FN SCARred for life

I have a DBoys Scar-H. Having bought it, I found myself not being a great fan. Not just of the replica - which we'll come to later - but of the gun in general; I find it quite bulky and the grip isn't to my liking feeling noticeably slimmer than I'm used to and not particularly comfortable. The magazine is ludicrously easy to release by accident. The stock is quite nice though and the moveable cheek rest is useful but quite far forward.

The replica came with its own problems. To be fair, it was cheap so I wasn't too surprised. The ubiquitous problem of being hot for the UK was dealt with by clipping the spring and it now fires at a slightly underpowered 322fps. I had a trigger mosfet kicking about - originally destined for a CQB M4 - but equally suitable for the SCAR and fitted that while I was at it. The selector switches are pretty vague, especially the right hand side one but I don't see any way to fix that. I might have a look and see if I can source VFC ones and see if they work better. The others issues appear to be intrinsic to the design. Not having seen the VFC version that the DBoys is based on I can only assume that the superior quality of the original has addressed these problems, although I do have my doubts.

DIY front end fix

The main issue was with the front end though. The lower RIS rail bolts pass through two mounting brackets to screw directly into the fairly slim outer barrel. Almost immediately it was obvious that this was not particularly secure and the thin pot metal attachment points quickly wore down under the hardened steel bolts preventing me tightening them and effectively making the gun unusable. I opted for a somewhat Heath Robinson approach and secured a suitable sized nut to the front barrel mounting point using some copper sheet and some JB weld. After some sanding and a quick coat of matt black it looked a bit rough but functional. More to the point it solved the problem and to date has worked fine.

Hole re-tapped to M6 size

The back though was somewhat trickier as the barrel went flushly through a metal block that was securely bolted to the receiver and there was no space to use my previous solution. However, now that the front end was fixed the outer barrel was pretty secure and I decided to secure the rear to the block itself - the hex bolt went through this block to attach to the barrel. Of course, it wasn't that simple. The hole was M6 size and the current bolt was M5. I went ahead though and threaded the hole with an M6 tap. The only problem was that a flush fitting M6 hex bolt would still protrude without modifying the RIS so I selected a shortish dome headed bolt which, while it was raised up somewhat from the RIS, looked much better than than expected. It would, and did, present a problem when mounting a RIS mounted magazine well type grip but the grip was plastic and the bolt was hardened steel. A Dremel sorted out the grip.

While it now feels as solid as a proverbial rock and much stronger than the original it could be strengthened further by dropping a 10mm by 5mm diameter rod and a spring in to mate it more firmly with the outer barrel.

Of course, I managed to break the hop unit while removing the receiver...

Variety is the spice of life

I like collecting guns - or more correctly, realistic imitation firearms.

I've bought one or two over the years with the current collection numbering just over sixty. Of these, four are inoperable; not because they are broken but either because they have been disassembled and I haven't yet worked up the enthusiasm to put them back together - TM IMI Desert Eagle and HK MP7 I'm looking at you - or, I've cannibalised it for parts, that would be the TM GSPEC with no PDI barrel since it's now in the Tanaka M700 AWS, which is still shit - or the TM MP5K, which at this moment lies on the work top just waiting to be put back together once I've figured how to wire a mosfet into a gun with no space. Or at least no space where I need the mosfet to go.

Anyhoo.

Of the sixty(ish), roughly half of them are pistols and roughly one third are 'clones'. I've nothing against clones at all but while, in general, they are inferior copies in some cases you'd need to be looking real close. The real reason I buy clones is probably the same as everybody else; they're cheaper. In some cases much cheaper. I can justify £150 on an AEG that I like the look of; £300 not so much. If it turns out to be not so nice as anticipated well, no great loss. However, most clone guns get 'detailed'. Screws get tightened, rough edges get polished, actions get smoothed, mosfets get fitted (sometimes) and other small niggly problems get ironed out. By the time I've finished the guns work flawlessly. My Double Eagle UMG has been my go to skirmish gun - it's seriously accurate and actually better than the G&G one I have - despite costing all of £99. On the other hand some of my first guns are still able to hold their own albeit with some fiddling. My Marui SIG552 has had the gearbox upgraded, rewired,  mosfetted, fitted with a PDI 6.01 barrel, runs around 340fps and is deadly accurate. The G&G G300S has had the benefit of a trigger mosfet board and a new motor and puts out a satisfying rate of fire on a 1,600mAh NiMH. 

