7mm Rem Mag Brass Problem

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DMT

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I reloaded some Federal brass that had only been shot as original factory loads. I did a full resize, and about 5 out of 50 were slightly harder to eject and pull the bolt back. They were shot from a Browning A-bolt, which has only had about 400 shots through it. The loads were below maximum (63 - 64 grs of 4831 and 150 SMK) and there were no signs of over pressure. When resizing, I only had no more than 1/16 - 1/8 of a turn after contact with the die.

On some previous Federal reloads with 4831 and Nosler 160's still under the maximums, I didn't have any ejection problems on the first 3 reloads (probably about 1/4 turn after contact with the die) and did have some bolt stickiness on the 4th reload (only about 1/8 or less of a turn after contact with the die). I junked all the brass after that reload as I figured having been able to get 5 shots from the brass including the orginal factory load was all I could expect.

The questions are:
How many reloads should I expect from Federal brass?
Does it make any difference other than how much effort on the handle, by using either 1/8 to 1/4 of a turn after contact with the die?
Any other brass recommendations?
thanks
DMT
 
im no pro but it sounds like you probably have a excessive head space issue. are you neck sizing after fire forming or always full sizing?
if you want to prolong the life of your brass i would invest in a instant indicator to determine the correct amount of shoulder bump to obtain the right amount of head space.
 
sizing die

Your die is not a perfect match to the chamber,this is not uncommon.
The solution is to shorten the die by 0.020. If I understand you correctly you are bottoming the die in your press and then adding an extra bit of a turn, this doesn't help and puts extra strain on your press and may create alignment problems.
Bill
 
b72471 said:
Your die is not a perfect match to the chamber,this is not uncommon.
The solution is to shorten the die by 0.020. If I understand you correctly you are bottoming the die in your press and then adding an extra bit of a turn, this doesn't help and puts extra strain on your press and may create alignment problems.
Bill
Click to expand...

Another thing to check is the "thickness" of your shell holder as it might have been made for partial sizing. I was using a Lyman for my 6.5-06, and it made contact with the die before the brass was fully resized so it wouldn't chamber at all. Bought an RCBS holder, and when I compared the two, the Lyman was 15 thou thicker.

I also had problems with Federal brass for my 7mm Mag, so I recycled it and bought Winchester. No issues after 4 reloads.
 
The above recommendations are sound ones, but something else comes to mind.... Have you checked the length of your brass, as you have made no mention of trimming?
 
Tell me. The cases that were hard to extract.... were they also hard to chamber (feed into the chamber before firing)?? It is fairly common for belted magnums to build up a secondary belt after a a few firings making the case hard to chamber. Standard sizing dies cannot solve this problem although there is a specialty collet die that can correct this.

Regards

Aubrey
 
Thanks for all the info, especially the point about not going to a full 1/4 turn after contact with the die. I will back it off to about 1/8 of a turn, which still needs just a slight effort to go over center on the lever and finish off the resizing.

Also the point about the shell holder. I will check the brand and also compare it to other brands.

Here is a couple more pieces of info that may help.

I had trimmed all the brass to the trim to length of 2.490" before reloading.

The cases that were hard to extract after shooting weren't hard to chamber, just extract. I measured the diameter just in front of the belt after extraction, and it was either right at the published dimension from my reloading book or just a couple of thou's over that dimension. I am thinking this larger dimension is the reason for the hard extraction. Maybe, the point about a "thicker" shell holder could be the answer, as the shell doesn't get a full resizing in the area just in front of the belt.... Thoughts??

Thanks in advance for all the help.

DMT
 
stevietangles said:
im no pro but it sounds like you probably have a excessive head space issue. are you neck sizing after fire forming or always full sizing?
if you want to prolong the life of your brass i would invest in a instant indicator to determine the correct amount of shoulder bump to obtain the right amount of head space.
Click to expand...

The 7mm RM headspaces off the belt not the shoulder
 
Belted mags have a tendency to thin out just above the belt. This forms a thin spot where case separation can occur. Also, the brass the brass will bulge a bit above the thin area. This may be the cause of the stiff extraction. The tell tail sign is a light coloured ring around the casing just above the belt. Many of the reloading manuals have photos.

http://www.ronterry.com/arms/images/338Head.jpg

If you see this ring toss the casing. Belted mags do not have the longevity of non belted casings. Sucks but thats the way it is. Better spend a little on new brass then face the problem of case separation. Thats not fun.
 
The cases that were hard to extract after shooting weren't hard to chamber, just extract. I measured the diameter just in front of the belt after extraction, and it was either right at the published dimension from my reloading book or just a couple of thou's over that dimension. I am thinking this larger dimension is the reason for the hard extraction. Maybe, the point about a "thicker" shell holder could be the answer, as the shell doesn't get a full resizing in the area just in front of the belt.... Thoughts.

A "Belted Magnum Collet Die" from Innovtive Technologies produces a special die that reduces only the pressure ring on belted cases. I have been using one for about one year and it solves the problem of expanded pressure rings. It does not size the body or neck of the case - just the pressure ring. It must be used in conjunction with a full length or neck sizing die - i've been using a neck bushing die only and and headspacing on the shoulder - not the belt. This extra step is a pain in the ass but it works. So far I'm up to 10 reloads with Winchester brass in my 7mm Rem Mag and all looks good with no case head seperations. An added bonus is that these dies work for all the common belted magnums so you only need to buy one.

If interested you should contact Larry Willis at it@mpinet.net or by phone at 1-407-695-2685

Regards

Aubrey
 
As an update to the stickiness after shooting, but not before when chambering, I reloaded all the brass. I had a full 1/4 turn on the die, and the handle required a good pull.
After reloading, I was only able to chamber some of the loads. It looks like the brass it is catching on the chamber wall about 0.1 to 0.3 inches above the belt. With the fingernail, you can definitely feel the catch.
As suggested I may have caused alignment issues with the die so these shells are going to be recycled.
When setting up to resize, how much of a turn do you make after contacting the die with the ram?
thanks
DMT
 
Last edited:
I think I figured out the problem, by going back through my reloading records, considering your advice, and doing some sleuthing on the internet.

The problem looks like a slightly larger bulge in the area just ahead of the belt as mentioned above.

While I was below the maximum loads previously used, I had changed my seating depth by about 0.050" longer. It could be that this shorter jump to the lands raised the pressure, caused the pressure ring, and made the cartridge had to extract. I am going to test this theory over the next couple of days and see if I go back to the shorter COAL, that the problem of hard to extract shells disappears. Alternatively, I will keep this longer COAL, but reduce the loads.

Also, I had a look at the Innovative Technologies website and think that the collet die could be a solution to ensure longterm chambering of loads.

Besides "Banished" does anyone else use the tool on 7mm Rem Mag? If you use it, what type of cartridge life do you get?

Thanks

DMT
 
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