Tight bore barrel question

VivGrise

I just recently bought a Thompson M1A1 and I want to upgrade the barrel, i was looking at getting either a Prometheus tight bore or a Tanio-Koba twist barrel.

I just have a few questions if anyone could help!

Would it be difficult to switch the barrels?

Which is a better barrel?

Do you have to have to use .2g bbs with the barrels, or can you use .25g?



Thanks!

CpcRc

You should've asked me UL airsoft, here to help.
Found a hopup disassembly guide for the Thompson. I've attached the links to the pics. Just copy and paste the words and pics into a word document and follow it. The first few steps will tell you how to take out the barrel, you just replace that with your new one and place it back in the unit. You will probably need to take the hopup rubber off the old barrel and put it back on the new one.
Tip: spray silicon oil on the outside of the barrel to attach the rubber easier and then on the outside of the rubber to slide it back into the hopup unit easier.

I'll attach the webaddress at the end for the full disassembly guide.

Hop-Up Disassembly

The hop-up can be removed by first removing the two screws holding the hop-up there.
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/27hop.jpg

Then you are free to pull the hop-up and barrel out of the gun.
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/28remove.jpg

Here is what it looks like:
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/29hop.jpg

To start disassembling the hop-up, pull off the little plastic stabilizer.
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/30rem.jpg

Next off, just pull off the hop-up wheel. Take a good look at the hop-up wheel and how the strike chamber interacts with it.
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/31hop.jpg

After that, pull off the barrel clip. Once that is done, you are completely free to remove the barrel and hop-up bucking from the hop-up chamber.
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/32clip.jpg

If you would like to replace the nub, the strike chamber is already able to flip up and down due to the release of the hop-up wheel (blue arrow). However, if you need to remove the strike chamber, then remove the screw (red).
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/33screw.jpg

Then, simply pull out the pin (red arrow).
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/34pin.jpg

And there you have it! A fully disassembled Thompson hop-up!
http://i261.photobucket.com/albums/ii74/dragonmxx000/thompdis/35final.jpg

that's the hopup part and the webpage is:

http://www.airsoft-barracks.com/forums/index.php?showtopic=4765

If you can disassemble a hopup, or even do the first few steps, you should be able to change a barrel or hopup rubber.

I can't say which barrel is best unfortunately someone else might be.

.2g BBs and .25g BBs isn't the main issue with tightbores, you have to use better quality BBs so they don't scratch the barrel if they shatter or jam in it. But heavier BBs are more accurate. I use .25s myself. And if my hopup wasn't so bad :mad: I would've had more range Saturday.

Hope this helps.

VivGrise

thanks a milion man, i'll def get crackin on this! :pac:

bullets

just to add a bit of info (not specifically tightbore related)
There are some interesting tips on barrels maintenance here
and getting more efficient performance:
http://shredderscs.proboards.com/index.cgi?board=read

The PTFE tape on the outside of the inner barrel/hopup unit is neet thing
to do in case of any air leaks.

~B