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"Death From Above"
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Dito leadbug. Russ69 if you are having trouble I'll pm you my email address and send them to me and I will post them.
Ok so here is russ69's safety bridge picture.
what is SAI doing to these bridges lately?
 

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What kind of Rube Goldberg Thing is that?GI3
 

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"Death From Above"
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I don't know Eric. Russ did yiu just get this rifle? What's it's history. I don't know if you read them but there were two recent maybe three recent posts with a sai receiver with the safety bridge in the same condition. One of the bridges looked just like the one in the picture. The member said sai actually did it when he sent it in for a problem. The bridge was eating up firing pin tails at a fast rate. We never did figure exactly what was up with the second persons rifle but sai wound up replacing the receiver and barrel. Your bridge has had heavy alteration to it. It does not even look normal anymore. I would imagine if yiu called sai they would say it's functional. I don't know what receiver serial number the other members had but I am going to take a guess and say they all were close at least I would like to think this problem was limited to a small range of receivers. I will look for the other three posts and place the links here in your thread. Something is not right in dodge city. How does it function?
 

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Discussion Starter · #7 ·
Russ did you just get this rifle? What's it's history....Something is not right in dodge city. How does it function?
It's my buddie's rifle, it has 30 rounds through it. It's a brand new production Springfield SuperMatch. The tail of the firing pin is rubbing on the bridge, is showing burrs and the firing pin gets hung up on the bridge.
He had an AD at the range. The bolt released while he was loading a magazine and the rifle discharged. I wasn't there but my friend, stopped shooting and started looking at the rifle and this is what he found. I don't know if this is related to the AD or not. My SuperMatch doesn't look anything like this. My firing pin is parkerized and has about a 1/16 inch clearance on the tail whereas his is rubbing. I'm having him contact Springfield but I suggested he take the gun out of service until it's looked at.

Thanx, Russ
 

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"Death From Above"
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So you have a rifle with a normal bridge to compare it to. I just looked at my SM and it looks nothing like that pic. I wonder if they recycled the receiver that was just changed out from the other member! Lol wouldnt that be hoot!
 

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This reminds me of a problem with a new SAI from 06 I had.
The gun didn't like going into full battery. after disassembly I found the firing pin beat to H$%L. I could more feel than see a burr on the bridge that was causing the problem. I have a variety of good small stones so I fixed the problem myself. Verified safe function and its worked ever since. I would not recommend a fix it yourself in this area unless you know what your doing.
SAI should take care of this. Send them the pic and ask if they see anything wrong.
 

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Here is a picture of the bridge that I had to fix. The firing pin tail was rubbing on the right side (as you look at the picture) and the bottom of the slot. This finished shape is closer to what the bridge on my other rifle looks like (circa 1980 and never had a problem with the bridge). When I look closely at the the tail, while the bolt is in battery, I can now see a slight amount of clearance between it and the bridge slot whereas before there was none.
 

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Dito leadbug. Russ69 if you are having trouble I'll pm you my email address and send them to me and I will post them.
Ok so here is russ69's safety bridge picture.
what is SAI doing to these bridges lately?
While both of my pre-ban M1As look like the second pic that was posted, I really can't see how the extra clearance in the pic above would make any difference. The important thing is that the FP is held back before the bolt starts to rotate into battery. Am I wrong in this assumption. dozier
 

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While both of my pre-ban M1As look like the second pic that was posted, I really can't see how the extra clearance in the pic above would make any difference. The important thing is that the FP is held back before the bolt starts to rotate into battery. Am I wrong in this assumption. dozier
I am not an expert but my interpretation, from reading Gus Fisher's info, is that it doesn't take very much interference from the bridge to stop the bolt from going in to battery. So yes, the primary purpose of the bridge is to stop the firing pin from moving forward before the bolt is in battery position but if it is burred or misshaped it can also stop the momentum of the bolt and or firing pin from moving forward as they are supposed to.

