Geco 158 grain truncated cone FP FMJ .38 & .357?

[OlongJohnson]

I picked up a box each of GECO .38SPL and .357M.

The case mouths do not appear to have any crimp at all. They are not flared out, like the FM junk I've commented on elsewhere, but just completely straight.

I'll shoot them carefully and see how it goes, but do not think I'll reorder .357s. Might be OK for practice .38s if they happen to be priced better than anything else when I need to buy.

[Wayne Dobbs]

I picked up a box each of GECO .38SPL and .357M.

The case mouths do not appear to have any crimp at all. They are not flared out, like the FM junk I've commented on elsewhere, but just completely straight.

I'll shoot them carefully and see how it goes, but do not think I'll reorder .357s. Might be OK for practice .38s if they happen to be priced better than anything else when I need to buy.

I wonder if the projectile is lacking a cannelure to crimp the case mouth into?

[TiroFijo]

I use taper crimp on my 38 spl and 357 loads. RCBS dies.

Works veeery well.

[willie]

I have a batch of Federal's +P FBI load. All show that crimping was omitted despite there being a crimp groove. Omitting this step put the entire batch in the shit category, though I fixed the problem by running them through a crimp die.

[TiroFijo]

I have a batch of Federal's +P FBI load. All show that crimping was omitted despite there being a crimp groove. Omitting this step put the entire batch in the shit category, though I fixed the problem by running them through a crimp die.

There was no crimping from factory? Or was it a taper crimp that is mor difficult to see?

Did you perform a pull test with an inertial hammer or something else?

[willie]

No pull test. Examination in conjunction with experience showed that mouth not crimped into available groove. Taper crimping by itself would not have been sufficient.This omission violates a best practice in reloading centerfire rimmed revolver cartridges. Had this ammo been used in a lightweight titanium J frame, some bullets would have jumped crimp and interfered with cylinder rotation. With really hot ammo, crimp jumping can occur even with correct case mouth tension and crimping into a crimp groove. Taper crimping is a requirement for straight wall pistol rounds headspacing on the case mouth. Current Lee handgun dies incorporate the feature even in revolver calibers but do not omit the traditional case mouth crimping in these.

Taper crimp dies were at one time avaiable only from specialty makers and were offered in .38 spl and .45ACP. Targeted customers were bullseye shooters. The long defunct Star company was one vendor. Before the advent of commomly supplied taper crimp dies, loading reliable pistol ammo required matching dies to cases and bullet diameter. Otherwise, achieving adequate bullet pull would not occur. Lead bullet shooters were able to use their chosen bullet diameter to achieve this end. Also using thicker military cases was another tactic.

We can make our ammo go bang but will eventually experience difficulty by not observing best practices. Ammo companies crank out 100's of millions of rounds per year. Sometimes batches escape QC measures. My opinion is that my Federal ammo was an example.

[TiroFijo]

I've shot maaany thousands of hot loaded 357 mag with taper crimp, no problem whatsoever... I'm pretty anal about reloading, decades doing it.

Most of them were not in a lightweight revolvers, but I do perform pull tests in my reloaded rounds (with an intertial hammer) and you can get a very firm grip on most lead bullets with taper crimp, even if they have a crimping groove or not. I do agree that is perhaps a bit simpler with a roll crimp, and you could get an even firmer crimp with it.

I've also shot plenty of 38 spl +P in lightweight snubbies (steel and aluminum frames, no polymer, Ti or Scandium), with no problems. I use the same set of RCBS dies for 38/357, just seat them differently on my Dillon 550 with spacers I made.

I shoot 90% hard cast bullets, several designs. But some jacketed bullets (and even lead or plated ones) don't have a crimping groove or it is very shallow. With these bullets it would be better to used a taper crimp, or you are swaging a groove into the bullet when you use a roll crimp. On the other hand, a properly adusted taper crimp is very versatile. I've seen revolver factory ammo with roll crimp pull bullets due to inertia (perhaps too little crimp, perhaps soft case at the mouth?), and revolver factory ammo wtih taper crimp and no problems.

My 44 mag dies do have roll crimp, but that's because the Dillon set came that way. Since my RCBS 38/357 set came with taper crimp and never gave me any problems, I never had the urge to buy a separate roll crimp die.

[richiecotite]

I have a batch of Federal's +P FBI load. All show that crimping was omitted despite there being a crimp groove. Omitting this step put the entire batch in the shit category, though I fixed the problem by running them through a crimp die.

I got a couple of boxes in a trade a few years back and that was my experience with it as well. We’re I to ever carry it I’d run it through through the crimp die.


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[willie]

Tiro, you know what you are doing and are getting excellent results.

[OlongJohnson]

Dumped the box of .357s on the bench and visualed all of them. Only one showed any witness mark from a taper crimp die, and had about 0.004" taper crimp, looking just-so. The other 49 cases were 0.375 all the way to the mouth until the calipers slipped over the edge onto the bullet (they all looked straight, and I measured about half a dozen), and not one of them showed any witness mark. The edges of the case mouths felt proud and snaggy, some with very tiny burrs and lumps from handling impacts.

The Sierra reloading manual recommends a taper crimp for most non-cannelure handgun bullets. I would think that .357 cartridges should at least show evidence of having been contacted by a taper crimp die.