However, these were not partucularly cheap guns to start with and with the various bits both guns would probably be pushing the £450/£500 mark. My Cyma M14 SOCOM on the other hand is around that sort of money in total but that's with a mosfet, a Visionking short dot scope, real steel Bradley cheek rest and a decent leather sling as well as the bits and bobs required to fit these. Most clone guns are, with added sights and the like around half of that. If I'd bought the TM version I could add at least £200 on to that for the base gun and then have to upgrade it to shoot as well as the Cyma which, incidentally, also has a TM hop unit.

Sure, I could buy less guns but what's the point in that. 😀

Marushin Ruger Mk1 Bull Barrel

I always liked the look of these and ever since I got a chance to fire a real one when I was over in the states some time back I wanted an Airsoft version. Compared to the other handguns I fired this was amazingly easy to handle, pointed very naturally and the low recoil made for extremely accurate rapid fire. While a pretty anemic round compared to centre fire cartridges I figure that a couple or three .22 long rifle rounds would take the fight out of most people and a shot to the head would likely ruin your day.

That said, I finally managed to blag a stainless bull barrel version off one of the forums; a Marushin which has all the right trades and looks pretty cool. The gun is essentially full plastic but the sights are metal with target type front sight and an adjustable rear sight. I didn't get a manual with the gun but it's simple enough to figure out and a quick google supplied said manual and take-down guide.

Overall the gun looks good; I like the bull barrel and the trades are pretty good - despite the 'MADE IN JAPAN BY MARUSHIN' bit. The fit of the external plastic parts are pretty good and the fact that the receiver, barrel and cocking lever/thingy are separate actual adds to the realism. The metal rear sight had a lot of play but some strategically place aluminium tape has firmed it up and, although the blade can still be moved slightly back and forth, it's orders of magnitude better. The trigger pull is long and heavy as is expected of a non-blowback gun but not unduly so. There's a bit of slack before the trigger engages and a very slight roughness just before it releases the hammer. No big deal and I'm sure I can improve it. 

However, give the gun a shake and it rattles. Not quite like a set of maracas but not far off :) Only kidding but it's annoying enough to me that something needs to be done and, since these are moving parts, aluminium tape is unlikely to cut it. Do bear in mind though that for most people it's absolutely fine; I annoy easily. Out of the box the gun perform flawlessly and I can't fault the overall quality.

Taking the gun apart to it's main components is straight forward and dismantling it further is pretty easy as well. It breaks down to six main parts; the bull barrel, the slide, the inner barrel assembly, the cocking lever, the main spring housing and the grip. The grip contains three sub-assemblies which from back to front are the hammer and safety, the trigger mechanism and the loading lever. The gun works by simultaneously cocking the hammer and pulling back the inner barrel assembly to load a bb when the trigger is pulled. There is no hammer sear and the hammer is released simply by pulling the trigger all the way back. The safety works  by engaging a notch in the trigger bar preventing the trigger form being pulled. I'm not sure if the hammer is locked when on safe but since it's completely internal it is unlikely to be able to activate the magazine release valve without the power of the mainspring behind it. Putting it back together from completely stripped is slightly more challenging but three hands are not required and it goes back together with little trouble.

Obviously, the whole point in taking it apart was to iron out the niggles and improve what is already a decent bit of kit. My main task was to polish all the moving bits that came in contact with other bits - moving or otherwise. Having done that it was pretty clear that the hammer tolerance was generous and the main cause of the rattling but due to the way it's designed no improvements came to mind. The trigger take-up slack was dealt with by inserting a small square copper shim where the trigger meets the loading lever mechanism and a standard 0.1mm gearbox shim sorted most of the side to side movement - which to be fair was minimal but that's just me. It improved the trigger no end with a smoother pull, and no sign of the slight roughness just a crisp release. However, it did have the effect of not returning far enough to to engage for the next shot which was a bit of a pisser. Much head scratching later I was about to dismantle it to remove the shim when I decided to see if inserting the magazine would make any difference. It did. The gun worked flawlessly. Essentially, when the magazine is in the trigger bar is prevented from dropping the fraction of a millimetre that prevented the trigger reset.

