Umerex Colt 1911 - Backstrap Safety

[short-carabine]

It might!
I should have clarified that these two guns have had the transfer plate in front of the valve removed as well.
So your hammer with the screw in is hitting the valve hard and direct.
The difference would be quite clear if you shot one of them!
Wait and see.If it wrecks the gun I will let you know.

But other Umarex models hit the valve direct.
The transfer plate on the Colt is to make the grip safety work-badly.

I should also make the point that these mods take you nowhere near the legal limit.
They just make the gun work better.

Ah, Nick (Magicniner) took out the transfer plate when he pinned the grip on mine and fitted an ali backstrap and beavertail. Must admit I am lacking a chrono at the mo so have never checked the FPS, although after the tune up its seems to hit harder (although I'm never bothered about getting near the legal limit- I have a Crosman Mk1 for that )

[Benelli B76]

I am well aware of that but none of the BB pistol I shoot seem to cool anywhere near as quickly as the Umarex co2 replicas and I believe that's because the process is augmented by so much metal contact.

Think you are wrong there. The cooling depends on the amount of gas liberated per shot, so your BB's may be more economic. I did all the work on gingernuts pistols and looking at them think I get more velocity by modifying the valve assembly. Will have to look for an old 1911 to do the full monty on and see what the limit is. That said I have had all the umarex pistols except the Beretta and I dont like any of them. When you try to make an air pistol look like a real firearm you always end up with compromise in performance. The only one that isn't is the Schimel GP 22.

Baz

[oling]

Think you are wrong there. The cooling depends on the amount of gas liberated per shot, so your BB's may be more economic. I did all the work on gingernuts pistols and looking at them think I get more velocity by modifying the valve assembly. Will have to look for an old 1911 to do the full monty on and see what the limit is. That said I have had all the umarex pistols except the Beretta and I dont like any of them. When you try to make an air pistol look like a real firearm you always end up with compromise in performance. The only one that isn't is the Schimel GP 22.

Baz

That is quite possible but I remember watching a video on youtube about a guy who cut off the majority of the metal in contact with the co2 in his Cybergun X Five and he said that it drastically reduced the cooling effect of the gun when rapid firing. I can't honestly see what else it could be other than an anomaly...

[Aimstraight]

We have had problems with the Umarex Colt not indexing correctly when firing single action. The pellet can be up to 20 thou out of line with barrel causing a misfire, or low power shots in single action, although when firing double action there is no problem.The problem can be with the pawl (hand) or with the complete trigger group. Both of these are available as replacements. Another mod we do to get better results from this pistol is after fixing the grip safety, we remove the floppy transfer bar altogether. This means the surface of the hammer needs to be increased by 1.5mm to make up the thickness of the transfer bar. We drill and tap the hammer 3mm and screw a modified bolt into it which has had the head machined down to 1.5mm to hit the valve correctly.After these mods you get really consistent single and double action shooting with the pistol.

Baz

Guess what, I'm getting the SA problem you mentioned! SA & DA 'feels' great since I removed the (rather strong) spring from the backstrap safety, but when gassed up for live firing all I get is 'phut' on SA and when I open the slide can see a bent pellet where is seems to have been misaligned and has hit the edge of the barrel. It does this repeatedly, whereas it works perfectly in DA.

So I'm going to carefully investigate the inner workings (without losing any small parts!) to see if it is something that can be easily repaired (i.e. one new part not several). I can see that DA brings the trigger blade right to the back of the trigger guard, whereas in SA cocking the hammer right back does not bring the trigger blade as far back (so maybe not advancing the rotary mag correctly...we shall see).

[gingernut]

Exactly the problem I had before any mods were made.
Problem went after a new pawl and trigger group were fitted.
Not able to find what the cause was.

[Aimstraight]

Thanks for the reply, at least I know that it very likely to sort this snag out. I was pricing up the cost of the pawl, spring and trigger group. Alternatively I might just stick to DA

I have done some checks and see that in DA the pawl comes up all the way and does not wobble, but in SA with the hammer back it comes up nearly all the way, then the final trigger pull causes it come up the last amount, but importantly when it does so it sort of wobbles/wavers from side to side. This suggest to me some wear in the either the pivot point of the pawl, the bearing for the pivot point, or the trigger group; as suggested replacement of all these bits (incl pawl spring) should cure it.

Confirmation of the problem can be seen when looking down the barrel (obviously no gas/ammo etc...), whereby in DA the mag rotates and centres on the barrel, whereas in SA it does not line up correctly.

Addendum: Actually the mis-alignement can be variable. If the trigger is used very lightly for the final stage in SA, the misaligment occurs, and increase with each index of the mag. But if the trigger is pulled with more vigour, the misalignment is not as significant and will probably fire no problem. This explains why at first it seemed fine in SA, then the problem arose when using SA more gently.