How do you enlarge the firing pin hole?!?!?

[CTtackdriver]

I got a new slide and the firing pin hole is roughly 1/16 of and inch slightly larger and it needs to be almost 5/16 of an inch ( im assuming since my kinber and colt are about that size) i cant find drill bits long enough to go in from the rear of the slide and i cont find a round file set to do it either. struck out at home depot , lowes , sears and brownells

[Ericthenorse]

Confused???? why would you need to find a dril bit if the hole is already too big??????

[Hawkmoon]

Specialty companies sell extra-long drill bits for special applications, but before you rush out to buy one, please provide more information. What caliber is this new slide, what make is it, and what caliber(s) are the guns you are comparing it to? And which end of the hole is it that you think is too small? .38 Super and 9mm pistols use a smaller firing pin than .45s. And I have read that Springfield Armory uses the smaller firing pin even in their .45s.

[pa_guns]

Hi

MSC is a reasonable place for odd stuff like long drill bits.

www.mscdirect.com

I'm not quite sure what you are trying to do here. Is the tunnel the firing pin rides in to small or is the hole in the breach face to small?

Bob

[CTtackdriver]

its an sti full frame commander length slide in .45 acp

the hole in the breech face is too small

[ArmscorBA]

Some companys use a small firing pin on purpose!!! Call STI.!!!!!! ;) ;) ;)
Ivan

[pa_guns]

Hi

A lot of companies use a "9mm" size firing pin on a 1911. It's definitely smaller in diameter than the "45 cal" version.

Unless I'm missing something the hole in the breech face only needs to be large enough to get the tip of the pin through by maybe 1/16th of an inch. Anything more than that and the primer's already gone off.

Bob

[Canuck-IL]

.091 is the nominal tip diameter on 45...many companies use a 38Super pin which I believe is .069...Springfield is a little different and, as memory serves, theirs is .072 and made of titanium. Small pin with a FP heavy spring can mean light hits so a lot of people replace it with a standard 1911 steel pin.

/Bryan

[pa_guns]

Hi

To get the firing pin to come out to twice the distance you probably only need to increase the hole diameter by a little bit. In any case the main issue is to make sure the firing pin does not hang up in the hole.

Bob

[CTtackdriver]

I will contact STI on monday to make sure they dont use a special pin. They originally told me stock series 70 parts fit so i assumed it was a stock pin size. It didnt even cross my mind they they would be using a .38 super or 9mm pin!

[pa_guns]

Hi

The theory seems to be that the smaller firing pin puts more pounds per square inch onto the primer and that results in better ignition.

Small primer holes translate to the primer being hit in the same place every time. If that point is dead center on the primer that also is supposed to translate to better ignition.

An awful lot of 1911's have fired an awful lot of rounds without all of these enhancements.

Bob

[CTtackdriver]

agreed. When the pistol was a bone stock colt mil spec it did just fine. It was just tired and beat to ****. Its had more then a couple barrels had the springs replaced a couple times ect. Since i have a kimber a few glocks and a pile of assorted other toys I figured I would start a project. So i set out on a frame up build and its going ok so far. If it turns out as I want it , it will be a real head turner...... we will see lol

[CTtackdriver]

OMG the word which describes the opposite of heaven is a WARNING offense. What a joke.

[pa_guns]

Hi

Simply put the list is set to a "G" rating level. You will hear worse language on the Saturday morning cartoons ...

I got caught a while back. Once you realize what the setting is it's not to hard to live with.

The firing pin hole is one of those interesting things on a custom pistol. I had never considered that you would want to start out undersize so you could work up to the "proper" size for your setup.

I suspect that a very normal number drill in an extender would do the trick just fine. Since you only want to go out a tiny bit power is not what you are after. I'd just glue a drill bit into the end of a stick and run it through nice and slow.

Bob

[Canuck-IL]

Try a few drill bits until one fits in the hole - measure it with calipers, now you know what STI was thinking. A #49 drill bit will open it up to a 45 std pin.
/Bryan

[CTtackdriver]

Actually I used a drill bit and said its about 1/16 thats .0625 a 1/16 drill bit is actually a tad loose.

Ed brown firing pin list

825 Firing Pin, 38, 9mm, 10mm 70 or 80, also any Brown, Baer, or Caspian slides, .065 pin diameter $5.95

So as said above its an undersized pin. I personally dont know WHY id want an undersized pin in a commander length slide but I may try it and if i break a pin once im hogging it out to standard size and using a normal pin which is .090

[pa_guns]

Hi

I'd get one of the Ed Brown pins and see how it fits. If it makes it through the breech face and doesn't hang up then you have a starting point. If it does hang up then I agree - grab a couple of number drills and open it up a little bit at a time.

Bob

[robot1911]

Find an industrial supply store and get a 6" drill. Go in from the back of the slide and drill through, then stone the face of the slide to remove any burrs. You could even touch the new hole with that drill just to put a small bevel on it to keep primers from catching as they pass it.

Bob

[BrianM]

STI makes all of their slides to use a 38 Super Pin with a nominal tip diameter of around .068". The reason for the smaller tip firing pin and corresponding hole diameter is to reduce primer flow back into the firing pin hole with high pressure loads. Using the same smaller diameter pin for the .45 ACP is a manufacturing decision. They only have to make one size hole and sell/install one size of firing pin. There is no downside to using the smaller pin for the .45.

Just be careful, sometimes the pins and holes don't quite match up for fit. I'm working on a batch of 10 STIs using Caspian 38Super pins and had to play around matching pins to slides. Due to manufacturing tolerances you may run into a situation where the two don't quite fit.

Just get a .38Super firing pin and you'll be fine.

[brickeyee]

"Go in from the back of the slide and drill through, then stone the face of the slide to remove any burrs."

I ream firing pin holes to size, not drill them.

[berkbw]

And what, perchance, is the difference? I use drills, reamers, adjustable reamers all the time. If you actually know where point "B" is, does it matter the route?

b-

[brickeyee]

A reamer leaves a much smoother surface than a drill, and when used correctly can hit tolerances a drill bit can only dream of.
Drill bits routinely leave holes that are at least 0.001 oversize.
No precision hole should be drilled as a final step.
Drilling, followed by reaming out the last few thousandths is a routine machine shop practice.

[berkbw]

A reamer leaves a much smoother surface than a drill, and when used correctly can hit tolerances a drill bit can only dream of.
Drill bits routinely leave holes that are at least 0.001 oversize.
No precision hole should be drilled as a final step.
Drilling, followed by reaming out the last few thousandths is a routine machine shop practice.


Of course you are right. I must have been having a "moment".

[brickeyee]

No big deal.