throat of the brass, gently feel around the inside of the base of the brass and see if there is the beginnings of a fracture ring on the interior of the brass, You get pretty good at finding them. Toss them immediately. Any questions shoot me a pm and I will give you my phone number.


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## KineKilla (Jan 28, 2011)

Checked the chamber with a set of Go/No-Go gauges, that's all fine as expected. 

The gunsmith believed the excessive push back that the Hornady dies are doing is the culprit as most here, and I, felt was the cause as well. While bumping the shoulder back is preferred to be no more than 0.002" my dies are pushing it back 0.02" which as you know is a TON in the world of reloading.

Guess I'm gonna have to buy a bullet puller and unload the 16 rounds of new, never fired brass and make some new ones. Not the end of the world, I have two weeks to get a bunch loaded. 

I first have to go shoot again so I have a new, once fired, fire formed piece of brass with which to adjust my sizing die.


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## waspocrew (Nov 26, 2011)

I find these to be helpful:

https://www.midwayusa.com/product/1012743827


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## DallanC (Jan 13, 2009)

KineKilla said:


> Guess I'm gonna have to buy a bullet puller and unload the 16 rounds of new, never fired brass and make some new ones. Not the end of the world, I have two weeks to get a bunch loaded.


If money is no object, get a collet puller. If you go with a cheap inertia puller, stick some wadded up paper towels in the end of it, otherwise it will bend the tips of your hunting bullets when they fly out of the case and impact with the hammer.

-DallanC


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## Critter (Mar 20, 2010)

Odd are your never fired brass should be fine. They are usually already sized from the factory except for the neck tension. 

At least that is what I have found with Hornady brass


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## KineKilla (Jan 28, 2011)

I set up my die to take the case from 2.121 to 2.119. I bumped them back and checked fitment in the rifle chamber until it closed with just a bit of firm pressure. The bolt would close at 2.120 and was a bit too easy at 2.118

Unexpected thing though as I worked the die down a little at a time was that the case actually grew prior to going back down. It got as big as 2.124.

Guess that's the brass stretching? Or the case mouth getting longer as it gets resized?

I meaured a small sample of new unfired brass and found that they are around 2.10. That makes for quite a bit of stretch on that first shot.

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## KineKilla (Jan 28, 2011)

After removing my ejector spring and pin I've found that I can chamber as large as 2.1215, maybe longer. I'm out of brass to size and test for now.

So, question is...

Should my goal be to leave the brass as long as possible (chambers and extracts well) between shots? Seems like this would be the best way to maximize case life and minimize base stretching.



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## DallanC (Jan 13, 2009)

KineKilla said:


> Unexpected thing though as I worked the die down a little at a time was that the case actually grew prior to going back down. It got as big as 2.124.
> 
> Guess that's the brass stretching?


Brass is springy... unless you really crease it, there will be some spring back.



> Or the case mouth getting longer as it gets resized?


All of that brass flows into the case neck as its stretched, shoulder set back. You also checking the overall length and trimming? I really like those LEE case trimmers. Such a simple idea for a trimmer, takes all the setup and guesswork out.

-DallanC


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## rtockstein (Mar 17, 2019)

KineKilla said:


> After removing my ejector spring and pin I've found that I can chamber as large as 2.1215, maybe longer. I'm out of brass to size and test for now.
> 
> So, question is...
> 
> ...


I've read alot on this topic recently on a long range hunting forum. It sounds like it used to be the norm for people to neck size only until the case would be too tight in the chamber, then they would bump the shoulders back with the FL die. Now, people say they get just as long of case life by just bumping the shoulders back with a FL die by 0.002 every time. Whether or not a person would choose to do one or the other depends on a lot of factors that probably matter mostly to the folks who are using custom reamed chambers and/or benchrest techniques that don't necessarily apply to factory guns for hunting.

It makes sense to me, that if you don't anneal, you could get the most accurate and long life from your brass by neck sizing with the Lee collet die (best neck die style for concentric cartridges) for the first few shots, or until it gets tight in the chamber, then bumping shoulders back, which you may have to do every time thereafter if you only bump 0.002 back.

