crimping questions and more

[sergeant69]

first of all, how many stupid questions do i get to ask b4 i get kicked off this site? my wife is recovering from surgery and so i am on leave for another 2 weeks ( from TDCJ-god i hate my job) so i have alot of time on my hands right now. i keep hearing "lightly crimp" on the posts i read but does that apply to a revolver like the .44mag. too? sure don't want the cylinder siezed cause a boolit stuck out due to a light crimp under recoil. also-i am casting lyman mold # 311041, a 30 cal for 308 and 30-06. being a flat nose, can i use it for my 30-30 too? its a 173 gr GC. and is the top groove a cannalure or a lube groove? theres a driving band ahead of the groove so my inclination is to crimp on the band. but i've only cast for revolvers in the past. thanks john

[Bass Ackward]

first of all, how many stupid questions do i get to ask b4 i get kicked off this site? my wife is recovering from surgery and so i am on leave for another 2 weeks ( from TDCJ-god i hate my job) so i have alot of time on my hands right now. i keep hearing "lightly crimp" on the posts i read but does that apply to a revolver like the .44mag. too? sure don't want the cylinder siezed cause a boolit stuck out due to a light crimp under recoil. also-i am casting lyman mold # 311041, a 30 cal for 308 and 30-06. being a flat nose, can i use it for my 30-30 too? its a 173 gr GC. and is the top groove a cannalure or a lube groove? theres a driving band ahead of the groove so my inclination is to crimp on the band. but i've only cast for revolvers in the past. thanks john



Regardless of launching platform, crimps are flexible load altering folds that work well as such up to about 25,000 psi. Above this level, it becomes situational driven and moves mostly into securing the bullet category that most guys recognize. Crimp also has more effect with faster powders in excess volume situations compared to full case loads.

Crimps are limited by the bullet design and like everything else in this sport must be individually tested. The anneal of your brass combined with your particular die characteristics can mean that you need very little crimp compared to me or that you may need more to perform what ever task you want / need.

But for a high pressure load in a revolver, you would pretty much start with a heavy crimp from a common sense perspective.

The 311041 can be a very good hunting bullet for any 30 caliber. The only requirement, like any other cast bullet, is that it fits the throat. For me it is a better 30/30 slug than for the 06. (throat length) Have you slugged to see?

[44man]

I check crimp by loading a cylinder full and shooting 5, then remove the last round and look at it to make sure it didn't move.
A moderate crimp has held everything even with the .475.
I depend more on case tension. It doesn't hurt to make it a little tighter but you do not want to ruin brass or squeeze down a boolit.
Looking at the tiny crimp grooves on Lee boolits that look like fingernail scratches, boolits still hold.
If you try to over crimp them it will buckle brass and destroy tension because there is nowhere left to fold brass into.

[mooman76]

What the other said and we don't kick people off for stupid questions. Our unwritten policy is the only stupid question is the one not asked. A few might get a little testy but it's all good in the end.

[mdi]

Good answers so far (you only have 3 questions left before you get the boot...:wink:). When I work up a load for my revolvers, I usually start with a heavy crimp; not only to hold the bullet in place, but some powders neeed a heavy crimp for good ignition/burning.

[HeavyMetal]

Where you've most likely read about "lightly crimped" has been in reference to taper crimping in auto loader rounds.

My experience with taper crimping has lead me to believe that most begining reloader learn on a revolver round, the 38 special being the most loaded round, and see a roll crimp in use.

Since it can be seen, and yes you can over do even a roll crimp, when they decide to move into an auto pistol, usually 9mm but 45 auto as well, they figure they must be able to "see" the taper crimp here as well!

Sadly most die set instruction really don't cover this as well as they should and many leading and accuracy issues are a result of the boolit being crimped way to heavy and actually "swaging" the bolit to a smaller size when the taper crimp is applied.

A good taper crimp should be just .001 to .002 smaller than case diameter and should be measured with a good dial Caliper.

This is much to small a difference in case diameter to be seen with the eye, at least mine, and should be checked with the caliper and a magnifiying glass during any die adjustment change or die set up.

As posted previously each and every die and pistol will want some thing a little different so a "plug and play" die set concept really doesn't work.

[qajaq59]

also-i am casting lyman mold # 311041, a 30 cal for 308 and 30-06. being a flat nose, can i use it for my 30-30 too? its a 173 gr GC. and is the top groove a cannalure or a lube groove? theres a driving band ahead of the groove so my inclination is to crimp on the band.
First off that is a good bullet for the 30-30, and it's all I ever use in mine. And I shoot thousands of them every year. Also my 30-06 always like it too, but my .308 doesn't. And I crimp into that top groove enough that I can see it is crimped with a mag glass.

