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Boltsniper Scar-n Rifle Bs-8

New pump-action mag-fed rifle

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#1 boltsniper

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Posted 18 March 2006 - 12:18 PM

So the FAR will celebrate its first birthday this month It’s hard to believe it has been around for one year. It has served me very well and I have probably put close to 1000 rounds through it. I used it in most every war I participated in. For the most part my friends and I stick to CQB style wars in an apartment or basement environment. The FAR shined in that type of battle. I did however occasionally use it in an outdoor war. It still performs well but the shortcomings become more apparent. The rifle I am presenting today was designed to address these shortcomings while still retaining the excellent points of the FAR. Technically this rifle is designated BS-8 Mk1. It will be the 8th gun I have designed past the sketch phase. BS-7 is still there and will eventually get finished. I have started on it but I need to decide a propulsion system and/or reevaluate it’s intended use. Anyway, some of you may be familiar with the real SCAR program (Special Operation Forces Combat Assault Rifle). The purpose of the program was to address the issues with the current system, the M16, such as carbon fouling, barrel interchangeability, etc. The resulting SCAR rifles from FN and a few others were very nice weapons and performed great. I have given BS-8 the designation of SCAR-N, but I am changing the acronym some to reflect what BS-8 is. SCAR-N stands for Specialized Carbine Assault Rifle – Nerf. I like the specialized title because it reflects the fact that BS-8 was designed for a specific purpose, to be a superior frontline primary. The Carbine term is self explanatory. I wanted this rifle to be as small as possible. It is 28 inches long which is about 6 inches shorter than the FAR. It is very compact and easy to handle and maneuver. The “N” stands for Nerf denoting the type of round fired.

So I present the BS-8 Mk1 SCAR-N. From here on out I will refer to the rifle as the SCAR.

1420585665-76722-1-SCAR3.JPG
1420585665-76722-2-SCAR4.JPG

It looks a lot like the FAR. A good portion of it is very similar. The gerneral layout is similar with the upper and lower receivers and the receiver cover. Below is a comparison picture to show the differences. Side by side you can see how much smaller the SCAR is. The FAR looks massive.

1420585665-76722-3-FARcsSCAR.JPG

Technical Specifications:

Description..........Carbine Assault Rifle
Designation.......................BS-8 Mk1
Release Date....................March 2006
Caliber..............0.54" (Micro Stefans)
Operation....Pump-action Rotating Bolt
Propulsion...................Spring Plunger
Magazine......Detachable Bottom Feed
Mag Capacity...............................11
Overall Length...........................28 in
Barrel Length............................12 in
Max Rate of Fire...................150 RPM
Max Range..............................110 ft
Effective Range.........................90 ft
Accurate Range.........................70 ft
Intended Use........................Primary

1420585665-76722-4-Labeled.jpg

The SCAR-N is a pump-action magazine fed rifle firing 1/2" micro stefans. it is capable of 110' and accurate out to 70'. The box magazine holds 11 rounds and is removable. The rotating bolt lockup allows the rifle to be fired shellless by simply breach loading a dart of any length and closign the bolt.


Design

The SCAR resulted from my desire to improve on the deficiencies of the FAR. I wanted to fire micro stefans with this rifle and I also wanted to utilize brass for the barrel and shells. A long while back I discovered that 17/32” brass will fit into a standard AR15 magazine. For a year or more I have this section of brass stuck in a magazine. Eventually it occurred to me make shells out of brass and use an AR mag for a Nerf rifle.

The fast-action of the FAR is quick and easy to use, but grew old of the need to move your trigger hand off the grip to cycle the weapon. I decided to make the SCAR pump action which would allow for higher ROF simply because there was no need to move your hand.

