I trim case necks to slip through a case length gauge or what the books say, but have am curious as to how long they could be. I was trying to figure a way to measure it without doing a chamber cast. I was using my Ruger 77, 7x57. I decided to run a 280 Remington case through my 7x57 die and start trimming back until it did not crimp the case mouth. Case length per manual 2.235, length that crimp disappeared 2.306, .071 longer. I know the case crimp issue. How long can the neck be before causing problems, and is their a better way to measure it? I realize every rifle may have a different length. Barlow
Case neck length
- Thread starter Barlow
- Start date
I watched a guy blow apart his bolt on the firing line. Trying to figure out why I measured some of his just shot hand load brass. They were .025 longer than max allowable and when asked about how he trims, he said he just chamfers. His loads were not exhibiting excessive pressure but the one that popped came out with the head distorted, primer blown out of course, bolt head in pieces in his factory Savage.
I concluded that he'd pinched a bullet with a too long case neck.
I can imagine a tool you could make if you had a lathe, but a chamber cast would probably be easiest. If you knew the exact dimension, you could trim close to that and help prevent carbon ring build up in the chamber.
Edit: just found the Sinclair link and posted it below.
I concluded that he'd pinched a bullet with a too long case neck.
I can imagine a tool you could make if you had a lathe, but a chamber cast would probably be easiest. If you knew the exact dimension, you could trim close to that and help prevent carbon ring build up in the chamber.
Edit: just found the Sinclair link and posted it below.
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NorCalMikie
Gold $$ Contributor
"Most" chambers are about .020 longer than the listed MAX trim to length.
Best to measure your chamber, write those figures down and refer to them when it comes to resizing/reloading time.
Sinclair makes chamber plugs that do just that. Shows you where the end of your chamber is. After you know those figures, you MAY NOT have to trim.
Depends on which type of dies you use to resize your brass. Shoulder Bump dies will keep the cases length from growing.
I have BR brass with 25 to 30 resizes on them and no trimming needed yet. All resized with Shoulder Bump dies. Throw in a body size when the bolt starts gets stiff on closing and you're good to go.
Best to measure your chamber, write those figures down and refer to them when it comes to resizing/reloading time.
Sinclair makes chamber plugs that do just that. Shows you where the end of your chamber is. After you know those figures, you MAY NOT have to trim.
Depends on which type of dies you use to resize your brass. Shoulder Bump dies will keep the cases length from growing.
I have BR brass with 25 to 30 resizes on them and no trimming needed yet. All resized with Shoulder Bump dies. Throw in a body size when the bolt starts gets stiff on closing and you're good to go.
I did not know about the Sinclair plugs. Thanks for the info. Barlow"Most" chambers are about .020 longer than the listed MAX trim to length.
Best to measure your chamber, write those figures down and refer to them when it comes to resizing/reloading time.
Sinclair makes chamber plugs that do just that. Shows you where the end of your chamber is. After you know those figures, you MAY NOT have to trim.
Depends on which type of dies you use to resize your brass. Shoulder Bump dies will keep the cases length from growing.
I have BR brass with 25 to 30 resizes on them and no trimming needed yet. All resized with Shoulder Bump dies. Throw in a body size when the bolt starts gets stiff on closing and you're good to go.
I have seen the Sinclair chamber length gauge mentioned on here many times. If you would have put case length in the search bar at top right you can find many articles
Other than finding out how long your case necks can be before being constricted is there a advantage to longer case necks. I full length resize and bump the shoulder back with all my factory rifles with the exception of a few older milsurp rifles that I neck size.
I always trim new cases to minimum length to ensure they are all the same length and uniform.
I wet tumble then trim and deburr to get rid of any case mouth peening. And all my cases are at minimum length, is there anything wrong with doing this.
I always trim new cases to minimum length to ensure they are all the same length and uniform.
I wet tumble then trim and deburr to get rid of any case mouth peening. And all my cases are at minimum length, is there anything wrong with doing this.
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i have read a well know shooter stated that he recommends a maximum .010 case length to chamber length clearance. and that any thing closer is bad ju- ju. I myself have run closer tolerances but i check every firing with out fail.
For example...IF you are one of those that keeps a close eye on the condition of the throat, and you seat bullets longer as the throat gets shot out to maintain accuracy (ie. "chasing the lands"), a longer case neck maximizes the amount of time you can do that. Just depends on what your rifle likes/needs to shoot to your satisfaction.
