Belted Magnum Brass Prep: False Shoulder?

[Chuck R.]

Working with my newly re-barreled 300WM and I'm getting 0.020" average headspace expansion on new FED brass using a Hornady comparator and taking 10rd samples.

New brass just had the necks sized, no shoulder bump.

AVG Measurement for new brass was 4.264"
AVG measurement for once fired is 4.284"

I've got the whole "belted mags headspace on the belt for their 1st firing thing, then headspace off the shoulder" thing. I'm trying to save some of the stretching on that 1st firing.

Question is, how many of you guys have done the false shoulder using a .32" or .33" expander, and has it done any good at limiting the thinning above the belt?

 

[Blue68f100]

If your setting up to head space off the shoulder the belt will not be moving any more. It's the only way I have ever loaded a belted cartridge. Now if the brass is soft with high pressure you can still expand the base.

 

[Legionnaire]

Tagging in to see the replies. The only belted magnum I still own is the 7mm Remington Magnum I inherited from my FIL, and I shoot it so infrequently I'm still working through my factory ammo for it.

 

[Chuck R.]

If your setting up to head space off the shoulder the belt will not be moving any more. It's the only way I have ever loaded a belted cartridge. Now if the brass is soft with high pressure you can still expand the base.

Agree, but the belt never moved, it's the shoulder getting blown FWD to fill the chamber.

My previous method was just to let it headspace off the belt for the 1st firing, then bump shoulders after that to ensure ease of chambering. I was just researching and read that some guys like either the false shoulder, or jamming bullets to ensure that the initial stretch doesn't come from the area above the belt, thereby reducing the chances of case head separation down the road.

Another solution is to just throw money at the problem and buy Peterson "long" 300WM brass. I'll probably do it some day, but I'm sitting on 200 pieces of FED 300WM.

 

[Walkalong]

I wouldn’t call it a “false shoulder”, you’re just sizing to headspace off the shoulder instead of the belt. The belt will be a non player.

Size to keep the shoulder where it is now on fired cases, should chamber just fine. If not, move them back .002 more, but the fired cases will chamber, so no reason they wouldn’t after sizing if you keep the shoulder there.

 

[Chuck R.]

No, it's actually a false shoulder created by oversizing the neck with an expander, then necksizing down incrementally untill the brass chambers.. The brass then headspaces on the enlarged portion on the neck.

 

[jmorris]

I've got the whole "belted mags headspace on the belt for their 1st firing thing, then headspace off the shoulder" thing. I'm trying to save some of the stretching on that 1st firing.

A reduced load (I use trailboss) will fire form the brass to the chamber. The only way to make them not stretch would be to put them into a smaller chamber.

You can still do this tough, it works with or without a belt.

Setting size die for bolt action rifle.

www.youtube.com

Thats not neck sizing though, the shoulder is what’s stopping it, not the neck. Your pushing it back, incrementally until the bolt can drop.

 

[Chuck R.]

A reduced load (I use trailboss) will fire form the brass to the chamber. The only way to make them not stretch would be to put them into a smaller chamber.

You can still do this tough, it works with or without a belt.

Setting size die for bolt action rifle.

www.youtube.com

Thats not neck sizing though, the shoulder is what’s stopping it, not the neck. Your pushing it back, incrementally until the bolt can drop.

It's my normal procedure for setting up dies. I use die shims to adjust the amount of sizing as I may Ioad several rifles with one set of dies.

 

[N555]

Nope playing with a false shoulder only causes problems.
If you want to reduce fire forming growth just load them with a start load of the fastest appropriate powder for 300wm and light them up.

 

[Chuck R.]

Nope playing with a false shoulder only causes problems.
If you want to reduce fire forming growth just load them with a start load of the fastest appropriate powder for 300wm and light them up.

Can you please expand on the problems?

From research it seems to be a fairly common practice for forming some wildcats.

For the rest, this article pretty much covers what I'm asking about:

https://www.handloadermagazine.com/7mm-remington-magnum

As with several other cartridges that utilize a belt to set headspace, new 7mm Remington Magnum cases and loaded cartridges are often short at the shoulder. The position of the belt does keep the case head in tight contact with the bolt face, but if a case is short on the shoulder, a belt does not prevent it from stretching at the web as a cartridge fires and expands to fill the chamber.

