1. GENERAL 2. Maintenance/Trouble Shooting.
DESCRIPTION
The purpose of this FAQ is for all those PMI3/VM68/VM-Magnum/
VM-EXC users, who are sick of seeing all those giant AUTOMAG/
AUTOOCKER/PROAM mega-bandwidth FAQS. This IS the paintball FAQ
to-end-all-FAQS. The PMI3/VM68/VM-Magnum/VM-EXC is, for the most part,
the same paintball gun. The PMI3 is an early version of the VM-68, and
all parts are compatible (except early PMI3's have NON-reversible
hammers, Reversible bolts, and liquid UNfriendly cup-seals). The
VM-Magnum is the same as the VM-68, plus a nice "Bull" barrel,
dual-bottle adapter, field strip screws, black (or "REAL TREE")
anodization, and is truly ambidextrous. The VM-exc is also the same as
the VM-68, except with a built-in expansion chamber, bottom line,
sight-rail, and is also ambidextrous. The typical price of VM68 is
$190-230, VM-magnum is $230-290, and VM-exc is $240-290. Throughout
this FAQ will refer to them simply as the 'VM', except when special
differences are noted.
The VM-68 is a .68 calibre, true blow-back semi, firing from an
open bolt. The VM is based on a design that Benjamin/Sheridan
designed about 20 years ago (for pellet guns). In many ways, the VM has
the same basic internal structure as the PGP, PMI-x, KP-x, and Sheridan
BB guns. Other famous guns that are derivatives of the Sheridan
design, are: BudOrr Sniper/Cocker, Promasters, F1/2s, Sterlings, and
Spyders.
NOTE: The Sheridan EQUALIZER has compatible barrels and feed
blocks with the VM, but otherwise they are TOTALLY DIFFERENT guns (more
similar to a 'mag then a Sheridan).
a. LUBRICATION
In my years, I have talked to 1000 people about their VMs. Each
one of them has their own separate idea on proper VM lubrication.
2-E of the AllAmerican's says that Sesame seed oil for the internal
hoses (if any), keeps any liquid co2 from clogging up the system.
The VM manual suggests vegetable oil, or vaseline, which I don't
suggest. Some local VM teams use a thin layer of AXLE grease, mixed
with vegetable oil. However, I have found that ordinary gun
lubricant, like GOLD-CUP or 3in1, works plenty fine. For the most part,
ANY lubricant will work fine, just as long as it doesn't contain 2
things: 1. Anything petroleum based, 2. Thicken when it gets colder.
This means DON'T put WD-40 in your VM. All petroleum based lubricants
EAT o-rings. While I realize VMs have far fewer O-rings then many other
GUNS. When your CUP-SEAL goes in the middle of a battle, you'll wish
you didn't use that WD-40. Also, LITHIUM grease, and other automotive
lubricants tend to thicken in cold weather, causing cycling problems
(see below). Plenty of fine paintball-only lubricants are available,
though, are expensive.
b. VELOCITY ADJUSTMENT
You would be surprised the number of newbies I find who cannot
properly adjust the velocity of a VM. Dont feel bad, though. The VM is
by far the most complicated paintball gun to change the velocity on.
(even more then changing springs). There are 2 methods of
adjusting the velocity on a stock VM: the bolt, and the valve. (plus a
few 'trick' methods further in the FAQ).
d. VM CYCLING.
It seems that everyone has a problem with
their VM cycling at one time or another (the 'full' auto effect).
Below is a step-by-step guide to solving the cycling problem.
1. Manually cycle the gun (with no air) to see if it has an excess amount of friction. For example: Remove the main-spring, and see if the hammer/bolt will freely slide from gravity alone. If it does, then excess friction is not a problem. If it is a problem, It could be a couple things: -
2 VALVEvi. MISCELLANEOUS TROUBLESHOOTING. A. ** Screws **. Keep in mind that the body of a VM is made from soft aluminum and magnesium. It is very to strip the threads for a screw. If the threads become stripped, they needs to be re- drilled and tapped to a larger drill size. Plus, it is also easy to strip the faces of the allen-bolts from over-tightening (which means you can't get the screw out). If this happens, try using a bolt-removal tool. If this fails, the bolt needs to be drilled out, as well as the hole. Then re-tapped to a larger size. This is a good reason to buy the field-strip kit for the VM. It is much harder to strip the screws with it. B. ** Bolt-Stick. Bolt-stick is a very rare occurrence of a bolt 'stopping' within mid-cycle. This often occurs with aftermarket parts, and can come from a variety of places. Often the bolt orings will become worn and cracked (especially stock), and can sometimes create enough friction to stop the bolt. Sometimes paintshells can get behind the bolt, and jam it (especially delrin). Some after-market hammers cause this. Probably becuase the sear is getting caught when sliding across the hammer (or maybe its the sear release pin)... still studying this phenom. C. ** Double-Feeding **. Double feeding can only mean one thing. Your "Magic Fingers" have gone bad. The Magic Fingers is my name for the rubber ball-detent found in the feed block. They can become damaged for a variety of reasons (including aftermarket bolts). Fortunately, they are cheap and you can get them at most pro-shops. D. ** Excessive Ball Breakage **. The VM rarely breaks paint, so if ball breakage becomes excessive, something might be broke. First: The VM might be double-feeding (see above). Second: You might be missing a bolt o-ring. Missing a bolt o-ring would cause excessive co2 to enter the feed elbow when firing, slowing the feed rate, pinching balls. Third: the stock brass barrels bends easily if dropped. Plus, check inside the barrel for excessive scratches. See if you can easily BLOW a paintball through the barrel with your lungs. Forth: Perhaps you are using bad paint, or even firing the VM faster then it can feed (unlikely).
