Hey guys I went to the range pretty early this morning with some proven loads in my 7rm, I had to buy some federal brass on my last visit to the reload store, not by choice but by need. I prepped the brass, the flash holes were egg shaped, necks bent,but on with my story, virgin brass grew from 2.490 to 2.495 on one shot and a couple was 2.497. Is this brass always this bad? too thin? too soft? what is the deal? I guess I'm stuck with it till I order it from midway or from my reload shop. any imput will be appreciated. thanks Darin
Brass extreme growth
- Thread starter red dawg
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Mikecr
Well-Known Member
Head space.
On fire forming, brass grows to your chamber and stretches back to the bolt face.
On fire forming, brass grows to your chamber and stretches back to the bolt face.
I had that checked a few months back gunsmith said it was fine, but I have had the gun right at 18 months and used custom nosler and hornady brass and never had a piece longer than 2.492 after firing. I thought that was normal to grow a little
Barrelnut
Well-Known Member
Do you full size your brass each time during prep? Or do you just neck size it until it is tight to chamber?
In belted magnum chambers it can be a long ways from the brass shoulder to the end of the chamber. 5 - 8 thousands is not uncommon. Since the cartridge indexes off of the belt on the first firing, the brass can stretch quite a bit before it hits the shoulder in the chamber. I have to fire new brass in my 7RM about 3 times before it hits the end of the my chamber. That is about 8 thousands away. I neck size it until it hits the end of the chamber. After that I bump it back 2 thousands to get longer life on the brass.
I think the FC brass is softer than what the rifle has seen before and has stretched more on the first firing. It might even stretch a little further if the brass is only neck sized and fired again.
I don't think Mickcr was saying you had a headspace issue, but was just saying brass stretches because of head space. Which, in a way, a belted magnum can have a lot of.
In belted magnum chambers it can be a long ways from the brass shoulder to the end of the chamber. 5 - 8 thousands is not uncommon. Since the cartridge indexes off of the belt on the first firing, the brass can stretch quite a bit before it hits the shoulder in the chamber. I have to fire new brass in my 7RM about 3 times before it hits the end of the my chamber. That is about 8 thousands away. I neck size it until it hits the end of the chamber. After that I bump it back 2 thousands to get longer life on the brass.
I think the FC brass is softer than what the rifle has seen before and has stretched more on the first firing. It might even stretch a little further if the brass is only neck sized and fired again.
I don't think Mickcr was saying you had a headspace issue, but was just saying brass stretches because of head space. Which, in a way, a belted magnum can have a lot of.
Hey Barrel Nut, thanks for bringing that up, I only F L resize when it chambers tight, usually after 3 or 4 firings, but trim neck length after once fired, I just like too know its at minimum length each reloading, I have always done that as a force of habit
Barrelnut
Well-Known Member
Ya know, I think it's more important to just keep the neck lengths consistent. I trim my necks back to documented case trim length each time I prep the brass. Unless, you are seating bullets way out there on a very short necked cartridge for some reason and want to get be last few thousandths of neck length possible, I don't think it is necessary.
MagnumManiac
Well-Known Member
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The throat is not part of the neck, the chamber is normally cut .020" longer than the MAXIMUM cartridge length, which allows a safety margin for neck growth.
If you want to know what your chamber measures, take a chamber cast, it's pretty easy to do.
Cheers.
gun)
I like to know the distance to the end of every rifle's chamber. Sinclair makes a plug they call a chamber length gauge.
http://www.sinclairintl.com/reloadi...s/sinclair-chamber-length-gage-prod32925.aspx
Cut off approx. .100" from the neck of a case. The plug is inserted a tiny amount into a case mouth. Some neck tension helps keep the plug from moving as you place it into the chamber. Close bolt which will push the plug against the end of the chamber. Measure from cartridge base to end of plug and you will have the distance to the end of the chamber. I like to do this measurement several times.
You might be surprised how far it is to the end of the chamber. Some factory chambers are so long that there may never be a need to trim the cases after many firings and partial full length sizings.
If you have any custom chambers the larger diameter of the plug may have to be altered to fit a smaller diameter neck. I have a lathe and make my own plugs out of brass or aluminum:
I would like to acknowledge Varmint Al for posting these dimensions on his website:
Varmint Al's Mini Lathe Page
http://www.sinclairintl.com/reloadi...s/sinclair-chamber-length-gage-prod32925.aspx
Cut off approx. .100" from the neck of a case. The plug is inserted a tiny amount into a case mouth. Some neck tension helps keep the plug from moving as you place it into the chamber. Close bolt which will push the plug against the end of the chamber. Measure from cartridge base to end of plug and you will have the distance to the end of the chamber. I like to do this measurement several times.
You might be surprised how far it is to the end of the chamber. Some factory chambers are so long that there may never be a need to trim the cases after many firings and partial full length sizings.
If you have any custom chambers the larger diameter of the plug may have to be altered to fit a smaller diameter neck. I have a lathe and make my own plugs out of brass or aluminum:
I would like to acknowledge Varmint Al for posting these dimensions on his website:
Varmint Al's Mini Lathe Page
