Belted Magnum - Won't chamber

[Zzuffendoffer]

I’ve searched the forum for a possible match to this issue I’m having… and nothing really answers my question.


Recently picked up some 257 wthby brass on gunbroker. The problem I’m having is that the brass won’t chamber in my Mark V.


I’ve tried about everything… originally bought some RCBS dies, no luck. Picked up a Forster Full Length resizing die… same issue.


Next, I tried the collet resizing die that everyone seemed to rave about… no luck there either.

I did notice some pretty significant buildup of brass just ahead of the belt so, being a problem solver, I tried a few experiments. By the way, if I forced the Collet all the way down to the belt, It was nearly impossible to run through the die…. No matter how much lube was applied.

Being new to belted magnums, and pretty clueless to head-spacing, I made an assumption the shoulders weren’t getting pushed back enough. No matter what trick I tried, I couldn’t budge them.

Next, having a Metal Lathe, I trimmed back what appeared to be the buildup of brass just ahead of the belt. I really thought that was going to be the ticket. No Go. They did however drop nicely into the built in gauge of the collet die.

Finally, I measured the diameter of the belt on a new cartridge and compared to the diameter of the another one of the fired brass I picked up…. Voila.. they were all somewhere north of 3 to 4 thousands bigger. Now I’m curious. Back to the lathe to bring one of them back into spec. That was the problem…. And the turned case chambered nicely.

So after a long winded story, is all this brass junk, or, can I turn them down to spec without fear that I’ve compromised the integrity of the cases? Of course, I don’t want to trash my gun… but I’m not a big fan of throwing crap away either.

Just a bit more to the story… ALL of the cases were SHORT. Nearly 60 thousands short… I contacted the seller and he stated… he trimmed them all back to be consistent.. An old-Timer I know said not to worry about the length… they’d stretch back out after a few firings… just make sure to c.o.a.l. was within spec for the loaded ammo. That sounds reasonable…

Any thoughts? I’m not new to reloading… been doing it for nearly 40 years now. Always like to hear what people have to say… there’s always room to learn. Ya, I know... you get what you pay for.. don't buy junk... etc etc. but as my pappy used to say... Why buy new with used will do?

 

[243winxb]

Neck sizing/minimum bump, lets the area in front of the belt become unsupported on firing. The brass bulges.

Turning off 4 thou doesnt sound like a safe idea to me.

Buy new brass, cheaper then a visit to the emergency room.

Disreguard the separation. Look at the brass thickness.

 

[gman47564]

belted cases headspace off belt .. i bet if you measured your brass that you have fired from the base to the front of the belt it will be a little shorter than the cases you bought that has been fired in someone elses gun...

 

[338 dude]

I’ve searched the forum for a possible match to this issue I’m having… and nothing really answers my question.


Recently picked up some 257 wthby brass on gunbroker. The problem I’m having is that the brass won’t chamber in my Mark V.


I’ve tried about everything… originally bought some RCBS dies, no luck. Picked up a Forster Full Length resizing die… same issue.


Next, I tried the collet resizing die that everyone seemed to rave about… no luck there either.

I did notice some pretty significant buildup of brass just ahead of the belt so, being a problem solver, I tried a few experiments. By the way, if I forced the Collet all the way down to the belt, It was nearly impossible to run through the die…. No matter how much lube was applied.

Being new to belted magnums, and pretty clueless to head-spacing, I made an assumption the shoulders weren’t getting pushed back enough. No matter what trick I tried, I couldn’t budge them.

Next, having a Metal Lathe, I trimmed back what appeared to be the buildup of brass just ahead of the belt. I really thought that was going to be the ticket. No Go. They did however drop nicely into the built in gauge of the collet die.

Finally, I measured the diameter of the belt on a new cartridge and compared to the diameter of the another one of the fired brass I picked up…. Voila.. they were all somewhere north of 3 to 4 thousands bigger. Now I’m curious. Back to the lathe to bring one of them back into spec. That was the problem…. And the turned case chambered nicely.

So after a long winded story, is all this brass junk, or, can I turn them down to spec without fear that I’ve compromised the integrity of the cases? Of course, I don’t want to trash my gun… but I’m not a big fan of throwing crap away either.

