Need more help 40 s&w Lee FCD

[schmooey1617]

Well, I taper crimp all my cast bullet loads so to get a proper "same tension" crimp on every case/bullet, I thought it was best to have every case the same length. The stated "trim length" in the manuals. It's just something I've always done for decades of crimping revolver cartridges so every case ends up crimped in the exact same spot of the bullet cannelure. Same spot, same tension, etc. As you know, most .357 mag and 44mag loads using say now Alliant 2400 and Winchester 296, require a a HEAVY roll crimp for proper ignition, standard deviation, complete burning of the powder.
I assumed the same tension crimp, and case length, and although it's a light taper, not heavy roll crimp, were equally important for good ignition and smaller standard deviation , hence accuracy as well. Certain fast burning powders such as Titegroup or Bullseye probably being more forgiving in that aspect though.

 

[RealGun]

Check to see if you've lost neck tension from the FCD, check before and after. If your sizing the bullet down, and lost neck tension, loose the FCD.

These are plated, not lead. The FCD should be perfect.

 

[schmooey1617]

I do not trim straight walled semi-auto pistol cases. If they are too short to headspace off case mouth, they will headspace off extractor.

I am currently sorting through over 8,000 indoor 9mm brass and separating them by headstamp for upcoming various THR myth busting range tests and none of them will be trimmed - https://www.thehighroad.org/index.p...ading-room-today.830858/page-50#post-11059079

BooYah, that there is a lotta brass. Awesome.

 

[LiveLife]

Well, I taper crimp all my cast bullet loads so to get a proper "same tension" crimp on every case/bullet, I thought it was best to have every case the same length.

Unlike revolver cartridges where "roll crimp" plays an important part for neck tension and chamber pressure build, "taper crimp" for semi-auto cartridges plays very little part for neck tension.

Reason is case wall thickness for semi-auto case is thinnest at case mouth where most of taper crimp is applies. As case wall thickness increases towards case base (Particularly 9mm case), it is resized case neck tension on bullet base that determines neck tension. So uniform resized case length for taper crimp is not necessary and most reloaders do not trim straight wall semi-auto cases. While many prefer to simply return the case mouth flare back flat on the bullet, I prefer to add .022" to the diameter of bullet for taper crimp amount which returns flare back flat and a tiny bit more (So for .355" sized 9mm bullet, I use .377" taper crimp).

Due to this reason, I seat 9mm 115/124 gr FMJ/RN bullets with shorter bullet bases deeper than longest working OAL (So instead of loading them longer at 1.150" to 1.160", I will load them shorter at 1.130" to 1.135" unless I am compressing powder charge at which point I will use longer OAL so as to not compress powder charge).

Here's case wall thickness at .100" below case mouth where most of taper crimp is applied - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10712225

Here's case wall thickness at .200" below case mouth where bullet base is seated and most of neck tension is produced - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10713822

 

[schmooey1617]

It would appear I've still got some long term habits and loading techniques to change and update from decades of loading for wheel guns. Glad I joined and met all you guys, I've already learned a lot. Each and every one of ya has learnt me something.
Tomorrow my first batch of plated bullets will be delivered, I finally decided to try some. I bought some 40 caliber, 165gr round nose- flat points for my 40 S&W's so we'll see how that goes and how they perform. I'll use the info I've learned in the past week and load up a couple batches. Can't wait to get goin on them.

 

[Walkalong]

Well, I taper crimp all my cast bullet loads so to get a proper "same tension" crimp on every case/bullet,

Taper crimp does not give you the desired neck tension, it merely removes the bell. Overdone, it can even hurt neck tension.

Neck tension comes from how much the sizer sizes the case down, how much the expander does, and the fit between the expanded case neck and the bullet.

 

[Walkalong]

Never mind, I see bds has already covered it.

 

[schmooey1617]

Taper crimp does not give you the desired neck tension, it merely removes the bell. Overdone, it can even hurt neck tension.

Neck tension comes from how much the sizer sizes the case down, how much the expander does, and the fit between the expanded case neck and the bullet.

