A1/A3 scope mount question

blcouch

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Also posted on M40rifles but I think this place gets more traffic:

I think I know the answer but I want to double check. Can the Badger Ordnance clip slot pic rail base and the Badger Ordnance 306-24 rings with 1” inserts be used on an A1 like they were on the A3? I seem to recall the A1s being made into A3s with the above mentioned parts being used to mount the MST. I seriously thinking of re-mounting my MST on my A1 in the Badger gear to give me more fore/aft adjustment on the scope. I will be keeping the A1 mount for historical/clone purposes but shootability is up there with clone correctness. Thanks in advance.
 

Pinmaster

Gunny Sergeant
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It may take some fitting to get the lug to match the receiver but I'm thinking that it can be done.
If even if the lug cut in the receiver are a tiny bit different than the mount... it will not fit. I have an A5 that is cut for a hogsden rail... I found a couple of issued DD Ross Rails that are for an A5 but the receiver cut is a very tiny bit different than the Ross rail so neither of the Ross rails will fit the receiver. @Raven 6 could answer your question and could make the mount fit your receiver if it is necessary.
 
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Random Guy

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If the clip slot cut in the receiver can accommodate the BO rail, it should work...but some minor fitting of the rail's bottom lug is quite possible..
I'll let others chime in, but I think the Unertl would be mounted a little higher as well, and thus your cheek weld might be a little lower than ideal.
 
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blcouch

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Got my answer from Raven6. Lug and screw sizes are different and the BO A3 rail wont fit the A1. I’ll go a different route.
 
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Random Guy

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Pictures help. The Unertl mounts typically start slightly oversize on the bottom lugs. A retired USMC 2112 who built M40A1s told me that they would very carefully file the back of the rear lug until it would just barely fit into the clip slot of the receiver. Mine is very, very tight with no lateral movement, which is what you want. So no one can really answer your question until you try to see if the BO rail fits in your clip slot (both front and rear cut-outs). I think a tiny bit of filing on back lug for a 'tight fit' is what might be desirable. A 2112 would be able to answer this question best.

(Note: Not all clip slots/lug slots are cut exactly the same each and every time, as a human being is involved in setting up the milling process...and I wasn't sure if the original M40/M40A1 "clip slots" had markedly different dimensions than the M40A3/A5 "lug slots", or if the depth is the same - see last pic)
 

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Skunk

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Badger makes several different lugged rails, or they used to. One was a true to spec copy of the USMC part and the other was similar in appearance but for a round bridge and that, I think, would be your biggest concern.
 
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blcouch

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Badger makes several different lugged rails, or they used to. One was a true to spec copy of the USMC part and the other was similar in appearance but for a round bridge and that, I think, would be your biggest concern.
I saw that one. Other than “round bridge”, the only real difference I saw was the lack of 30 MOA of slope. Both claim to be able to fit the A3/A5 clip slot. The screws may be different to. I can’t remember.
 
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Skunk

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I have the round bridge rail installed on a receiver with the A1 clip slot, like you're talking about doing. Fits perfectly. I installed it myself in minutes...

Except for the flat bridge and 8-40 screws, I don't know if there's much difference, dimensionally, between the A1 and A3/5 slot.

I'll get a better pic tomorrow if you want to see exactly what it'll look like...
 

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alibi

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I have the badger round rear bridge mount on an A1 cut receiver with the .886 issued type rings. It works well. Need to build up your cheek piece.
 
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blcouch

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I have the badger round rear bridge mount on an A1 cut receiver with the .886 issued type rings. It works well. Need to build up your cheek piece.
I went with the Bradley adjustable kydex unit last year. I love it and it should do the trick. It’s a great unit if anyone hasn’t seen it before. Easy on, easy off for cleaning/bolt removal. I put a thin piece of green felt on top for comfort/micro cushion.