Hi:
As there is a gazillion 853's out there in CMP, 4H, ROTC and various clubs I thought this might be of interest. It has probably been dealt with before, but I couldn't find much searching here and on other sites, so here goes.
I've tried the inexpensive Daisy sights that come on the Avanti 853 on my 953. I shoot mostly target and wanted target style diopter (peep)sights. They are about the only ones avaialble on a limited budget. Out of the box, the examples I have leave a bit to be desired.
The 853 front consists of a stamped metal housing spot welded to a heavy barrel weight. The barrel weight is considerably heavier than the one on both the 953 and the 753 (they are identical). Some shooters prefer a heavier barrel weight as it provides inertial damping, resulting in a steadier hold. As I have to place the butt high on my shoulder (just notched in at the top) to achieve Natural Piont of Aim, the heavier weight causes strain and doesn't allow for a relaxed hold.
On the example I have, the sprung tension collar that traps the insert doesn't fully seat the insert, allowing movement. Also the inserts are fairly crude. I tried filing the housing but could never get it to hold properly. I finally bent the small tabs on the insert at a slight angle (towards the rear) and that provided enought tension to stop the movement. Sometimes the easy fix is the best.
My current front sight solution is the 753 front sight with inserts. It only costs around $5 for the sight and $3 for the inserts and it mounts directly on the 953 muzzle weight once the fibre optic blade is removed. The sight is plastic but is well made. The inserts are held in by screwing in the rear cap and it holds the inserts squarely and firmly in place. The inserts, 1 with the sight and 4 additional are a nice step up in quality from the ones with the 853. The assortment goes form 4.4 mm down to 2.6 mm. Try one of the larger ones, say 4mm and you may be surprised to see tighter groups.
Over the years I've tried two of the 853 rear sights with good results. The first (earliest) had the plastic body and would sometimes bind, not moving for several clicks and then jump a bunch with and additional click or two. I'm not a nob twirler so it wasn't too inconvenient and I generally try to get final adjustment by always going in the same direction, adding 3 clicks past and then back 3 where necessary.
The second has the metal body (the later and current model as far as I can tell) and it wasn't perfect but much better than the first. It didn't bind like the first but it wasn't exactly smooth. Not being able to leave anything alone, I disassembled it to see what gives.
What I found was all plastic parts with the exception of the adjustment screws springs, detent balls, and the housing. Not a Gheman but servicable. There is a small opaque white insert on the left side (looking foreward) that tensions the sight carrier in the frame and it was decideably rough. It just slips in and tensions the carrier against the housing. I smoothed the central ridge that bears on the carrier with 600 wet or dry being careful to just smooth it and not remove too much material. As this keeps the carrier pressed against the housing, if you go too far you will get slop in the carrier and you will then have to shim it, so be careful. I also eased the corners of the carrier, just removing the sharp edges to prevent binding on the housing.
The vertical adjustment shaft is necked down at the bottom and is threaded for the retaining nut that holds it in place and provides tension for the detents. Alarmingly it also seems to be threaded where it goes through the housing. As this is essentially the bottom bearing for the vertical adjuster, this is not good. Rotating a threaded steel shaft in a pot metal bearing is certainly a recipe for rapid wear. As current rules do not permit much in the way of modification to the rifle or sights to remain legal, you don't have a lot of options here. My solution, was to put a dab of blue locktite on the offending portion (after threading on the retaining nut). I had noticed that blue locktite will dry into an epoxy like solid from previous experience. I used a tooth pick to put on just enought to fill the threads, but not form a glob - not too difficult realy. If you get too much, just wipe it off and try again. After 24 hours remove the nut and test the fit in the housing. If its too big for the hole in the housing replace the nut and use a needle file to carefully resize it to fit. I was lucky and it fit without filing. I reassembled using lubriplate. Not a scientist, so don't know anything about the stuff except that it is the only thing I have found that seems to work realy well on plastic. Can't attest to any long term problems, but it made a huge difference in my Crossman 1066 mags and trigger(which were pretty dreadful out of the box). They're still going strong after 3 years so I guess it's OK.
With everything back together, it works fine, no slop and smooth and precise adjustments. Hopefully the locktite fix will hold and atthe very least reduce wear somewhat over time .
For anyone using the 853 rear sight who is serious about target shooting, I would suggest a disassembly and clean out plus whatever lube you find works for you. Oil or Silicone don't seem to be as slick and oil might be a problem with the plastic. Silicone with PTFE might be good but don't have any so didn't try it. Maybe Mach1 "Secret Sauce" would work, I seem to remember that it is ok for plastic. Whatever.
I have far too much time on my hands.
Cheers,
Fatman
