Chain adjusters

Get a couple of reduced hex nuts.

Turn the o.d. of the washer to just clear the hexagon on the adjuster. Not much would need to be removed looking at the photo.

Either the wheel spindle nut reduced section diameter is too small or the end stop on the adjuster bolt is to short.
Have you though of chamfering the edge of the adjuster bolt hex that's catching the washer?

Hi,
I'm sure the originals had a reduced size hex to overcome this issue - featherbed ones certainly did. Surely one of the various parts suppliers has them with the correct thread for a Commando?
Regards, 
George 

Nookies Nuts.

How about a 0.10" smaller diameter washer under the head of the axle. That should give the adjuster hex nut enough clearance all round.

The original adjuster bolt had a 1/8 Whit head. Nasty fiddly thing. Any improvement in this area must be worthwhile. (Royal Enfield snail cams come to mind)

Featherbed frames used reduced head adjusters but Commando doesn't. The head should be 1/2 inch AF. Either take some metal off the washer or off the edge of adjuster hex nearest spindle.
 

On my 1974 850 MK2 the chain adjuster head size is 7/16" and the lock nut 1/2" spanner fit.
This is as fitted by the factory and correct as I've owned the bike since new.

You have aftermarket junk, send them back for a refund. 

Those are the correct chain adjusters you need, 7/16" spanner size on the adjuster head, designed to clear the axle washer. 

Sorted.
https://andover-norton.co.uk/en/shop-details-2/15347/rear-wheel-adjuster
 

Here are some numbers from original parts on a 1974 850 Mk2a:

• Diameter of spindle at adjuster: 0.86"
• Diameter of spindle washer: 1.125"
• Height of adjuster bolt beyond hex 'nut' towards spindle: 0.15"
• Adjuster hex size: 1/2" AF

The clearance between adjuster and spindle washer is small but sufficient to slide a piece of paper thru - using the numbers above you will get 17 thou.

From your picture, it looks like the spindle has been reduced too far. You could modify the adjuster by turning (as in - in a lathe) the hex 'nut' back to give you the clearance you need.

I found with my Mk.III Commando that when the adjusters were equally level in terms of amount of thread left on each bolt, although the wheel was central in the swinging arm, it was not in line in with he front wheel.  It needed to be offset in the swinging arm for it to align correctly.  When parked, a number of knowledgeable enthusiasts advised me that the adjusters were not level.  When the adjusters were level the rear disc became warm and sometimes quite hot because of the mis-alignment; it now runs cool and correctly.