[sergeant69]

First off that is a good bullet for the 30-30, and it's all I ever use in mine. And I shoot thousands of them every year. Also my 30-06 always like it too, but my .308 doesn't. And I crimp into that top groove enough that I can see it is crimped with a mag glass.

so that top groove IS for crimping and not lubing. thanks

[lwknight]

Yes , the top groove is a crimp groove and the top band is really more of a bore rider than a driving band.
Relatively speaking , brass is very weak compared to a 30,000 psi full house magnum load so crimp would play a really small part as far as internal ballistics go. Its mostly to hold the bullet in place under recoil.
As stated before , light loads will be affected more by the crimp. A heavy crimp is harder on your brass and is generally unnecessary.

[Char-Gar]

John, I do not crimp rifles loads UNLESS they are to be used in a tubular magazine. Then I will turn the case mouth in, just enough to prevent the bullet from being pushed down by pressure of the magazine spring and loads in front. I use the crimp groove if the bullet has one, if not then in the top grease groove, just below the top driving band.

In all other rifle loads I will run them through a crimp die just enough to take out the bell on the case mouth, but no more.

I have been doing this for years and see no reason to change.

[Wayne Smith]

Likewise with Charger, in bolt guns and Single Shots I don't crimp unless the rifle shoots better with one - rare but true sometimes, one of mine so far. My 30-30's are all lever guns, Marlins, with tube mags and they all get crimps so the boolits don't get pushed back into the case thus increasing pressure. The one exception to the tube mag rule is my 44-40, I load a full case of Black and don't have to worry about the boolit pushing back.

All of my revolver rounds get some crimp, relatively light to essentially none in the 32-20 to a good solid roll crimp on the 44Mag. and the .357Mag.

[kbstenberg]

John i have been working with the 311041 in my 30/30 the throat is short so my bullets are seated deep enough that i can't put a crimp on the bullets.
Kevin

[leftiye]

Note that in revolters, boolits PULL OUT of the cases under recoil. In everything else they get pushed backwards INTO the cases by recoil. Two completely different doggies!

[sergeant69]

never thought about it but UR RIGHT!

[Buckshot]

.............I actually feel that sufficient 'Boolit Pull' via caseneck tension is probably more important then a crimp in most situations. A crimp is most important IMHO in tube feed firearms. Caseneck grip can be overdone with cast lead whoever so some common sense has to be used. A jacketed bullet can stand about any tension you'd be liable to apply. Not so cast, and especially a soft slug.

I like to use one special example written about by Dean Grennel. He was loading experimental ammo in 44 magnum with jacketed bullets. Due to the nature of the powder (H110 or W296) he KNEW a good solid crimp was required and applied one he said "Had the grip of a rabid weasel". At the range he said the velocities were all over the place. In addition he said they all sounded different, and on a couple he actually had to check to see that the bullet had cleared the barrel.

Checking things out he eventually discovered that while the cases had a magnificent roll crimp into the cannelure, he found that a large number of the slugs could be actually rotated by hand in the cases. The casemouths effectively had zero grip, and in shooting his 'Rabid Weasel' roll crimps weren't very effective by themselves.

..............Buckshot

[sergeant69]

so basically all the crimp did was prevent boolit set back into the case. but isn't that what its supposed to do? but i'm just ASKING. ur the expert!

[HeavyMetal]

In the case of a revolver the crimp is supposed to keep the boolit from moving forward under recoil, just like in a kenitic bullet puller, and then tying up the gun.

Case neck tension controls boolit pull and thus ignition or lack thereof.

In an auto loader the crimp is to keep boolits frm setting back in the case, when the nose of the boolit "bounces" off the wall of the magazine AND to "straighten" out any flare from the expander die so the case has no "lip" on it to catch on the feed ramp.

Again case neck tension controls ignition.

All of these things have to happen during the reloading process in a controlled and, more importantly, balanced manner!

Done correctly you get good accurate loads that do not lead.

To much neck tension, to much crimp, or to little neck tension and issues with leading and accuracy can be annoying!

[sergeant69]

thanks a lot! it was simple till you told me all that!

[Eagles6]

There are no stupid questions, just stupid people asking questions.;-)>
Just kidding.
If you don't ask...
All good advice here and I can't think of anything to add but glad I stopped by.