Just a bit more to the story… ALL of the cases were SHORT. Nearly 60 thousands short… I contacted the seller and he stated… he trimmed them all back to be consistent.. An old-Timer I know said not to worry about the length… they’d stretch back out after a few firings… just make sure to c.o.a.l. was within spec for the loaded ammo. That sounds reasonable…

Any thoughts? I’m not new to reloading… been doing it for nearly 40 years now. Always like to hear what people have to say… there’s always room to learn. Ya, I know... you get what you pay for.. don't buy junk... etc etc. but as my pappy used to say... Why buy new with used will do?

Don’t screw up your chamber trash the brass

 

[bozo699]

Larry Willis makes a die that will fix your problem
Wayne

 

[bozo699]

belted cases headspace off belt .. i bet if you measured your brass that you have fired from the base to the front of the belt it will be a little shorter than the cases you bought that has been fired in someone elses gun...

I never headspace a fired belted Magnum off the belt. However in this case where it wasn’t fired in his rifle you may be correct.
Wayne

 

[243winxb]

Brass at the correct trim length helps the neck seal the chamber.

The Collapsed Shoulder is in an old Speer manual. Light loads & slow powder are the cause. Use a faster burn rate of powder. Pressure is low & neck not expanding to seal. Make sure the bullets have enough neck tension. Magnum primers must be used. A to long OAL, will not let powder burn correctly.

 

[jepp2]

belted cases headspace off belt

Only for the first firing. After that, if you size your brass to headspace off the belt repeatedly, you will have this to reload on about the 3'rd firing.

The shoulders blows forward ~0.016" on the first firing when it headspaces off the belt. If I treat the cases like a typical bottleneck rifle case and set the shoulder back 0.002" and don't seriously overload the brass, it will last a long time.

You pick which you want.

 

[dave@aDave]

Only for the first firing. After that, if you size your brass to headspace off the belt repeatedly, you will have this to reload on about the 3'rd firing.
View attachment 1170000
The shoulders blows forward ~0.016" on the first firing when it headspaces off the belt. If I treat the cases like a typical bottleneck rifle case and set the shoulder back 0.002" and don't seriously overload the brass, it will last a long time.

You pick which you want.

Loaded .264 WinMag for some time always running the dies all the way down. Was lucky to get 3 loads.

When I went to sizing until I felt a slight pressure when closing the bolt, I'm getting over 6.

Some custom dies helped also.

Live and learn.

 

[Dusty Stevens]

They load the wby mags so hot and factory rifles are usually on the sloppy side so buying used wby brass is a shot in the dark

 

[bozo699]

Only for the first firing. After that, if you size your brass to headspace off the belt repeatedly, you will have this to reload on about the 3'rd firing.
View attachment 1170000
The shoulders blows forward ~0.016" on the first firing when it headspaces off the belt. If I treat the cases like a typical bottleneck rifle case and set the shoulder back 0.002" and don't seriously overload the brass, it will last a long time.

You pick which you want.

Spot on!
Wayne

 

[Zero333]

Start with new brass.

After first firing you want to headspace using the shoulders (like others have mentioned). That means you need a headspace comparator (from hornady) and bump the shoulders 0.001" or up to 0.0002".

I've loaded belted magnums for a long time and brass can last a long time if you bump shoulders 0.001". I have never worn out the brass. The barrel always goes first. And with a new barrel I use new brass.

I have some 300winmag brass I've reloaded 10+ times and it shows no signs of thinning above the belt.

If you really want to reuse this brass, the only thing that can help is the Larry Wills belted magnum Collet (as mentioned by others).

 

[Uncle Ed]

Finally, I measured the diameter of the belt on a new cartridge and compared to the diameter of the another one of the fired brass I picked up…. Voila.. they were all somewhere north of 3 to 4 thousands bigger. Now I’m curious. Back to the lathe to bring one of them back into spec. That was the problem…. And the turned case chambered nicely.

The manufacturing tolerances for the belt diameter is .532 to .527 so what is the belt diameter of your problem cases.
Or a woman's perspective, "Honey do my overloaded cases make my ass look too big."

