7mm chambering issue

[KRasmussen]

I recently purchased some once fired, plated Winchester brass in 7mm mag for reloading. The brass was said to be all ready to go, sized, trimmed etc. I did not trust that they were good and ran them all through the press, full length, trimmed cleaned etc. I loaded some of them up with a known load I had been using but in Federal brass. I dropped the load a few grains just in case the brass made a difference. While at the range I found that some of them would not chamber at all. The round would feed into the chamber but not completely. The bolt was stuck to the point of having to tap on the handle to remove it. I have measured them and they are identical to the others that chambered and fired without an issue. I am stumped.....Any ideas?

 

[mtmuley]

Do you have the Stoney Point for measuring sized brass? Since it wasn't fired in your rifle, maybe sizing is an issue. mtmuley

 

[beartracks]

If you full length resized them and they are properly trimmed to length, the cases should not be the issue. From your description, you did not fire them, you just tried to chamber them, and upon not being able to cam the bolt into position tried (with difficulty) to open the bolt and extract them (let me know if I mis-interpreted that).

Sounds like the bullets might be engaging the rifling. Besides checking your cartridge OAL, some bullets do have an ogive that can touch the rifling. Simply take a loaded round and color the bullet with a black magic marker all the way around just above the case. Then try chambering a round and see if the bullet is contacting the throat of the chamber. If it is, your rifling will show up in the black magic marker on the bullet.

This is basically the same process you can use to determine how far you are jumping your bullet to the lands of the rifling.

If your bullet has marks on it, adjust your seating die accordingly to back the bullet out of the rifling.

Good luck!

BT

 

[KRasmussen]

If you full length resized them and they are properly trimmed to length, the cases should not be the issue. From your description, you did not fire them, you just tried to chamber them, and upon not being able to cam the bolt into position tried (with difficulty) to open the bolt and extract them (let me know if I mis-interpreted that).

Sounds like the bullets might be engaging the rifling. Besides checking your cartridge OAL, some bullets do have an ogive that can touch the rifling. Simply take a loaded round and color the bullet with a black magic marker all the way around just above the case. Then try chambering a round and see if the bullet is contacting the throat of the chamber. If it is, your rifling will show up in the black magic marker on the bullet.

This is basically the same process you can use to determine how far you are jumping your bullet to the lands of the rifling.

If your bullet has marks on it, adjust your seating die accordingly to back the bullet out of the rifling.

Good luck!

BT

You are reading it correctly. I never did fire them as the bolt would not close. It seems to be random as some will chamber very easily while others will not. The COAL of all the rounds are the same and .050 off the lands. However, I may need a different way to measure. I will try with a marker and see if they are engaging the lands, its always a possibility, I guess.

 

[MThuntr]

I've had something like this happen with my 7mmMag. I was using once fired brass from a different rifle and just ran them thru the die. Turns out the rifle that fired them originally had a sloppy chamber and the rounds weren't "square". To resolve, I had to pull the bullets and run them thru the full length die a second time (or third) time. You can take the depriming pin out of the die and try that. I now run cases through the FL die and then rotated it 180 degrees and run it again. I also test fit samples prior to loading

 

[Bambistew]

Most likely they're over length and hanging up on the shoulder because they been worked twice and shot once. This is due to running them through a FL sizer and over the expander (stretching) twice. Pull the bullets run them through again but take the expander pin out. Check to see that they chamber.

Good luck.

 

[sbhooper]

This topic was just covered on Predator Masters. I had fought this battle off and on for 20+ years. What seems to happen with some cartridges-in particular the 7 mag for some reason-is that it is very critical how the press is adjusted.

I, like many people, have always adjusted the sizing die down to where it just hits the shell holder. There are differences in shell holders and so this does not always work. To make things come out right, the die needs to be turned another 1/4-1/2 turn against the shell holder. There should be a bit of an over-camming action when you cycle the case to be resized. This is caused by flex in the press and shows that it is getting the full resizing effect.

Some have also put a thin shim inside the shell holder to help this. I hope this link works for the total discussion.

http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=2538286#Post2538286

 

[Bambistew]

To make things come out right, the die needs to be turned another 1/4-1/2 turn against the shell holder. There should be a bit of an over-camming action when you cycle the case to be resized. This is caused by flex in the press and shows that it is getting the full resizing effect.

Isn't that the procedure to set up any FL sizing die? I've never seen anything different.

