This write-up builds upon SGNerf's streamline compatible breech tutorial.
So, I play with the urban gaming club whenever they host nerf gun events here on campus. All sorts of players show up, from the many fresh-out-of-the-box players excited with their high capacity raiders, to the few but present stefan-smiths. As such, I wanted a brass breech that would accept the streamlines littered all over the grass and sidewalks as I hunt for ammo mid-games. But the problem with streamline-compatible LS brass breeches is that the draw on the LS is barely longer than the length of a streamline. The dart has to be loaded perfectly in the clip. Any dart too far forward or too far back in the clip will likely cause a jam. I do not want to be hassled with making sure my darts were positioned just right, even if it's in between games.
With this set draw length comes the tolerance of the brass breech mod too. Your measurements and cuts have to be exact. The 9/16" barrel and 19/32" breech only have about 3-4 mm of overlap to create that airtight seal. There's only room for about 1-2 mm of error. Any more and you have to re-establish the airtight seal by moving the breech and the barrel closer, meaning less room for the dart to properly chamber, and more frequent jams. Sure, I believe in "measure twice, cut once", but not all of us are robots with unwavering hands that make precise, straight cuts all of the time. And what if you wanted to ream the outside of the 9/16" lip and the inside of the 19/32" for smooth chambering like I did? That takes away from the overlap too. In the end, you are left with a hairline overlap that jostles apart as you are busy having fun around campus.
That's where my update on this timeless mod comes in. With this mod, you can increase the draw of your LS by about a centimeter Might not sound like much, but this does enable you avoid jams no matter where your darts are positioned in the clip and still have ample airtight overlap that will hold securely as you run around.
Here is my longshot breech. Notice where the bolt sled can now reach.
I noticed that when there were no other parts in the longshot but the bold sled, it could naturally reach this forward position! So it must be the other parts that halt its movement. I went right to work.
The first step I did was to cut this orange piece down. It connects to the back end of the faux pipe. The green highlights show where to trim, or where there used to be plastic. It's just cutting off the cross pegs on both sides as well as trimming down the top of it away so that the bolt can move forward.
I'm also going to take this opportunity to promote one of my favorite tools y'all may not be aware of. It's a hobby model spruce cutter. Unlike wire cutters which do not cut flush, plastic hobby cutters do. I use this for lazily trimming away plastic or cutting pegs like the ones abouve without busting out the power tools. I got mine from a gunpla tool kit.
Back to the mod:
You may need to trim the front of the bolt tooth too.
Once that's done, we need to clear the path of the priming bar. Get out your cutting wheel and make this slot in the shell about half an inch longer on both sides. Smooth it out at the front end of the slot with a round file if you so desire.
Last step is to adjust your brass measurements accordingly. I made my 19/32" 0.8 centimeters longer(I did not increase the length by 100% of the draw increase, leave a little room so you can still pull the breech all the way forward and get that internal o-ring between the plunger tube and the back of the breech to seal). I increased the 1/2" dart pusher length by only half a centimeter, because the 9/16" brass barrel won't be moved forward that much. The half(or quarter pipe in my LS) is still kept the same length on both the 19/32" and the 9/16".
However, during transportation while my parts were out of the shell, the quarter pipe on my 9/16" brass got warped a little. It kept catching onto the 1/2" dart pusher and prevented me from pushing the breech forward whenever I primed back my LS. I remedied this by making the quarter pipe 1/2" to 3/4" longer.
It now reaches further back, so it always stayed in between the 19/32" bolt and the 1/2" dart pusher, even when the breech is primed all the way back. This might only work with the extended draw mod, as the brass measurements are slightly longer. It might hit against the 17/32" and 9/16" stubs in the back of the breech if you were to extend the half-pipe on a stock-draw LS.
So now your LS is now ready to chamber darts smoothly and perfectly without any jams! One thing to keep in mind when using your new LS is to prime back ALL THE WAY.
Here is where the catch is engaged.
Here is how far back your bolt sled can actually go. This is where you need to pull back to so that you will always chamber your darts. Keep in mind, if you have added springs in there, they make take up too much length and not allow the breech to be pulled out all the way. I had a nitefinder added in mine and it kept the back of darts from chambering. I removed the NF spring, and replaced the stock longshot spring with an orange modworks spring that was exactly the same size. You could also accomplish this by cutting a few coils off the springs you added if they stop your breech from going back all the way.
I took mine out first thing, but you may need to get rid of this "Primed Indicator" arm at the very back of the longshot if it keeps you from priming all the way back.
And you're done! This is not a mod to increase power so ranges will depend on your own spring(s).
Oh, and apart from extending the draw on my LS I also replaced the springs in the stock that hold clips in place. Just unscrew that orange plate, take out the old spring, put a stronger one in, and screw everything back together! If you're having trouble screwing the orange plate and the peg and its spring back on, try doing it sideways, or even upside down. No more 18-dart clips falling out from my stock anymore!
Right- Stock Spring
Enjoy your improved Longshot! Or at least, enjoy this picture of my Longshot.
Edited by AceDudeyeah, 25 July 2012 - 09:15 PM.