Ona side note about your FL die making your brass longer before it started to get shorter when you were incrementally adjusting it, mine did the same thing. I'm talking about length from base to datum, or at least the measurement you would get when using a Hornady case comparator, because that doesn't actually measure to the datum. It's really just a reference measurement from r your specific chamber. Anyway, my die would actually make my base to datum dimension longer when I FL sized, until I had the die adjusted wayyy passed where it was supposed to be. At that point, the sizing wasn't consistent and was probably hard on my press. So, I used some 600 grit sandpaper and cutting oil to sand down the bottom side of my die to make it a few thousandths shorter. That way, my case would go farther into the die before hitting the shell holder. Now, I can bump my shoulders back correctly while having my die adjusted correctly. I guess this sort of thing happens on some dies. I don't know if it's a manufacturing tolerance thing, or if it's according to brand. It of course also has to do with the gun manufacturer chamber specs.

Maybe more info than you wanted, but I thought it was pretty interesting and very revelatory when I figured it out.


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## KineKilla (Jan 28, 2011)

I'm also using the Hornady case comparator.

When people say "bumping back" when talking about the shoulder, is that bumling it back from its fired size (2.1185 in my case) or bumping it back from its longest length which is somewhere during the resizing process as it grows?

All of this brand new brass I have measure at 2.101. That means that this brass is stretching by .017 or more in its first firing. That amount is a ton by most standards I've read.

If it starts at 2.101, grows to 2.124 or so during the sizing process it seems I've already stretched all the life out of the case after just one firing. I plan to get a neck sizing die only in the near future.

I'm just not sure how much "stretch" a piece of brass has in it. Almost feels like I'm using its entire quantity in one shot.

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## rtockstein (Mar 17, 2019)

That would be bumping back the shoulders from the fired size, which could be at it's max or not quite. It might take two or sometimes three firings with neck sizing only to get the case fully there, depending on the brass makeup and the load charge.

With my gun, I've been using Winchester brass and when new and I think it usually measures 0.008 shorter than max. But I'm not 100% sure because I don't always measure it. With belted magnums, I know they initially set the headspace off the belt, not from the base of the head. This doesn't really matter when you're measuring to resize, but I wonder if that means the case usually stretches more from first firing on a belted magnum. That does seem like a lot of stretch on your first firing. I've got some new starline brass coming today, so I'll measure a few of those and let you know what it looks like.


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## rtockstein (Mar 17, 2019)

The starline brass I just got today actually measures longer on this dimension than the Winchester I've been using. It measures only 0.002 or 0.003 shorter than the max size for my chamber


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## KineKilla (Jan 28, 2011)

I picked up a Redding 7mm Neck Sizer last night on KSL (along with a few other die sets I was missing). I plan to use it moving forward with new brass until the brass gets tight in my chamber and needs to be "bumped" a bit more. 

I'm hoping that by going this route I can determine what my max brass size is for my chamber and get better case life or at least stay safe when shooting.


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## DallanC (Jan 13, 2009)

Your brass will expand to the size of your chamber on first firing... no mater what. The question for hunting rounds, is how concentric your chamber is. If the shoulder or neck is off by just fraction and you only neck size, if the round is put in 180 degrees from the last time it was fired, it will double any out of round error, and cause binding.

Like others said... never only necksize with hunting loads. 

Oh and you can neck size only using FL dies, you just don't crank them down so far they touch the shoulder. I created a nice dummy round years ago for all my rifles with the proper setback. I place it in the press and tighten down the Sizing die onto the dummy until it gets tight and call it good. I also have a crimped in bullet to set the seater die on.

I really need to reload again. I went at it hard a couple years ago and havent had the need to reload since. I do have 4-500 pistol cases that need some love (they are cleaned and prepped, just need to set up the Lee Turret and get'at'er.

-DallanC


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## KineKilla (Jan 28, 2011)

DallanC said:


> Oh and you can neck size only using FL dies, you just don't crank them down so far they touch the shoulder.


I set my dies to do just this thing but as I have mentioned, the case gets lengthened to 2.145 or so before the neck is ever fully resized. I've used sharpie, smoked the necks, etc. and it happens every time. The fired case goes from 2.118 to 2.145 then after bumping the shoulder it goes to whatever end point I have it set to. Currently that is 2.120.

