44marty wrote:

I found out I was getting up to 800 fps variation with uncrimped, but only 30 fps or less variation from crimped rounds.

Marty, Please tell me this is a typo !!!

I don't crimp and the worst spread I've had is about 150 fps. On my .45-70, I've had shooters recommend that I don't even neck size, just slip the bullet in.

chambered221 wrote:

44marty wrote: I found out I was getting up to 800 fps variation with uncrimped, but only 30 fps or less variation from crimped rounds. Marty, Please tell me this is a typo !!!

No, unfortunately. I'll look up the actual numbers tomorrow when I get home - was going on memory (but, being older than dirt, this is not too reliable.) The way I remember it, I got a range from 2390 to 3245 fps with uncrimped bullets having the same powder charge. At any rate, the spread was extreme. The groups reflected this, but were still on the 8 x 11" paper at 125 yards.
Crimped loads grouped under 3/4" with the best group 1/8"

I then repeated an OCW test with crimped loads, and since am getting 1/2" groups or better consistently with the OCW charge: 77.1gr RL 22 pushing a 180 gr bullet at 2775 fps.
This is a pleasant to shoot load for whitetail (most of my shots come at 125 yards or less).
There was a second OCW node at just over the max listed in the reloading manuals. (The loads I gave the chrono data for were a little under the max - before I did my OCW testing.)

All shots were loaded single-shot (not exposed to recoil in the magazine), so no changes in cartridge length from recoil could have occurred in the uncrimped loads.

My guess is that I was getting incomplete, or at least inconsistent, powder ignition without a crimp. Lighter loads such as my whitetail load are supposed to be prone to this.

There may have been a problem with the chrono setup, or any number of other factors involved. I did repeat a test of crimped versus uncrimped after buying the Forster seating die (no crimp). I still got a wide spread of velocities. I will look up these numbers too, but I am sure it was also a spread in the hundreds of fps.

I hope this isn't too much information. I am hoping that someone smarter than I am can confirm my guess, or come up with a better one.

One thing that I am definitely sure of - I am getting great groups with crimped ammo - and lousy groups with uncrimped.

Glad to see the crimp has worked out for you as good as it has !!!

Some questions on the issue if you don't mind;
Are you using a mag primer?
Have you checked (measured) the ball expander in your re-sizing die or are you running a neck bushing without a expander?
What is your OAL? Possible you don't have much bearing surface of the bullet in the neck ???

Chambered, thanks for the input.
I am using mag primers - tried Rem and CCI I also FINALLY got hold of some Federal primers, but haven't had the chance to try them yet.

The more I have thought about it, an 800 fps spread seems impossible. I DID find the data showing 300 fps variance - still a TON - that I got with both HDY GMX bullets and Speer BTSP bullets, both 165 gr.

I also found my data from 220 gr Nosler Partition SP, also an uncrimped bullet. Here I had a 240 fps spread.

For the 800 fps variation, all I can think of is that I may not have reset the chrono when switching from 220 gr to 165 gr bullets. 800 fps is 25% to 30% of the total velocity. I can't see how this could have happened without causing hangfires.

The bottom line, though, is that uncrimped bullets have grouped very poorly (averaging 6" groups at only 125 yards) with a wide spread in velocity. Crimped rounds have grouped very well, with around 30 fps spread or less.

One of the first things that I thought of was that my die was giving insufficient neck tension. I did not measure the ball expander. I pulled a few bullets with an inertia puller, and it took 5 or more very heavy whacks to remove the bullet - so I figure that there is plenty of tension.

I am loading to SAAMI spec overall length. The bullets contact the entire length of the neck.

I am getting the same issue regarless of brass manufacturer, and with both factory new and used brass.

I AM STUMPED. I guess that I shouldn't worry about it. The crimped 180 gr bullets give me a great group, consistent velocity, and are exactly what I need for my whitetail hunting. It just bugs me that I have no clue what is causing this. It really does seem to point to inconsistent powder ignition with uncrimped loads in this rifle. But WHY ???

Uncrimped bullets tested (ALL gave wide velocity spread):
220 gr Nosler partiton SP
180 gr Sierra spitzer
165 gr Hornady GMX
165 gr Speer BTSP

Crimped bullets tested (BOTH gave slight velocity spread):
180 gr Rem PSP
180 gr Hornady RN

44marty wrote:

It just bugs me that I have no clue what is causing this. It really does seem to point to inconsistent powder ignition with uncrimped loads in this rifle. But WHY ???

I'd want to figure it out too !!!
I believe you'll find that the Federals will do better and you might not need the crimp.

Do some pressure check loads first, don't just swap the primer. If it is weak ignition you could go the other way and end up with more pressure than you want.

Please post back on the issue after you do some testing........I'm curious !!!

44marty wrote:

I pulled a few bullets with an inertia puller, and it took 5 or more very heavy whacks to remove the bullet - so I figure that there is plenty of tension.

