Taper crimp - am I doing it right

[kaiserkudo]

Just wanted to check and make sure I'm applying my taper crimp properly.

Some info:

Dillion XL650 press with Dillon 9mm dies

Mixed brass (Lapua, Federal, WInchester)

Berry HBRN 124gr projectile seated at OAL of 1.125"

Using info from other threads, I seated a projectile into a sized (but not belled) case and got measurement of 0.374-0.376" diameter near case mouth.

Ran them through the tamper crimp die and they remeasured the same around 0.375'

I then proceeded to load 10 rounds as normal (without powder or primers) through the press.

OAL varied from 1.125 with the Lapua brass and up to 1.131 with Federal brass.

Diameter remained the same 0.374-0.375".

Going my that description and the photos below, does my taper crimp look correct. First time loader so I'm not sure what to look for.

They cycled through my gun by hand ok, one got stuck on the feed ramp and required a tap on the slide to feed.

As seen below some have a very slight gap between case and bullet, only really visible in photos.

[Steve RA]

Crimp looks ok, pull one and see how the plating looks. Should be no scrape marks or bare spots.

[CZinZA]

Looks like you need a bit more crimp.

I usually hold the crimped case to the light against a straight edge. I want the case to be straight where the bullet is seated, but with the very tiniest inwards movement right on the very mouth of the case (extremely small amount) - where the crimp die has just started acting. When this happens you will see a slight shiny ring on the mouth of the case. This has worked very well for me for decades now, without feeding, setback or headspace issues.

The best test of your crimp is to measure the length of a loaded round and then push it head first against the wall as hard as you can. Measure it again. If there is no decrease in length then everything is good.

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[prairiefire]

he best test of your crimp is to measure the length of a loaded round and then push it head first against the wall as hard as you can. Measure it again. If there is no decrease in length then everything is good.

Great tip - I'm a novice reloader as well. Will try this tomorrow.

[kaiserkudo]

I brought the taper crimp die down 1/8th of a turn. I can now see the bright ring at the case mouth CZinZA described. I pulled the bullets and they have a indented ring, but coating is intact. Too tight or good?

[CZinZA]

I think those should be ok, but you could try experimenting by backing off very slightly to reduce the deformation a bit.

the crimp die at the point where you now have it, very small changes make a difference. Try backing off with barely a movement on the die. You want minimal deformation of the bullet while still making sure of a tight grip. It's a fine balancing act.

Having said that - I think the bullet in your pictures would have shot fine and would have been safe from any setback.

I would be interested to see what other opinions you get. Although my method works well for me, there are always many paths to happiness

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[jayhkr]

I brought the taper crimp die down 1/8th of a turn. I can now see the bright ring at the case mouth CZinZA described. I pulled the bullets and they have a indented ring, but coating is intact. Too tight or good?

If you happen to duplicate the bright ring again could you take a picture of it like you did in your first post? I too am just beginning reloading so this will help me out as well!

[CZinZA]

Now that I'm briefly at a PC instead of using my telephone, I can type a bit more to explain the reasoning behind the crimping technique I have described.

Everybody will tell you that the objective of crimping a semi-auto pistol case is simply to remove the flare and straighten the case walls. This is absolutely correct.

However, I found it difficult to measure this objectively. Sometimes, IT CAN LOOK like all the flare has been removed from the case, but the bullet is not gripped tightly enough. Then you can suffer setback issues. Because I am an engineer and fussy about such things, I needed some way of objectively measuring or determining when the crimp has been correctly applied.

My method aims to ALMOST take the crimp too far, but only by a very very very tiny amount. Once the crimp die has finished straightenting the case walls and has removed all the flare, it will start to push the mouth inwards. I look for the signs of this, and make sure that they are just (very) barely there. If I can see them, then I know the crimp has been effective - and if I make sure that the amount of "over-crimp" is extremely small, then there are no negative effects.

As I mentioned above, the signs that I look for are a slight inward movement of the mouth of the case (using a straight-edge) and the shiny mark left on the mouth of the case when the crimp die starts to engage it. The inward movement must be very small (to avoid any headspace issues or bullet deformation), but if you can start to see it, then you know that the crimp die has been fully effective at removing the flare. The bright ring is also just the barest shine on the case mouth. Don't overdo these things, or you will have too much crimp.

The changes that you need to make to the die to achieve perfect adjustment are very small (fractions of a turn). It takes a bit of experimentation, but it can be done. Since I started using this method, I have never had a single failure to feed in any of my reloads, and there is no problem with accuracy or setback or headspacing. But, as I said, I am sure there are many ways of skinning this cat....

[noylj]

Do they chamber in your gun? If so, there is enough "crimp."

Can you push the bullet into the case with finger pressure? If so, you don't have a crimp problem, you have a sizing/expander problem that needs to be fixed immediately.

Do they mark the bullet? Is so, there is an excess "crimp."

There is no need to measure, but "everyone" seems to want to measure things, whether it matters or not (and not measure many of things that I find should be measured).

Simply looking at the round against a white background will tell you if the case mouth is excessive flared or not.

If one goes by SAAMI, a loaded 9x19 should have a case mouth OD of 0.3800" +0.0/-0.007, where 0.3800" is the targeted nominal diameter.