I will just say this once. The stock VM barrel is garbage (except the Magnum barrel). The finish is always poor, and brass barrels get scratched VERY easily. Plus, the ID is .690 which is way to tight for big bore paint (ie Nelson, Bullseye). However, the STOCK barrel can be easily modified to shoot good. All it really needs is to be bored to .692 and honed/polished. A good honing kit will do both. An airsmith can also hone the barrel for you, but it might actually cost less to simply buy a new one.
Almost ANY aftermarket barrel is a great replacement, which should yield better range then any 'mag. Part of the reason for the poor range and accuracy is the inherent turbulent nature of a blow back semi. When the 68-special, Golden Eagle (chuckle), and PMI3 first came out many years ago, many pro players stayed with their bushmaster pumps, due to the poor accuracy of the smooth-bore semis. When RIFLED barrels came out, this changed everything.
Expansion chambers allow the co2 to pre-expand before being used, thus more efficient. There is a number of different types, some do very little while others are very helpful. The most common is the original Black-Rain system (by AirAmerica), which can be setup in a BACK_BOTTLE (Terrorist), or BOTTOM-LINE setup. This is the best chamber, and most expensive at $100-$160. If you already have a DUAL-BOTTLE setup, and a 3oz (ie MAGNUM), COOPER-T makes a special valve, that fits on the 3oz, that turns it into an expansion chamber. I hear this works well. Taso makes many different styles of CHAMBERS ranging from small ($20) to large ($100), all are quality devices. Avoid cheap small chambers, they're not worth the money. Also, a remote system also works as a partial expansion chamber. SmartParts makes an REMOTE/EXPANSION CHAMBER for about ~100. The Chamber (designed by AIR- AMERICA) fits on the bottle, and also features a quick-disconnect, allowing it to switch from gun to gun (great deal). Taso, and I&I also sell similar setups.
The one cure-all for velocity problems, cycling problems, cold weather problems, and consistent velocity problems is to use a SIPHON tank. Siphon tanks allow the VM to drink straight LIQUID co2. This allows for a GREATER operating pressure. Most other blow- back semis use SIPHON tanks (ICON Z1/2, PROAM/LIte). The only drawback is efficiency. With a siphon, expect only 100-150 shots from a 7oz. This means a 20/32/40oz is a MUST. Although, if the VALVE it drilled out bigger, you'll get 130-175 shots from the 7oz. VMs CANNOT run on a SIPHON and EXPANSION chamber at the same time, as they are contradictions (people really ask me that). Plus, the VM will blow giant VAPOR clouds which impress the newbies (and give away your position). Make sure your VM was made after MAY 1992, as it may have the 'old' cup-seal. Siphon tanks are the same as regular PV tanks, except have a special $10-15 SIPHON VALVE. (TIPPMAN or TPI makes the best). It should be noted that since running on a SIPHON means your velocity rises when rapid firing, you should crono this way, to get an accurate fps reading. NOTE: Most tournaments require you to chrono this way if you use SIPHON, which is a GOOD thing becuase its nearly IMPOSSIBLE to get a HOT shot if you chrono on 'liquid'.
Two common aftermarket VAVLES are the MAGNA-PORT valve, and the PRO-VALVES. The MAGNA-PORT valve reduces the number of CLOCKS to one, plus features VENTURI recocking jets. Its advertised to raise velocity, efficiency, cycle rate, and cold weather performance. Pro-valves are similar to the MAGNA-port valves (with one clock), plus feature delrin cup-seals which last longer then the stock cup-seal. I would suggest that you avoid aftermarket valves. It is true that the raise velocity, and cold-weather performance, but they SEVERELY hurt co2 efficiency (more so when using Expansion chambers). Your efficiency could drop up to 60% with the custom valves. They are ONLY useful in SEVERE cold weather, without an expansion chamber. Plus, I have heard people say that they have a hard time installing them, especially in VMX's.
