Paper Clip Check
- Thread starter Nathan
- Start date
Yes, it is to check to see if there is a chance the case head is going to separate. I straighten a paper clip, sharpen one end with a file, then put a 90 degree bend about 1/8th inch from the sharpened end. Insert into the case and try and feel for a dip near the case head. I do this to cases I've loaded 5 or more times. If I feel an indentation I toss the lot.
I only do the paper clip test to my belted .300 Win Mag casings. I've loaded thousands of rounds and have had 2 case separations , both of which were .223. I did the saw cut method to see what happened and one was from a thin spot in the brass at the base , the other casing looked fine. I think it was a faulty piece of brass.
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Yes I do. Partly because the round I like (.303 British) is famous for it, but I also do it with other cases as I once had an unexpected case head separation & it was a mess to fix.
Even though it looks like nothing on the outside you may be surprised how much is happening inside!
(Photo (c) Wogpotter 2011)
When it happens you'll definitely notice the *BUMP* as the tip passes the groove.
Even though it looks like nothing on the outside you may be surprised how much is happening inside!
(Photo (c) Wogpotter 2011)
When it happens you'll definitely notice the *BUMP* as the tip passes the groove.
Note that it's more common to find the thinning further back near the head than in Wogpotter's example, but a case that has thicker walls coming away from the head, as his do, can thin further forward as the photo shows. So feel all the way down the inside when you do this test.
"...(.303 British) is famous for it..." That's because so many Lee-Enfields were assembled out of parts bins with zero QC. Literally thousands assembled and sold by Century Arms, et al without ever bothering to ensure the rifles were safe to shoot. Headspace is bad on many of 'em. It has nothing to do with the cartridge.
If you're cases are close to separating, you'll have other indications. Biggest one being the ring seen on Wogpotter's .303's.
If you're cases are close to separating, you'll have other indications. Biggest one being the ring seen on Wogpotter's .303's.
math teacher
New member
The problem is common with belted cases that are repeatedly full length resized.
Two things increase the chances of head separation on bottleneck cases. It's all about how much the back end of the case stretches at peak pressure.
One is too many full length sizing cycles that sets the fired case shoulder back too far. .003" is about the maximum; .001" to .002" is better for bolt guns.
The other is using rimless cases with small shoulder angles that set back too much from firing pin impact before they fire. .30-06 rifles may have the highest incident rate (separations per X thousand rounds reloaded) as they have a small shoulder angle.
Chamber length from breech face to its shoulder that's excessive compounds the problem.
One is too many full length sizing cycles that sets the fired case shoulder back too far. .003" is about the maximum; .001" to .002" is better for bolt guns.
The other is using rimless cases with small shoulder angles that set back too much from firing pin impact before they fire. .30-06 rifles may have the highest incident rate (separations per X thousand rounds reloaded) as they have a small shoulder angle.
Chamber length from breech face to its shoulder that's excessive compounds the problem.
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I disagree. The problem of the .303 is endemic to the .303, not because it has a rim, but because it has a rim, the rest of the chambers were cut "generously" (is the term I've heard) to allow for battlefield crud. After all, the military only cares about firing the case, ONCE. Proper headspace on the rim, the case easily fits the chamber, the military is good to go. Extra "slop" in the chamber just helps ensure battlefield reliability.
The downside for the reloader is very short case life.
Other rimmed cases, like the .30-30 or the .22 Hornet are not "famous" for having the problem. its not the rimmed case design that is the problem, its how they made the .303 SMLE rifles. Also, note that SMLE pattern guns in .308 do not have the reputation for having excessively short case life.
Now, this may be simply because there aren't a lot of reloaders shooting the .308 SMLEs, and there is a problem that we just haven't heard much about,
BUT
I think the real reason is that since the .308 headspaces on the shoulder, rather than the rim, chamber dimensions HAD to be kept closer to spec for reliability. So you don't get the excessive case stretching often found in .303s.
Now someone might come along, with valid info that the .308SMLEs do stretch the cases more than front locking bolt guns, and case life is shorter than it ought to be, and I won't dispute that is a possibility.
