COAL: Considerations for handguns

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Tony k

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I don't fully understand how cartridge oal affects semi-auto handgun cycling. I know that you need to seat the bullet deep enough to fit in the magazine. I know you need to seat it deep enough to ensure that the bullet does not make contact with the rifling. On the other end of the spectrum, you don't want to seat the bullet too deep so as to create pressure issues.

I've been working with 200 grain .45 caliber Hornady XTP bullets for use in a Kahr CW45 and a Taurus PT1911. I'm loading them to 1.230" oal with both power pistol and longshot. The rounds fail to feed about 5% of the time. The FTF looks the same in both guns: the round makes it past the feed ramp, but makes contact with the top of the chamber at too steep of an angle, thus preventing the round from chambering.

Yes, there are other factors to consider such as condition of the magazine, the strength of the recoil spring, extractor issues, feed ramp issues, etc that are the fault of the gun, not the load. For the sake of discussion, let's assume those aren't the issue.

Can you change oal to minimize this type of FTF? Make them shorter? Make them Longer? Or am I barking up the wrong tree?
 
Do both of the pistols reliably feed and chamber factory JHP ammunition?

I usually determine the max OAL/COL first using the barrel and incrementally decrease the length until the dummy round (no powder/no primer) feed/chamber reliably from the magazine when the slide is released without riding it.
 
bds-- I've never tried factory ammo with XTPs in the Taurus, but I get similar FTF issues with factory XTPs in the Kahr. I know that makes it sound like a fools errand, but I have a lot of these bullets and when they do shoot they are pretty accurate. Plus, I just want to treat this a learning opportunity. Take something that apparently does not work, figure out why, and make it work.

Generally, both pistols prefer bullets with rounded ogives, rather than the straight ogive on the XTP. Both pistols function most reliably with Hornady Critical Duty and Critical Defense.

Thanks for the link Steve4102. Basic steps in that great thread:
  1. make 45acp dummy load at 1.275 oal, and back it off until it passes the plunk test
  2. once it passes the plunk test, make sure it fits the magazine
  3. once it fits the magazine, reassemble the pistol and begin cycle testing dummy loads from long oal to shorter oal
  4. once you have an oal that reliably cycles, begin load development with minimum charge. Work up load as need/ desired. If you end up with a relatively short oal, be cautious with loads at the higher end of published data.

I guess I was going about it wrong. I was starting with the oal listed in the hornady manual, then standing there scratching my head wondering if I should go longer or shorter. This system is much more straight forward.

Thanks:)
 
I drop a sized empty case in to the chamber this shows me the proper head space in relation to the barrel. I seat a bullet in a empty unprimed case until it matches the same depth as the sized empty case this is the Max COL. I make at least three dummy rounds with no crimp and check for function and feed with the magazine, I shorten the COL as needed. I usually find myself shortening the COL in this process until it the dummies cycle through the gun without a hitch, I look for dings in the bullet and check for set back.
 
Honestly, I feel pressure relativity is something that is managed during work up. In other words, if you work a load up at a particular oal, you'll be fine. It's when you shorten the oal with an already developed load, that you get into trouble.

As far as functional oal's, I've pretty much always used the longest oal that will fit the firearm magazines and chambers, of the firearms I own in that caliber. As long as I feel it's seated deep enough to provide good neck tension, I use the longest, or longer oal. This has rarely, if ever caused me a feeding problem, or any problems for that matter.

BTW, I only load full throttle jacketed Longshot loads. Really, really like my Longshot.

GS
 
Gadawg88 said:
The following link will tell you everything you want to know. It is written with the 38 super round in mind, but the concepts apply to all semi-auto rounds. Particularly read the part on bullet shape and clambering and feed timing.

http://38super.net/Pages/Overall Length.html
Click to expand...

The discussion on timing and tip over angle is EXACTLY what I had been trying to work out in my head. Thank you Gadawg.

I went through the whole max oal establishment with my Kahr CW45 and Hornady XTP bullets this evening (again). Bullet passes the plunk test at about 1.235. However, rounds will not reliably chamber until 1.220. At that length,I can chamber the first round of a full magazine even while easing the slide forward. Anything longer causes the type of malfunction described in my OP even while chambering a round with the slide release as recommended in the Kahr instruction manual. That's counter to the "timing and tip over angle" concept from the 38super.net link because the longer oal should result in shallower tip over angles.

