nmbarta
Well-Known Member
Indeed, I won't bother with the math, but can tell you that with normal dies (14 tpi) 1/36th of a turn = about .002"
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Anything wrong with tight headspace?
- Thread starter Oldschool280
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25WSM
Well-Known Member
Nmbarta that is correct. I made a tool that I was going to market that was exactly what you just described.
It was a lock ring I cut in the lathe and made the indicator marks on. So basically a lock ring with a graduation mark every 1/36 around its circumstance. All you do is screw it down on top of the dies lock ring with some extra turn on it. Run your die down to touch shell holder and lock it in place. Now give 1/4 turn up on ring with marks on it. Lock it down. Your ready now. Just size a brass and measure the difference between fired and sized. Let's say you got . 005 crush and we want . 003 you just loosen the lock nut only 1 graduation mark and lock it back down. Then you can remove the big ring off the top of the die. Works like a champ. Most can make one at home.
I didn't market it because you learn in very short order how far to turn a lock ring to get the crush you need with out it. Plus if you look at the whidden die with the clicker that came out it does what mine did plus makes noise. I made mine up when Hornady came out with the comparators. Sorry another hospital rant here. Just need this to get me through a situation here. Plus we just had a huge thread on setting dies up to give the perfect bump that that die makers never tell how to do. Thanks guys.
Shep
It was a lock ring I cut in the lathe and made the indicator marks on. So basically a lock ring with a graduation mark every 1/36 around its circumstance. All you do is screw it down on top of the dies lock ring with some extra turn on it. Run your die down to touch shell holder and lock it in place. Now give 1/4 turn up on ring with marks on it. Lock it down. Your ready now. Just size a brass and measure the difference between fired and sized. Let's say you got . 005 crush and we want . 003 you just loosen the lock nut only 1 graduation mark and lock it back down. Then you can remove the big ring off the top of the die. Works like a champ. Most can make one at home.
I didn't market it because you learn in very short order how far to turn a lock ring to get the crush you need with out it. Plus if you look at the whidden die with the clicker that came out it does what mine did plus makes noise. I made mine up when Hornady came out with the comparators. Sorry another hospital rant here. Just need this to get me through a situation here. Plus we just had a huge thread on setting dies up to give the perfect bump that that die makers never tell how to do. Thanks guys.
Shep
Shep,
First, God speed with whatever is going on in the hospital. Second, I have always done tight chambers whether I was going to shoot shelf ammo or not, however I am changing my tune to only do that with rifles I plan on using shelf ammo with.
Seems people get headspace confused. You mention AI and they say, "oh, you shorten the headspace by .004" ". In actuality, you're increasing headspace on that round since the measurement is base to datum point. Went thru this when talking about a 7-08ai. 280ai is the only ai with a saami spec(not talking about other 280 ai variants) and it is pretty clear headspace increases with AI. Rant complete
First, God speed with whatever is going on in the hospital. Second, I have always done tight chambers whether I was going to shoot shelf ammo or not, however I am changing my tune to only do that with rifles I plan on using shelf ammo with.
Seems people get headspace confused. You mention AI and they say, "oh, you shorten the headspace by .004" ". In actuality, you're increasing headspace on that round since the measurement is base to datum point. Went thru this when talking about a 7-08ai. 280ai is the only ai with a saami spec(not talking about other 280 ai variants) and it is pretty clear headspace increases with AI. Rant complete
25WSM
Well-Known Member
All the hoopalhoop that happened when Nosler made Sammi 280ai brass and had to use a datum point. Not the neck shoulder junction like PO did.
People still think that nosler brass isn't 280ai. But it fits perfect in every 280ai chamber I make. You are correct that the datum line is longer because if you blow the shoulder forward and the datum line follows it has to be longer. The PO Ackley Improved is . 004 shorter at the neck shoulder junction only. That is why an unfired 280 will snug up in there right around that point.
Sometimes you can go blue in the face trying to get that in someone's head. 280ai probably the best one he ever did.
Shep
People still think that nosler brass isn't 280ai. But it fits perfect in every 280ai chamber I make. You are correct that the datum line is longer because if you blow the shoulder forward and the datum line follows it has to be longer. The PO Ackley Improved is . 004 shorter at the neck shoulder junction only. That is why an unfired 280 will snug up in there right around that point.
Sometimes you can go blue in the face trying to get that in someone's head. 280ai probably the best one he ever did.
Shep
nicholasjohn
Well-Known Member
Shep,
I think K & M makes something like you just described, and it can be used with any manufacturer's dies. I like the Whidden concept, too. Things with detents that click, either audibly or just feel, are very helpful. It's good to know how much adjustment we are making. "By guess, by golly" has never been my favorite way to operate. Also, please don't let up with what you are calling "rants." I look forward to them.
