My Benjamin Discovery Tune and Stock Finished

Hi there,
i’m new to this forum, my name is Bruno Silva, i’m from Portugal and i’m 23 years old and i decided to share my most recently project with you guys.

Few months ago I bought a Benjamin Discovery .177 from MAC1 (tim if you’re seing this i would like some bolt oring, do you sell them?), some may think that because she’s 250$ dollar PCP so she’ll not shoot well and it’s wasting money. Well i can say i’m very surprised with this gun. I read a lot before buy one and i knew she was a good gun but damn this is a VERY GOOD gun and shoots like hell!

Specs:
* Noise: 4-Medium-high
* Weight: 5lbs – 2.3 Kg
* Comprimento do Cano: 24″ – 60.6 cm
* Comprimento Total: 39″ – 99 cm
* Repeater: Single shot
* Barrel: Crosman Rifled
* Front Sight: Fiber Optics
* Rear Sight: Fiber Optics
* Scope mount: 11mm dovetail
* Trigger weight: 1.7 Kg
* Butt Pad: Plastic
* Repeater Type: Bolt
* Fuel: PCP or CO2
* Safety: Manual
* Body: Rifle
* Power .177: 24J

photo:

This is the original model.

After many shots and tests this is my opinion:
– Very light gun, this is very good for hunting.
– The trigger is just terrible, the heavy trigger weight takes all the accuracy apart and it’s plastic made, looks like a toy, i really hate it and the feeling of the plastic on the finger it’s horrible.
– About accuracy, i managed 4/5″ (20mm) groups at 37yd (35m) with CP’s i think this is great with that horrible trigger and a 25$ barrel.
– The stock is a little short but that’s why they sell longer butt pads 😛

Tunings:

This is where the Discovery steps up! there are very good mods to her with low cost and really improves the accuracy of the gun.

– Stock:

I don’t like the stock, i think it’s ugly and short but again, for 250$ we have to understand…
My solution:
A little bit of aluminum and a longer butt pad that i had here from a Hunter 440.

The stock doesn’t end here, i’ll talk about it later.

– Trigger:

Well, like i said the trigger sucks what i didn’t said it’s with just a little work and some usual pieces it can be really really improved.

By [urlhttp://profile.imageshack.us/user/vakeiros1]vakeiros1[/url] at 2010-09-19
Just adding 3 screws and swapping a spring the trigger weight can be reduced by 60% or more!
– point 1, 1º pseudo-stage tune (it’s just a space between the trigger blade and the transfer bar)
– point 2, tune of trigger overtravell, we have to be carefull here. If we leave this to close to the shooting position may occur sear drag.
– point 7, tune of sear engagement, here we can adjust how much the sear engage the hammer. After adjusting this make sure you arm the gun and give her some bumps to make sure there’s no accidental shooting.
– point 3, down there we can see a little spring, we should swap the original one by a weaker one (that ones on the pens would do the job right)
Now if we polish well the contact places on points 4,5 and 6 we can get a much much much better trigger. But in some cases will have a problem (at least i had). If we slowly pull the trigger you’ll have sear drag that will bring serious velocity and inconsistency problems.

To solve that ther’s two easy mods:
If we remove the transfer bar (piece 8), we can see 3 align holes on the trigger housing, the transfer bar had the vein on the second hole we just have to make one hole on the transfer bar so we can put the vein on the third hole (right hole), the holes are spaced 1/4″ center-to-center so just have to drill a 1/8″ hole 1/4″ right to the center of the existing hole (near the point 8 on the photo) and put the vein there instead of the original position.Doing this we are improving A LOT the leverage effect so when we pull the trigger the sear will move much faster and the pull effort is much smaller and you should not have sear drag anymore. If you still have sear drag this second mod will eliminate it for sure! I did the 2 mods at the same time so i can’t say if the first one resolved the sear drag problem or not, anyway to be completely sure I’ve cutted a groove on the hammer from about 0.04″ from the engage position to the other end of the hammer, with about 1/5″ width and about 0.08″ of dept. So after this all the surface where sear could drag is gone, so no sear drag. I drew this the best i could 😛

By [urlhttp://profile.imageshack.us/user/vakeiros1]vakeiros1[/url] at 2010-09-19

At black ink it’s the hammer, purple the engage position and red is the groove.

Still not completly satisfied with the trigger (plastic blade) i made a Aluminium trigger blade (1st version):

Note: on these pictures we can see the vein is on the second hole.

This trigger was very good, but for some reasons i had to move the trigger backward, so i made another trigger blade (2nd version):

For the same reasons i had to remove the safety of the gun, so i made this piece to replace it:

Another mod is a power regulator (basically it’s a hammer spring tension regulator ):

we’ll need to do some kind of an hammer string guide like in the picture:

By [urlhttp://profile.imageshack.us/user/vakeiros1]vakeiros1[/url] at 2010-09-19

and put a screw behind that guide:

the hole with screw is already on the gun, just need to find the right screw and screw it in! When you screw in, you’ll apply tension to the hammer spring so the hammer will go faster and you’ll get more power.

About the barrel two things should be done:
– Polish the in-lead and the transferport hole to avoid damage on the pellet when loading (anyone can do this with a dremel and JB Bore paste)
– recrown the end of the barrel, this is more complicated and can do more bad than good, you can search how to do it or leave it away

At the end of all this mods the gun can made 1/5″-1/3″ groups at 35yd without any problems…

Well, after all this work i really love this gun!! light, accurate and funny!

So i took my addiction to the next level… as i know you prefer pictures to text so i’ll shut up now.

pictures:

By [urlhttp://profile.imageshack.us/user/vakeiros1]vakeiros1[/url] at 2010-09-19