For example, new Remington cases measured .018 inch short from the case head face to the datum line on the shoulder compared to a case fired in the Browning X-Bolt rifle. Federal Premium Vital-Shok and Hornady Precision Hunter cartridges measured .016 inch short at the shoulder compared to those brands of cases fired in the X-Bolt.

In contrast, cases that do not have a belt headspace on the shoulder and have a much tighter fit in a chamber. Winchester Supreme .270 Winchester cartridges measured only .003 inch shorter from the case head face to the datum line on the shoulder compared to fired Winchester cartridges.

That big of a stretch of 7mm Remington Magnum cases on the first firing has most likely excessively stretched the cases at the web and ruined them. It will not matter if the belt is ignored and headspace is set on the case shoulder when sizing the cases, because the damage has been done and cases have at least had their life significantly reduced.

To fix the problem with new brass, expand the necks by running them over a larger expander ball, like a .30 caliber. A bit at a time, size the necks back down so the cases just fit in a chamber. Load the cases with a minimum amount of powder listed in a handloading manual, add a bullet and fire them. The remaining portion of the expanded neck keeps the case tightly in the chamber at the shoulder and against the bolt face, and shooting them fireforms the brass to match the chamber with no stretching at the web.

The Peterson solution:

 

[N555]

Yeah the cases being 16 to 18 thousands short at the shoulder is going to cause a lot of stretch. If you think it will work try to run it. That's bad, that's like 30-30 bad I'm used to old cartridges having chamber suggestions, I figured winmag would be new enough to not be that loose.

 

[Chuck R.]

Yeah the cases being 16 to 18 thousands short at the shoulder is going to cause a lot of stretch. If you think it will work try to run it. That's bad, that's like 30-30 bad I'm used to old cartridges having chamber suggestions, I figured winmag would be new enough to not be that loose.

The weird part is that it's a known "issue", done on purpose, and the only commercial fix I've found is the Peterson brass..

I've got a bunch of once fired FC (different rifle), so it looks like I'll anneal some and try it.

 

[N555]

The weird part is that it's a known "issue", done on purpose, and the only commercial fix I've found is the Peterson brass..

I've got a bunch of once fired FC (different rifle), so it looks like I'll anneal some and try it.

I figured the only stuff that far out would be 30-30, 32-20 stuff that's been around for a hundred years and has chamber suggestions more than specifications.
I'll likely get a 300wm or 264wm eventually. New brass that has weird head spacing would cause a few problems.
Probably have cases come up short after shoulder bump, fire formed cases would probably need their own loads assuming I bought new brass and wanted to load full power ammo.
How are you going to feed them?
Load up the mag and let them bang around or single feed?

 

[MEHavey]

I've been sizing my father's (now mine) `03 Springfield 300WinMag for "shoulder headspacing" for 26 years now.

Chambers just like any other conventional bottleneck.
Minimal case length growth.
No other issues at all.

 

[Theinkman]

I recently shot some 7mm RM factory rounds I've had for a while. Using the Hornady comparator, I measured the unfired factory rounds at 2.106. Fired rounds measured at 2.125. Wow almost 20 thousandths in stretch. I realized why belted magnums frequently show incipient case head separation after just a few reloads.

If that brass is FL sized it is going to stretch close to the same amount on the next firing. Easy to see that it won't take too many cycles of FL sizing and firing before the case head separation happens. As others have said, belted magnums will headspace off the belt on the first firing. Once that has happened it will headspace off of the shoulder unless it is FL sized which would cause it to continue to headspace off of the belt.

For my rifle I use a Lee collet die and will size the neck only. When I do need to bump the shoulder, I do so with a Redding S-body die; no bushing. I also use the Redding competition die set which helps me to precisely set the amount of bump I want. Brass is too precious right now.

 

[Chuck R.]

I figured the only stuff that far out would be 30-30, 32-20 stuff that's been around for a hundred years and has chamber suggestions more than specifications.
I'll likely get a 300wm or 264wm eventually. New brass that has weird head spacing would cause a few problems.
Probably have cases come up short after shoulder bump, fire formed cases would probably need their own loads assuming I bought new brass and wanted to load full power ammo.
How are you going to feed them?
Load up the mag and let them bang around or single feed?

