Tuning Help with mac1 please........

[Dankleinman]

Hello I have a used mac1 that is leaking behind the pressure gauge but I am pretty sure it's not leaking at the threads on the gauge .also I need to know how to get the barrel off so I can swap it with the 177 I have. Plus does anyone know the oring sizes or is there a Oring kit that I can buy it is a regulated one but I also have the big tube that goes on it to go back to unregulated if I want to . I have looked online and can not find any videos or instructions on how to work on this beautiful gun . 



Thanks 



dan 

 

[Franklink]

Two big screws underneath the gun to remove the barrel.....typing up a response to your pm right now.

Edit: In case somebody stumbles across this in the future and could find this helpful, this is what I sent to OP

Remove the barrel by first taking off everything underneath the gun in the for-end section. There will be 4 big honking allen bolts in a rectangular pattern coming up from the bottom of the gun and through the breech. The two on the same side of the slit in the breech need to be loosened the most. The two on the other side may not need to be loosened at all, or maybe minimally. Once these bolts are loose enough, barrel simply slides out of the breech. Per Tim's recommendation, I'd put some sort of witness mark on the barrel so that you can get back to the same point of impact more easily. I used a punch and lightly tapped a small dimple into the side of the barrel dead center in the slit of the breech. From playing with a couple guns that lack transfer ports (like the USFT) cut into the barrel, I've been really surprised to see how much the point of impact rotates around a center point, depending on how the barrel is fixed in the gun (from a rotational perspective). 

 

[Odoyle]

Do you have the regulated bottle version or the HUGE unregulated 1550psi air tube?

How do you know it's not leaking at the manometer threads or fill nipple?

They are super reliable and I most certainly wouldn't start disassembling everything till you know for certain what exactly is leaking.

Soapy water spray bottle time.

If the manometer itself is leaking not at the threads you could fix it with a soldering iron if it's cracked and leaking at the bordon tube solder point.

 

[Odoyle]

If it's leaking at the fill nipple then it's probably only dust or debris in the check valve since the nipple is uncovered exposed to the elements unless you put an AOA Foster fill cover or a carburetor vacuum hose line plug to cover that exposed nipple.

All's you gotta do is degass the gun unscrew it and clean it well. Flip that seal around if it's flattened.

Leaking at the threads? Use yellow gas line Teflon tape properly with thread in wrap orientation.

 

[BC]

The only way to detect where its actually leaking is to do it the way I and Tim at Mac1 would do, fill it with enough air, remove the scope from the rifle and cheekpiece if you are going to dip it that far, and submerge it in your bathtub or swimming pool to see exactly where its leaking. I thought my old USFT was leaking in one spot and to find out it was another spot. I had the long tubes versions. I now have a Thomas. Have you called Tim at Mac 1, he always answers his phone and will give you information if you ask. He will have the correct o rings to buy from him for your entire gun also.

 

[SAZ]

I know this is a pretty old thread..........but I didn't want to start a new thread for my question and couldn't find the answer in the "search" function.

I want to buy a couple breech o-rings to have on hand in case the one on my (Hunter, non-regulated) gun ever goes bad. On the breech block, not the barrel.
The o-ring on it now looks OK, but the gun is new to me so I don't know how long they last.

Does someone know the size and what material they're made of so I can try and order a couple of these?
Haven't had any luck contacting the Mac 1 shop.
Thanks!