[RDA]

Now that I'm briefly at a PC instead of using my telephone, I can type a bit more to explain the reasoning behind the crimping technique I have described.

Everybody will tell you that the objective of crimping a semi-auto pistol case is simply to remove the flare and straighten the case walls. This is absolutely correct.

However, I found it difficult to measure this objectively. Sometimes, IT CAN LOOK like all the flare has been removed from the case, but the bullet is not gripped tightly enough.

I believe the case should be providing the tension and not a crimp. The act of crimping in this case should only remove the bell in my opinion and crimping further risks case springback and loss of tension. A properly sized case should hold the bullet and avoid setback.

[Steve RA]

Agree with the above, I'm a great believer in the "Wasp Waist Effect" as the case tension is what should hold the bullet tight enough to resist setback. If the bullet "sets back" by pushing it against the edge of a bench or counter, then you need to reduce the diameter of the expander slightly.

If you hold a straight edge, single sided razor blade works well, against the side of a factory case you'll see that the case is straight. This is what you should strive for.

I'd back off on the crimp slightly based on the pics of the pulled bullet.

[v1911]

Try a .378 crimp.

As stated above, it's the neck tension that hold the bullet in place. The only purpose of your crimp die is to remove the flare/bell.

[GJGary]

The picture with the ring from the crimp is to much crimp. There should be no visible lines. Agree with the wasp efecyt also but you shouldn't over flare the case which looks like what happened in the first pics.

[bowenbuilt]

Taper crimping in no way secures the bullet in the case. As has been stated only the case tension holds the bullet in place and prevents set-backs. When you taper crimp a plated or coated pistol bullet it should NOT leave the slightest mark on the bullet, if it does it is too much. You should only be trying to straighten the case flair and nothing more. Also you must flair the case mouth enough as to not damage or scrape the plating or coating when seating or you will start crushing cases. With no case flair and over crimping you are going to see large groups, tumbling, smoking and leading with coated or plated bullets.

[texasref]

When you said you see a shinny ring at the top, that's all you need.

The lightest crimp that produces that shine. I do that with all my calibers, and have no problems.

[kaiserkudo]

Thanks for all the advice guys. I backed off the crimp to 0.377-0.378 and there is no longer a mark on the bullet like posted above.

The Berry's seem slightly undersized at 0.355" and average case thickness is 0.013"(Lapua) .Or maybe my calipers just read slightly low- theyre only the cheaper digital ones.

In any case, the rounds pass the plunk test and chmaber/cycle ok. Going to start with an OAL of 1.14" and some conservative Win 231 charges and see how they go.

[CZinZA]

Glad you got yourself sorted out. Now go shoot lots pf homemade ammo!

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[kaiserkudo]

Update on how these went on the range

I went to the range today to test my Berry's 124gr HBRN 9mm with Winchester 231 - using my new CZ SP01 Shadow.
Not sure what I'm meant to look for for over pressure signs?? Flattened primers? Split case mouths?
I've placed a fired case from each group in the photos.

Test was done at 10m or around 11 yards for you state side shooters;) I was resting my wrist on a small sandbag and this is the third time I've actually fired a pistol.

Loading specs:
BRASS: Lapua
POWDER: WIN 231
PRIMER: CCI Small Pistol
Projectile: Berry 124gr HBRN 0.356" (9mm)
COAL: 1.132"
CZ SP01 Shadow with 11lb recoil spring - no other mods.


3.8gr - Soft recoil - all 5 shots cycled the slide - 1 flyer.


4.0gr - couldn't tell difference in recoil. Was having too much fun




4.2gr - Noticed a bit more of a push with the recoil. This was my best grouping of the session.


Second group of 4.2gr



4.3gr- Slightly more of a snap - still very managable and less recoil than factory ammo I'd been shooting last time.




I think I like the 4.2 and 4.3 loads - although they all functioned without failures and were all fun to shoot.

Next session I will take the distance out to 25m which should reveal more.

Thanks for the help guys.

Edited February 26, 2014 by kaiserkudo

[kaiserkudo]

One last group without the rest, unsupported 4.3gr

And off topic - but Slide Glide works awesome - feels so much easier and smoother when racking the slide.

Edited February 26, 2014 by kaiserkudo

[Hi-Power Jack]

Great groups at 10 m. Can't wait to see the 25 m. groups.

I don't see any signs of pressure on the primers.

What velocity did you get?

I'd say the crimp is PERFECT >..

[kaiserkudo]

Thanks. No chrono at the range today unfortunately. Will chrono the 4.2gr load on Saturday though.

[Steve RA]

I'd probably go with the 4.2 - pending results of the 25 yard test -, also I'd suggest you definitely use a rest for the longer test.

Looks like good results so far !

[Laughingdog]

The best test of your crimp is to measure the length of a loaded round and then push it head first against the wall as hard as you can. Measure it again. If there is no decrease in length then everything is good.

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The best test for your crimp is to measure it with dial calipers and compare that to the spec in your reloading book (0.381" or 0.380", depending on the manual you check). In fact, in my experience, Glocks are prone to keyholing issues if you overcrimp plated bullets.

As mentioned before, if you pull the bullet after crimping, and see any deformation of the bullet at all, you crimped too much. Granted, if you're running jacketed bullets, I don't think it's possible to cause those to deform.