some brass modifications to a 1377

[John_c]

I have had fun looking through the posts to get ideas so here are a couple of ideas that I tried.  None of them are very original but it was fun making/modifying the parts.  I am fortunate in having a 10x22 metal lathe and a Tiag mill.

My 1377 has the steel breech and I found that the front sight was quite low (I built a rough rear sight a while ago and couldn't get it low enough).  Looking at the front end I figured I'd try and fix a few problems:
- low front sight.
- roll pin very tight.
- pump lever a little bit wobbly (not that bad actually).



The sight pin is a piece of 1/8 brass rod turned down on the bottom end to fit inside a 7/64 in. hole.  I haven't bothered to secure it as it fits quite tightly.  I may modify this portion later but for now it allows for quick replacement with a longer or shorter pin.

The muzzle piece is fitted well enough that it goes onto the end of the barrel easily but stays in place without any attachment.  I may eventually use some weak thread locker to hold it in place.  I had planned on using a set screw however there isn't much room between the barrel and the pump tube and I couldn't leave enough material for a set screw.



The plastic piece that fits inside the pump tube, was replaced with a brass piece the same dimensions.  The slot was made a little under width on the mill and then hand fitted with a file.  There is absolutely no wobble now.  The roll pin was replaced with a short piece of 3/16 drill rod.  I left it a bit long in case I need to fit it for snap rings.  It is not heat treated but if there is appreciable wear it can easily be hardened.

The bolt was a problem as it would slide forward while trying to load a pellet.  I found a small rare earth magnet that was the same diameter, turned the back end of the bolt down in length (removed the same length as the thickness of the magnet) and placed the magnet at the back of it.  I had planned to epoxy it in place but found that glue was not necessary.  Now, once the bolt is cocked, it will stay back until pushed forward to load the pellet.



The magnet is the shiny piece just behind the bolt.  Also visible is my temporary rear sight.  I provided a few photos some time ago in another post. 

I've done a few other tuning items on the 1377 (thanks for all the ideas and suggestions) and have it now just under the legal limit for speed (around 400 fps at 6 pumps which is quite nice).  The trigger needs a little bit more work but is pretty good.  Next will be wooded grips and pump handle - not sure when as I have a long list of other non airgun things to do.

A question:

- some pellets are a bit difficult to load because the recess around the breech screw interferes with their travel forward.  I believe I've seen somewhere that filling around the top of the breech screw with wax is a way to fix this - can anyone comment.


Thanks,

John.

[quickster47 †]

I have used wax but then went to using melted Crayons.  You can also use a drop from a hot-glue gun.  It sets just a little bit harder than wax or crayon but is easy to remove for doing work.

Carl

[dockie]

Are you selling those muzzle brakes? 

[John_c]

Dockie:

I'm not planning to sell anything like that for now anyway.  Just experimenting.

John.

[1377x]

nice work!

[ScottyB]

Not bad!  Wish I could do my own.  How bout a pic of the whole gun so we cen get the full effect?

[quickster47 †]

John,

I forgot to mention that you did a great job on those two brass pieces.  Especially the tube end piece.  Great job. 

Hope you don't experience the magnet coming off the bolt and sticking to the hammer pin.  Might be a good reason for a drop of thick CA glue on the end.

Carl

[Brutuz]

Very nice 

[John_c]

Gentlemen - thanks for the comments.

A little more info.  Here's the full photo of the gun - not much else to see:



A photo of the gun with the muzzle removed:



A "pencil cad" drawing of the muzzle brake with dimensions - in case anyone wishes to build one.  I would have used aluminium for this however didn't have any stock that was suitable so brass it became.  It may be a bit heavy, will have to see:



Note:  All measurements in inches.  Most are not very critical.  "B" is critical as it must fit closely on the end of the barrel (the wider portion of the barrel, not the small diameter nub at the end).  You may wish to measure yours before drilling/boring this to size.  On mine, B = .436 in.

"A"  can fit closely to the nub end of the barrel or be larger if you wish.  Keep it under 0.436 in. so that the muzzle brake does not push too far onto the barrel (and obviously over 0.177  ).

D = 0.731 in. - not critical but 3/4 in rough stock would work well if making this.

So far the magnet on the end of the bolt has been staying in place however I will glue it if there are any problems.  Thanks for the tip Carl.

John.

[Crosshairs]

Good ideas and nice work. 
                        Mike

[hellgrips98]

2 thumbs up...