BUT
Even if true, the .308 guns don't have the reputation for it like the .303 guns do. and I think, probably with cause.
just a thought...
And of course, if reloaders were more mechanically inclined we would not be having this conversation over and over etc..
Chamber are not adjustable, case length from the shoulder to the head of the case is. Threads are on the press and die, I find it handy to adjust the length of the case to off set the length of the chamber from the shoulder to the bolt face.
I know, there are barrel nuts on Savage barrels.
Then there is that firing pin, the case, powder and bullet out runs the firing pin to the front of the chamber to avoid being hit.
F. Guffey
Chamber are not adjustable, case length from the shoulder to the head of the case is. Threads are on the press and die, I find it handy to adjust the length of the case to off set the length of the chamber from the shoulder to the bolt face.
I know, there are barrel nuts on Savage barrels.
Then there is that firing pin, the case, powder and bullet out runs the firing pin to the front of the chamber to avoid being hit.
F. Guffey
Guffey, some cartridges are full forward against the chamber shoulder long before the trigger's pulled.
Do they know what's about to happen and move as far forward as they can 'cause they're scared because their bottom's gonna get smacked really hard? If they can outrun a firing pin, surely they can walk forward a few thousandths of an inch.
Do you know which ones are? If you know firearms well and are mechanically inclined, you'll know. I don't know if you're willing to let us know either way.
Do they know what's about to happen and move as far forward as they can 'cause they're scared because their bottom's gonna get smacked really hard? If they can outrun a firing pin, surely they can walk forward a few thousandths of an inch.
Do you know which ones are? If you know firearms well and are mechanically inclined, you'll know. I don't know if you're willing to let us know either way.
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Not if the case fits the chamber like a peanut with hull fits a punch bowl or the proverbial violin case. Then there is the one or the other but can not be both. The last few times this went around there were claims the firing pin shortened the case .005". With the difference in length between the case from the shoulder to the case head and chamber from the shoulder to the bolt face as in the difference in length of a minimum length/full length sized case and a go-gage length chamber that would be .010" for a 30/06 case and chamber.
I checked ammo from a range that had 5 failed to fire out of 20 new R-P rounds, there were at least 5 attempts at firing the failed to fire rounds in three rifles. the cases did not shorten, I pulled the cases down, removed the bullets and powder and primers, fine ammo, I installed the primers back into the cases and fired all 5 primers in one of my rifles with killer firing pins, the cases did not shorten from the shoulder to the head of the case. 'AND!' the primers did not protrude from the head of the case.
F. Guffey
I couldn't agree more. If I resize I match the die to the once fired dimension as closely as possible by "Partial full length" resizing.
It definitely helps, but it can't eliminate things like the wildly differing chamber shoulder shapes. I've seen everything from a "Z" shape with dead strait lines before during & after to a semi spherical shape!
Not doubting that either. As reloaders we are trying to make the design do something it wasn't designed for. Reloading brass.
Military rifles were the first "Fire & forget" system. They were designed to be utterly reliable & one shot & ditch for brass. As long as it fed, fired, extracted & ejected no-one cared about what happened to the brass immediately after exiting the action. All attention was now directed to stuffing the next round in there.
I've also been told that using fire formed casings with a typical .002-003 shoulder bump minimizes the case stretching. So I do both to my 300WM casings, the paper clip test , and using fire formed casings. I also take it a step further and if needed I use Larry Willis magnum collet die. I've heard both sides of the belted case bulge argument,
Before the Willis collet die, people cut the bottom of a belted FL sizing die off just above the belt clearance ridge, then cut its top just below the shoulder. After sizing a fired case in a standard FL die setting the shoulder back .002" that body die would be used to size the case body does all the way to the belt. That eliminated the sharp ridge caused by the case body expanding against the chamber at the edge of that headspace shoulder. Best accuracy with fired belted cases so sized.
The above aside, neck sizing with a full length die backed off a bit or a regular neck sizing die will often produce better accuracy than cases full length sized such that their shoulder's set back too far.
This happens a lot when the full length die's set in the press so its bottom touches the shell holder when sizing a case.
This happens a lot when the full length die's set in the press so its bottom touches the shell holder when sizing a case.