A quick rundown of the features of the SCAR:
• Pump style action allows for higher ROF than the fast-action of the FAR
• Brass barrel for firing ½” micro stefans
• Brass shells. This allows for much smaller shells and in turn a higher magazine capacity
• Rotating bolt for lockup to prevent bolt bounceback
• Lightweight plunger: The plunger assembly has gone through an extensive weight loss program
• More rigid construction for higher durability
• More compact design for a compact weapon
• Ability to fire shellless


One problem I experienced with the FAR was shell seal. The seal between the shell and the barrel and bolt was held by the action spring alone. When the rifle is fired the bolt will bounce back slightly as the plunger hits home. This releases the pressure behind the dart and if the dart has not left the barrel yet will impede range. This led to some in consistency in ranges as different dart with different frictions would exit the barrel at different times. Ranges could range from 50-80 feet. If you have an exceptionally tight dart you could get some really pathetic ranges. This was pretty rare though. The solution to this problem was to have some kind of lockup for the bolt to prevent the bouncing. There are a variety of different systems for bolt lock. I decided to borrow another page from the AR15 and use a rotating bolt to lock it in the closed position. This involves a reciprocating bolt that move along a path defined by the bolt carrier. The bolt has lugs along its rim. These lugs engage a similar set of lugs on the end of the chamber. I will discuss this further when I talk about the bolt.

The bolt lockup led to another idea I wanted to implement. I wanted to be able to fire the rifle without shells. Because the bolt makes such a good seal with the barrel on its own, you can open the breach hand load a dart into the chamber and close the breach and fire. The performance is slightly less at maybe but there is no shell involved. This means that you can just pick up darts off the ground and fire off as if you had a modded Xbow or so. The ranges and ROF are still better than most.

Durability was anothar issue I wanted to address. The FAR had some balsa in it for flas surfaces. This has held up better than I expected but I have cracked the mag well walls a few times. Nothing a little glue won`t fix but it annoying and makes me cautious when I use the rifle. In the SCAR I replaced all the balse with lexan. The made the rifle much more durable and stronger. There is no balsa at all on the SCAR. I also beefed up the components that could be fragile. I used SCh40 PVC for the receiver cover which makes it rock solid now. The stock got special tratment to ensure its bonds with the lower receiver.

1420585665-76722-5-CAD1.jpg


Components

There are a few more parts in the SCAR than the FAR. This is because of the lockup system and the pump action. But, many of the parts will look familiar.

1420585665-76722-6-ExplodedLabel.jpg

Barrel

As I said above the actual barrel is made of brass. 17/32" Brass for firing micros. The barrel is a 12" section with the chamber attached to the end. The chamber is 9/16" brass so the shell makes a perfect seal when seated. The brass barrel insert is sheathed in 1/2" PVC to protect it. Electrical tape was used to position the barrel in the sheath.

1420585665-76722-7-Barrel1.JPG

As in the FAR the chamber is attached to the barrel. The barrel can be removed by removing hte assembly screws and pulling it out of the front. Only four screws fold it in. There is a section of the receiver fixed to the top of the barrel. This is done so that the pump slide can be removed after removing the barrel. that section of the receiver has the slide stop as well as the front receiver cover studs.

1420585665-76722-8-Barrel2.JPG

Edited by CaptainSlug, 20 November 2018 - 02:18 PM.

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#2 boltsniper

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Posted 18 March 2006 - 12:22 PM

The locking lugs are also part of the barrel. This is necessary to preserve headspace when the barrel is removed. The bolt locks into these lugs and they must be at the correct distance to ensure the shell is seated properly. The lugs are sections of PVC bonded to the inside of the 1" thin walled PVC.



Plunger

I should have figured this out before now but experience from the FAR clued me in that plunger mass is a big deal. If you jsut think about Newtons second law it makes sense.

F = ma

We want the plunger to accelerate as fast as possible. This will create the largest pressure behind the dart and cause the dart to accelerate accordingly. So we want the largest "a" possible. The force, F, is coming from our spring and for a given spring is constant. You can maximize this value by picking a high stiffness spring and having it fully compressed when the gun is cocked. So that just leaves the mass, m, to manipulate. If force is constant and we want the highest acceleration, a, then that means we need the smallest mass, m, possible.

For some reason this idea didn`t really occur to me on the FAR and I just built the plunger from what I had. I used 1/2" PVC, dual O-rings, a large steel washer for the catch surface, etc. It is heavy. You can tell it's heavy because you really feel it when it hits home.

On the GNS I started to get the idea. I used a single o-ring on a 1/2" CPVC shaft. This proved to be very effective and also very durable. I borrowed this plunger design and adapted it for the SCAR.

