Most guys who have vsr type bolt action rifles will probably have come across how "hit and miss" they can be, I have some that are Ok, some have been useless and modifications have been of no revelation.
I have a few spare ones now as most of my rifles and some I've built for others have been replaced with better aftermarket items, so not wanting to give up on improvements on them, I've had another go at a "mod" on one.
The plastic slide adjuster arm for the hop seems to be the bone of contention, as it will bend in use along with the movement of the plastic hop arm, so the first no brainer is to change it for an airsoft pro alloy arm, this is a big improvement but by no means the end of the problem.
I have now hopefully improved on the sliding arm, cut off the plastic arm, drillout 2.5 hole ( where the arm was!) replace with longer metal rod (I used brass brazing rod) now this won't fit as the left side of the hop unit has a blank "wall" on that side, so after marking it out, drill out, smarten up with needle files, so that the new arm rod goes through and runs smoothly.
So far, no lifting, no twisting of said adjuster arm and hop arm. I have to go through a bit more testing yet but it does seem to be a big improvement for very little money and effort.
Andy
I have, of course superglued the brass bar into the plas arm.
Another pic
A common mod here on our fields, for the VSR hop-up units, is the Top Dead Center - or just TDC - mod. You remove the external adjustment arm completely, drill and tap a hole through the receiver above the hop-up unit, and then use a grub-screw to press directly onto the hop. It makes a world of a difference to adjusting and locking in your hop.
Yes, I have seen this done on a couple of "modern" vsr's, one had made up a saddle with flat platform and bolt adjuster head, so he does'nt have to remove his scope, just don't think it would look good like that on a ww2 lookalike, although the grub screw adjuster idea could be covered by the top hand guard wood ( with a small hole) so not to be seen.
Andy
Spent a bit of time with this " mod" today, a big improvement. I've fitted it into a "scout" version of the vsr ( short barrel well MB03) and it's working very well, got a good range too, reaching 60 metres, a little bit windy where I am, so will do some more testing somewhere else, but has produced some very straight shots, FPS about 460.
Andy
Yes, I have seen this done on a couple of "modern" vsr's, one had made up a saddle with flat platform and bolt adjuster head, so he does'nt have to remove his scope, just don't think it would look good like that on a ww2 lookalike, although the grub screw adjuster idea could be covered by the top hand guard wood ( with a small hole) so not to be seen.
Andy
On my springer K98, that adjustment grub sits underneath the rear sight - so I just flip the ladder sight up, tweak, and then drop the sight again. Nothing visible from the outside.
One of my biggest issues with the factory design, where you slide that adjustment arm forwards and backwards, is that the firing recoil of the spring can cause that arm to creep back/forth over time, since both the recoil and the arm movement are along the same axis (especially when using 500FPS springs, which is what our Sniper class is allowed). The grub screw route eliminates that completely.
That's a great mod on the k98, if the sight mechanism covers it, no "unsightly " hole (forgive the pun!)
I have had a loose adjuster, on one vsr, used a bit of electrical tape on the barrel slide clamp, solid as can be, has not been a problem since, has been on there at least a year, so now that you reminded me, I thought I would strip it out and check. I'll do my upgrade mod on the hop unit while it's out.
I'm in the process of doing a few K98's so I will use your tdc mod and then I can compare myself.
Personaly i find that these hop units are more accurate when it is pulled right back or full on.
The little bar that moves in the hop arm slot is directly above where arm touches the hop rubber and provides support where the pressure is and provides more consistent shots.If the little bar is at the other end of the slot away from the end touching the hop rubber it has no support.Obviously you need the have the right ammount of backspin on the BB when the arm is pulled fully back.
if you want to keep your original hop arm strips of bean or coke can make good shims to make it fit better in the slot (side to side)in main hop unit housing ,there is half a mm clearence here on my Cyma 701,the less play the better it will shoot..
The thin plastic sliding arm that moves the main hop arm flexes and can be braced with a strip of metal,this is held in place with the same screw that holds the sliding plastic arm.Info of what the brace should look like is on the net.
The Cyma 701 hop rubber is utter crap get a maple leaf.Thats the only money i spent on mine and its Ok .Out of the box it was a disaster and was all over the place,when cold the hop rubber would not even let the gun shoot at 3deg,put it on a radiater for half hour and it would shoot again.
I've tried "shimming" on a few bolt action hops, Cyma 701, and 702, Well mbo1 and mb4404's and the result is not always of good result, the little arm from airsoft pro, and ASPUK do one too, saves a lot of time and hit and miss effort in my estimation, but each to his own methods.
This "mod" I've done is working really well, done some more testing today in a more sheltered area, not one stray shot up to sixty metres (hitting a 20litre plastic drum most times) as there was before with this hop, could be "beginners luck" with this method, time will tell and I'll do a few more mods on some more spare hops and see if they are consistent, the alloy arm I used is the one with the concave nub area to contact with maple leaf hop rubber of course, as you're quite right in saying the original rubber is total poop....most of the time, (I am running one in a rifle that's worked great from the start! )
Considering the hop rubber and arm cost about £25, and my conversion takes 15-20 minutes to do, that's a lot cheaper than action army, and airsoft pro hop units at around the £40 mark and you still have to buy the hop rubber!
