I ordered a type III rear sight for my garand with the intentions of making the rear peep the larger.  The reason is my Astigmatism is bad enough I can not fire my rifle accurately.  I know on my A4 that the close combat peep is a pretty
good size to go with.Does anyone know the size off hand?Is there any reason i should not do this?  And yes I am keeping the original peep with the rifle.

Update
Ordered a replacement sight from Apex Gun Parts.  Shipping was fast. I did have an issue with an AK sling not being included but I called and they were very helpful in getting it to me.  The sight had some kind of synthetic string in it as well as cosmoline.  I degreased it and drilled it out using a vise and hand drill.  The front of the peep is cone shaped and worked well as a guide. I then sooted the sights.  I will report back with an accuracy test.  
Attached File

Also may be interesting:  http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=2110760

I have a burris.  the astigmatism makes it look like a slash    . One plus to irons is they work for me. Makes me sad.  I will let you guys know how it comes out

I opened mine up to 0.125" and it made a world of difference for me.

Thats a 1/8 correct? . I am wondering how wide I can go before I am doing no good

Yes, that's 1/8".  I'm not sure I would want to go any bigger than that, the rear starts to ghost out at that diameter.

Got it.  Thanks.  Soght should be here tomorrow. Hoping to get to it Sunday or monday time permitting

Turned out good at 1/8 . I will drop the bit in my A4 combat sight and see the comparison. I still see an oval distortion . Attached File
Attached File
OP updated.

@lafmedic1  Any range time updates? I'm curious as to how this worked out for you because I have considered doing the same thing.

I went a few days ago and shot for hunting season. I was facing into the sun so the glare didnt help . My
group at 25 was better and I managed to hit a cow skull I had on fence at 100 yards 4 for 4 rounds. I still had some distortion but not nearly as "oval" shaped before . The real test will be in lower light conditions this hunting season as I am in a wooded lease. I will update some more . Hope this helps and I know its not scoentific

ETA , Apex sells the rear for 10 bucks . Its no big loss if this doesnt work for you

I got one of these for my "shooter" M1.  Makes even using the NM front sight blade work for me.

b jones sights.com

I also put an Amega Ranges scout scope mount and LER 2X7 scope on that M1.  If I was hunting with it that's what I use.

The Amega Ranges (there are other companies that make similar mounts) replaces the lower handguard and can be removed if you want to go back to GI configuration.