Taper crimp

[Dietrich]

I think the most confusing and elusive phrase I`ve come across in the reloading process is the taper crimp.I`ve set the machine [Dillon 550] up the way the instructions said to and adjusted the crimp die but for the life of me I ain`t sure I`ve got it right.The ammunition works fine and so do the firearms but I can`t see any type of crimp.With a roll crimp,that`s a horse of a different color and I have no problem with it but the taper crimp is something I`m missing.Can you actually see a crimp or what?My finished product looks like factory ammo and when I slide my fingernail along the bullet lenghwise it feels like factory ammo but how do you know if it`s right,too little,or too much?

[slowpoke]

Back when I use to reload autos I'd use dial calipers and compare to a factory round.
For safeties sake I run some through the gun with the slide release and recheck the overall length.
For the last decade or so I been too lazy to chase brass and mostly reload now for my revolvers.

EDIT:
.40s are real picky about OAL and bullet setback, particularly with the heavier bullets. Chamber pressures can go bananas.

[MW surveyor]

I measure my crimp with my calipers. Especially when reloading with lead bullets. Too much and it can resize the bullet. Usually do pretty good with the taper crimp using the Lee FCD at about 7/8 to 1 turn.

[Bawanna]

The Factory Crimp Die was the ticket for me as well. I just fought it before. I wanted to make sure I had enough and of course you don't want too much.

The factory die resizes the whole case on the way out as well so you should have a real good cartridge that should feel well. They say you can't over crimp but I think Melissa is using one and her "Go to guy" (on my list) said to back off, not sure how he can see this. Not saying he's wrong but its darn hard to see.

[melissa5]

The Factory Crimp Die was the ticket for me as well. I just fought it before. I wanted to make sure I had enough and of course you don't want too much.

The factory die resizes the whole case on the way out as well so you should have a real good cartridge that should feel well. They say you can't over crimp but I think Melissa is using one and her "Go to guy" (on my list) said to back off, not sure how he can see this. Not saying he's wrong but its darn hard to see.


He said that there was a shiny ring around the top of the case that was caused by friction and that meant it had too much crimp. What do you guys think?

[Bawanna]

I get a slight shiney ring on mine but when you crimp something it would seem like you gotta put some pressure on it to make it happen. I've tried from half a turn to almost a full turn and the ring was still there.
MW says he goes 7/8 to a full turn. So I'm not sure that's a conclusive observation.

It could be though, I don't have the definitive answer on that. I recall in the instruction booklet that it said you couldn't overcrimp. The die won't let you.

I'd probaby try backing off, not sure how much you turned yours down and if you don't get any bullet set back and everything works your good. It works now so I don't think you got any real issue.

Less you work that brass on a crimp the longer it will last, course this is far more prevelant on a roll crimp for a revolver.

[melissa5]

I think I started out with it set the way the manual said, but it didn't feel like it was doing anything, so I turned it down a little. :eek: I guess I'll just go back to the what the manual said.

[Bawanna]

I think the manual says something like from 1/2 to 1 full turn, so you have some room to play with. Your probably fine.

[MW surveyor]

Not sure if you can or can not over taper but the 7/8 to 1 turn works for me. I also start out with a 1/2 turn on some never loaded/fired test loads and then do a "push test" against the bench. Just a light to moderate push of the bullet against the bench, then measure the OAL again. If it moved, I go to the 3/4 or more but 7/8 seems to work the best.............but this does vary depending on the case used. The Wins are a bit thicker and the RPs are a bit thinner in the case walls. As with everything YMMV.

Make sure the round plops in to your barrel with the head flush or a just smidgen below. Flush is better. If it is below, you may have crimped too much.

[Dietrich]

As Slowpoke and MW surveyor stated above,I`ve used calipers and checked against the factory crimp.It was dead on so I reckon it`s OK.I just checked some .45 reloads and thought I saw that shiny ring that Melissa`s buddy was talking about until it occurred to me I was looking at a nickle plated cartridge and the whole thing was shiny.Moron!! I don`t see any shiny ring on the brass cases so I suppose it`s good.

[OldLincoln]

I had to pull 250 rounds and found the bullets were squeezed pretty well by the factory crimp die. Hard to see after crimping but they are in there pretty good. If you have the hammer type bullet puller you can take 1 apart and actually see what kind of crimp you have.

Another tip: mark your box of reloads with the date you reloaded. If you have an issue someday it may keep you from tearing apart more than 1 loading session's output.

[Bawanna]

I keep a reloading log. I assign each box a Lot # with date and all the recipe. Anything that I did differently. I leave a place to make notes after shooting.
It's kind of a waste once I found a load that works and I don't change anything but like you suggest, all I gotta do is look at the log and I know everything about that box including lot #'s for powder, primers, etc.

