What diameter is a flash hole?

[ghh3rd]

Does anyone know what the flash hole diameter is on say a .45, .38, 45-70, etc?

I'm asking because my tired old eyes find it impossible to use iron sights on my rifle, and I thought a peep sight might be the ticket.

I figured that if any cases had flash holes that approximate the nomimal size of a peep, I could use the case to test whether a peep would be work for me.

Thanks,

Randy

[dave roelle]

Hi Randy:


0.081/0.082 inches in diameter

[oneokie]

Could be as small as .062".

[MtGun44]

No standard AFAIK. Just what the mfgr decides on.

Bill

[frkelly74]

I have used 5/64" drill to open tight ones so my decapping pins don't hang up and pull out. A La' IK007 brass.

That is also the drill I used on my 03A3 rear sight to open it up to the same diameter as my 1917 which worked better for me.

[ghh3rd]

It sounds like a flash hole might be a good test to see if a peep will work for me. All of the sizes mentioned are in range for 'normal' peeps (.096 being Skinner default).

Thanks - Randyh

[HollowPoint]

"What diameter is your flash hole?"

That's kind of a personal question; don't you think?:holysheep

OK, my bad. I misread the question.

HollowPoint

[ghh3rd]

...sorry to hear about your hollow point :wink:

[Canuck Bob]

Peep apertures can be quite large and still work just fine. I've drilled out aperture inserts to the size of the large hole with good success. The key is where the sight sits in relation to your eye. You might find a flash hole too small for a good test.

A receiver sight on a lever needs a larger aperture than a tang sight. The target 22 sights sit on arms to get the sight as close to your eye as possible. They use very small apertures. So test your make shift sight with the hole at the spot you will be using with the actual sight. Most receiver sights sit on the receiver about where the trigger sits on a rifle.

I and many others hunt with ghost sights by leaving my insert out of the sight which is a 3/16 hole, #10 thread less the thread height. I have aperture inserts drilled out to 1/8 that work dandy with the normal 4 or 5 inches of eye relief from my receiver sights. With my eyes I find the larger apertures are fine for accuracy at hunting ranges. You will find a huge improvement with a peep sight I suspect.

[Simonpie]

An aperture acts as a "camera obscura" which sharpens the image by lengthening the focal length. It allows the front sight and target to be in focus at the same time. A big aperture at a great diatance from your eye will give you the same sight picture as a small aperture close, but the big aperture loses this focusing effect. On the flip side, small apertures start to perform poorly in low light. Hunters tend to big apertures for this reason. You just need to play to find something to match your eye.

[leadman]

For my Rolling block in 40-65 I bought the adjustable eye cup so I can select the size aperature hole I need for the light conditions.

Works great but not available for all peeps.

[10 ga]

Old and tired eyes here too. I use lyman peep sights on 3 of my smokey MLs. I like the larger aperature. Put a nice "fire" type on the front and it makes a he// of a diference in me being able to hit stuff. I long ago found that the MLs, with proper loading, could shoot better than I could, and that was when I had good eyes. I can shoot 2 moa but the guns can do better! 10 ga