[Bullet]

What’s enough & what’s to much? Any way to measure taper crimp? How do you know if you have it right?

[P95Carry]

Measuring can be done with vernier calipers ....... but as to how much?! In many cases like 9mm, the sizing of the case makes for a tight hold on the bullet anyways, the ''crimp'' sometimes being no more than cancelling out the slight flare applied before.

Too much would probably produce bullet distortion and real excess could make diameter so narrow as to prevent headspacing, which would be brass thickness times 2 reduction. - NOT desirable. Unlikely tho to go that far.

I think most of us experiment - I use a mild taper crimp which cancels flare and just a bit more. Have to see if bullets remain in place with no change of OAL, as produced at time of loading. Might be worth taking a test set of rounds ... fire one ... check next in mag - and also chamber a round ''sling-shotting'' to see if bullet is set back at all when it hits feed ramp.

If using .45acp in a revo then desirable probably to have more crimp, to avoid intertial disturbance to seating depth - in this case bullets can tend to try and come out of case.

Main thing you do not want at all - is seating depth increasing thru cycling in semi - which with 9mm in particular can raise pressures - real quick. Maybe sacrifice a loaded round and use grips on case and bullet - see if bullet will turn. If it won't turn then probably crimp/case grip is good.

[Deavis]

Bullet,

I've always used a taper crimp on my pistol loadings and for some calibers, like the 357 Sig, it is mandatory to avoid bullet set back. You have to tension the neck to hold the bullet in place. The Sig is the only cartridge I've loaded (9mm, 40S&W, 45, and 10mm are the others I do) that I spent any significant time trying to work out the right crimp.

For the other calibers I simply sized the brass, measured the case mouth diameter, belled it just enough to get the bullet in, and then tapered it so it was just under the size I started with (belling removed). I make sure that it is above the minimum diameter set forth in the SAAMI stadard and that it is close to a a factory load with similiar bullets. I've done the setback test (see below) on those rounds and never had a problem.

For the Sig, I used a similiar process and at the end I tried to get the bullet to setback by turning the cartridge over and pressing it bullet first into the bench my hand. If the OAL changed at all, I increased the taper and tried another round. Once I found a setting that had no setback on 5 rounds, I measured it and it was almost exactly what the Factory Ranger Talon ammo was. I've "sling-shot" and done measurements when firing the weapon and the OAL stays very close on those rounds.

I've never reloaded for a roll crimp, so I can't really comment on that. Be aware that if you are reloading plated bullets, it is very easy to over crimp. The bullets are very soft and a crimp that gives a nice tight fit on a jacketed bullet will dig into a plated bullet. I usually crimp them and pull the bullet to make sure that the crimp isn't too tight. The impressions the case mouth leaves are very easy to see if you are over-crimping and tearing through the plating.

I hope this helps!

[Bullet]

The reason I’m asking about taper crimp is that I recently purchased a 50 Beowulf upper. These cartridges headspace on the rim hence taper crimp. The load I’m loading calls for 38.8 gr of H4227 powder. I usually load for revolvers (roll crimp) or rifles that headspace on the shoulder (no crimp). With the 50 Beowulf using a lot more powder than anything else I taper crimp I wondered about the amount of crimp I should apply. I test most of my taper crimps by pushing on the bullet to see if I get any setback. With the 50 I’m not worried about setback. I’m wondering how the crimp effects pressure or powder burn. In 44 Mag when using slower powders it is recommended to use a heavy crimp. I believe with slower powders the heavy crimp is to hold the bullet a little longer (before movement) so that the powder will have a better ignition or a more complete burn. With 38.8 grs of powder I believe I need a heavy taper crimp and was wondering if there was a way to measure it. If I measure the cartridge case at the base of a seated bullet and then measure at the end of the case I believe this should show how much crimp is applied but what amount of difference between these two measurements would constitute the right amount of crimp to get a complete powder burn if possible? It’s funny that in someways reloading is very precise but checking crimp by pushing on the bullets just doesn’t seem very precise. Any help with this or comments would be appreciated.

[P95Carry]

Bullet - the crimp as a ''powder burn starter'' is only IMO of use when a stiff roll crimp - per 44 mag etc.

I honestly don't think with taper crimp this is worth worrying about.

I still think a test for turning of a bullet gives a good idea of ''case grip/hold''. Measurements are relative but to what? Sized case, fired case? I reckon you have to go thru a short period of load testing and increase taper crimp until you are satisfied.

Log the dimensions of a finished round - relative to the sized case .... and look up the max diameter too - as a reference. From then on - I think this is ''development'' time - IMO, no hard and fast answer.

[Bullet]

P95Carry

I think you might be right. I guess this is like asking which load will shoot best in my rifle.

Thanks