My Benjamin Discovery **Finished**

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My Benjamin Discovery **Finished**

Postby Vakeiros » Tue Sep 21, 2010 3:45 pm

Hi there
Few months ago I bought a Benjamin Discovery .177, 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:
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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 :P

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.
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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.
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By vakeiros1 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 :P

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By vakeiros1 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):
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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):

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For the same reasons i had to remove the safety of the gun, so i made this piece to replace it:
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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:
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By vakeiros1 at 2010-09-19

and put a screw behind that guide:
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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:
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By vakeiros1 at 2010-09-19

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now it has 6 hands of linseed oil, soon will post more photos

*****Update*****

here are some more photos:

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By vakeiros1 at 2010-09-23

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By vakeiros1 at 2010-09-23

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By vakeiros1 at 2010-09-23

Finished:

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5 shot Grouping at 38yd (35m) (chumbo não escolhido/pesado):

HN Barracuda Match 4.5mm 10.22Gr:

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(0.27")

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(0.31")

Crosman Premier Domed Heavy 4.5mm 10.9Gr:

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(0.31")

Crosman Premier Domed 4.5mm 7.9Gr:

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(0.47")

Hope you liked

regards

Stay Tuned

regards

Stay Tuned
Last edited by Vakeiros on Fri Sep 24, 2010 12:17 pm, edited 1 time in total.
Air Arms S410 Xtra FAC .22 + Leapers 4-16x50 AO
Benjamin Marauder .177 + ZOS 10-40x60
Benjamin Discovery + ZOS 10-40x50
Diana 75 T01 + Match Diopter
Diana 75 + VitaScope 4x40
Vakeiros
 
Posts: 124
Joined: Fri Feb 19, 2010 10:25 am

Re: My Benjamin Discovery **Updated**

Postby Vakeiros » Thu Sep 23, 2010 3:05 pm

updated
Air Arms S410 Xtra FAC .22 + Leapers 4-16x50 AO
Benjamin Marauder .177 + ZOS 10-40x60
Benjamin Discovery + ZOS 10-40x50
Diana 75 T01 + Match Diopter
Diana 75 + VitaScope 4x40
Vakeiros
 
Posts: 124
Joined: Fri Feb 19, 2010 10:25 am

Re: My Benjamin Discovery **Finished**

Postby monsoon » Mon Nov 29, 2010 11:18 pm

very nice,,,,welldone ...appreciate your project!!
monsoon
 
Posts: 3
Joined: Tue Nov 23, 2010 10:06 pm

Re: My Benjamin Discovery **Finished**

Postby urenaf » Fri Dec 17, 2010 10:10 am

Hello friends,

Great job!

Other question: What is the maximun PSI or weight of CO2 I should applay to this air rifle (Benjamin discovery)?

Regards,

FU
urenaf
 
Posts: 6
Joined: Mon Oct 25, 2010 8:18 am

Re: My Benjamin Discovery **Finished**

Postby DaveShooter » Mon Jan 17, 2011 2:28 pm

Hats off to ya very nice job. :D
DaveShooter
 
Posts: 235
Joined: Sat Jun 13, 2009 9:28 pm
Location: Ohio

Re: My Benjamin Discovery **Finished**

Postby jessierauder » Mon Sep 12, 2011 9:17 am

I know I saw this post late now that we're in 2011, but just had to say that your work on the disco is just fabulous! Your work is so good that I wouldn't be surprised if lots of guys asked you to make them one, not that you'd be willing of course, because of all the work involved. Great stuff wish I hand your hands and talent! I've got the Marauder rifle in 22-cal, it likes C-p's they seem to be the most accurate so I bought quite a few. Now I polished the barrel looks like a mirror, but will it change preference now?, it's a picky gun for pellets. It's nice that your benji is good with several pellets! My New gun is the S510 AA and I'm am thinking, and actually always believed English guns in my opinion are best, take care, and thanks for sharing your info...
jessierauder
 
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Joined: Sat Aug 20, 2011 4:40 pm

Re: My Benjamin Discovery **Finished**

Postby 0351 - Vet » Mon Nov 28, 2011 8:37 am

Nice work.....I like it. :D
0351 - Vet
 
Posts: 6
Joined: Wed Sep 14, 2011 2:35 pm

Re: My Benjamin Discovery **Finished**

Postby Busey » Wed Nov 30, 2011 1:40 pm

Wonderfull job on the stock man, it is a true work of art. I love the pistol grip cap... mmmmmm shiny. Its prob one of the nicest discoveries Ive seen in a long time. Thanks for posting
Busey
 
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Re: My Benjamin Discovery **Finished**

Postby mvhunter » Sun Dec 04, 2011 5:30 pm

VERY NICE WORK....THANX FOR POSTING
mvhunter
 
Posts: 25
Joined: Sat Jan 09, 2010 7:38 pm


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