Firing Pin Measurements

original: forum.m1911.org
Retrieved: December 02, 2011
Last Post: June 15th, 2009

Operator Two
2nd May 2009

I have a SA PX9105ML Operator and a PB9108L Mil Spec. Both seem to have the wrong firing pin. The Operator firing pin measures 2.286 in length but the pin size is .068. The Mil Spec measures 2.287 in length and .065 pin size. The Mil Spec was a raffle winner and I believe was tuned by Bar Sto. A very beautiful pistol. However the Operator is fresh out the box. According to everything I have read the 45ACP should measure about .093 in. I don't understand this. Both are Series 70 models.


log man log
2nd May 2009

Springfield uses a proprietary size that is in between 9mm/38super and 45acp. And they are made of Titanium. Ed Brown makes a steel one especially for the Springfield and is #826.


Operator Two
2nd May 2009

I didn't know this. Thanks. The fireing pin on the MilSpec is steel and I understand slipups can occur. That's why I was was concerned about the Operator.


log man log
2nd May 2009

Some more investigation is in order as the correct Springfield pin should measure .070"-.075" the .075" being the EB pin. It's quite common for a 9mm/38super pin to be used and will work, however the extra clearance can led to primer flow at which time chips of brass can lodge uninvited in the firing pin channel and stop the show. So do some checking.


Operator Two
2nd May 2009

Yes I think you're right. I may at least try a standard firing pin for fit. I was concerned about primer flow. I'm new to this so caution is the way. I'll probably try the same with the MilSpec.


Hawkmoon
2nd May 2009

Quote:
I may at least try a standard firing pin for fit.

I hope you meant a standard Springfield firing pin. A GI standard .45 firing pin should not fit in a Springfield slide.


10851Man
27th May 2009

What is an acceptable range for the firing pin tip in a .45 pistol? The pin in my 1927 Colt measured .089" on the tip and my new replacement measured only .091" in diameter. My firing pin hole was probed and came out to about .095" or so, with a .010" wide, 45deg chamfer at its junction with the breechface.

Input?


log man
27th May 2009

Quote:
Input?

The spec. for the firing pin tip is .091"-.002", so the .089" is okay also.

The spec. for the FP hole is .094"+.003", so your .095" is great, the .010"wide 45deg chamfer isn't correct as that gives the primer cup a place to go under pressure. In 45 you may not have a problem from it , but it isn't preferred. A clean burr free hole is.


10851Man
27th May 2009

Thanks... I had read here in this forum that a light 45deg chamfer was desireable around the firing pin hole?


log man
27th May 2009

.010" 45deg isn't light, just a de-burr.


10851Man
27th May 2009

Guess my eye needs calibrating... not much over .005" overall. I used a 45deg carbide burr turned by hand.

Here is a close-up of the breechface and firing pin hole chamfer...Robert


10851Man
27th May 2009

Any opinion on that chamfer?


log man
27th May 2009

Looks fine!


10851Man
27th May 2009

By the way, I did go ahead and get one of the extra power firing pin springs... seemed like a good idea.


Hawkmoon
28th May 2009

Quote:
What is an acceptable range for the firing pin tip in a .45 pistol?

The specified diameter at the business end of the firing pin is .091" -.002

The specified diameter for the hole in the breech face is .094" +.003


10851Man
15th June 2009

Just got my new EGW .093" firing pin this weekend. Very nice piece and a nice fit into my .0955" firing pin hole. This one has a large step about halway down the length of the pin. George at EGW said it will replace the original 82 year old pin perfectly without modification.


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