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Posted: 1/1/2008 8:05:17 AM EDT
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Can someone tell where I can find the drawing for drilling the Oly ejector holes in the upper. I thought I had a copy of it, but I can't find it. Thanks in advance! Johnny C! |
| Caution!! I am not convinced this drawing is accurate. I used this very drawing to drill a Colt A3 receiver for my 9MM Oly setup. The ejector rides the bolt with to much tension which can cause the bolt to slow and not go into battery in some instances. I would like to see other Oly owners measure the distance from the lip of the receiver to the smaller hole of the ejector spring. This is what controls the relationship of ejector and bolt. Kind of hard to explain. I wish I would have drilled it an eyelash higher to releave some of the tension. Kind of a one shot deal unless you egg the hole out. Wes |
Easy fix Bend the spring to get less pressure on the bolt |
The drawing above originated from the Hahn Precision website. The holes are in the right (and same) place for 45ACP and 9mm. From the Oly's I've seen I don't think they are even sure where the holes are. The Oly ejectors (frikkin springs) vary quite a bit from my experience. Some will need tweaking so they don't ride the bolt too hard others may sit too low. You do want to make sure that the spring does ride the bolt all the way to the brass on the bolt face. Bend it too low and you'll miss the brass and not eject. I am not too keen on my Oly uppers (or Oly itself) but they do work well to that drawing. |
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I've done around 30 .45 uppers using this drawing There is some forgiveness in the height of the cross pin holes. Yes, too high and the bolt carrier will drag, too low and ejection can affected. But the gun will still run and eject fine if the holes are a few thousnadths too high/low. There is no forgiveness on the distance from the cross pin hole to the hole for the tail of the ejector spring. Too far apart or too close and the tail of the spring will not go in the hole and then the spring will have nothing to push against to work. I took to drilling to cross pin hole, inserting the cross pin so it stuck out of the hole aways and installed the ejector spring onto the cross pin on the outside of the upper. I then drag the tail of the spring over the upper so it makes a slight scratch marking it's exact distance from the cross pin hole. Measure the height and drill away. It is not an improperly drilled corss pin hole that makes the bolt carrier drag. It is the hole for the ejector spring tail. If this hole is to0 low, the spring will have excessive pressure on the bolt carrier. I ruined 3 customer uppers that I had to replace before I figured out the problem. |
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Hey! I have a very reliable Oly 9mm rifle in the safe that I haven't gotten out to look at yet. I wanted a drawing to check against it. TC, I like your scribe method. That's the way I like to lay things out if at all possible, prior to drilling/cutting anything. I haven't checked on this in a while, but I have heard that Oly supplies Ejectors in the last few years that are larger in diameter than previously supplied. Is that true? My wire diamter is .050. Thanks for all of the input. I bought/ built my Oly a few years ago, so everything I learned then, is a little fuzzy now. Later! Johnny C! |
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I was told by Oly that early on the 9mm springs were breaking in the .45 conversions, so they increased the spring diameter. I believe all there springs are the larger diameter as theyonlu off one part m=number for all calibers for the ejector spring. I'm not in a position to measure one but they are very stout. i have about 2000 rds through my AR45 with no issues. |
Johnny C, Here's a couple of links with some good info. In short: Uses unmodified M3 Grease Gun magazines (30 rd.) Standard AR lower parts kit Just slap on a complete Olympic style .45acp upper and go I absolutely love mine !!! www.cncguns.com/projects/AR45lowerHistory.html www.khalan.com/shop/default.htm (click on firearms then receivers then AR45) |
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