C.O.L. vs factory length


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edpm3
December 27, 2007, 08:48 PM
Brand new to reloading. I have the basic equipment and for the last couple of weeks have been reading and doing case cleaning and preparation. I have just started to press some practice bullets (no primer, no powder) to get the dies set up and learn the process. Caliber is .45 ACP and I'm using FMJ round nose 230gr bullets. Basically the same as Remington hardball that I use for general range practice.

My question concerns cartridge length. The manuals list C.O.L. as 1.275". The factory Remington cartridges I have measure 1.257". So what I'm asking is, for making range practice ammo, is it smarter to press directly to match the factory (in this case, Remington) length, or should I start at max length and then try progressively shorter lengths and see if accuracy changes? Thanks.

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Jim Watson
December 27, 2007, 08:52 PM
Book length is the SAAMI maximum. Most factory and reliable reloads are a bit shorter. I am loading my .45 hardball to 1.255" - 1.260" which is essentially the same as what you are seeing from Remington.

John C
December 28, 2007, 02:10 PM
To address another point in your post, COL is probably one of the last variables to look into when loading for accuracy in pistols. I shoot bullseye with some top shooters, and none of them have adjusted for accuracy by testing different COL. They simply find the COL and crimp that works in their tight chambered guns and then focus on finding the powder type and charge that works best in their pistol.

In fact, most top shooters are shooting 185 or 200 grain bullets, which are shorter than your 230 grainers. The critical factor when loading these bullets is ajusting the shoulder (in the case of SWCs) or ogive (round nose) so that the cartridge will chamber reliably.

What kind of pistol are you shooting?

-John

jfh
December 28, 2007, 02:37 PM
...and a third variable is the location of the cannelure, if the bullet you are using has one.

However, most of my .45ACP loading is done to accuracy standards using a 200LSWC. Since the load is not +P or +P+ loading, I set up the OAL to provide 100% feeding on my 1911s.

With the 230 gr. RN FMJ, you could consider starting with using the same OAL as a factory round that chambers reliably--or, in your post, 1.257." As long as you aren't shooting max power loads, you could then try shortening--but there's no reason to; get the feeding right.

edpm3
December 28, 2007, 11:00 PM
Thanks for the information.

The .45s I shoot are an H&K USP Compact and occasionally, a Colt Mk IV/70.

lordgroom
December 29, 2007, 12:29 AM
Can someone explain the process of adjusting the shoulder, ogive, and/ or cannelure?

Thanks

jenrob
December 29, 2007, 01:28 AM
Bullet on the left has a cannelure on it it is a place to apply crimp if you would like bullet in the center is approx the ogive this is the best and most uniform part of the bullet best place to measure for length also the first point on the bullet that is going to make contact on all sides point just before bullet is at full diameter. far right bullet is a Lasercast 200gr LSWC it has a shoulder. adjusting the depth will determine where the shoulder is if you have feeding issues you can adjust the length if it is catching the shoulder or other issues.
http://i228.photobucket.com/albums/ee13/jen-rob/000_0002.jpg

ArchAngelCD
December 29, 2007, 03:15 AM
The data provided in load manuals is correct only if you use the same components and COL. If you seat the bullet deeper than listed in the data you will get higher pressures than listed in the data. If you change the seating depth by only a few hundredths and you aren't at the Max charge you probably won't even notice the difference. I'm mentioning this because you should keep it in mind because in some high pressure rounds slight changes can cause over-pressure when you are near the Max charge.

jenrob
December 29, 2007, 05:47 AM
You can also get higher pressure by setting the bullet out farther. more than likely the rounds wont fit in the magazine if you have them set out far enough to cause a pressure increase.Most of the high pressure issues you would run into are just as ArchAngelCD stated, but can also happen the reverse

lordgroom
December 29, 2007, 04:49 PM
Jenrob- That was very helpful. Thanks for the reply and the photos.

jenrob
December 29, 2007, 05:56 PM
anytime. I look at it this way one of these days I might be asking you "hey how did you do that?"

buenhec
December 29, 2007, 07:26 PM
I started at 1.275 just like the Lee book said. Once I shortened it to 1.233 I had way less feeding problems. I still have a malfunction every 60 rounds but I am tracking that to something else. I am loading 6.5 of Unique with 230 RN.

John C
December 30, 2007, 01:18 AM
lordgroom:

To add to jenrob's excellent explanation, the general guideline for determining the appropriate amount of shoulder on a SWC bullet is to have a bit of lead the thickness of your thumbnail showing. The purpose of the shoulder of a SWC bullet is threefold: first, it's to cut a full-caliber hole in game or paper (important for scoring); second, the distinct shoulder maximizes the amount of bullet in contact with the grooves of the rifling, for better internal ballistics; and third, and most important in the context of this thread, is that the exposed shoulder of the bullet acts as a bearing as the round is chambered. Too little shoulder, and the brass of the case is contacting the feedramp, leading to possible malfunctions. Too much, and the bullet won't chamber.

-John

The-Fly
December 30, 2007, 01:37 AM
I use 230gr RN lead, and i run my COAL at 1.235. Works just fine out of my XD.

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