This page encompasses the SFT o-ring, feedneck, barrel, and detents. Most of these are just minor features of the marker, but deserve some explaniation nonetheless.
Seal-Forward (SFT) O-ring:
The seal-forward o-ring (or SFT o-ring for short) is a ring placed in the front of the breech, right behind the barrel, which seals with the bolt during firing. The purpose of this o-ring is to prevent any of the pressure firing the ball to blow up into the feedtube (also known as blowback into the feedtube). When blowback occurs, efficiency decreases due to more air being required.
The SFT o-ring can infrequently be the cause of paint breakage problems in the barrel. This can either be due to low-quality paint, dirty SFT o-ring (or the o-ring clogged with paint from previous chops), cold weather problems, or due to severely enlarged paintshells. These are explained in further depth in the Troubleshooting section (see the Related Links).
When replacing the SFT o-ring, I suggest you always use a clean, new 17/90 o-ring. This is more "stiff" than the o-rings that are used throughout the bolt assembly (which are 70 durometer instead of 90, see the page for o-ring information for details on this). Some users have found that a softer 17/70 o-ring can help with barrel breaks, however I don't personally recommend doing this. If a 17/70 is used, it is likely that it will pop out of position, which then jams the bolt and forces you to disassemble the marker to remedy the problem. This is why a 17/90 is used in the first place, and I recommend following it.
Feedneck:
The feedneck threads on the Shocker NXT are unique to the NXT only at this time. Previously other SP markers used the same threading, but this has changed with the NXT models.
The stock feedneck on the Shocker is oversized and houses a pair of large o-rings which are used to tightly hold onto your hopper. ONe or both of the o-rings can be removed for a pneudo-adjustable feedneck size. The stock feedneck will fit Revvi-feedneck sized necks found on most agitators and gravity-fed hoppers. Halos, eVolutionIIs, VLocities, and Pulses won't fit until you remove at least one of the o-rings.
Many aftermarket clamping feednecks are available, from a myriad of manufacturers, in a variety of styles. My personal recommendation is the SP Q-Lock, which features a large cam-operated lever to tighten the neck, and is available in multiple colors. I'm not going to list any more because there are simply too many out there (nearly every online store carry several brands to choose from).
Feedneck Installation:
1. You must first remove the current feedneck. They are loctited from the factory, so a lot of force may be required. I suggest using a hairdryer or other heat source heat up the connection between the body and the feedneck. Heat it until it is too hot to touch, wrap the hot material in a layer of clothing and untwist. If you don't want to deal with the hairdryer, you could also try vicing down the feedneck and unscrewing the body from it, however this will most likely scratch the current neck.
2. Clean the threads in the body, remove as much of the old threadlocker as you can.
3. Apply threadlocker to the threads of the new feedtube. DO NOT apply thread locker to the threads in the body. I recommend red loctite, in liquid form (no loctite sticks). You can also use a strong epoxy, or a standard metal-to-metal epoxy.
4. Align the new feedtube with the body and gently screw them together. Go slow to avoid cross-threading; if there is resistance, you're most likely beginning to crossthread the neck, back it off and try again. Screw the feedneck down ONLY hand-tight; do not simply tighten as hard as you can. If you screw it in too tight the feed tube will shatter during the game if enough force is applied, and may even damage the threads in the body.
5. Allow threadlocker or epoxy substantial time to cure. 12 hours at a minimum, 24 hours recommended.
Barrel:
The barrel threading on Shocker NXT markers is the same as the Ion, Impulse, SP8, Epiphany, and Nerve markers. This threading is generally referred to as Impulse threads becuase the Impulse was the first marker to use it. There are many aftermarket barrels available, both from SP and otherwise. The stock barrel on the Shocker NXT is a two-piece All American, bore sized to 0.693. This will accept any SP substitute All American or Freak fronts, as well as non-SP fronts if compatible.
The barrel hood is fitted with a large o-ring to prevent the barrel threads from locking up against the body. This can be replaced with another o-ring of similar size, the exact size doesn't matter. The SP barrel fronts are fitted with a 19/70 o-ring to seal against the SP barrel backs.
Detent/Cover Assemblies:
Located on each side of the body are the eye covers. The eye covers serve two purposes, they firstly cover the eyes from dirt and debris, and also contain the detent assembly. The purpose of the detents is to prevent multiple paintballs from rolling down into the barrel while the bolt is open (while the marker is idle).
The eye covers are removed using a 1/16" allen wrench, inserted into the exposed hole on the outside of the covers. After unscrewing the eye cover, it will release off the side of the body and allow you to separate them.
The eye screw is sunk into a notch on the inside of the eye cover. It's held in place by the small foam disk located under the screw. The foam disk is used to hold the eye in position. The screw can be removed by tucking the foam disk down and sliding the head of the screw over it and out from its notch.
Detents:
Shocker NXTs use a detent system which is integrated into the inside of the eye covers. The detent assembly consists of the detent piston and a hidden spring which is used to actuate it. The detent is removed only by inserting a tool into the bottom hole under the piston (detent access), which is used to tuck in the "lip" of the piston and allow it to be sprung out.
Removal of the detent piston tends to place a lot of wear on the piston lip, so once you remove the detent it will likely need to be replaced. To reinstall, simply position the detent spring inside the piston and insert it into its bore in the eye cover.
Vision Eye System:
This is described in the upper board and Vision system page (refer to the Related Links section below).
Overview:
· The SFT o-ring is located right behind the start of the barrel, it is a 17/90 o-ring.
· The SFT o-ring can be the cause for some barrel breaking problems.
· Shocker NXTs use a unique feedneck threading that doesn't fit on any other bodies.
· Shockers NXTs use Impulse-threaded barrels. The stock barrel is a 14" 0.689 All American two-piece.
· The integrated eye/detent covers are used to cover the eyes and detents.
· The detents can be removed for replacement but otherwise will remain assembled with the cover.
Related Links:
· Vision system
· Troubleshooting (chopping problems).
· O-ring information
· Private Label Shocker guide