This being the case the only way I could think of to re-size only the neck is to get a neck sizing die. Also, if only sizing the neck is ok using FL dies then why is it not ok to use a neck sizing only die to accomplish the same thing?

If hunting with brass that has been neck sized only is hazardous in some way, why do so many people say to "only size the neck until it needs to be bumped back".? Hunting scenario or bench rest doesn't matter, I'm fairly sure people don't meticulously chamber every round to ensure that the case is oriented the exact same way every time...or do they?


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## KineKilla (Jan 28, 2011)

I'm really trying to learn and figure this out.

It seems I can't neck size only, I also can't "bump" the shoulder back without the case stretching first and I can't FL size every time either. So what is a guy to do?

I've been watching some how-to's and many of them talk about "bumping" the shoulder back to the point where it will just allow the bolt to close nicely. Their cases typically don't allow the bolt to close prior to beginning their die adjustment process. My bolt closes no problem on a fired case and wouldn't need to be "bumped" at all if I could just get the neck to hold a bullet properly.

It's extremely frustrating to get so many conflicting directions. If you set up as directed in the manual, you overwork the cases and you get case head separation after a few shots.

If you only size the necks you can't use them for hunting.

If you resize just the neck using a FL die you stretch the case way out before the neck gets sized properly so you've not solved the issue of over working the brass.

I've neck only sized 270win brass using a neck sizing die and they shot fine at the range as long as I used that case in the same rifle as before.

Any links to better videos, how-to's or any other material I can study to help clarify and take some of the confusion away?


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## Critter (Mar 20, 2010)

You just need to start putting some brass through the dies and then you will see what everyone is talking about. 

As for neck sizing you will find that when you push brass from the neck area of the case that the extra brass needs to go somewhere and it is usually towards the neck. And you will find that the case you could close the bolt on before now has grown in size.

The best experience for this is to start doing it 

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## rtockstein (Mar 17, 2019)

You can hunt with neck sizing only, so long as you have plenty of headspace. I've seen numbers of around 0.004" clearance being plenty. If your cartridge binds due to the chamber neck being slightly off center, well then your chamber is messed up regardless because there should be plenty of clearance between the brass and chamber neck. In some custom guns, the neck dimension of the chamber is tighter and with some brass brands like norma whose brass is a bit thicker, you could more easily have an issue with binding if your cartridge is not concentric enough. Or, if your cartridge binds due to excessive runout on your case neck, then you have a serious issue with your neck die. That's why a lot of people use Lee neck collet dies even though they're cheap... They do the job correctly with minimal runout added to the neck when sizing. Also, virgin brass doesn't always size to the chamber on the first firing. You can see that by measuring with your comparator tool. It might be varying amounts of brass springback... I don't know.

Trying to neck size only with a FL die is harder because it tends to produce more neck runout on the case when using some brands of dies.

I would just go through a few sessions of shooting and neck sizing and see how your cartridges feed. If you're worried about hunting with neck sized rounds, then 
make sure you have some FL rounds to hunt with and only practice with neck sized. 

If you want to play around with modifying a FL die like I did, I'd get a Lee because they're less than $20 and if used correctly they'll also load very concentric ammunition.


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## Critter (Mar 20, 2010)

Irregardless of how you size your cases, if you are going to use them for hunting run all of the rounds through your rifle before you need them. 

I loaded up a couple hundred rounds for a friend and I full length sized all the rounds. Of of all of them there were a couple that would not chamber in his rifle and a few that were fairly hard to get the bolt down and locked. 

The rest chambered as smooth as factory ammo


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## KineKilla (Jan 28, 2011)

I've put hundred of rounds through these dies and just recently started having issues with case head separation.

I'm trying to wrap my head around the idea that freshly fired brass (2.118) fits just fine, so why stretch it out to a longer length (2.124) just to shrink it back down to a length that is actually longer than when I started (2.120+).

Does not seem logical or I'm not understanding the reasoning behind it. If the end goal is to get more life from cases then sizing only those parts necessary for proper function and nothing else (neck sizing only) seems like the way to do that.