I think I might be barking up the wrong tree. I'm beginning to think I have an issue with the extractor interfering with the rim during chambering. I suspect that the extractor is restricting the head of the case from sliding into position against the breech face unless the case head is almost parallel to it. So...maybe not a reloading topic after all.

Nonetheless, I still think this has been a good discussion about establishing oal for pistol loads. Yep, it comes up all the time, but this is the first time I've understood feed timing and tip over angles. Good stuff! Thank you all.

BTW Gamestalker: You've helped validate my love of Longshot in 45acp. When it comes to loudness, recoil, and muzzle blast, is there anything that compares :D? Sure, Powerpistol and one or two others generate similar velocities, but my friends tell me they can feel the percussion of my full house Longshot loads in 45acp when they are standing 20 yards behind the firing line. I think JMB would approve :), but I digress...
 
You might try polishing the breechface to help the case head slide up into position. I would also suggest polishing the feed ramp, but every Kahr I've ever seen has a feed ramp the looks like a mirror.

This problem sounds an awful lot like a gunsmithing solution.
 
Funny thing; I have Kahr and Kel Tec pistols in 380 Auto. The Kel Tec will shoot anything I put into it. The Kahr chokes on hollow points.
 
The gun has been prepped as described on kahrtalk, and it has about 2200 rounds through it. It handles ball ammo just fine, but is finicky about JHPs.

I think I've done about as much as I can with regard to OAL to make this bullet feed in this gun. I'm with toprudder; time to look at gunsmithing solutions.

Still, I'll follow through and load up some live rounds at 1.215-1.220 oal and see what happens. I'll probably use longshot powder :)
 
In my cast I usually load to the longest length possible short of exceeding the SAAMI limits. Like many others I will start at the SAAMI limits and seat the bullet deeper until the rounds reliably pass the plunk test. If you have more than 1 gun using the same cartridge load all the ammo to the gun with the shortest OAL needs.

There is another method new reloaders can use, set the OAL to factory ammo of the same type. Factory ammo has to be set to reliable work in a WIDE range of handguns. If you're loading a 230gr XTP bullet 45 Auto round you can set the OAL to factory Hornady 230gr XTP Hornady 45 Auto ammo.

Be careful when changing the OAL from what the load data uses. In short low capacity cases like the 9mm or 40 S&W small changes can increase/decrease pressures more than you would expect.

I hope this helps some.
 
tony k said:
Still, I'll follow through and load up some live rounds at 1.215-1.220 oal and see what happens. I'll probably use longshot powder
Click to expand...

Loaded up 30. OAL 1.217-1.221 with 200 grain Hornady XTPs. 8.0 grains of longshot. All fired well out of CW45. no failures.

ArchangelCD, I've tried factory XTPs with a high rate of FTFs. Dang it, I always forget to check the OAL. My guess is that they are about 1.230"
 
kitsapshooter said:
Just worked through this issue. It is the ogive of the bullet you are using.
Click to expand...

I think that's a big part of it. I have no problems with hornady's FTX bullets they use in Critical duty and critical defense. I attribute that to a "pointier" profile and the rounder ogive. Had reliable cycling with Remington ultimate defense compact and federal guard dog as well. Both of those have a round ogive as well.

But like I said. I tested 30 today loaded at about 1.220 and they ran flawlessly. With this bullet, you really can't go much deeper than about 1.215 before the shoulder/ogive is deeper than the case mouth. Don't know if that's safe.

I'm researching this from a gunsmithing perspective as well. I'm getting odd gouges on the case rims. The firing pin track and the ejector mark make it very easy to tell the orientation of the case when fired. All the cases have this strange gouge at about the 7 or 8 o'clock position on the edge of the rim. I think the case rim is making contact with either the bottom of the ejector or something on the slide while chambering. This might be the real reason for the chambering issues, and a short oal might be a band-aid/ work around.

Sorry that this is a digression from reloading, but sometimes ammo construction, gun design, and gun smithing are all tangled together.
 
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