1420585665-76724-1-Plunger.JPG

The shaft is 1/2" CPVC. For the catch surface I used a section of aluminum. You`ll notice the catch surface does not go all the way around. The plunger is indexed in the receiver similar to the GNS to maintain the correct attitude with the catch. You can see the indexing slo and the screw in the trigger video. I also cut slots in the guide. This reduces weight but also allows air flow between the dead area behind the plunger head and the guide to the back of the receiver. As in the FAR the back of the plunger guide is beveled to depress the catch as it is retracted.

I gave up the dual O-ring setup I had on the FAR. 2 reasons. First was the continuing weight reduction. Second was length. I was trying to keep this rifle as short as possible. A second O-ring would add length. i still maintain that the second ring is not a bad idea but it didn`t fit into this rifle.

1420585665-76724-2-PlungerHead.JPG



Bolt

To acheive the rotary bolt lockup, the bolt group was broken into a bolt carrier and a bolt. The bolt carrier supports the bolt and is also the plunger tube as in the FAR. The bolt itself is the portion that interacts with the shell and engages the locking lugs on the end of the barrel. It contains the extracter and ejector systems. The bolt rides int he bolt carrier and is retained with a pin dubbed the cam pin. This pin passes through the bolt carrier through a curved slot and fits into the bolt. The slot cut in the bolt carrier dictates the movement of the bolt as it moves in the receiver. The following two images show the bolt open and closed.

1420585665-76724-3-Boltopen.JPG

1420585665-76724-4-Boltclosed.JPG

The rotating bolt is very common as a lockup system. It works well with gas oeprated systems because it delays the extraction of the shell as the bolt carrier starts to move. Almost every modern assault rifles use rotating bolts. It can be found elsewhere too. The Desert Eagle uses a rotating bolt. I used three lugs. The AR15 uses 8 lugs but then again I am not holding back 50000psi of pressure. I am just trying to prevent the bolt from bouncing when fired.
When the bolt is open the lugs sit in a position to pass eachother. When the bolt is closed the lugs on the bolt and barrel pass eachother. The bolt then hits home on either the end of the shell or the end of the barrel. The bolt carrier continues moving and the cam pin slides along the track cut in the bolt carrier. that track causes the bolt to rotate and the lugs engages eachother preventing movement of the bolt. See the action animation video below

The bolt face is made of brass like the shells. The extractor is just cut from the 9/16" brass. It is nto removable as it is still connected to the bolt. It just flexes to pass over the shell rim. The ejector is a piece of brass that rides in a slot cut int he bolt. A spring is inserted from the rear and retained with a pin to give the ejector its power.

1420585665-76724-5-BoltDetail.JPG


Fire Control

The trigger system int he FAR worked well and I never had it fail to fire but I wasn`t very happy with the feel of it. Because of the lack of mecahnical advantage the trigger pull was quite high. Also because of the transfer far that was trying to buckle the trigger felt kind of spongy. I got used to it but it would be nice if it was not there. On the other hand the trigger pull on the GNS pistol was very light and crisp. The pistol has been through a lot alreay and the system on that is only geting better with time as it wears in. I decided to not change a good system and just modified the GNS trigger to fit a rifle.

1420585665-76724-6-TriggerMech.JPG

The aluminum trigger plate remain but elongated. A trigger made of lexan is bolted to the plate and protrudes through the lower receiver. The same music wire catch and spring system as found in the GNS is on the rifle.

1420585665-76724-7-Catch.JPG

The catch is retained by a section of 1" PVC. About 1/8" of the catch pin protrudes into the receiver to engage the plunger.

1420585665-76724-8-Detail1.JPG

Edited by CaptainSlug, 20 November 2018 - 02:20 PM.

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#3 boltsniper

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Posted 18 March 2006 - 12:23 PM

Magazine Well

I had decided on using AR15 magazine for this rifle so I had to come up with a way to make a magazine well to accept it. Since the magazine are already setup for a certain type of magazine catch and I actually had the spare catch I decied to integrate that as well. Conveniently, the AR15 magazine inserts into the rifle ina vertical attitude there is not curvature or slant to worry about. A mag well could be easily constructed from balsa wood or polycarbonate. Since I had alreay drawn the rifle up in CAD and I had a model for the magazine well already I decided to just build it with the rapid prototyper at my disposal.

