Step 8: Assembly and miscellaneous
There are a few more house keeping tweaks here before I actually slap this thing all together.
First and foremost is the valve spring. Most bushmasters I've worked on really struggle to hit field velocity with the stock valve spring. It's too stiff. Luckily, 2k+ autococker valve springs are REALLY close to the same length, and it was a super common mod on ICD-O to swap them out. After a lot of experimentation, a number of years ago I settled on the SLPS autococker valve spring as being the best valve spring for these and I haven't really deviated from it. It works flawlessly every time AND ensures a nice good seal while being very soft. I usually keep a number of them on hand just for bushmasters, and luckily my pile wasn't depleted yet so I tossed one in here.
Next was the vert ASA/Reg adapter. Stock Bushmasters use a banjo screw with a 3/16" hole to attach the reg adapter. Most aftermarket reg adapters (OTP, Eclipse, Lapco, Shocktech) also have a 3/16" hole in them, but more recently I noticed that both the MacDev and Zenitram reg adapters both have 1/4" holes. Turns out that 1/16" is usually good for shaving at least 10-15 psi off your HPR, possibly more depending on what other parts are in your marker, so out came the drill again. I would not recommend drilling out the one piece reg adapters since the walls do get pretty thin and I'd be concerned about the soft aluminum holding up long term.
Once that was done, I hunted around my shop until I found a nice length of steel braided hose that magically was the correct length. All my tanks are 950 psi output, so I strongly prefer steel braid to macro line on anything I'm planning on actually using.
I've been lucky enough to never actually have to run a stock ICD HPR, and this gun was no exception. I have heard rumors that the stock ICD HPRs were designed around a 500 PSI output tank and work way better with them, but I haven't actually confirmed this. Since I have had that dust silver CP reg kicking around for over a year anyway, I slapped it on. At this point in time, the gun airs up with zero leaks and cycles beautifully, all that's left is to get more air, and chrono it in!
There are a few more house keeping tweaks here before I actually slap this thing all together.
First and foremost is the valve spring. Most bushmasters I've worked on really struggle to hit field velocity with the stock valve spring. It's too stiff. Luckily, 2k+ autococker valve springs are REALLY close to the same length, and it was a super common mod on ICD-O to swap them out. After a lot of experimentation, a number of years ago I settled on the SLPS autococker valve spring as being the best valve spring for these and I haven't really deviated from it. It works flawlessly every time AND ensures a nice good seal while being very soft. I usually keep a number of them on hand just for bushmasters, and luckily my pile wasn't depleted yet so I tossed one in here.
Next was the vert ASA/Reg adapter. Stock Bushmasters use a banjo screw with a 3/16" hole to attach the reg adapter. Most aftermarket reg adapters (OTP, Eclipse, Lapco, Shocktech) also have a 3/16" hole in them, but more recently I noticed that both the MacDev and Zenitram reg adapters both have 1/4" holes. Turns out that 1/16" is usually good for shaving at least 10-15 psi off your HPR, possibly more depending on what other parts are in your marker, so out came the drill again. I would not recommend drilling out the one piece reg adapters since the walls do get pretty thin and I'd be concerned about the soft aluminum holding up long term.
Once that was done, I hunted around my shop until I found a nice length of steel braided hose that magically was the correct length. All my tanks are 950 psi output, so I strongly prefer steel braid to macro line on anything I'm planning on actually using.
I've been lucky enough to never actually have to run a stock ICD HPR, and this gun was no exception. I have heard rumors that the stock ICD HPRs were designed around a 500 PSI output tank and work way better with them, but I haven't actually confirmed this. Since I have had that dust silver CP reg kicking around for over a year anyway, I slapped it on. At this point in time, the gun airs up with zero leaks and cycles beautifully, all that's left is to get more air, and chrono it in!
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