Simple Trick for Monitoring Pressure of Your Rifle Reloads
http://www.hodgdonreloading.com/rel...-trick-monitoring-pressure-your-rifle-reloads

One of the first rules of handloading is to always follow the approved reload data. The cautious reloader gradually works up to approved maximum loads to ensure his particular gun does not show pressure signs. Generally this is visual observation of the fired shell case head and primer. There is another slick way to check for pressure signs if you are interested.

Using a blade micrometer that measures in ten thousandths (.0001"), new, unfired cases can be gauged before and after firing to determine reasonably accurate maximum loads. Micrometers measuring in thousandths (.001") are insufficiently accurate to perform these measurements, and should not be used. Previously fired cases cannot be used accurately due to various levels of brass hardening. Measurement is taken just ahead of the extractor groove on the case head and must be taken at the same place on the case before and after firing. By placing a small mark on the case head – entering the cartridge in the chamber with mark at 12 o’clock – a consistently accurate measurement can be taken with each firing.

Lower pressure rounds, like the .30-30 Winchester, usually yield maximum pressures at .0003"-.0004" expansion. Modern cartridges, like the .223 Remington, will show maximum pressure at .0004"-.0005", while .308 Winchester, .270 Winchester, etc., typically yield .0005"-.0006" expansion at max pressure. Magnums, like the .300 Winchester Magnum, show maximums at .0006”-.0007” expansion, and should be measured on the belt.

In conjunction with these measurements, case head signs of pressure should be monitored as well. These signs include very flat primers, slightly cratered primers, ejector marks on the case head, and stiff extraction. All these case head signs indicate high pressure, and loads should be reduced until these signs disappear.

As always, start with the beginning load listed, and cautiously work up to the maximum shown for that set of components, using the methods listed herein.

 

[gman47564]

I never headspace a fired belted Magnum off the belt. However in this case where it wasn’t fired in his rifle you may be correct.
Wayne

I should rephrase what i said.. a belted magnum headspaces off the belt when setting the rifle headspace.. and a new case is headspaced at the belt.. fired cases are then headspaced at the shoulder.. at least thats my understanding.. i still believe the op will find his issue between the base and belt..

 

[gman47564]

Only for the first firing. After that, if you size your brass to headspace off the belt repeatedly, you will have this to reload on about the 3'rd firing.
View attachment 1170000
The shoulders blows forward ~0.016" on the first firing when it headspaces off the belt. If I treat the cases like a typical bottleneck rifle case and set the shoulder back 0.002" and don't seriously overload the brass, it will last a long time.

You pick which you want.

You are correct sir..

 

[Dgd6mm]

Search the archives here for the .300WM. There is a fellow shooter that used to frequent this site but only comes on as a guest now and then anymore. His screen name is Catshooter, he definitely has the skinny on the belted magnums.

 

[Zzuffendoffer]

TO Uncle Ed... I measured 3 random cases... they were .538, .533 & .537. Thanks everyone for replying. There were a lot of things written here I need to look into. I'll dump this brass and work with the once fired out of my gun.

 

[AlNyhus]

I'll dump this brass and work with the once fired out of my gun.

Once fired from your chamber is what you want to do. Set the dies up to push the should back .001-.002 and take the belt out of the equation. You'll need some way to accurately measure the shoulder set back...the Hornady kit is excellent. They don't show bushing for the 257 WBy but anything that fits reasonably well will work as it's just a reference point.

The Hornady comparator is one of the first things any hand loader should buy.

https://www.hornady.com/headspace-bushings#!/

Good shootin'. -Al

 

[243winxb]

257 Chamber slop-Tolerances .011" maximum. This is the difference between .224" chamber headspace max & .213" cartridge min.


Head to shoulder (not datun) 2.1131" chamber maximum & 2.1047" cartridge minimum. A difference of .0084" (slop) An estimate because there is no SAAMI datum diameter.

So, in a sloppy chamber, it may be possible for the area in front of the belt to become unsupported & bulge with maximun pressures? This is when setting the die to size with a .002" shoulder bump. Head clearance of .002"

The unsuppored cartridge area may be as much as .008" in a sloppy factory chamber?

Right or wrong?? This gave me something to do while in lock,down.

 

[nmkid]

http://www.larrywillis.com/