1420585665-76725-1-MagwellCAD1.jpg

1420585665-76725-2-MagwellCAD2.jpg

Sunce the machine was building it for me it was easy to integrate the accomodations for the magazine catch. I also drew it to mate right up with the 1/1/4" PVC of the upper and lower receivers.

1420585665-76725-3-Magwell4.JPG

If you look closely on the left side you can see the markings

Boltsniper Armament
Model: BS-8 Mk1
SRL: 10001

The "Boltsniper Armament" came out ok but the smaller lettering didn`t come out completely. One of my co workers pulled this part out of the machine for me and didn`t clean it well enough. No big deal though.



Performance

The rifle shoots 1/2" micro stefans 1.5" long. The maximum distance I have gotten has been about 110'. They consistently shoot into the 90's. i am amazed by the accuracy of the rifle. After sighting the red dot in, I could shoot cans over from across the room (about 40 feet). That was jsut screwing around. I will get some videos up of the rifle in action as soon as I get some shells made. The pump action makes it very easy to fire off a few rounds really quickly. The compact design makes it feel really nice when holding it.



Videos:
Below are some lo res videos of points of the rifle that I shot real quick. I only have one shell at the moment so I could only show the chambering of the one. When I make more I will shoot some more video of the rifle cycling a few rounds. The video of the chambering round is jerky because I was trying to go slow.

Cycling
Bolt Detail
Bolt Lockup Detail
Pump Actino Detail
Slow Chambering of a round
Trigger Mechanism Detail
CAD Render of the bolt rotation (Bad quality at the moment)

Stay tuned for more videos of the rifle in action as soon as I get some shells made.

As soon as I can I will get a SCAR page up on boltsniper.com. If you have questions feel free to ask them here or on the QnA page on boltsniper.com

More pictures

1420585665-76725-4-SCARdetail1.JPG

1420585665-76725-5-SCARdetail2.JPG

1420585665-76725-6-SCARdetail3.JPG

1420585665-76725-7-SCARdetail4.JPG

1420585665-76725-8-SCARdetail5.JPG

To make a note regarding safety. This rifle looks even more real than the FAR. For the FAR I made a barrel sheath that threaded on and was bright organge. I can use that same marker on this rifle. I also plan to take a magazine and paint it bright orange for use during wars. Some other bright markings may be in order. But jsut so you know I am not going to be running around outside with it as you see it here.....


I know I have left a lot of content out of this thread. please ask questions if you have them. I will work to get more content in the form of videos, pictures, and animations up soon.

Edited by CaptainSlug, 20 November 2018 - 02:21 PM.

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#4 TT

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Posted 18 March 2006 - 12:30 PM

Man, you seriously never cease to amaze me. The FAR was amazing enough, and now you've improved on it with a completely new rifle. I'm am quite positive you are the main influence of everyone who makes homemade Nerf rifles.
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#5 Chessler

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Posted 18 March 2006 - 12:36 PM

I'd give my first-born for a screw of this thing.

Awesome work there, as always.
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#6 ompa

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Posted 18 March 2006 - 12:36 PM

Love the rotating bolt. Although I'd worry that it would be a point that could potentialy have some durability issues.

Use the felt.

~ompa
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#7 Carbon

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Posted 18 March 2006 - 12:42 PM

I'll state the obvious and just say, "beautiful". The bar (which was already so high as to be unreachable) has been raised again.

I've been wondering about a catchface on only part of the plunger, but wasn't sure about the off-center weight, or the best way to guide the plunger. Once again, these plans require study.

I was wondering, what is the actual mass of the plunger? I'd be curious to see how much lighter this new style is compared to others...

Another question...what are you using/doing to smooth your glue joints? The seams look a lot nicer than on the FAR...

Edited by Carbon, 18 March 2006 - 12:52 PM.

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#8 Shwifty

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Posted 18 March 2006 - 12:44 PM

You are amazing!




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#9 WratH

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Posted 18 March 2006 - 12:50 PM

That is pure sex. And the word filter got you under intended use.

Edited by WratH, 18 March 2006 - 12:56 PM.

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#10 Paloose

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Posted 18 March 2006 - 12:57 PM

That is glorius.