I haven't chronoed it yet but from all the indications I've come across is that it runs hot. I'll see what it does on Ultra gas and drop to 144 if it's still over 350fps. Overall, I'm quite delighted with this while the silver finish isn't exactly skirmish friendly I can see me using it anyway.

The photos this time aren't mine and the qudos goes to k.a. on the Zero-In forum that I bought it off of. 

Marui MP5K/SP89 Upgrade - Part 1 and a bit

Well, I decided to put a thread adaptor on the MP5K. I ordered a King Arms standard threaded one and being steel it does look quite cool. I prefer the look of it to the MP5K with the tri-lobe adapter – technically an MP5KN –  which to me makes it look like you’ve just ditched the stock on your PDW. I decided it needed to be tapped and threaded to allow a grub screw to secure it since there was the possibility that it could move when attaching either a suppressor or sound hog. In theory, a sensible decision. In reality, not so much.

The hole drilled quite easily with the indicated drill size for an M3 thread and I proceeded to tap out the hole. Just as the tap started to protrude into the threads that take the adaptor it snapped. Well, shit. I now had about 1½mm of tap sticking out either end. A pair of pliers failed to grip it and simply broke of the remaining bit of tap on the outside. The next step was to drill the tap out. Funnily enough, it turns out that taps are really fucking hard and promptly blunted the drill bit. The outside part was now virtually flush but a quick run over with a tungsten Dremel grinding bit took it down to a smoother finish. The only option was to do the same on the inside, wearing down the original threads until the broken tap was ground down flush to the depth of the thread. It actually now looked  pretty cool with the interrupted thread. The outside is a bit the worse for wear but it’s hidden by the handguard when fitted so ultimately of little concern.

Of course, it turns out that the King Arms adapter proved to be an extremely tight fit anyway and with a reasonable amount of brute force is now more or less permanently attached. It’s going nowhere.

I still haven't finished the upgrades but having discovered the Gate PicoSSR 3 mosfet, which is absolutely tiny, I've ordered some direct from Gate in Poland, one of which will go into the K. 

Marui MP5K/SP89 Upgrade - Part 1

My long in the tooth Tokyo Marui MP5K with SP89 grip. Other than adding a front sling pin and silver dry brush to give it that used look this is bog standard. Even the battery is an old 1,400mAh NiMH that hasn't been removed in eons.

Now it's dead. Expired. Ceased to cycle.

Obviously, the sensible thing to do would have been to check the battery so with that in mind I never bothered my arse and decided that it was something more terminal. In my defence, I had always intended to upgrade this anyway and not working was convenient excuse. As stated in a previous post, I wanted 320(ish) fps and as many rounds per second as I could wring out of it. However, as long as its under 350fps it'll be okay and if I can get 900 rounds per minute that would be great!

I thought I had a Lonex Titan high speed long motor kicking about but it turns out that it is a short version. Bugger. Loathe to spend another fifty quid on a new motor some research on tinternet turned up the SHS motors which seemed pretty decent for around £27 if I was willing to wait until it arrived from Hong Kong or £33 if I wanted to get it from the UK. Grudgingly I forked out the thirty three notes; and the fucker's still not here.

Tool Door. Every door needs hex keys and pliers.

I'd have liked a PDI barrel but they don't make one for the K. They do make one for the PDW though it's a tad longer extending into the flashhider. I found that the PDI 6.01 added about 5% to the muzzle velocity of the TH G18C AEP. That's around a 10-15% increase in efficiency and I would expect a similar result with the short barrel in the MP5K. Spring wise, a Guarder SP100 should do the job though with some spacers to fix the angle of engagement and a bearing spring guide this will likely come in at the wrong side of 350fps - my site limit. I decided to short stroke the gearbox by two teeth which should drop it down by 20fps or so.

The piston is a full metal teeth job which on reflection makes it fairly heavy but I've left the bearing out of the piston head which brings the weigh back down slightly - I'm sure shaving two metal teeth off has had negligible affect though... I did decide to swiss cheese it but gave up - the way I'd drilled it precluded cutting more out so the effect has been minimal and is down to my lack of patience and shit drilling than anything else.

On a side note, the tool door is now looking quite full with almost everything usable or used for airsoft work - although the Knipex mini bolt cutters  and wire snips have yet to come into play...