[runfiverun]

yep it's simple.
start light enough to hold the boolit in place under recoil by testing.
add a bit, strange as it sounds crimp can affect accuracy.
my 38 specials need no crimping i have enough boolit in the case to hold them, and i actually leave some of the flare on them to help center them better.
it's one more thing to try.
case neck tension affects accuracy in jaxketed rifle rounds too.
donuts on case necks from partial sizing, slight case flair to stop blowback and center the boolit.
or enough tension, to keep the bore rider in place when un chambering.
or both.
it's what we do.

[nicholst55]

I personally feel that a lot of people over-crimp, in an attempt to make up for insufficient neck tension. How many times have you seen someone start a thread about bullets that spin in the case, and everyone's reply is to 'buy a Lee Factory Crimp Die,' or something similar?

I'm sorry, but if there isn't any neck tension to begin with, you can crimp the case until it buckles, and it's not going to help! Properly sized expander plugs and properly annealed brass will frequently do all that's required to solve this particular problem (no neck tension).

As in the anecdote that Buckshot referred to, a 'rabid weasel' crimp won't solve neck tension problems. You'll just have very well crimped, loose bullets.

[qajaq59]

I've never had that problem, but.... It seems to me that if you didn't have enough neck tension to start with, a really hard crimp is likely to make the situation worse. Because while it's pushing the mouth portion of the neck in, it could be prying the rest of the neck further out, lessening the tension even more.

[Buckshot]

............That's why reloading your own is so dang much fun, you get to experiment! I have a few instances and in particular actual pictures using a 6.5 Swede (with cast) where crimps substantially improved accuracy. I was shooting at 100 yards. This was some years back and a I KNEW for a fact at this time that crimping cast lead boolits was a sin of the first water. Now too much crimp can be the destroyer of accuracy, but as Kenny the rangemaster said, "Sometimes a bit of a crimp can straighten up a boolit."

Of course he didn't SAY 'Boolit' as the word hadn't been invented yet :-) but it did get me to thinking about crimps and cast, whether I believed what he said was right or wrong about the accuracy improvement.

................Buckshot

[sergeant69]

well, i have one of those hornady tools that not only checks for concentrencity but can also correct it (bullet being straight in case) so......?????????

[leftiye]

Do you ever wonder just exactly what it is that bends when you straighten a round?

[sergeant69]

nope. just thought that the boolit was repositioned in the neck. why does something have to be bent? maybe stretched microscopically. we're not talking about auto body shop work here straightening fenders.

[walker77]

Is it possible the lack of a crimp to cause leading???

[oldtoolsniper]

As I learn more from this site I experiment more. Brass will spring back and lead will not. Make a dummy round with no powder or primer but everything else as though you were going to shoot it. Size it, bell the mouth, add the boolit and crimp it then take the primer punch out of your sizing die and lube the case well and resize it with the boolit in the case. Result = boolit you can remove with your fingers in most cases. The brass will spring back and the lead boolit will not. I do use the LFCD but only to remove Glock bulge from range brass.
__________________

[mpmarty]

As a rule I only reload for pistols and rifles, no wheel guns. On my pistol loads I measure the area at the mouth of the case and seek a dimension that is the same as the boolit plus twice the thickness of the brass. Loading a batch of 10mm today my taper crimps wound up at .424" which is due to a boolit (200gr jacketed h/p) of .400 plus two .012 thicknesses of brass. All I want to do is smooth out the cartridge so it feeds. Rifles are a whole 'nother story. Bolt guns don't usually get crimped at all. Lever gun (45/70) gets a Lee Factory collet type crimp that is visible just like the crimps on GI rounds.

[44man]

Is it possible the lack of a crimp to cause leading???
No, too much crimp with soft lead will cause leading because the boolit is what opens the crimp. Old thinking was that the whole case springs open at once to release the boolit, can't happen, so the crimp scrapes the boolit and if your lead is soft enough you will still see some crimp on fired brass.
This can make the boolit too small after all the work of getting a boolit to fit.
If a gun needs crimped loads, the lead must be hard enough to resist sizing when seated and also to open the crimp without being sized as it is forced through it.
I have had to pull some cast factory loads with a puller and it is surprising how much damage was done by the crimp. These were fairly hard boolits too but were over crimped.
Some shoot soft lead and use a Lyman "M" expander which reduces tension so the boolit is not damaged when seated. Then they put a crimp on it like a bulldog to help powder burn. I have to ask what was accomplished? This expander works best on single shots, etc where crimp is not needed and soft lead is used like in a BPCR, most times brass does not even need sized if the boolit is large enough. In these I even leave some flare on the mouth.