I tried to use an inertial puller on my .270 bullets. With an unfired case, I could get a bullet out but it was more than 5 whacks. In a brass case that had been fired, however, I couldn't get the bullets out or barely move. I was concerned I was going to break the impact tool and had to return it. I figured the powder residue just caused too much friction. Maybe that is why I'm doing ok without crimps.

Inertia pullers can be tricky !!!
The tighter you grab the handle the harder it is to remove the bullet. Grasping the handle tight does not allow the full force of the blow to be transmitted in the proper way. What you are hitting also plays a role. It's best to use a good piece of hard wood that deadens the blow rather than a cement floor that allows it to bounce.

I ended up using a collet puller that grips the bullet and is used in a press. One of my shooting buddies had this set-up. It worked dandy and everything was reuseable.

I came across this tip to check crimping - from another website (northeastshooters.com)

The crimp does a couple of things. It keeps the assembly together during firing (with all that recoil, if it wasn't crimped, the parts would loosen up, and bullets typically go deeper into the cases). It also holds onto the bullet a little longer, allowing the powder to fully burn inside the case, allowing only gas to push the bullet out.

If your crimp isn't tight enough, the bullet will start on it's journey early, allowing burning powder to also travel down your bore. When it does that, a couple of things happen.
1) You get a LOT of smoke
2) Your gun gets very dirty and sooty
3) The bullet travels SLOWER than expected, because the powder didn't burn completely in the case, giving the bullet the full force of it;s expansion from the case to the muzzle.

So, as has been offered up many times, here's my tip for checking how good your crimp is:

Fire a round or two, at a blank piece of paper, from a distance of about 8 feet.

If you get only a round hole, the crimp is good.

If you get a round hole with a dark gray spiral pattern around it, the crimp is too loose. The dark gray spiral pattern is powder residue caused by burning powder, traveling down your bore.

44marty wrote:

1) You get a LOT of smoke 2) Your gun gets very dirty and sooty 3) The bullet travels SLOWER than expected

Ok, 44m, I'm going to throw a flag here on the info you found. I do not crimp my loads. I have loads that fill the case with powder.

When I shoot them:

1) I do not get a LOT of smoke. I do get muzzle flash which I also get on my crimped factor ammo.
2) My gun does not get dirty and sooty. I'll shoot 60+ rounds between cleaning and that is to remove any copper fouling I have which is slight.
3) My bullet does not travel SLOWER than expected. My measured velocity is within 100 fps of published load data with a shorter barrel.

Crimp is for holding a cannalured bullet against recoil.

A sized case will have a .001 interfearance fit with the bullet, in almost all cases- at the most (otherwise the bullet will de-size the case to same), and this will have more grip than a crimp.

And once the case and powder gasses start to expand that bullet is gone to the lands, crimp aint gonna hold it back.

slimjim wrote:

44marty wrote: 1) You get a LOT of smoke 2) Your gun gets very dirty and sooty 3) The bullet travels SLOWER than expected Ok, 44m, I'm going to throw a flag here on the info you found. I do not crimp my loads. I have loads that fill the case with powder. When I shoot them: 1) I do not get a LOT of smoke. I do get muzzle flash which I also get on my crimped factor ammo. 2) My gun does not get dirty and sooty. I'll shoot 60+ rounds between cleaning and that is to remove any copper fouling I have which is slight. 3) My bullet does not travel SLOWER than expected. My measured velocity is within 100 fps of published load data with a shorter barrel.

I do NOT crimp loads for my K-31 or my .204 and also do NOT get smoke, fouling, or a big spread in velocities. Velocity is very close to published data.

What I have been trying to figure out is the extreme variation in velocity (and accuracy) with uncrimped bullets in my .300 WBY Mag. I posted on this thread - .300 Win Mag loads - to ask if anyone is having a similar effect in their .300 Win loads.
I also do not get smoke or fouling from the uncrimped WBY loads, but do get more muzzle flash. With crimped bullets, 180gr - the same weight as tested uncrimped, I get very consistent velocity and extremely good accuracy.

The copied post from the other site was because I thought the "paper test" would be a good way to check to confirm my suspicion that I am getting poor powder ignition with uncrimped bullets. This is suggested as a possiblity in several reloading manuals.
I'm just trying to figure out what is going on here with the WBY.

*** stumped ***

Marty, I'm in agreement with what you've posted but believe it to be geared toward handguns and not necessarily rifle cartridges !!!
I hope you do some testing with the Federal mag primers.......I think you'll find they help.


stovey, If I understand you correctly you disagree with the fact the crimp has a second job of delaying bullet release.
I can assure you that this is true but not necessarily needed in all applications.
Slow handgun powders like W296 and H110 need a heavy crimp applied to allow time to achieve complete ignition.

Crimp is for holding the bullet still during recoil.

Shot 44m etc in TC's/singleshots w/o crimp and they do just fine.

Crimp is for keeping a bullet from jumping in a revolver and causing a jam/getting set back in a magazine from recoil.

Complete ignition is a product of a good recipe/propper pressure for the load. Not crimp. If crimp is used to clean up a load then...not sure what to say there.