Case Neck Tension and Crimp?

[AxeHandle]

You guys remember the thread a few weeks ago where the 510 size die did not size the brass small enough to provide case mouth tension to hold the bullet... Writer said that Reeder recommended that he depend on just crimp to hold the bullet... You know we all thought that was a bad idea. While loading 500L last week I primed some new cases without sizing and then noticed that the brass needed to be sized. The bullet would slide into the case with just a small amount of pressure... On a lark I decided to drop some AA#9 and crimp some bullets... Put on a good crimp but I could actually spin the bullets in the case with my fingers.... Shot them at the range today... Expected squib loads and a barrel full of unburned powder. They burned as clean as anything I have seen, kicked like a mule, and seemed to shoot to where the gun pointed...

[fltbed]

I did some experiments with crimp in the 45 colt about 20 years ago and discovered most faster burning powders (like 231, Unique) don’t need much crimp to be accurate.

With the slower burning powders (like 296/H110, 2400, I never tested #9) what is needed is enough bullet resistance to build ignition pressure. If you have enough bullet mass (I was using cast 300 gr.) the amount of crimp has less effect on things. You still need some bullet pull but in my tests, it effected accuracy, not ignition.

When I was testing Speer’s 225 gr. JHP I concluded that bullet tension was way more critical to building correct ignition pressures due to less bullet mass. (Especially with 296/H110)

Jeff

[AxeHandle]

My only past experience with #9 was in a 454 a decade ago.. I had installed a lighter hammer spring and it turned out to be a nasty thing.... Went back to the factory spring and all was well but I can still see the unburned powder.... The 440s in the 500L along with CCI LR magnum primers may have played a part in the Saturday experience too...

[Len]

I'm the guy that was given that advise.

I phoned a friend of mine who is one of the top ballistics experts in the country Ed Matunas. He has been the editor on numerous loading manuals, written books on the subject and serves as an expert witness on firearms court cases.

Per Ed

Bullet pull is critical to proper combustion. Accuracy is what suffers.


Faster powder will sometimes work with crimped only cases.

Slower powders get erratic without adequate and uniform bullet pull.

Even Bowen in his book recommended a very tight case to bullet relationship.


Len

[Aggie01]

I think Bowen, or maybe some other "name" used the term "wasp waisted".

Women and pistol cartridges, heavy on top, narrow in the middle and hot on the bottom?

[AxeHandle]

Lee Jurras talks about it too... As we would expect from Lee I don't believe the idea of no case tension was a option. His studies were comparing new brass and recycled brass. Sizing the brass was a given. Even at that seems like his studies at Super Vel provided such stark differences that he recommended using only new brass... At this point I can say that 24 grains of AA #9 under a 440 WFNGC burns clean with no more than a crimp to hold the bullet.... Shoots to the same general point as a sized and crimped case at 25 yards.. Of course these few rounds were on new brass which may have provided a little more consistancy. IMHO Kicks like a Mule too! ;D

[groo]

Groo here
Some say that to much neck tension will resize the bullet.
Keith said always use a heavy crimp with smokeless powder.
I think that both is required to get the most out of are powers.
Remember that the factory uses new brass a heavy crimp and
sometimes seals[glue] the bullets in.
When was the last time you saw a factory wc 38spec target load
that did not have a heave crimp over the mouth??

[dale53]

Years ago, and I mean YEARS ago, I tried H110 with a .44 Special (manual load) with a 250 gr bullet. First time out I had a stuck bullet. I had no dowel rod with me so that range session was a bust. I did an investigation and learned that my old CH .44 Special die set did not give me enough case neck tension (the bullets could be seated with my fingers). I ordered out a RCBS Carbide die set and had NO further problems. Heavy crimp did NOT solve the problem. Case neck tension DID. That has been over forty years ago and I have had no further problems with H110 and have loaded lbs and lbs of it in a number of calibers.

So, as a result of my "experiment" I am a believer in case neck tension. I consider that the crimp is just to keep bullets from jumping forward from recoil. Case neck tension is of ballistic necessity (extremely heavy bullets CAN provide enough inertia to reduce the need) IMO.

FWIW
Dale53

[Len]

"So, as a result of my "experiment" I am a believer in case neck tension. I consider that the crimp is just to keep bullets from jumping forward from recoil. Case neck tension is of ballistic necessity"

ABSOLUTELY CORRECT

On a single shot rifle or T/C handgun no crimp is necessary but a consistent neck tension is important.

Len

[Bowenbuilt]

In my experience it's the chronograph that tells the tale. A few years ago I loaded some over seas brass that I don't remember the head stamp. I believe it was some IMI .44 mag. brass. The case tension was not good at all. Like you said, I got the big boom and the kick but across the chrono it was all over the place and so were the bullets on the target. I posted a picture yesterday showing a group shot at 25 yards with a custom Ruger .45 Colt. The variation of those 18 rounds were less than 8 FPS and all the bullet holes were touching. I have found that in not every case does the shot to shot velocity mean accuracy but in every case when I do get groups like that it is with good case tension, a good consistent crimp, consistent bullet weight and sorted cases. No neck tension with just a crimp on a large caliber and slow burning powder cannot be a good thing in the accuracy department. Homey won't play that game.