I had originally intend to run the motor on a Firefox 7.4v 1,600mah LiPo but with the way the wiring comes out of the battery it's not possible to fit it without crushing down the wires where they come out of the battery; it would be useful if battery leads came out the end of the battery rather than the side! However, I've ordered aa Turnigy 7.4v 1,300mAh 25C LiPo which looks more than suitable. Overall length is similar to the Firefox at 168mm compared to 170mm but crucially it's slightly thinner at 18x12mm rather than 20x12mm. I did have a look at using a rear wired battery connector which would cut a significant amount of cable out of the circuit but space is at a premium and routing is tight once the end plate is on. The connectors take up a surprising amount of space so I'd probably end up having to use a smaller 1,000mAh LiPo. So, for the moment the front wiring stays.

The bushes on the Marui gear boxes are 6mm - tiny by today's standard - and are plastic to boot. This is actually fine for the standard Marui power but since we're upping that by a fair margin I'll fit some metal bushes to be on the safe side. Obviously, it'll need re-shimmed but that should be a straightforward if time consuming job.

So, to summarise, SP100 spring, short stroked by two teeth, metal bushes, bearing spring guide, SHS High Speed motor and a 7.4v 1,300 25C lipo. Currently in bits on the kitchen table/trolley thing.

Expired Marui MP5K

Well, it ain't working 😕

Battery is okay - powers a UMP just fine - and the fuse is intact. Hmmm. Looks like it has to come apart for an examination and, since disassembling a Marui MP5 is a pain in the ass, I'll do some upgrades while I'm at it. The target is around 330fps and whatever rate of fire I can wring out of it.

With that in mind I've got a high speed motor kicking about somewhere which I think is a long shaft model for a version 2 gearbox and I've just received a piston head and piston in the mail which I ordered specifically for this. I was quite impressed with the result I got from short stroking the cut down G3 by a couple of teeth and I think I'll do the same here. I'd like to be able to put a silencer on it  or more likely some sort of sound hog. I tend to find the most impressive guns are high rate of fire either nearly silent ones or high rate of fire loud as fuck versions - the sewing machine sounding ones don't cut it in my opinion 😉. That said it needs a screw in fitting so I'll have a hunt about something completely inappropriate. 

I'll get some pictures up in the next post.

Sector Clip thoughts...

Well, once more the MC51 is in bits in an attempt to fix the strange, high fps one minute low the next. My thoughts turned to the sector clip.

Essentially, the sector gear - so named because it only has teeth on one sector of the circumference of gear -  is the one that pulls back the piston and lets it go when said sector runs out of teeth. It also serves two other functions one of which is to pull back the tappet plate which, in turn, pulls back the nozzle thereby letting a bb move up from the magazine. After a point, the tappet plate slides off the pin that is pulling it back and the tappet plate with attached nozzle move forward shoving the bb into the barrel and, hopefully, sealing it. A fraction of second later the piston also slams forward pushing the bb out the barrel - preferably at a reasonable pace.

Still with me? Good.

However, the thoughts behind a sector clip is that instead of a pin we have a small rounded triangular(ish) bit of plastic or metal that attaches to the pin and expands the pins influence to either side. Basically, the tappet plate now starts to be pulled back earlier and moves forward later thereby giving a bb more time to get from the magazine into a position in front of the nozzle. Fine in theory. I find that while the tappet plate moving backwards earlier is a good thing I'm not convinced that moving forward later is a benefit. In fact, I'd say it is distinctly not a great idea.

As far as I can see, the problem lies with the tappet plate not returning the nozzle to its position quickly enough. In other words, the delay to allow the bb time to get from the magazine to a position in front of the nozzle means that the piston can complete it's cycle before the tappet plate is fully forward resulting in a poor air seal and significant drop in performance. Two real options here; beef up the tappet plate spring or modify the sector clip. Removing it is also an option but you do lose the benefit of the nozzle moving back early.

With this in mind, I had a look at the sector clip on the MC51. Unlike most sector gears there is no tappet pin as such - the symmetrical sector clip and pin are two pieces of metal fixed together. My solution was basically to remove some material from the side that delays the return. As it transpires I took most of that side off leaving the clip somewhat lopsided; while the nozzle retracts earlier it returns with only minimal delay. After polishing it smooth I refitted it.

Worked like charm.