Through the mag.

I "formed" some test loads last night, there's no issue feeding and chambering. It's really only one additional step.

1. Clean and anneal once fired brass (skip for new brass)
2. Run the .32 neck expander into brass (can also use a .33) really the only additional step
3. Neck size to achieve a "crush fit" on the false shoulder created in step 2. I used my die set up for FL sizing and backed it off using Skip's Die Shims. Brass is all "short" so I won't trim till it's all fire formed.
4. Load. I'm using a bunch of Midway 168 OTM "2nds" that I bought for practice.

I'll shoot this as practice loads while fire-forming.

I recently shot some 7mm RM factory rounds I've had for a while. Using the Hornady comparator, I measured the unfired factory rounds at 2.106. Fired rounds measured at 2.125. Wow almost 20 thousandths in stretch. I realized why belted magnums frequently show incipient case head separation after just a few reloads.

If that brass is FL sized it is going to stretch close to the same amount on the next firing. Easy to see that it won't take too many cycles of FL sizing and firing before the case head separation happens. As others have said, belted magnums will headspace off the belt on the first firing. Once that has happened it will headspace off of the shoulder unless it is FL sized which would cause it to continue to headspace off of the belt.

For my rifle I use a Lee collet die and will size the neck only. When I do need to bump the shoulder, I do so with a Redding S-body die; no bushing. I also use the Redding competition die set which helps me to precisely set the amount of bump I want. Brass is too precious right now.

This is what got me started on this "project"!

Once that 1st firing happens, in theory the damage is done, and you've already shortened case life. Neck sizing only, and bumping when needed does prolong case life without a doubt.

I almost never shoot factory ammo, so I don't normally take any measurements off it. A friend of mine is bringing in a bunch of factory 300WM ammo from different manufacturers just so I can take some measurements for comparison. From what I've read, it should all be short of the SAAMI specs and quite a bit short of my fired brass.

 

[Laphroaig]

I was just researching and read that some guys like either the false shoulder, or jamming bullets to ensure that the initial stretch doesn't come from the area above the belt, thereby reducing the chances of case head separation down the road.

I don't get it. If you're trying to avoid the initial stretch come from the area above the belt, are you saying you want it from below the belt? That's going to be tough because the case within and behind the belt is solid brass and is going to compress if anything. The expansion of the brass occurs violently at 50K+ psi in a couple of milliseconds, and at the end of the day the shoulder is going to be pushed forward .020. I can't see where the case is headspaced will have any effect on how the case expands to fill the chamber.

IMO the false shoulder concept is working the neck way too much and fireforming is going to use up one good reload until the primer pockets get loose.

I've got the whole "belted mags headspace on the belt for their 1st firing thing, then headspace off the shoulder" thing. I'm trying to save some of the stretching on that 1st firing.

Even non-belted cases are going to stretch on the first firing. Its how you size them after that determines case life and minimizes separations. Maybe I'm lucky, but I've never had an incipient separation. Neck cracks and loose primer pockets usually do it for me. Don't overthink it.

 

[Chuck R.]

I theory and according to the article I read and posted. The false shoulder causes the brass to "expand" at the shoulder rather than move FWD from the web. Like I posted above:

To fix the problem with new brass, expand the necks by running them over a larger expander ball, like a .30 caliber. A bit at a time, size the necks back down so the cases just fit in a chamber. Load the cases with a minimum amount of powder listed in a handloading manual, add a bullet and fire them. The remaining portion of the expanded neck keeps the case tightly in the chamber at the shoulder and against the bolt face, and shooting them fireforms the brass to match the chamber with no stretching at the web.

The neck expansion is minimal and a 1 time deal. I'll anneal before and for subsequent firings.

