7mm Rem Mag Case Stretch

[cajun]

I worry more about the dimension at the web. I have seen rounds loaded for 5 years, "normalize" with the brass springing back out with the result of not being able to chamber in the barrel.

Due to a mis fit between brass, dies, and chamber, often we are forced to push the shoulder back more than we like, and .006 is not uncommon at all in order to get the brass to cycle in the chamber.

Keep your ammo fresh if possible, from year to year. I will generally load 100 rounds after I have verified my load 3 X, but I leave the bullets seated .100 long, seating 20 or so rounds to the ogive length prior to the hunting season or as needed, then cycle the rounds through the gun. All rounds were fired in that chamber when new, if the brass was previously fired.

The smaller the tolerance between the new brass and chamber dimension, the more apt you are to get into trouble from Brass expanding out after sizing, "normalizing". This whole issue of Brass spring back is one heck of a can of worms.

Well I only resize .002 and have shot ammo thats been loaded for several years mostly as foulers as I do reload fresh hunting ammo and never had a round not chamber or be hard to chamber.

 

[VinceMule]

cajun, most of the problems people have with cases "normalizing" over time, come from range pick up brass, or brass fired in other rifles with HUGE chambers. Cajun, my post was not directed at you, but to teach only.

In my 7 Rem mags, If I only bumped the shoulders back .002, the rounds would not chamber due to web not being sized enough.

 

[cajun]

cajun, most of the problems people have with cases "normalizing" over time, come from range pick up brass, or brass fired in other rifles with HUGE chambers. Cajun, my post was not directed at you, but to teach only.

In my 7 Rem mags, If I only bumped the shoulders back .002, the rounds would not chamber due to web not being sized enough.

I've never run into that issue yet. I wonder if a body die would work. I know Larry Wiilis used to make a die for this specific purpose. I also know if you run your loads hot you may be more likely to have an issue.

 

[Hydra6]

This is what you want, Peterson 7MM RM Long brass. The headspace will be about 0.003 less than your chamber on average. You get more loads since you are not going thru excessive stretch on first load. Grafs out but sign up and maybe score. I bought same for 300WM and love the headspace new brass measurement. I know you have brass but I would keep as backup once you grab these.

Peterson Brass 7mm Remington Mag Long Unprimed Bulk Box of 250 - Graf & Sons

This is a Bulk package of Peterson Cartridge casings, they will not come in one of their plastic ammo boxes. Made in the U.S.A. Peterson Cartridge Co is committed to producing Match-Grade Brass that enables our customers to get more reloads per casing than industry average. Warning: Only use...

www.grafs.com

Learned something new, thanks. Just got a 300 WM. Ordered Peterson 300WM "long" brass for it. Thanks

 

[Lefty7mmstw]

I wouldn't neck size brass for a hunting rifle. I fl size my brass with the sizer set to just let the casing chamber easily. Usually this is termed partial fl. sizing and is usually about a .002" shoulder push. My 15 year old kid is shooting the Tikka 7rem we have and is dropping groups in the .3's and .4's with it at 100.

 

[BountyHunter]

A Guy always neck sized his 7 Rem mag, till it was hard to chamber the rounds. Then fl sized, controlling the shoulder bump. Still hard to dhamber. More bump, no go.

Because of neck sizing, the unsupported area in front of the belt became to large in diameter. Standard fl dies dont size there.

https://www.larrywillis.com/The fix.

Problem with NS until hard to chamber work hardens the brass and very hard to push back after that. Simple, fire 3x until shoulder moves forward to full extent or false shoulder and fire 2x THEN adjust FL die and FL size every time thereafter., You are moving your headspace from the belt to the shoulder as it should be. NS will eventually get you into trouble one day with not chambering, or bolt will not close. IF you are dead set on NS then run every loaded round thru your chamber before a hunt or competition. You will see the issues. A knowledgable smith can order a belted round reamer to headspace off the shoulder immediately.

 

[VinceMule]

Cajun, I had a larry willis die for at least 10 years, never used it.

My loads are at max for the rifle or close to it, and this is where the accuracy is best. I am not trying to run hot loads, I am just chasing accuracy.

 

[L.Sherm]

Cajun, I had a larry willis die for at least 10 years, never used it.

My loads are at max for the rifle or close to it, and this is where the accuracy is best. I am not trying to run hot loads, I am just chasing accuracy.

Listen to Vincemule theres some wisdom in what he's saying.
If you shoot any gun to its full potential you can not get away with just Neck sizing very long.
What i mean by full potential is Speed and accuracy.

 

[xsn10s]

7mm Remington Mag Body Die

7mm Remington Mag Body Die by REDDING RELOADING PRODUCTS Body dies are designed to full length resize the case body and bump the shoulder position for proper chambering without disturbing the case neck. They are made without internal parts and intended for use only to resize cases which have...

www.midsouthshooterssupply.com