Is my taper crimp tight enough?

[rfwobbly]

Therein lies the potential problem.

Precisely, my dear fellow. When you run these crimp die adjustment tests, you have to start with a new "test cartridge" every time. You cannot make a small adjustment and expect the crimp diameter on an already crimped cartridge to be reduced by an additional .001", the materials just won't allow it.

However, on the good side, in my experience once the crimp diameter is set, you're good for a year or more. Especially if you have your die sets in a "tool head" where their adjustments are not disturbed between use. So you won't need to do that testing over and over with each new bullet.

 

[LiveLife]

the aol is 1.250 , i guess it is seating so deep getting into the roundness of the bullet itself. I found some load data for accurate 2 and this bullet, and that is the aol they called for.

Should I play with increasing the aol a bit to get the gap tighter, or leave it alone??? I test fired a few and they did cycle and shoot good

slick001, OAL is based on the bullet nose profile and whether the loaded round will feed/chamber reliably from the magazine. You can try 1.260" and 1.27" and see if the gap problem goes away.

Most 230 gr RN profile at 1.250" OAL have fed in all pistols I have shot. BTW, Winchester white box factory loads them to 1.275"

As others posted, you might be deforming the bullet with such tight taper crimp of .470". I taper crimp jacketed/plated .451" bullets to .471"-.472" and .452" lead bullets to .472"-.473".

Fact: No amount of proper taper crimp on an auto case can make up for poor neck tension.

As to taper crimp vs neck tension, this hijacked topic may warrant another thread discussion.

Here's my experience. I have flared case necks too much (especially in tapered 9mm cases) to the point that the bullet would move when I pushed on it with my thumb. I thought if I applied more taper crimp, the bullet would not move - Well, no. Applying taper crimp did hold the bullet, but the hold was not enough when I pushed hard on the bullet against the bench top, which is my proof of neck tension.

Well, there's some evidence that excessive crimp can actually decrease neck tension, especially with lead bullets.
Brass can exhibit "spring back" ... Lead really doesn't show this property. So, you can "size" the lead down during crimping, unintentionally, and have the brass return to a larger ID after the case is removed from the die.

If you use range brass, the hardness/characteristics of brass will vary depending on headstamp, powder charges used and number of times it was reloaded. This is especially true of smaller high pressure case like 9mm. When I applied even more taper crimp less than the diameter of the bullet+thickness of case neck, I found myself deforming the bullet (resizing) whether it was jacketed, plated or lead. Increasing the taper crimp did not increase the neck tension; instead, it reduced the diameter of the bullet and bullet moved even more (on the tapered 9mm case the bullet actually fell into the case).

if you can push a bullet deeper in the case by hand before taper crimping ... your expander is too big and needs to be turned down a thousandth or two smaller.

+1. Your sizing die reduces the case diameter all the way down so the case wall applies pressure on the bearing surface of the bullet to the base. Taper crimp die doe not reduce the case neck all the way down to the bullet base, just at the case neck where nose profile starts to reduce in diameter. So if the expander die applies too much flare to increase the resized diameter of the case, taper crimp die reducing just the case neck end will not add to the neck tension ENOUGH to hold the bullet when pushed hard against the bench top.

 

[mdi]

Don't know where people pick up this nonsense. Its certainly not from practical experience. I have taper crimped both reloads and factory ammo specifically Speer Gold Dots to correct set back problems when feeding in particular handguns of mine. The bullets where indeed held in place by the taper crimp.

Theory: "Neck tension holds the bullet in place and not the crimp". Fact: Neck tension is the result of how tight the case fits against the side of the bullet and that fit is determined by the ID of the case. The smaller the ID the tighter the fit.

Fact: Taper crimp reduces the ID of a portion of the case against the bullet after seating.

Rational conclusion: Taper crimp increases the neck tension holding the bullet tighter.

I can only give my personal experience shooting 45 ACP in my Rock Island 1911 and my Ruger P90. I can load ammo without any type of crimp and get no bullet movement prior to firing. I cannot push the bullets deeper with my thumb on the ammo I've tried. So, if it's not neck tension holding what is? I don't remember Super Gluing them...

FWIW in my turret I use a Lee sizing/de-priming die, a Pacific die for flaring, a Lee seater die, and an RCBS taper crimp die (just enough to de-flare the case no crimp)...

 

[918v]

Theory: "Neck tension holds the bullet in place and not the crimp". Fact: Neck tension is the result of how tight the case fits against the side of the bullet and that fit is determined by the ID of the case. The smaller the ID the tighter the fit.

Fact: Taper crimp reduces the ID of a portion of the case against the bullet after seating.

Rational conclusion: Taper crimp increases the neck tension holding the bullet tighter.

Wrong again.

The brass and the copper have different springback rates. Brass springs back more. Copper springs back less. Pressing brass against copper will reduce the diameter of both, but the brass will still spring back more, hence you will have less case tension.

The only way a round will stay together is if the ID of the case is smaller than the OD of the bullet. Once you start to press brass against the bullet via the taper crimp, you make the ID of the brass case and the OD of the bullet THE SAME. If both are THE SAME, you don't have the tension necessary to hold the bullet in place.

 

[Ridgerunner665]

Its too tight...don't crimp it, just remove the "bell" (.471")

Case tension, not crimp, is what holds 45acp bullets in place...crimping loosens case tension.

 

[nulfisin]

Why not just drop a round in the barrel?

Seriously. If the round gives you a nice "plunk" sound and is the right overall length, what are you worrying about? The bell is obviously gone, which means your crimp is tight enough.