A quick google search shows numerous posts on other forums on it, and one from THR some time ago:

Using a false shoulder when fire roming belted magnum brass - Google Search

Into lands or false shoulder to fire form belted brass

I am getting ready to start load development with some new brass in my 7RM. This will be the first time I have started with new brass in a belted mag. In order to prevent excess stretch in the new brass I plan on one of the above to hold the base of the cartridge against the bolt face. I have...

www.longrangehunting.com

THR:

7 mag headspace problem

i think i have a headspace problem with my 7 mag.im getting case seperation ahead of the belt and its hard to open the bolt.i got some virgin brass to reload.can i put 10 grains reddot,some filler and then wadding to fireform mycases.then can i set my die to headspace on the shoulder instead of...

www.thehighroad.org

Another Article about the process:

Make a trip to the range and fire the ammo. The auxiliary shoulder adds a second point of support centered at the front of the case. When the pressure rises, the remainder of the shoulder "catches up" with the auxiliary shoulder without drawing nearly as much material from the head area. This minimizes the stretch that shortens case life, and you have a strong case custom-fitted to your chamber.

Belted Case Blues - Shooting Times

At the risk of tipping someone's sacred cow, I'm going to talk trash about the belted rifle case and how it can negatively affect the average reloader.

www.shootingtimes.com

So I think it's at least worth a try..

 

[AJC1]

Where is the material going to come from if not from in front of the belt. False shouldering may slow the process by giving you short necks but if fully fire formed will still result in material moved from the same place. There is no where else it can come from.

 

[243winxb]

From research it seems to be a fairly common practice for forming some wildcats.

Neck as a false shoulder.

Using the neck as a false shoulder is used on non- belted wildcat cartridges, when forming brass. This is to avoid misfires, by keeping the case head against the bolt face.

A belted case will not misfire, doesnt make any difference if the shoulder is there or not.

Pressure needed on fire forming, to move shoulder forward, must be high enough to expand the brass. A load thats to light can make the head to datum measurement shorter after firing.

Online- Oil has been used to allow the brass to stretch without damage on the first firing. Never tried it.

When i had factory guns in 7mm & 300 belted mags, i shot factory ammo for the brass, then reloaded it, with shell holder touching the bottom of the fl dies. (Before internet). Dont remember any problems.

 

[Chuck R.]

Where is the material going to come from if not from in front of the belt. False shouldering may slow the process by giving you short necks but if fully fire formed will still result in material moved from the same place. There is no where else it can come from.

That's the gist of it.

Again, in theory IAW 2 articles and numerous forum posts, it removes less brass from the web area. I'm not the author(s), just relaying what I've found.

IAW my initial post:

Question is, how many of you guys have done the false shoulder using a .32" or .33" expander, and has it done any good at limiting the thinning above the belt?

And it looks like I have my answer.

So, I'm going to risk a $75 box of new 300WM brass and about 30 minutes of time by trying it. I keep my brass separated by "lots" and track loadings, how it's sized, trimmed and when annealed. I'll now have two 50 rd lots in circulation, someday I'll know that lot A lasted X loadings before case heads started to separate, and lot B last Y loads.

Next go around I'll probably just go the Peterson brass route.

 

[Walkalong]

When I fireformed 6 Dasher from 6 BR all I did was load bullets long with strong neck tension to hold the case back against the bolt and a 95% charge. Bingo. Then load as normal after that. Those cases are at 7 and 8 firings with zero issues.

 

[Chuck R.]

When I fireformed 6 Dasher from 6 BR all I did was load bullets long with strong neck tension to hold the case back against the bolt and a 95% charge. Bingo. Then load as normal after that. Those cases are at 7 and 8 firings with zero issues.

I've done it that way going forming an AI, but that was really to solve the potential ignition problem.

With the belted mags, that's a non-issue, the belt IS holding the brass against the bolt. That's the reason I'm not going with the lubed brass technique.

It's really an "either or" from what I can tell between jamming and false necking. Some of you had the same discussion here:

Reduced Load for fireforming 300WM

My goal is to fireform new Peterson brass so that I am starting load development with brass headspacing off the shoulder, not the belt. I know I can use a reduced load with H4895 (https://hodgdon.com/wp-content/uploads/2016/11/h4895-reduced-rifle-loads.pdf). Is that a reliable way to fireform...

www.thehighroad.org

 

[243winxb]

strong neck tension

Using a bushing die allows adjustment of the neck tension, like Walkalong. The 45acp may need over 100 pounds pull to move a bullet, at .005" NT.
Another test has .003" NT to produce 95 PSI to pull the bullets, 30-06 annealed brass.

Many firing pin springs are rated at 25 pounds.

 

[243winxb]

the belt IS holding the brass against the bolt

Not against, but close enough to fire a primer.