I collected the British .303 Enfield rifle that on a worn barrel had cordite throat erosion. Cordite had more nitroglycerine content than many pistol powders have today. Meaning on a worn Enfield barrel there wasn't any "chasing the lands" even with a bullet seated backwards looking for the lands.
NorCalMikie
Gold $$ Contributor
I prefer full or as much neck/bullet contact I can get with my ammo. Only thing about having a shorter case neck is the chance of carbon buildup ahead of the case neck. Watch that close.
As far as the Sinclair "plugs" for measuring the chamber length, I have and use them for EVERY caliber I shoot. Measure it, write it down and refer to it when resizing your brass.
I also watch the throat wear and seat my bullets accordingly. Know your chamber measurements and refer to them often. That way, no surprises.
As far as the Sinclair "plugs" for measuring the chamber length, I have and use them for EVERY caliber I shoot. Measure it, write it down and refer to it when resizing your brass.
I also watch the throat wear and seat my bullets accordingly. Know your chamber measurements and refer to them often. That way, no surprises.
Assuming the carbon ring is managed, does trimming brass show on paper? To me it seems that worring about brass trimming is similar to worrying about primer seating depth.
Ben
Ben
NorCalMikie
Gold $$ Contributor
Brass length trimming is to "keep you out of trouble".
One crimped neck and you'll understand the reasoning.
YOU set the length of YOUR brass.
And some of us didn't learn this stuff over night either.
Been there, done that DOES make a difference.
Then there's some of us that know it all but won't cop to our mistakes AND, never will.
Beware of the guy that knows everything.
You set the way you do things and if it works for you, keep doing it that way. Being consistent is the key. If not, adjust accordingly.
Primers are seated to the bottom of the pocket. Set short and you get FTF cause the case gets pushed forward in the chamber by the firing pin. Ask me how I know.
Not sure if trim length shows up on paper or not. They're all going in the same hole.
Never tried different trim length to see if there IS a difference.
One crimped neck and you'll understand the reasoning.
YOU set the length of YOUR brass.
And some of us didn't learn this stuff over night either.
Been there, done that DOES make a difference.
Then there's some of us that know it all but won't cop to our mistakes AND, never will.
Beware of the guy that knows everything. You set the way you do things and if it works for you, keep doing it that way. Being consistent is the key. If not, adjust accordingly.
Primers are seated to the bottom of the pocket. Set short and you get FTF cause the case gets pushed forward in the chamber by the firing pin. Ask me how I know.
Not sure if trim length shows up on paper or not. They're all going in the same hole.
Never tried different trim length to see if there IS a difference.
Brians356
Gold $$ Contributor
Here's how I made my own chamber length fixtures for a Hornady (Stoney Point) OAL gauge (for 22 and 6mm shown - an unmodified fired 25 ACP case would work for a 7mm chamber.):
http://forum.accurateshooter.com/threads/headspace-gauge.3875237/#post-36585857
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Link
Silver $$ Contributor
I also wonder why this wouldn't work if the 280 brass neck were the right OD to use? Don
Brians356
Gold $$ Contributor
I'm starting to wonder, are you just curious about your chamber's length, or do you need to let the necks run very long? The 7x57 has a generous neck to begin with. Are you trying to load very light/short bullets near the lands, and running of neck engagement?
It would take a lot of loadings without trimmings for your necks to grow dangerously long, but you could just make sure they never exceed SAAMI Max Case Length (probably 2.245") and never worry.
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It would take a lot of loadings without trimmings for your necks to grow dangerously long, but you could just make sure they never exceed SAAMI Max Case Length (probably 2.245") and never worry.
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It makes no more sense to trim all cases to a shortest anomaly than it would to turn all to thinnest anomaly, or bump all shoulders to a shortest.
Throw anomalies away, and focus on what you believe is correct.
I measure chamber end, and fire form/reload cycle my cases until they get within a couple thou of chamber end, and then trim them all to -5tou of clearance.
With this and rational neck clearances I get no carbon sooting on necks, and no ring buildup in the chamber.
It may help with SD (I don't know for sure), as necks are sealing faster/better.
Throw anomalies away, and focus on what you believe is correct.
I measure chamber end, and fire form/reload cycle my cases until they get within a couple thou of chamber end, and then trim them all to -5tou of clearance.
With this and rational neck clearances I get no carbon sooting on necks, and no ring buildup in the chamber.
It may help with SD (I don't know for sure), as necks are sealing faster/better.
I cut the end off a sized case yesterday and did the slip fit procedure per info in a previous post. It measured the same as the resized case method. Barlow
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