[OldLincoln]

I do the same load so stopped with all the data. My issue was I had moved the completed boxes around (out of order) before I discovered my squib. Like cockroaches, for every 1 you find there must be more. Now I put the date on the box which would have made it 100 rounds, not 250. Had a dickens of a time getting those once crimped bullets to be tight in the reload.

[Scimmia]

I load cast bullets, so I use them to set my crimp. Seat and crimp a bullet then pull it back out. If you see that the case was pressed into the lead, it's crimping too much. Usually only takes a few times to get the die adjusted. I don't use a FCD, though, and I've heard they aren't meant for cast bullets, so I don't plan to.

[CJB]

If you think of the taper crimp as an "undo the case mouth bell" die, you'll have a better idea of what its really doing.

You're just undoing the bell that was introduced to facilitate insertion and seating of the bullet. The "roll crimp" actually turns the case mouth inward upon itself. The taper crimp just irons out the case mouth straight.

There is a huge margin of error when using a taper crimp die, even in an autoloading round. I suppose you can "over crimp" but its hard to do. The result would be potential excess headspace....but I dunno if that is actually achievable. You simply want enough results to make for a nice smooth edged cartridge when you're done. If you're going for real close fit match ammo... then you'll have to adjust the die and drop a round by hand into the barrel (removed from the gun)... checking the fit and adjusting the die until fits in the chamber the way you want.

[Dietrich]

If you think of the taper crimp as an "undo the case mouth bell" die, you'll have a better idea of what its really doing.

You're just undoing the bell that was introduced to facilitate insertion and seating of the bullet. The "roll crimp" actually turns the case mouth inward upon itself. The taper crimp just irons out the case mouth straight.

There is a huge margin of error when using a taper crimp die, even in an autoloading round. I suppose you can "over crimp" but its hard to do. The result would be potential excess headspace....but I dunno if that is actually achievable. You simply want enough results to make for a nice smooth edged cartridge when you're done. If you're going for real close fit match ammo... then you'll have to adjust the die and drop a round by hand into the barrel (removed from the gun)... checking the fit and adjusting the die until fits in the chamber the way you want.
I knew that somebody on this forum would be able to explain it in a way I could understand.Thanks CJB!!

[muggsy]

As a last resort I always read the instructions. :)

[Charlie98]

I use a taper crimp on most of my handgun ammo... everything except heavy magnum rounds, they get a good roll crimp.

What is a crimp for? Following the technique used by some rifle reloaders (myself included) you DON'T crimp at all, using neck tension to hold the bullet. If the brass is in good shape, that's plenty.

Handgun rounds are a bit different, however. The crimp holds the bullet in place and should prevent setback (from recoil, chambering, etc...) and some amount of crimp may be require to get some powder charges to light and burn more efficiently. For this reason, a slight crimp (roll, taper or FCD) needs to be used.

Can't overcrimp? Never say never... Overcrimping not only is hard on the brass, it deforms the bullet, especially FMJ and other bullets with no cannelure, with a possible effect on accuracy. If you seriously overcrimp, as the die is pushing the rim in... you may slightly bow the case just below it out and away from the bullet... resulting in less neck tension against the bullet.

My rule of thumb is to hit the brass just enough to take the reloading flare out of the case and juuuuust start to turn into the bullet (both FMJ and cannelured bullets.)

[starkreiten]

Deitrich, looks like this thread is a bit dated, but it made me remember the way I figured out how much to taper crimp for my Glock .40s.

First, a few caveats; these rounds were light reloads for a single .40 Glock used for punching paper and an occasional pin shoot. I put a LOT of lead rounds through my numerous Glocks over the years without any trouble. Glock does not recommend cast lead rounds -- period. This technique worked for all types of rounds.

It's basically just taking the next step to CJB's excellent post about "If you think of the taper crimp as an "undo the case mouth bell" die, you'll have a better idea of what its really doing."

I would flare the case mouth 'just enough' to not shave or deform the bullet when seating. Even jacketed bullets will shave copper off if you don't flare enough -- lead takes a bit more flare. Over-flaring accomplishes nothing, and might cause the case to split sooner.

My taper crimp step uses the same 'just enough' concept, except that now I want the round crimped 'just enough' to fit MY chamber.

To do this, I'd seat the bullet to OAL spec, and give it a VERY light taper crimp. Now, with the barrel OUT of the gun, I'd lightly drop the round into the chamber. If the crimp was light enough, the round will NOT freely drop in all the way (do not force!). Give the same round a bit more crimp until it will freely drop all the way in, then a bit more so it will freely drop out too.(gravity is your friend!) This might also help the brass last longer, since it will minimize the amount of case expansion in the chamber.