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## rtockstein (Mar 17, 2019)

Read through this thread. It has some good information as well as a lot of crap to wade through. There's some good insights, but unfortunately not a ton relating to hunting-sized cartridges.

https://www.longrangehunting.com/threads/full-length-vs-neck-sizing.230522/#post-1762107

Yea, I think the main part of deciding which route to go on sizing is just making sure it functions flawlessly when hunting and getting as much case life as you can or want to. Some people do their "FL" sizing with a bushing to knock the shoulders back and then a mandrel type die that is similar to a neck sizing die. Two steps, accomplishes nearly the same thing as a "partial" FL sizing.

LOTS of ways to skin the cat. You can't go wrong by making plenty of measurements and making sure your cartridges function and the process is repeatable.


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## rtockstein (Mar 17, 2019)

KineKilla said:


> I've put hundred of rounds through these dies and just recently started having issues with case head separation.
> 
> I'm trying to wrap my head around the idea that freshly fired brass (2.118) fits just fine, so why stretch it out to a longer length (2.124) just to shrink it back down to a length that is actually longer than when I started (2.120+).
> 
> ...


I missed the info on your brass.... did you determine if there could have been an issue with the current batch of brass that separated? Or did the sizing die setting somehow change on that batch of brass?


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## KineKilla (Jan 28, 2011)

It's unlikely that the dies moved as they were locked in place and set up according to the die manufacturer's directions which is bottomed out against the shell holder + 1/8 turn. 

Never been an issue until recently. Unfired brass measurements leave A LOT of room for case stretch, too much in my opinion. I'm not 100% sure I'm reading the SAAMI specs correctly but if I am these cases start out .008 under cartridge Max measurement and .03 +/- under Chamber Minimum. 

IF I have a chamber at the high end of the spec and cases that are at the extreme low end of the spec I could see as much as .035 growth in the first firing.

I would expect them to be under by some amount to fit many different rifles but SAAMI does not give me a cartridge Minimum to go off to see if they are under that.



On that topic though: Who makes GOOD brass for a 7RM? Lapua does not and I've heard they make the best brass around.


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## Critter (Mar 20, 2010)

If your die is set where the die touches the shell holder then you are full length sizing the cases. 

I like Federal brass and have never had any problems with it. Hornady is also good. I use Norma for my .340 Weatherby and it is also good.


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## rtockstein (Mar 17, 2019)

KineKilla said:


> It's unlikely that the dies moved as they were locked in place and set up according to the die manufacturer's directions which is bottomed out against the shell holder + 1/8 turn.
> 
> Never been an issue until recently. Unfired brass measurements leave A LOT of room for case stretch, too much in my opinion. I'm not 100% sure I'm reading the SAAMI specs correctly but if I am these cases start out .008 under cartridge Max measurement and .03 +/- under Chamber Minimum.
> 
> ...


Yea that's a lot of case stretch. I saw your thread on another forum and noticed a couple of people saying it's normal for a 0.02" stretch on first firing for a belted magnum...I didn't know that. It certainly stands to reason that if your chamber is on the high end of spec and the brass is on the low end, you could end up with alot!

I've always heard of people really liking Winchester brass for brass that isn't $1/case. It's apparently tough and reasonably consistent for the money. It's what I've been using until I start this box of starline brass and I haven't found any issues.

Hopefully your neck die works well!


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## waspocrew (Nov 26, 2011)

If you can find it, ADG brass is great stuff. Extremely tough and very consistent. Pretty reasonably priced for 50 cases as well.

https://www.creedmoorsports.com/product/adg-7mm-remington-magnum-brass/ADG-Brass


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## KineKilla (Jan 28, 2011)

Not to sidetrack the discussion but I noticed that the shelves at Sportsmans were picked clean of most common calibers, powders, projectiles and other components.

It looks almost like it did after Sandy Hook. Uncertainty sure sells guns and ammo.

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## Critter (Mar 20, 2010)

And that is why I now only purchase my powders by the jug and primers by the 1000's. 

Pistol bullets are purchased by 500 count boxes and rifle bullets I'll try to stock up as often as I can. 

But then I have all my load recipes and don't have to build any up anymore. I know what my loads will do and I am quite happy with what I have.


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