[maxcactus]

Sept 10, 2009 19:53:39 GMT -5 groo said:

Groo here
Some say that to much neck tension will resize the bullet.

I have never heard such a thing, but some gun magazines publish some dubious stuff on occasion, not to mention the bull bandied about in gunshops, hunting camps, etc.

I can't imagine how this could be possible as others have mentioned Bowen's recommendation (complete with pictures in his book) that cartridges for heavy hitting revolvers be wasp-waisted - and they are - VERY! On some I have seen you the lube grooves can be seen through the brass - on others the base of the slug is noticeable.

Also, given the amount of force required to size a lead bullet in a sizer, I can't see any way for a thin brass case to exert anywhere near the pressure necessary to reduce a cast slug in size, let alone a jacketed. It certainly is possible to shave some lead off the heel of a bullet when seating if the belling/case mouth opening process isn't sufficient, or if the slug is started into the case off center or at an angle, but that's a technique problem, not one case neck tension. This is one reason some chaps like bevel base or boat tailed slugs. Gas checks can also prevent this from happening.

I am nowhere near as experienced a handloader as some here, but so many bonafide experts have weighed in on this issue (case neck tension with heavy slugs) as to negate my usual desire to find out for myself. John Linebaugh wrote of "dwell time" and mentioned case neck tension being critical with heavy slugs in big bores.

Axe's experience is interesting and I'm sure there is a logical reason why it would seem to be an exception to the above rule. It's certainly one of the reasons so many of us find handloading and ballistics so interesting.

Max.

[fltbed]

If you use a Lee Carbide Factory Crimp Die it is very easy to resize a bullet in the casing. (Kinda hard not to in my experience)

I bought a couple of these for USPSA ammo as they were all the rage a few years ago. They are supposed to end feeding jams in bottom feeders due to screw ups in your reloading techniques. The only thing they did for me was hurt accuracy.

I punched out the carbide sizing rings and just use them as a crimp only die.

Jeff

[J Miller]

Sept 29, 2009 20:15:52 GMT -5 maxcactus said:

Sept 10, 2009 19:53:39 GMT -5 groo said:

Groo here
Some say that to much neck tension will resize the bullet.

I have never heard such a thing, but some gun magazines publish some dubious stuff on occasion, not to mention the bull bandied about in gunshops, hunting camps, etc.

I can't imagine how this could be possible as others have mentioned Bowen's recommendation (complete with pictures in his book) that cartridges for heavy hitting revolvers be wasp-waisted - and they are - VERY! On some I have seen you the lube grooves can be seen through the brass - on others the base of the slug is noticeable.

Also, given the amount of force required to size a lead bullet in a sizer, I can't see any way for a thin brass case to exert anywhere near the pressure necessary to reduce a cast slug in size, let alone a jacketed. It certainly is possible to shave some lead off the heel of a bullet when seating if the belling/case mouth opening process isn't sufficient, or if the slug is started into the case off center or at an angle, but that's a technique problem, not one case neck tension. This is one reason some chaps like bevel base or boat tailed slugs. Gas checks can also prevent this from happening.

I am nowhere near as experienced a handloader as some here, but so many bonafide experts have weighed in on this issue (case neck tension with heavy slugs) as to negate my usual desire to find out for myself. John Linebaugh wrote of "dwell time" and mentioned case neck tension being critical with heavy slugs in big bores.

Axe's experience is interesting and I'm sure there is a logical reason why it would seem to be an exception to the above rule. It's certainly one of the reasons so many of us find handloading and ballistics so interesting.

Max.

Max,

I have had tight case neck tension resize soft swagged bullets. But never normal cast bullets.
Somewhere I read an article where the writer suggested different expanders for different hardness bullets. The harder the bullet, the tighter you could make the case neck tension. I have found this to be true.

I use a Lyman carbide sizing die for my .45 Colts for lead bullets. Then I use either the .450" or .452" expander depending on what bullets I'm using.

I've found it works really good that way.

Most of my cartridges show some "wasp waist" where the bullet base stops.
And I do roll in a good tight crimp. With my 57 year old eyes I don't get groups like I used to, but I get clean burning with Unique and 2400 this way.

I must be doing something right.

Joe

[Mark Terry]

Sooooo...

At the risk of demonstrating my lack of knowledge and poor education, I was about to ask what a reloader is suposed to do if he determines he has a lack of bullet / neck tension. Joe may have already answered this if the answer is to buy a smaller diameter expander plug for your dies (is this possible??). I'm using off the shelf RCBS Carbide dies. Can I buy a smaller expander plug or do I reduce the diameter of the one I have now?

Thanks

[Len]

First you need to know what is causing the problem. Make sure your bullets are the correct diameter, that the die is sizing the neck down prior to pulling the expander button back threw it.

If you narrow it down to an over sized expander button in a bottle neck die and it is not a carbide button you can reduce its diameter by spinning it in a drill and polishing it with emery cloth. Carbide should be replaced by the manufacturer.

I haven't experienced an over sized expander button problem in many years I think today's dies are made far more accurately than those made say 20 years ago.

Len