7mm Rem Mag Case Stretch

[243winxb]

unsupported area

The minimum shoulder bump may move the belt back as much as .015" in a sloppy chamber.

Study the SAAMI drawings. Took me a while to figure out his problem.

 

[shortshot1]

Measure the depth of the belt. I have found the factories have the belt too long , usually by .012. Headspace willl measure to the belt OK and be short measuring to the shoulder and cause the brass to stretch.

 

[Mike Matteson]

The stretch is normal. To size belted mags, you MUST fire it 3 times while neck sizing for those firings…then measure, then adjust your FL Die to bump .0015" and keep it there.
There truly is no need for long brass as long as you don't bump your shoulders back more than the above, .002" is MAX for good brass life.

Cheers.

I think that will work. I changed to neck sizing a long time ago, and stopped the case separation at the base. Lost the case to primer pocket getting to big to hold primers.

 

[Jasbo]

you can form a false shoulder on the standard length brass , this will help on case stretch .from what I've seen it's to be about .015" is what belted cases stretch .


+1 on the long brass , this will solve this problem .

I've been successful establishing a false shoulder per Lane Pearce's Dec 2022/Jan2023 Shooting Times article. See attached.

 

[jimbires]

I've been successful establishing a false shoulder per Lane Pearce's Dec 2022/Jan2023 Shooting Times article. See attached.

exactly right . the false shoulder makes the brass case push the shoulder forward , instead of stretching the case right in front of the belt . this will extend case life . I let the false shoulder long enough that the case is tight to chamber . I haven't used a fire forming load , I just use my regular load . thanks for posting up this article .

 

[MagnumManiac]

exactly right . the false shoulder makes the brass case push the shoulder forward , instead of stretching the case right in front of the belt . this will extend case life . I let the false shoulder long enough that the case is tight to chamber . I haven't used a fire forming load , I just use my regular load . thanks for posting up this article .

The case only stretches when the case is sized too much after the FIRST firing, and then subsequent firings…there is absolutely no truth to your statement that a false shoulder changes ANYTHING on the first firing.

Cheers.

 

[Mike Matteson]

The case only stretches when the case is sized too much after the FIRST firing, and then subsequent firings…there is absolutely no truth to your statement that a false shoulder changes ANYTHING on the first firing.

Cheers.

It changes a lot to start with. The biggest thing is not bumping that shoulder back more than needed. In my belted mag I've been able to shot several firing before having to bump my shoulder.

 

[jimbires]

The case only stretches when the case is sized too much after the FIRST firing, and then subsequent firings…there is absolutely no truth to your statement that a false shoulder changes ANYTHING on the first firing.

Cheers.

the brass is not even fully expanded after the first fire . THERE IS ABSOLUTELY NO TRUTH TO YOUR STATEMENT .

 

[MagnumManiac]

the brass is not even fully expanded after the first fire . THERE IS ABSOLUTELY NO TRUTH TO YOUR STATEMENT .

Really, here's PROOF that what you preach is WRONG!
Prove what you say is TRUE!
This is a case fired several times, sized correctly each firing…where's the stretching? The first 3 firings had zero sizing other than neck sizing for .0015" neck interference.
Show proof that a case stretches at the web and not at the shoulder, as you say occurs.
Quoting falsehoods off the interwebs does NOT make it true.

 

[Bob Wright]

My 7RM grew .019 total at the shoulder, but I annealed the neck shoulder junction after reload #2. Prior to that they varied ~.004 due to incomplete forming.
Save yourself some components and anneal the neck/shoulder junction. That should get you to fully formed quicker.

 

[jimbires]

Really, here's PROOF that what you preach is WRONG!
Prove what you say is TRUE!
This is a case fired several times, sized correctly each firing…where's the stretching? The first 3 firings had zero sizing other than neck sizing for .0015" neck interference.
Show proof that a case stretches at the web and not at the shoulder, as you say occurs.
Quoting falsehoods off the interwebs does NOT make it tr

when this crap starts , the OP learns nothing . the thread gets turned into a ****ing contest
do you know why you get banned ? you are an A$$hole , now prove your not , theres no proof your not . and like to shoot off your big mouth . I've paid attention to your post since you were on here crying about being banned . I can see why . you like to argue . you act like you are the smartest guy on the forum . for a smart guy you sure are stupid . go argue with the next guy . my time is too precious to waste on you and your crap .