BallisticsGuy
Well-Known Member
I run zero headspace specifically to keep brass life at maximum. I neck size only as much as possible and I don't bump shoulders back unless I actually have to. This does in fact cause reliability problems which bites me once in a while in a match. Hell there was a period of about 4 months where some bad brass snuck back into my match pile and I was having my gun get locked up on match courses, cost me a TON of points and stage DNF's. The price I pay for being able to push fairly firmly on my load heat without having brass give up after 5 firings.
25WSM
Well-Known Member
So how does neck sizing give you maximum brass life? How does full length not give you maximum life? What ends the life of the brass? I can tell you right now I full length and bump . 003 and the life of my brass always comes down to one thing. Primer pockets. And it doesn't matter how you size that can fix this. So please tell me me how neck sizing with no setback extends the brass life. You already admit that it's bit you in the butt neck sizing. I don't know why you do it.
Shep
Shep
BallisticsGuy
Well-Known Member
It's simple, the words you're looking for are WORK HARDENING. Not working the brass more than necessary makes brass last longer. Sizing brass works it so size the fewest parts of it possible. It's not complex.
elkaholic
Well-Known Member
I think work hardening is actually a benefit to the case head is it pertains to loose primer pockets. Thats why easing off the throttle the first couple of loads , IMO, gives the pocket a chance to take a set and stays there longer with the case head hardening from firing and sizing. The neck is a different story and is why we anneal but my cases dont fail from the neck first but the primer pockets, as 25wsm noted.
keithcandler
Well-Known Member
- Joined
- Jan 30, 2005
- Messages
- 650
Primer pockets usually give out before you get case head separations.
Another problem I ran into that brass will "normalize" after a while. You size the brass down, it has a memory of the chamber it was fired in. So, it can expand back out after a period of time. For this reason, it is a good thing to use brass that has only been fired in that chamber if you want to let the ammo sit around for a while. So, using range pick up brass, or brass that has been fired in a large chamber can cause problems down the road. I have seen this in 270, 7 Rem mag, and 300 Wm.
It is not unusual to push the shoulder back .006 in order to get the web dia to a point where the bolt will close easily on some factory rifles. Brass spring back is a bitch.
Best to keep your ammo fresh if you are using brass purchased once fired or range pick up brass. If I am shooting ammo loaded last year, I will cycle all rounds though the chamber of my rifle to make sure there are no "tight" cases. Obviously, I have a lot of brass purchased once fired from test rifles. When I shoot this brass up, I will NOT buy anymore.
Same kind of thinking would apply if you have several rifles of the same caliber and you are not keeping the brass separate for each rifle.
You hear of guys talking all the time about not pushing the shoulder back more than .002, but you have no idea if the web of the case in that chamber is within spec of the dies you have on hand. Factory rifles's web dimensions can give you fits. So, don't be surprised if you push the shoulders back .002 and you still have a hard time closing the bolt. Just keep adjusting the die down in 1/16 turns, then check and see if the case will chamber. THEN, measure and see how much the shoulder has been pushed back. If it has been pushed back .006 or more, then just watch the area in front of the web for a bright line forming, indicating that the case is about to have a case head separation. At one time, I had various lots of brass Rockwell tested for hardness, and there was a 12% variation between brands of brass and a 6% variation in hardness of the same Lot. I was not testing Lapua at that time.
Soft brass is going to loose primer pockets sooner and tend to have case head separations in factory chambers.
The best shooting factory rifle I have ever owned was a Browning Stainless stalker in 7 Rem mag. With a muzzle break and 36x leupold(load development only)I could shoot 140's in the 2's, three shot groups. The chamber was egg shaped, and I had to push the shoulders back .009 on every full length sizing to get the rounds to chamber properly. Rem cases would last 5 firings.
Another problem I ran into that brass will "normalize" after a while. You size the brass down, it has a memory of the chamber it was fired in. So, it can expand back out after a period of time. For this reason, it is a good thing to use brass that has only been fired in that chamber if you want to let the ammo sit around for a while. So, using range pick up brass, or brass that has been fired in a large chamber can cause problems down the road. I have seen this in 270, 7 Rem mag, and 300 Wm.
It is not unusual to push the shoulder back .006 in order to get the web dia to a point where the bolt will close easily on some factory rifles. Brass spring back is a bitch.
Best to keep your ammo fresh if you are using brass purchased once fired or range pick up brass. If I am shooting ammo loaded last year, I will cycle all rounds though the chamber of my rifle to make sure there are no "tight" cases. Obviously, I have a lot of brass purchased once fired from test rifles. When I shoot this brass up, I will NOT buy anymore.