I would also make a 'setup' (sans primer and powder) round for each type of bullet that I would regularly reload. It made it easy to set the OAL and crimp, since I'd just have to 'snug' the seat and crimp dies to the 'setup' round and (after double checking, of course) reload away. :)

BTW, trimming was also something I always did with 'once-fired' brass -- it was disturbing how much case length variation there was with factory ammo. With my light .40 reloads there was no case stretch after the initial trimming.

Good luck,
Dana

[muggsy]

If you think of the taper crimp as an "undo the case mouth bell" die, you'll have a better idea of what its really doing.

You're just undoing the bell that was introduced to facilitate insertion and seating of the bullet. The "roll crimp" actually turns the case mouth inward upon itself. The taper crimp just irons out the case mouth straight.

There is a huge margin of error when using a taper crimp die, even in an autoloading round. I suppose you can "over crimp" but its hard to do. The result would be potential excess headspace....but I dunno if that is actually achievable. You simply want enough results to make for a nice smooth edged cartridge when you're done. If you're going for real close fit match ammo... then you'll have to adjust the die and drop a round by hand into the barrel (removed from the gun)... checking the fit and adjusting the die until fits in the chamber the way you want.

I agree with what you said 100%. You nailed it.

[Bongo Boy]

WAY too much:

http://i182.photobucket.com/albums/x150/Bongo_Boy/Handloading/CGNDCripm05.jpg

A good bit too much:

http://i182.photobucket.com/albums/x150/Bongo_Boy/Handloading/crimp.jpg

http://i182.photobucket.com/albums/x150/Bongo_Boy/Handloading/Crimp03.jpg

More than necessary:

http://i182.photobucket.com/albums/x150/Bongo_Boy/Handloading/N100Loads02.jpg

Pretty close to just right:

http://i182.photobucket.com/albums/x150/Bongo_Boy/Handloading/HappyHandloading2.gif

[DM123]

"Crimp" is one of those nebulous terms that has a different meaning to different folks. My understanding is that it is actually the squeeze on the bullet prior to the bullet-brass junction of a jacketed or in Berry's case plated round that holds the bullet. Over crimping is a bad thing and can cut right through the plating or jacket if severe enough resulting in catastrophic failure of the barrel. What I try to achieve is a bit of coke barrel shape to my reloads of 8 thousands in the area of mid brass with the area of "crimp" being the same measurement as the base.

You can take the barrel out of you gun and check for fit. The shoulder area is a key spot. You shouldn't have to push the round into the chamber. It should fall into what would be full battery if in the gun.

Lead bullets are a different deal.

[U.S. Patriot]

An easy way to test your crimp is this. Make up a dummy round with no powder or primer. Check the OAL then cycle the round 4-5 times. Then check the OAL again, that will let you know if the round is setting back.

[Replay13]

An easy way to test your crimp is this. Make up a dummy round with no powder or primer. Check the OAL then cycle the round 4-5 times. Then check the OAL again, that will let you know if the round is setting back.

+1 on this test. Also you will find that the best bullet retention is no crimp, as some suggested just take the bell out. Even better retention is not to bell or expand the case, just size and load. If you deburr and chamfer the case mouth this is possiable, but not practical for everyone. If not carefull you can seat a bullet crooked this way. But I even load Berry bullets in .40 cal this way with a single stage press.

Why no crimp on the taper crimp, you just squeeze the bullet down and the brass springs back some. But don't take my word for it, do this simple test that U.S Patriot suggests. Write down the number of cycles before you start getting bullet set back with all the different ways.

That being said you don't need the most retention, but it should cycle a few times without any bullet setback. Loading self-defense ammo you might cycle a bullet several times without fireing it. Also like some suggested, pull the barrel out of your pistol and see how it fits. Again, over crimped ammo can leave a brass ring shaved off the bullet and that makes the headspace a little long. You can get around this by seating and crimping in different steps but I suggest trying just taking the bell out.

I am only talking about taper crimp, roll crimp is a whole different ball game.
James

[MudMarine]

Do you have a saami cartridge gauge? http://www.lymanproducts.com/lyman/case-prep/pistol-max-gauge.php

When I crimp I just set the die so it "bumps" the edge of the case at the end of the stroke. On a non canneleured bullet all your looking for is enough pressure from the case to keep the bullet from experiencing setback during recoil. Ideally, you are using a powder load that is 100% or more (slightly compressed) in your case when the overall length has been achieved.

As long as it fits your chamber or a chamber gauge and you have no bullet setback you should be good to go.