Crimp ?

I'm wondering about crimping. When reading about he 357 Max. I came across one forum, I forget which right now. But some guy said he always crimps AFTER seating the bullet, separately. This is because he doesn't want to be crimped at the same time when the bullet is moving downwards into the case. This makes sense actually, I've thought about it as I've been reloading this past week.

And how much crimp? This is another thing that keeps me awake at night. I thought a bullet should be crimped just enough to keep the bullet from sliding around in the case.

But then I read somewhere else, you need a somewhat heavy crimp to in effect, slow he bullet to allow slow burning powders time to build pressure. How true is this?

Maybe I should stop reading.

I've tried various amounts, and I'm not sure I can really tell the difference.

Will crimp affect accuracy in anyway? That is something I haven't tried to experiment with, i.e: Same load data with two amounts of crimp.

Thanks for any comments about this. I've been reloading for about 10 years now, and feel that I've improved a lot because of the great information here.

Thanks,

I've only had one squib too. In my SP101 with 327. I never found out what cause it. I didn't consider crimping to be the cause. Hmmm...

The topic of crimping can get really involved with many opinions. For my revolver rounds I roll, Profile or collet crimp, depending on caliber. My 44 Magnums get all three, mainly because I use some slower powders (and a stiff crimp aids powder burning) and the heavy recoil. Easiest way to start is copy a factory round's crimp. Measuring a roll crimp would be pretty difficult so I have always jut rolled a few thousandths of an inch into the crimp groove or the cannalure of the bullet. I have "bench press" tested some of my Magnum rounds to make sure the bullets stay in place (press the loaded round against the bench with moderate pressure). I started reloading in '69 and very early on separated the seating step from the crimping step. I believe I have more control and although many combine the steps, getting the adjustment just right can be a pain...

When in doubt,, often,, you can compare a factory round to your crimp to get an idea of what MAY be "normal."

That said,, in general,, your studies are correct. Heavy & recoiling calibers often need a serious roll crimp. Many folks prefer to crimp in a separate step to insure uniformity. You haven't noticed much difference is likely due to the distances you are shooting. Little things really come into play when you start shooting at 100 yds & beyond. And,, experimentation is the key to finding which works the best for you & your gun.
If you want real answers,, look hard at handgun silhouette shooting,, and how the serious shooters there do things. You will see a pattern.

Reloading to most people is a hobby and treated as such. To me it is an acquired skill. I could not afford factory loads when I first started shooting. When I started studying this craft most of the writers talked about turning out better quality ammunition than could be purchased from commercial markets. I started watching out for techniques revealed in the text I was reading. There came a point that I became convinced crimping in a separate operation from seating to be beneficial to the quality of the cartridge I wanted to load.

Today, there is a major belief in auto-indexing blue presses that turn out ex number of loaded round per hour. I have one myself. But, for ammo I carry for hunting or self protection, I demand the highest standard of accuracy. Now that my eye-sight is not what it was when I started reloading, it is even more important to me. When I get new to me cases, be they once fired factory cases or ones ordered from starline, they all get the flash holes uniformed, primer pockets uniformed, trimmed to a uniform length, and sized. When the load is chosen these cases get the M-die treatment for the bullet they are about to receive. This is for uniformity. By having the same length case, If you roll crimp it gives you the uniform amount of crimp with each case. With a factory crimp die it is not a factor. But, with a roll crimp or profile crimp the case uniformity is the only way to get consistence in each crimp. This does effect accuracy. Not at seven yards or ten yards that many people shoot at. But at real world hunting distances it makes a difference. Now that handgun cartridges are commonly shot from rifles chambered for them also, it can be very beneficial.

I have no quarrel with those who will claim it has no "significant" difference in groups in their shooting experience. I have heard that for many years. The only reply I have to that is, it is a free country and I have no demand they load the way I do. But, I don't seem to have the loading problems they ask about. My mindset is to eliminate the ammunition quality and the gun quality in the shooting equation. That way when I miss, I know it was me. I have known for a long time now that every time I shoot a group it will not be one ragged hole, but I will keep trying as long as I continue to shoot.

A good tight crimp is very beneficial when using slow burning powders. As has been said above, it not only facilitates ignition of the powder, but keeps the bullet from moving because of heavy recoil. In my experience, trimming the cases to the same length is the best way to assure consistency. Also only using brass from the same brand is helpful. If these two things are done, then crimping and seating bullets at the same time is fine.

Crimping semi auto cases into bullets without a cannelure is a little tricky. Too much crimp can result in a crumpled case. Too little crimp can result is the bullets being pushed further back into the case during the feeding cycle resulting in increased pressure....sometimes dangerously higher pressures.