My experience leads me to believe its because of the inconsistencies with brass dimensions and the nickel platting thickness. I've run into the same situation every time I load nickel. Matter of fact I just ran into the same issue a few months ago with my new 308. The only cases I could find/get were nickel platted

The case are standard sized brass with platting. The nickel plating makes the dimension of the neck just a skosh thicker. Consequently when you run one through the die, the neck is sized from the outside, making the inside diameter slightly smaller than with a standard brass case would be... when you pull the case back out it hits the expander ball and it takes more force to pull some (due to inconsistencies) of the cases through, and consequently stretches the case slightly more than some. The extra force pulls the shoulder length out of spec, causing them to be tight fitting, or not fit. Since you sized them twice, you stretched them twice... its much easier to stretch a nickel case than to press/size one. Nickel cases are nice, but not my preferred type for loading.

The 7mm head spaces off the rim, but you can get them to head space off the shoulder... which you are, hence the reason for them not chambering.

my method... I size and then check to see that they chamber. The ones that don't, I toss. I suppose you could turn the necks, but I've never tried to neck turn a nickel platted case, not sure you could get the cutter to bite?

 

[danr55]

I've noticed a substantial difference in chamber sizes in rifles recently that I didn't see 8 or ten years ago. Brass fired in one rifle will not, even when or especially when, full lenght resized, fit easily into another rifle's chamber. Usually, the first rifle has a chamber that is a bit on the longer side. When the brass is sized, it stretches even further. Generaly if you can close the bolt with a bit of pressure and fire the round, after szing a second time, the brass will fit your chamber easily. That is not, however, always the case. The largest differences I run into are between Sako/Tikka rifles and Winchester/Browning rifles. The brass is not generally interchangable.

 

[emrah1028]

First off, I do not own a 7mm Mag. However, I've read that full-length sizing them can be tricky due to the belt. As in, some die/shell holder combinations don't allow you to fully get close to belt during sizing, so the area just above the belt is still a little large, even after running through the sizing die.

Not sure if this could be your problem?

Emrah

 

[s1n2i3p4e5]

Had the same problem with 7mm mag fresh out of the box, would not completely chamber

 

[KRasmussen]

Just out of curiosity I pulled a few cases that have not been loaded but have been sized and trimmed. I found that out of 10, 2 would not chamber. That is just empty brass. I measured them and compared to rounds that would chamber and they are identical. I don't get it. I do not have a real accurate way to measure from base to shoulder so, that may be the culprit. I am going to get things set up and re-size them again and see where that gets me. I am beginning to not like Winchester plated brass

 

[sbhooper]

I think that there is definitely some chamber issues anymore. A buddy got some used 22-250 brass that would not chamber in his Remington and worked fine in mine. Go figure. They were both run through my dies.

 

[jryoung]

I highly recommend the Hornady Lock-N-Load Headspace gauge, same think with the Comparator Kit too. Super useful tools that I use frequently in reloading.

http://www.hornady.com/store/Lock-N-Load-Headspace-Kit-With-Body-1-Each/
http://www.hornady.com/store/Bullet-Comparator-Kits/

 

[mtmuley]

The Stoney Point I recomended earlier is now owned by Hornady. With it, you can measure a fired case from your rifle, and size it accordingly for the shoulder of the case to be pushed back just far enough to fit YOUR chamber. mtmuley

 

[Kerryt38]

Your chamber might be really tight. and you won't be able to use brass fired in another rifle.
It could be your die but since the brass is already sized that is probably not it.
see if you know someone with one you can borrow.

 

[WapitiBob]

Just out of curiosity I pulled a few cases that have not been loaded but have been sized and trimmed. I found that out of 10, 2 would not chamber. That is just empty brass. I measured them and compared to rounds that would chamber and they are identical. I don't get it. I do not have a real accurate way to measure from base to shoulder so, that may be the culprit. I am going to get things set up and re-size them again and see where that gets me. I am beginning to not like Winchester plated brass

If the brass does not chamber but ejects, it's probably hitting on the shoulder. A std fl sizer, set to sit hard on the shell holder should bump the shoulder back about .010. Get a comparator base and inserts so you can measure shoulder bump. In the mean time, smoke the shoulder with a lighted candle. Chamber the sticking brass and if it's hitting the shoulder you'll see the marks on the soot.

If the brass won't chamber and bolt sticks, it's probably hanging on the pressure band just ahead of the belt. The only way to get rid of that is to fl size with a good sizer. The die will need to sit down hard on the shell holder to get to the band and unfortunately, a side effect will be bumping the shoulder back further than is desirable. The set back shoulder will allow the case to re stretch ahead of the belt.

Plated brass isn't going to move as easily as non plated in a sizer die...

 

[GKimPrice]

one thing you can try is to purchase a set of Redding competition shell holders (5) Set the sizing die using the 0.10 holder then begin sizing with the 0.02, graduating to the 0.04 if the 0.02 won't chamber and so on - nickel brass is tougher than plain brass and sometimes there is enough tension upon extraction that it slightly stretches the brass, Q-tip with some sizing wax on the inside of the shoulder/neck would fix it if that turns out to be the problem