Same kind of thinking would apply if you have several rifles of the same caliber and you are not keeping the brass separate for each rifle.
You hear of guys talking all the time about not pushing the shoulder back more than .002, but you have no idea if the web of the case in that chamber is within spec of the dies you have on hand. Factory rifles's web dimensions can give you fits. So, don't be surprised if you push the shoulders back .002 and you still have a hard time closing the bolt. Just keep adjusting the die down in 1/16 turns, then check and see if the case will chamber. THEN, measure and see how much the shoulder has been pushed back. If it has been pushed back .006 or more, then just watch the area in front of the web for a bright line forming, indicating that the case is about to have a case head separation. At one time, I had various lots of brass Rockwell tested for hardness, and there was a 12% variation between brands of brass and a 6% variation in hardness of the same Lot. I was not testing Lapua at that time.
Soft brass is going to loose primer pockets sooner and tend to have case head separations in factory chambers.
The best shooting factory rifle I have ever owned was a Browning Stainless stalker in 7 Rem mag. With a muzzle break and 36x leupold(load development only)I could shoot 140's in the 2's, three shot groups. The chamber was egg shaped, and I had to push the shoulders back .009 on every full length sizing to get the rounds to chamber properly. Rem cases would last 5 firings.
25WSM
Well-Known Member
Now on to my point on work hardening. You get about the same Amount of work hardening in a cycle of brass either way. I will explain. Full length sizing will set you back a few thou. Some like .001 and some .003 these are the 2 most common numbers thrown around. On annealed brass this is nothing but it's there and has never ruined any of my brass. Now onto the neck sized only work hardening. Most neck size guys think there is no work hardening happening at all. I mean if you don't crush the case it didn't get worked And since it fits the chamber already it can't expand any further to harden any more either right? Nope. That neck sized brass gets work hardened just as much as the full length one. Here is why. When the firing pin hits the primer the force of that hit collapsed your shoulder about .007 to.010 before it fired. That .007 to .010 is far more than the 0 you left it at. And far more than the .003 I leave mine at. So now you see that even if you don't do the crushing it still gets crushed and worked. Want proof. Put a primer in a piece of your neck sized brass and measure your shoulder to base dimension. Now fire that primer and take the brass out and measure it. Yup it crushed didn't it. They all do. How far is a matter of how thin the brass is. How annealed it is or hardened. So now we see that no, neck sized brass doesn't work harden less. So we've almost gotten full circle why you should just full length size. I bet someone is going to say neck sizing is more accurate.
Shep
Shep
25WSM
Well-Known Member
Ballistic guy I promise I'm not picking on you in any way and at the end of the day I would sit down with a cigar and bourbon with any body on here and talk to the cows come home. I bet even in the cave man days some guy says. The big heavy stick hits them harder. Another fellow says my skinny fast stick hits them quicker. And another guy shrugs his shoulders and said dead is dead.
Shep
Shep
codyadams
Well-Known Member
If your cases are failing from work hardening by bumping a couple thousandths, you need to get better brass or anneal. Or both. I was having issues in my .260 AI with brass getting cracks in the neck, it was remington brass. Switched to lapua, no issues in 12+ firings with shoulder bumping. Primer pockets finally gave out. I'm trying peterson brass now, on my 4th firing with no signs of failure thus far.
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25WSM
Well-Known Member
I shoot Lapua in my Creed right now and it's been the best so far. This is in a 17 pound bench gun for 1000 yard. I ran my Peterson brass to 10 firings and they were still serviceable. I did test the adg 6.5 Creed brass with 5 pieces pushed to failure. My load is a 147eldm at 2850fps with h4350 28 inch barrel. It shot these loads over 15 times and still had primer feel. All these brass were annealed and bumped 003. I am getting the most consistent accuracy from the Lapua SRP so I use it. I had some Hornady bulk brass I got in a 200 box and sorted out 100 and prepped them. Neck turned them the whole works. Couldn't even get them to 2800 fps without wrecking the primer pockets. I threw all 100 cases in the recycle bin and gave the other 100 to a friend who liked them. Some friend I am right. But really it's all he uses and he wins a bunch. Primer pockets are definitely the killer of brass and over pressure is the reason. Neck sizing or tight chamber won't fix that. The only difference between a tight chamber and loose one is .003 in length if the rest of the chamber is in spec. That's not going to have much to do about anything. Nothing wrong with min or Max chamber. Just as long as you set your brass back based on your chamber it's going to be fine.
Shep
Shep