I used the word momentum because it looks to me like the forward movement of the bolt is not due to a smooth pressure applied by the op rod but rather a smack from the op rod that shoves the bolt forward. So you can have a situation where the bolt is under free forward momentum rather than applied forward pressure and in that case it won't take much to stop the bolt from moving. With enough slop between the op rod and the bolt you could have a situation where the bolt is stopped from making a full turn in to battery and the op rod would not be able to push it the rest of the way.

In my case the bridge was misshaped in a way that it was actually rubbing the tail of the firing pin and preventing it from moving smoothly and in some instances it was actually stopping the firing pin from moving all the way forward. I say some cases because there is enough clearance around everything that the tail would not always strike the bridge the exact same way every time. I was only able to see the problem by holding the receiver over my head and moving the bolt back and forth very slowly. When the tail would catch I slowly examined everything to see where the tail was touching the bridge and I removed material as necessary. Mostly I ended up creating a bit of an angle on the contact area of the bridge but the slot did need to be deepened just a little. I don't think I took more than maybe a 32nd of and inch of material from any one spot and most was probably only a few thousandths of an inch.
 

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RAMMAC, was it necessary to heat treat the area after your modification, or was the repair so shallow the original heat treat remained unaffected?
 

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"Death From Above"
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Hold the fort everyone! After recently reading three or four post in the last couple of weeks regarding sai receiver bridges I decided to take a look at mine. What I found did not please me. I to have a SAI SM M21 it would appear that the bridge in the picture is correct. What I discovered is sai's bridges have a conical taper from the back of the bridge to about halfway to the front of the bridge. That is want gives the appearance of such a huge gap at the back end. However if you look at the bridge from the front the bridge fully supports the bolt and is machined with a square edge.
What I did find was the rear bottom of my bolt is smashed and deformed. I check the bridge carefully to see if it was deformed as well and it's not. The only thing that part of the bolt comes into contact with is the hammer. I am cleaning the grease off the action and plan on making a closer inspection. The trigger group is gi with a winy hammer. At this time I can only assume the bolt is soft and it is damaged from contacting the hammer. I plan on taking some pics and posting my finds under a seperate thread. Looks like mine is going back for a bandaide as well.
 

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All this talk of bridges made me look mine over closely. I've never had problems and occasionally have checked to ensure correct camming and clearance.

First one is a '94 manu'd M1A. Looks rougher and has a couple points of impact that either formed during manufacture or possibly breakin when I first bought it. Rifle has ~500rds down.

Second rifle is a 23XXX serial number made in the early-mid 80. Looks nicer finished. Rifle has only 60rds through it.
 

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Here are pics with bolt forward

1st '94 model

2nd 80's model
 

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Looks to me that the older models were formed much nicer. That said the '94 model works and cams correct and the bolt and pin looks clearanced to allow ignition and the firing pin has no damage.
 

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RAMMAC, was it necessary to heat treat the area after your modification, or was the repair so shallow the original heat treat remained unaffected?
I didn't anneal or heat treat the area that I worked on and so far I haven't noticed any unusual wear but it has only been a couple months. Then too I only took a very little material off.
 

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My Scout has a receiver dating to 2002. It actually looks as it should look. The cut out is crisp and well defined. And appears that it was cut out.

They did send my rifle with a bad gas cylinder (the piston stuck to the rear and required a mallet thump to get it loose), but I would rather replace the gas cylinder myself than have to deal with a receiver issue or send the entire rifle back to SAI.

Not knowing how SAI manufactuers theri receivers, it is hard to imagine that the cut out would be ready to go after casting. I would imagine there is another step that requires the goove and angling to be cut in the finish process, just like the finish cuts that still have to be made. If that is the case, from the looks of that first picture, it appears that the cut out process was skipped.

If quality control consists of test firing and not much else, the rifle will probably shoot, but I would not consider it to be ready for sale.

Just my observation based on zero knowledge of SAI's manufacturing process, but sounds like as good an explanation as any. Maybe someone with knowledge of how these receivers are manufactured and finished can chime in.
 
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