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Old 09-16-2019, 07:26 PM   #1
musubi
Registered User
 
Join Date: Jan 2017
Location: Big Island
Posts: 220
My Invert Roller

Hey Everyone,

I thought I'd share my invert roller gun that I put together almost a year ago.
It's been the most accurate gun I've had so far. The following are the specs on it:

- MVD Handle
- Invert Roller G3 Muzzle, with Inox bearings
- Ronstan Block Pulleys (the MVD pulleys didn't give me confidence in holding)
- Nautilus Carbon barrel (110 cm)
- 3 pairs of 9" 14mm (small I.D.) bands
- 7.5 mm, euro, wire fin, Rob Allen shaft

I'm all about accuracy with my guns and I'm very picky about its function over anything else. With that said, it can be a pain to load compared to my other classic style band setups. Things get tangled more easily and everything needs to wrap just so.

When I first built it I was encountering problems with my shooting line tangling with the 6 bottom bands. MVD's videos show the shoot line running between the pairs of bands and it was tangling with that configuration. Also, the shaft didn't slide into the mechanism nicely. The shaft butt was coming in too high to the mechanism and so I needed to raise the shaft front up a bit to get it in. Both of these issues were causing shot inconsistencies and it was frustrating me.

Discouraged, I gave up on the gun for months, but then decided to give it another try and resolve the issues. To resolve, I added a SS line wrap/anchor at the side of the barrel, near the muzzle. Second, the shimmed the handle higher to allow the shaft to slide right in with no fuss.

I target shot the gun at about 15' from the muzzle and I was able to hit center in a repeatable fashion.

I've been using this gun the past few months and I'm VERY happy with the accuracy. The gun also has extremely low recoil and an amazing line of sight, since no bands in the way. This has become my Mu gun.

With the 9" bands all loaded, the gun is powerful. If I recall correctly, I measured the pull of one band pair at 50 lbs. So for 3 bands, 150 lbs. My 110 KAP speargun, two bands, also measured at 150 lbs with two bands pulled back, except the invert has the longer throw (which we know).

The modifications I've had to make resolved two issues, but also created other minor ones in the process. If you scrutinize what I've done in the pictures below (at the muzzle), it's odd, and it makes loading a bit more difficult and, at times, causes my roller line to be pushed off the roller when first pulling back. So I have to be careful.

I'm planning to grind off the plastic line guide/wrap on the muzzle and replace with a more standard SS line guide/anchor. The plastic one is fraying my line and a little too far forward, near the muzzle.

Aside from this gun, I'm still planning on building a wooden gun, but this gun is really making me think about building an invert roller style wooden gun.

Question, why do some invert roller guns also have a single classic band on top? Does it give the shaft more initial velocity?











Last edited by musubi; 10-02-2019 at 02:51 PM.
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