I noticed above that collet crimp dies were mentioned. I use collet dies for cases that have thin fragile necks such as the 32/20, the 25/20, the 22 Hornet and a few others. In their place, collet crimping dies are the best way to get a good consistent crimp, without crumpling the necks. I have not tried them on semi auto cartridges, but I am open to trying it on 9MM, 40 S&W and others. Whatever you do, be careful.

jgt & I think a lot alike.
I like to say; "I want to eliminate as many mechanical errors as I can,, so if I miss an animal,,, it's the loose nut behind the trigger,, not the gun or ammo."

I was shooting yesterday,, and I was also setting the dot on my newest .45. At 25 yds,, I shot a nice tight almost one hole group. But when I moved to 100 yds,, it opened up to 7"! Distance magnifies tiny imperfections. Consistent ammo is one of those tiny things you CAN work on.

What's the point of reloading if you do not strive to make the best ammo possible?
For me that's what it's all about especially for my hunting ammo, rifle and revolver.
Pistol plinkers not so much. ps

Hey! See, look at all this good info here.

I try various things. I'm using coated, cast bullets with a cannelure, and I know in the 45 Colt I have a good crimp. At least it looks good, and my load for them are pretty accurate. Some of my others I'm not so sure.

Some people mention shooting at distance. Yes, I can imagine minute differences are amplified at greater distances. Unfortunately, 50 yards is about the most I can shoot, simply because I don't have access to a longer range.

Thanks!

Rule of thumb - Medium crimp on revolver rounds. Heavier crimp on lead bullets. Lighter crimp on plated bullets.

I always crimp and post size the round in a separate last operation. That is what the Lee 'factory crimp die' is for.

Nothing wrong with seating and crimping at the same time.

For consistent (roll) crimp trimming cases is a must , taper not so much.
I personally load mostly my own cast boolits & seat then roll crimp in a separate operation to keep from deforming the meplat & oglive AKA nose of the boolit & even on the few jacketed I load .

If you seat & crimp in the same operation & the nose of the bullet is deformed your seating depth CAN NOT be uniform or consistent wither roll or taper crimping.

Again as you approach hi pressure loads this becomes an important factor .
But in lower pressure loads not so much ,BUT ME as a reloader I like to remove inconsistencies even if I can`t shoot worth a hoot.

GP100man

I like seating and crimping separately. And I like pumping the press handle so adding an operation is fine with me. Now I have upgraded my .41 mag stuff with a Redding Competion seating die so crimping separately is required with that one.

If you do not trim all cases to same length, you will eventually have longer cases shaving lead or copper as you seat and crimp in the same operation. Not only does it make for dirty ammo in your cylinder, it can also raise pressure due to restricting case expansion upon firing.

As stated before, a good crimp helps in powder ignition as pressure has to build before the bullet releases. No only does this give more consistency it also helps utilize all of the ability of the powder charge. Years ago i was given an accuracy load for my revolver using blue dot. I tried the load and it was dirty. Horrible mess in my barrel. I told the officer that gave me the load how dirty it was in my revolver. He was shocked! Dirty? That load isn't dirty. Met him at the range to shoot. Our ammo looked identical, except for the crimp. He had a good concentric roll crimp into the cannelure. My crimp was whimpy and even missed the cannelure on some of the rounds. I tried my buddies ammo in my revolver. Much crisper shot to shot. Actually blew some of the crud out of my barrel.

I have shot some of my revolvers to 350+ yards. Consistency is everything that far away.

If you are serious about crimping check this out. Be sure to view the videos at the bottom of the page.
https://www.titanreloading.com/consistent-crimp

recumbent said:

If you are serious about crimping check this out. Be sure to view the videos at the bottom of the page.
https://www.titanreloading.com/consistent-crimp

Click to expand...

Umm, sorry but I think that's much ado about nothing. The "Consistent Crimp" handle is a torque wrench attached to the press to alert the user when a specific pressure is being put on the cartridge and allowing "precision" crimping. All the presses I have owned will only crimp as much as the dead stops or in the case of a "cam over" the crimp is only as much as the cartridge enters the die. None of these change from cartridge to cartridge, crimp to crimp and while a crimp is important, very few need a +/- .5 inch pounds of torque applied to the handle. Perhaps the 1,000 yard shooters can see a difference, but I'm a little doubtful about that. I have been reloading for a very long time and I have developed a feel for the amount of crimp applied to some of my handloads and can apply a consistent crimp by feel (especially 44 Magnum and 38 Special which I have reloaded many thousands) and for many/most of my crimping I adjust the die to a specific amount of crimp when the press reaches it's stop. But like any reloading tool, those that believe the new and improved method is better should buy one and find out for themselves...

Load six rounds and shoot 5. Remove the sixth round and measure to see if the cartridge has gained any length. If it has, you need a firmer crimp. Repeat until the last cartridge does not gain any length.