Case mouth tension???
12-07-2004 | 06:45 PM
#1
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Nontypical Buck
Joined: Jun 2004
Posts: 3,171
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From: A flat lander lost in the mountains of Northern,AZ
Case mouth tension???
I talked to a gentleman today who was explaining that case mouth tension plays a major role in rifle cartridge accuracy, he said that reloads only have about 40 lbs of case mouth tension but to obtain the optimum level of accuracy you need atleast 100 lbs of case mouth tension. He explained the only way for a reloader to get this kind of tension you have to use a crimp with a bullet with a canilure and that the crimp has to be uniform otherwise it makes no difference. I'm just curious what everyone else has to say about this? or if anyone has any pointers on how to obtain that kind of tension without using a crimp? Or is this guy full of it and should i just forget about what he was saying?
12-07-2004 | 07:12 PM
#2
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RE: Case mouth tension???
Some benchrest shooters I know have a case mouth thickness of like 10Mil. It has alot to do with chambering and how tight your throat is. If you got a real tight throat, and you ammo is straight, and you have enough tension to hold the bullet thru chambering and recoil, then he's full of it. If your tension is so loose you can move your bullet with your hand or recoil changes your COL, you need more. Most of the time crimping can actually hurt your accuracy. With crimping you have a hard time getting consistent tension. I have had success crimping A-Frames for my 300RUM over non crimp. You got to try but most of the time its another step thats a waste of time. FL dies with 1st or 2nd fired brass has plenty of neck tension. You can get loose with collet dies. But this can be remedied with by polishing your collet down 1mil or so. Usually the lower tension the straighter you can load that bullet, I have found. 3rd or 4th fire, you can have some problems I believe. depends on the cartidge too.
12-08-2004 | 08:18 AM
#4
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RE: Case mouth tension???
When is the last time you saw everyone offering match grade bullets with canlures???
Only times when crimping is a good thing, is when your useing a very slow burning powder, and you need to increase neck tension to get it ignited better, or when you are useing straight wall cases, like 444 Marlin, or 44 mag...
The factory ammo is crimped, to "idiot proof" the ammo, as you never know "who" will do "what" with it...
Drilling Man
Only times when crimping is a good thing, is when your useing a very slow burning powder, and you need to increase neck tension to get it ignited better, or when you are useing straight wall cases, like 444 Marlin, or 44 mag...
The factory ammo is crimped, to "idiot proof" the ammo, as you never know "who" will do "what" with it...
Drilling Man
12-09-2004 | 01:45 AM
#5
Thread Starter
Nontypical Buck
Joined: Jun 2004
Posts: 3,171
Likes: 0
From: A flat lander lost in the mountains of Northern,AZ
RE: Case mouth tension???
When is the last time you saw everyone offering match grade bullets with canlures???
Only times when crimping is a good thing, is when your useing a very slow burning powder, and you need to increase neck tension to get it ignited better, or when you are useing straight wall cases, like 444 Marlin, or 44 mag...
The factory ammo is crimped, to "idiot proof" the ammo, as you never know "who" will do "what" with it...
Drilling Man
Only times when crimping is a good thing, is when your useing a very slow burning powder, and you need to increase neck tension to get it ignited better, or when you are useing straight wall cases, like 444 Marlin, or 44 mag...
The factory ammo is crimped, to "idiot proof" the ammo, as you never know "who" will do "what" with it...
Drilling Man
LOL kinda my thoughts too, but have to agree with what big country is saying too
