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45 auto chamber

991 Views 4 Replies 5 Participants Last post by  Dave Sample

I suspect my chamber is a bit short (Kart EZ fit, did it myself so could very well be my mistake) and I'd like to check it.

I know a headspace gauge works best, but does anybody know a rough depth (face of hood to shoulder) dimension for a 45 auto? I'm at about .892, which I think is about .007 short.

Appreciate any help,

He who fights and runs away had better run pretty damn fast.
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DT, you should try for about .905 from the chamber shoulder to the breech face. That is not necessarly the same as from the hood, in fact it is pretty much guaranteed not to be unless the barrel is fitted very tight in that area. Here's what I'd suggest to know exactly (well, pretty close in lieu of a gage or exact measurement)what you have. First, make a little tool for making sure you can measure to the chamber shoulder and not to the crud that may be built up on it. Take an empty case and file some serrations into the mouth of it, and then hack saw a slot in the case head, so you can stick it in the chamber, and press it to the bottom of the chamber while turning. If you've done the serrations right (like a little hole saw), you'll get down to clean bare steel in short order. Now take a case and measure its over all length. Add some layers of Scotch tape to the back until the thing measures say .900, and trim them with your pocket knife so they don't hang out over the edges of the case head. Pull your extractor out and with the pistol otherwise completely assembled but minus the recoil spring, chamber the round by just dropping it in the barrel, and close the slide by hand. Repeat this with additional layers of tape until you feel some resistance to closing, and that's about what your headspace is. Nominal case length is .898 but I don't think I have EVER seen one that long. If you are indeed at a true .892 you are too short, though. I believe you can easily get away with even .895, but .900 minimum would be better.

[This message has been edited by Ned Christiansen (edited 10-16-2001).]
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Originally posted by Ned Christiansen:
Nominal case length is .898 but I don't think I have EVER seen one that long).
Truer words were never spoken; neither have I. In fact, I have seen a few measure as short as .882. Wouldn't be surprised to find some even shorter than that. Case length dimension in .45acp just doesn't seem to be a major concern to the ammo manufactures. Sure would be nice if they would hold'em a little closer to spec.-TR
Ned, you stole my method! And I was going to make a killing on re-labelling tape dispensers as "Bench-Adjustable Headspace Measuring Tools."

I've seen brass in the low .880's OAL, and measured factory guns (Colt commercial, not rebuilt Gov't) that would gobble a .910" case. Gov't guns were even worse.

If the .45 worked at a higher pressure than 17K there might be problems.
As I've mentioned before, Fred's barrels need to be reamed by a chamber reamer of fairly stock demensions. I use a Cramer. They need some leade or freebore to work. Mosst smiths I know always ream a chamber on a match barrel.
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