Anyone ever get banned from a forum?

Len, if this is not OK, please remove. As above, anyone get banned after being attacked/reported by other members for replying endlessly over matters that didn’t concern them and DEFENDING yourself? I won’t mention the forum, as it’s not worth my time to do so. Just wondering if this has...

www.longrangehunting.com

 

[jimbires]

OP , I went digging back and found this thread I did on forming a false shoulder . there might be something there that helps you . it's really a simple process , it takes little time to do it to a new batch of brass .

forming a false shoulder

all this false shoulder talk got my interest up , I had to do it . I wasn't sure if it would be worth the effort . I found there is nothing to this .if you have the means do it , it can only help case life . I doubt I have I have 15 minutes in getting things measured , until I had 5 pieces...

forum.nosler.com

 

[MagnumManiac]

when this crap starts , the OP learns nothing . the thread gets turned into a ****ing contest
do you know why you get banned ? you are an A$$hole , now prove your not , theres no proof your not . and like to shoot off your big mouth . I've paid attention to your post since you were on here crying about being banned . I can see why . you like to argue . you act like you are the smartest guy on the forum . for a smart guy you sure are stupid . go argue with the next guy . my time is too precious to waste on you and your crap .

Anyone ever get banned from a forum?

Len, if this is not OK, please remove. As above, anyone get banned after being attacked/reported by other members for replying endlessly over matters that didn’t concern them and DEFENDING yourself? I won’t mention the forum, as it’s not worth my time to do so. Just wondering if this has...

www.longrangehunting.com

 

[VinceMule]

I will be the odd man out here. My 7 Mags are hunting rifles, Sporters in Rem 700, and Browning A bolts, and I have barrel blanks waiting their turn for the 7oos when the barrels get shot out. These factory rifles are extremely accurate, and that is an understatement.

For dies, I have:
Forster Benchrest
Redding Competition set
Wilson Bushing Full-length sizer
RCBS Full-length die set, with '79 stamped on top, indicating that it was made in 1979.

The best accuracy achieved in these rifles happens with the RCBS full-length sizer. Bullet seaters used are either the Forster or the Redding comp seater, does not matter as long as the bullet touches the lands with both dies producing less than .002 run out on a seated bullet..

The loads I shoot are right at the top of the pressure curve, so I have to full-length size on every firing. My Rem and Win brass is worked hard with the 140g at 3250-3300, 150g at 3200 and 162g at 3100 on 26" barrels.

When adjusting the full length sizer, I screw the die down in the press maybe 1/32 of a rotation at a time, barely moving it as I am trying to adjust the die where the bolt handle goes down easily when the brass is chambered in the chamber. I am reducing the dia at the web, and I really do not give a darn what is happening at the shoulder, why would I? I have be able to cycle a loaded round a loaded round that was picked up from the mag box. I firmly believe in throwing the brass away as case head separation lines appear in the brass. The softer brass in the lot will start showing problems somewhere around 7 firings, and that indicates that the barrel is near the end of it's life. I start off with 100 new Rem or Win cases in a case guard 100, and I go through the entire 100 before starting over, Heads will be exploding over this, I am sure.

Some would argue that my loads are too hot, but I am hooked on 3/8" and smaller three shot groups that repeat time after time, and 2.5-3.5" groups at 600 does not suck.

I see the merits of both what jim and magnum are saying, two different approaches, and I don't see that either is wrong in their approach. I for one am not going to neck size my 7 Rem mag cases, it was an absolute disaster for me when trying to shoot to the accuracy/pressure nodes I am shooing. I figure that 100 cases for a new gun/barrel is not much to ask and little expense. The barrels turn into copper mines somewhere around 800-1000 rounds max, where accuracy is opening up, time for a new barrel or new gun. I will have lost around 15 pieces of brass from case stretch, with the remainder of the brass having around 10 firings on it.

New brass shoots in tiny groups, fired/fully formed brass may take a tiny adjustment on the powder charge, quickly figured out when loading at the rifle range.

Peterson brass could solve some issues on headspace length, I would worry about the dimension at the web and how my dies measure in this respect. If the Peterson brass was larger in the web than Win and Rem, it could be another ****er to deal with. Since I have the Rem and Win brass loads figured out with dies on hand, I don't think that I will complicate my life any further. I anneal on the 3rd-6th firing, propane torch and bread pan of water, not going to change as long as I get 3/8" and below groups.