The Delrin BOLTS are made from DELRIN, a fancy plastic, and are light. They usually contain no o-rings, so expect more blow-back exhaust in the feed elbow. Cooper-T makes an unusual DELRIN bolt called Maximizer, designed to give the ball a backspin, and an extra 150' range. Results though, are mixed. (I have one, and believe they work, but most people have had problems with Maximizer bolts). Some Ventrui bolts have oversized OD's (causing cycling problems) and I typically find that delrin bolts usually cause more problems than they fix. Usually. NOTE: You should check the face of the delrin-bolt often. The high-pressure CO2 often causes to face to distort, which will brake paint.
The STOCK hammer on the VM is FINE for the most part. However, aftermarket Hammers can add some special features. Some hammers are made from aluminum, or are drilled for lightness. Light hammers cycle faster, providing for a greater rate-of-fire. Other hammers are designed to allow for velocity adjustment from the back of the VM. Probably the standard replacement hammer for the VM is the PHAZZE II. Both TASO, ABC, I&I, PRO_COMP, and COOPER-T also make quality aftermarket hammers ranging from $50-120.
The purpose of the powerfeed, is to allow for faster feeding of paint, from the loader, into the breech, by making use of exhaust co2. On a STOCK VM, this is NOT USEFUL, as it cycles much to slowly to make use of the blowback effect. But, many custom VMs can cycle very fast, faster then the loader can feed, requiring a powerfeed to prevent ball chopage. Some people argue that POWERFEEDS were designed for 'mags, and simply don't work on VMs. But, many others say different. If you can fire your VM faster then it can feed, get a POWERFEED, if it doesn't work, send it back. Pro-line makes both a VM- powerfeed, and a UNIVERSAL powerfeed (which fits on the VM, and is $20 cheaper!). POWERFEEDS are pricy ~$25-50.
There are 2 basic ways to increase the VMs cycle rate. First, is lighter INTERNALS (see above), second, is a better trigger. The VM trigger is slow, complicated, and tends to break down. For a trigger job, I recommend that the trigger be sent to a professional, as it is very easy to break (I KNOW, I have broken 2!). A trigger job usually includes a lighter pull spring, and a block behind the trigger. Trigger jobs are around $30.
Probably the best TOTAL UPGRADE for a vm is the PRO-COMP kit. First, they take 3 pounds off the body. Then they replace all the internals with CUSTOM parts (bolt/hammer/valve/trigger). They put on a quick trigger, power feed, and better barrel. The final gun rather resembles a pro-master IMO. For about $350, they make the VM a TRUE tournament level marker. PRO-COMP went out of business a couple years ago (due to internal problems), but hear that they may be starting back up soon.
If you're like me, you think you can save money by doing custom work yourself (and you probably don't read the manual for anything either). Alot of the CUSTOM work below was summarized because the full length description took up too much space. If you email me, I'll me happy to explain the idea's more fully.
. The easiest thing you can do is drill a hole in the block behind the trigger, and tap a screw into, this keeps the trigger from going back a certain distance. Next, if you are BRAVE/STUPID you can take the trigger apart, shave down the sear, and adjust the spring, making the trigger pull short and crisp. (I broke mine doing this). In fact, when I called Sheriden, as soon as I mentioned the word 'trigger', they simply said "send it in!". Keep in mind, that its usually best to send the trigger to someone else. That way, if he breaks it, he buys a new one.....not you! Also, the hammer cycles about 1/4" past the sear before it catches. For a slight increase in rate-of-fire, putting spacers behind the bolt shortens the cycle.
vi. ADJUSTABLE AUTOMAG SPRING KIT.
vii. REAR COCKING KNOB/EXTERNAL VELOCITY ADJUSTER KIT.
Before buying -ANY- paintball gun. Ask yourself, how much do you plan on playing? Also, ask, do you want to ability to upgrade in the future? For the NEWBIE, there are basically 5 choices of ENTRY level SEMIs: 1 Stingray ($100), 2: VM ($200), 3: PRO-LITE ($250) 4: F1/2 ($250). 5: SPYDER ($200). If you plan to play a couple times a year, with friends, perhaps the STINGRAY is best, but otherwise, I would recommend the VM. Its cheaper then the PRO-LITE and F2, and can be UPGRADED much further then the SPYDER, and is superior in many ways to all 4 guns. BEFORE you make the choice, go to your local field, and ask to TRY some guns out. Different people have different opinions.
®Teflon is a registered trademark of DuPont
| Copyright © 1992-2019
Corinthian Media Services. WARPIG's webmasters can be reached through our feedback form. All articles and images are copyrighted and may not be redistributed without the written permission of their original creators and Corinthian Media Services. The WARPIG paintball page is a collection of information and pointers to sources from around the internet and other locations. As such, Corinthian Media Services makes no claims to the trustworthiness or reliability of said information. The information contained in, and referenced by WARPIG, should not be used as a substitute for safety information from trained professionals in the paintball industry. |