Is the pump action very smooth? Because it looks like a lot of the paint has been scraped off the slide's runner.
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#11 Ronster

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Posted 18 March 2006 - 12:58 PM

I'm speachless...
My first reaction was that of my avatar. :o


Will you be willing to sell one of those custom mag wells?
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QUOTE(baghead @ Oct 25 2006, 09:55 AM) View Post
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#12 Denaeron 12

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Posted 18 March 2006 - 01:24 PM

<jaw hits floor>

I'm with Ronster, I would love to buy a mag well from you.
Possibly several.

Edited by Denaeron_12, 18 March 2006 - 01:25 PM.

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#13 sam

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Posted 18 March 2006 - 02:24 PM

You have really out done yourself. When I first saw the FAR I thought it was the most amazing piece of nerf firing equipment ever. I have the same feeling now. But alas I am sad because I will never be able to make one of these.
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#14 Black Wrath

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Posted 18 March 2006 - 02:48 PM

Pure sex.

Awesome job. I'm going to try and study the pictures and captions to try and and understand this rifle better, but as of right now I just like staring at those custom parts.
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#15 CrazyBerry

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Posted 18 March 2006 - 03:32 PM

Bolt, when you say this rifle has the ability to fire shellless, does that mean you can use the magazine without shells or does that mean that you have to insert the darts by the ejection port 1 by 1?

OOPS! Good job by the way.

Edited by CrazyBerry, 18 March 2006 - 03:33 PM.

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#16 fobpawwor

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Posted 18 March 2006 - 03:38 PM

Out of all the homemades I've seen, this is the best. How do you even think of making such a complicated design. You have really found your talent, so keep 'em coming!
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#17 Denaeron 12

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Posted 18 March 2006 - 03:39 PM

Bolt, when you say this rifle has the ability to fire shellless, does that mean you can use the magazine without shells or does that mean that you have to insert the darts by the ejection port 1 by 1?


You insert them one by one, the darts would not work shell-less in an AR-15 mag because of their diameter and how soft they are.

Edited by Denaeron_12, 18 March 2006 - 03:40 PM.

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#18 Enigma1313

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Posted 18 March 2006 - 03:46 PM

Wow...and I thought Nerf Weaponry couldn;t get much more advanced than the FAR...and then you throw this thing at me. Love the entire Carbine look of the thing, and pump action is a definite plus. Simply amazing,Bolt. Doyou have any idea how much one of those would rake in? At least 200 bucks...at least.
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#19 duce

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Posted 18 March 2006 - 04:09 PM

I'm gonna go change pants.
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#20 Whiplord

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Posted 18 March 2006 - 04:30 PM

Great job. Could you check your PMs though?
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#21 Rambo

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Posted 18 March 2006 - 04:38 PM

Wow, you could probably become a gun designer, like real guns, that is. I think the SCAR is a rifle in Ghost Recon Advanced Warfighter, not that it really makes a difference...
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#22 NinjZ

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Posted 18 March 2006 - 05:04 PM

Posted Image
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#23 GeneralPrimevil

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Posted 18 March 2006 - 05:31 PM

^^^what he said^^^


Dayum...



.
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#24 Maverick Master

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Posted 18 March 2006 - 06:45 PM

Bolt so are so amazing. How the hell do you do that :blink:, also i sent you a pm about the barrel i should use.

Edited by Maverick Master, 18 March 2006 - 08:19 PM.

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#25 Pineapple

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Posted 18 March 2006 - 07:26 PM

You'd best put a BRIGHT orange barrel tip on that thing...it's kind of scary. I think the AR mag is the key.

Plus, I hate you. :blink: In a loving way, of course.


-Piney-

EDIT; I see you mentioned orange accessories. You win. *cries*

Edited by Pineapple, 18 March 2006 - 07:47 PM.

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<!--quoteo(post=209846:date=Feb 5 2009, 06:27 PM:name=boom)--><div class='quotetop'>QUOTE(boom @ Feb 5 2009, 06:27 PM) View Post</div><div class='quotemain'><!--quotec-->
It's to bad you live in hawaii I bet there are not many wars there.Wait what am I saying<b> you live in hawaii you lucky bastard.</b>
<!--QuoteEnd--></div><!--QuoteEEnd-->


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