Thank you. Yes, I did read that, first thing, when I bought my Lee taper crimp dies. It's not necessarily to actually "crimp" the bullet, but straighten the case mouth because semi's "headspace" on the case mouth not on the rim or the case shoulder.
But in the whole front section of the Lyman 50th edition, there is a whole chapter by Mike Venturino, whom I'm sure you all know of that had an incident with a 9mm load of his where by the time one of the bottom cartridges in the clip reached the chamber and was fired, the case blew out down near the head because due to recoil, even in the 9mm, the uncrimped bullet had worked itself deep into the case, he has been taper crimping ever since.
So even though it's not really a crimp, per se, it does just enough to keep bullets from creeping under recoil.
As y'all know, case mouths must be belled a little more to accommodate cast and poly coated bullets to prevent the scraping off of lube and poly coating. So yeah, I don't really crimp the bullet, I just straighten out the bell. So even though it doesn't actually say, "roll into the bullet" like it does with a cannelure bullet, it must tighten the case mouths "grip" on the bullet somewhat. Yes ??

 

[LiveLife]

I just straighten out the bell. So even though it doesn't actually say, "roll into the bullet" like it does with a cannelure bullet, it must tighten the case mouths "grip" on the bullet somewhat. Yes ??

Yes somewhat but not enough to prevent bullet setback. If you experience neck tension issue that results in bullet setback, primary cause will be insufficient neck sizing vs too much expanding of case mouth or flaring vs bullet diameter, not insufficient taper crimp.

incident with a 9mm load of his where by the time one of the bottom cartridges in the clip reached the chamber and was fired, the case blew out down near the head because due to recoil, even in the 9mm, the uncrimped bullet had worked itself deep into the case

This issue has been discussed multiple times and myth busting threads done before on this forum subcategory and why I now test neck tension by actually feeding and chambering rounds from the magazine and measuring bullet setback.

While I prefer no bullet setback, most jacketed diameter bullets (depending on pistol/barrel) can experience bullet setback when fed from the magazine and bullet nose bumps the feed ramp. Most reloaders fuss over "finished OAL/COL variance" but if you are concerned about consistency of chamber pressures and accuracy, it is the "chambered OAL/COL variance" that will actually dictate the consistency of chamber pressures and accuracy.

Actual bullet setback using different bullet types were myth busted on this thread using various headstamp cases - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

I consider bullet setback of a few thousandths acceptable but if you experience significant bullet setback or prefer none (for greater accuracy), consider using larger sized bullets that won't produce any bullet setback - https://www.thehighroad.org/index.p...re-sized-the-same.818806/page-2#post-10567453

 

[schmooey1617]

Strangely enough, Venturino's experience happened with a 9mm. I could see it more feasible to happen with a 10mm or a 45acp but like you say, maybe the bullet didn't necessarily methodically creep into the case in the clip, but hit the feed ramp awkwardly, compounded say with a thin walled case or some other anomally.

 

[vaalpens]

I am currently sorting through over 8,000 indoor 9mm brass and separating them by headstamp for upcoming various THR myth busting range tests and none of them will be trimmed

bds, If you want some help sorting your brass by headstamp and don't mind paying shipping one way, send some brass to me. I will decap and clean (wet tumble) them if needed, sort/bag them by headstamp, and then ship them back to you, paying for the shipping from me to you.

Looking forward to another THR myth busting chapter/episode.

 

[LiveLife]

Thanks for the offer but the latest box of several thousand 9mm brass I got were from RMR. They are "BrightFired" brass wet tumbled with stainless steel media and look like these - https://www.rmrbullets.com/shop/cas...rabellum/9mm-luger-brightfired-brass-cases-1/

 

[schmooey1617]

Thanks for the offer but the latest box of several thousand 9mm brass I got were from RMR. They are "BrightFired" brass wet tumbled with stainless steel media and look like these - https://www.rmrbullets.com/shop/cas...rabellum/9mm-luger-brightfired-brass-cases-1/

Wow, purty !!