Does Throating a Pistol Increase Accuracy?

[yodogsandman]

Does throating a pistol increase accuracy? This weekend I had a chance to shoot my Dad's 1911. With the snow so deep and not plowed, I was only checking for function at 50 Yards. Didn't bother to set up a target and just shot for center of mass of the target backing. Happily, it shot a magazine of my reloaded 200 gr SWC 452460"s with no problems at all. The big surprise was when I went to retrieve 100 yard rifle targets and saw the holes in the snow behind the 50 yard target. I wasn't even trying hard but, all shots were inside the size of a soccer ball. This is all I can do with my RIA with aimed fire! Now, his barrel chamber is quite different from my RIA chamber, his is nicely throated and mine is not. I'm wondering if the throat makes that much difference. Can't wait to shoot his again and see how I do when really trying.

 

[freebullet]

"Does Throating a Pistol Increase Accuracy?"

Sometimes.

It makes the possibility of better fit with a broad(possibly more so than unthroated) selection of loadings.

There is a point of diminishing returns.

 

[Reed]

When a semiautomatic barrel is throated, what happens to the headspace shoulder? In the picture I have in my head, it gets touched. Just looking at my barrel, the shoulder looks pretty narrow as it is.

 

[gman]

Throating a barrel on the 1911 is done more for reliable feeding of various bullets. Correct me if I am wrong here but that has always been my understanding. Would that help accuracy? Like freebullet said, maybe.

 

[Reed]

Several folks have urged me to have my 9mm throated for the very reason you give. My question is what happens to the shoulder that the cartridge headspaces on? I'm guessing it gets narrowed/tapered somewhat?

 

[freebullet]

The headspace is not changed unless something goes horribly wrong. That is done with a chamber reamer.

Your lead in to the rifling looks nice, Reed. The throat entrance looks tight to me. It should have the same gentle taper the start of the rifling employs. Most guns that need the throat opened have an abrupt start at the rifling too. That leads me to believe your example has been shot a bunch. You just want it open enough for the proper bullets to fit without being loaded so short to prevent achieving full velocity due to running into pressure signs earlier in load development than should be, or improper bullet to throat alignment/swage damage to occur upon firing.

Here's a bad one-

Bad chamber, bad throat, bad rifling lead, bad, bad, bad! That's a new ria.

Yours just need the ridge tapered on this one.

Let's not forget, shot out barrels have to much throat. It's a critical area often done wrong at the factory.

I'm no expert or gunsmith but, that's how I see things.

 

[Reed]

Freebullet, thanks. I'm beginning to understand what we're talking about here. Your arrows on my picture helped. Maybe shooting has modified the lead into the rifling, but it's had probably under 200 jacketed bullets ever fired in it, and somewhere between 1500-2000 cast rounds. Would that do it?
Reed

 

[fiver]

not really.
I was looking at it like it had 4-5,000 jacketed rounds through it.

a better done throat has a gentle taper into the rifling like yours shows only the edges of the rifling are square to the chamber and ramped at about a 40* angle.
I think [like freebullet point's out] that if you took out that sharp edge in front of the chamber [and had the end of the chamber cut square with just one smooth face] you'd have better luck.

I'd bet that RIA is cut slightly off center some.

I wish you guy's would quit showing pictures of new pistol chambers, I stressed enough when I bought my 9mm worrying about this stuff.
now I'm just seeing picture after picture of exactly what I was afraid of.

 

[Brad]

You need to get the bullet from case into rifling without a sharp edge shaving one side of the bullet. A proper throat does that.
I had my 1911 throater and it no longer leads with loads that leaded in the past. I had it done to reduce leading, not for improved accuracy. Reducing leading certainly isn't going to make accuracy worse!

 

[Ian]

That step at the end of the chamber is funky, almost like the reamer was chipped. How does it headspace with the plunk test?

My camera sucks almost as much as my photography skills, but here's a sorta decent shot of the .45 I just fixed with a turned-down alloy steel bolt after ruining a Manson throating reamer. There's some freebore which I didn't want, but that's what it took to clean it up and save the barrel. The throat entrance is .455", right where I wanted it, notice the transition of the throat into the grooves. Even crimped at .467" there's plenty of meat for the case to headspace on...if that were even how it works (a 1911 headspaces on the extractor claw). It shoots very well after throating and stopped leaving powder coat residue in the first half-inch of barrel.

 

[fiver]

you can see the angle to the rifling I was talking about in Ian's picture.
most barrels used to come like that only not quite so far down to the rifling.
now when they are re-cut that distance gives the bullet a chance to get into the barrel and most are cut this way aftermarket.