Does anyone have the benjamin trail np xl and the Gamo Magnum
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All Springer/NP/PCP Air Gun Discussion General
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Does anyone have the benjamin trail np xl and the Gamo Magnum
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Topic: Does anyone have the benjamin trail np xl and the Gamo Magnum (Read 1430 times))
Bullpuppy
Shooter
Posts: 51
yes
Real Name: Tim Eastman
Does anyone have the benjamin trail np xl and the Gamo Magnum
«
on:
February 22, 2018, 08:05:35 PM »
Hi,
I have a gamo magnum in .177 and I like to switch to .22 cal. Its quite hard and expensive to get parts from gamo but a knowledgeable air gunner suggested that I should get a Benjamin trail xl barrel and block and fit it gamo. If any member here that has both rifles I love to know how close hinge pin, lock pin and cocking lever pin line up between then two. Any pictures of the blocks next to each other and on top would be helpful.
Any help would be most appreciated.
«
Last Edit: February 22, 2018, 08:25:28 PM by Bullpuppy
»
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USA, Mckees Rocks, PA
Bullpuppy
Shooter
Posts: 51
yes
Real Name: Tim Eastman
Re: Does anyone have the benjamin trail np xl and the Gamo Magnum
«
Reply #1 on:
March 19, 2018, 09:44:14 AM »
I was able to fit a Crosman Benjamin Trails Xl NP barrel to a Gamo Magnum.
Steps
1) order a xl barrel assembly , alive jam and spring , breach seal, 2 barrel washers, and the pivot sleave from Crosman. total cost $20
2) remove the cocking arm from the gamo and put it on the xl barrel. The linkages are the same length between the two but the intermidiate linkage point is different location in addition to the roller position. The Crosman linkage is a bit thicker. I tried to use the Crosman linkage but it would take some mods to the stock.
3) remove the jam pin from the gamo receiver.
4) remove the seal from the transport port on the gamo receiver. You should not have a breach seal on the xl barrel yet.
5) mount the xl barrel on gamo via the link pin. Do not put the alive jam in the barrel block. The barrel will not close. The xl barrel block is longer than the gamo by about .5 mm.
6) start filing the breach on the xl slowly until it will closes completely. The breach face has to be parallel to the receiver when you are done. Don't go too far, you can't put it back. You will know when you are done when the receiver is level with the top of the barrel block when you close the barrel. I mount the receiver in a vise and put a level on the receiver and another on the barrel block. You will be checking this alot.
7) put the jam pin back in the receiver. Now you have to file beneath the breach face until the rifle will close. The barrel block will rest on the jam pin. Don't go too far. You will know when you are done when the receiver is level with the top of the barrel block when you close the barrel.
modify the alive jam by filing lengthening the flat rearward away from the points as far as you can. The alive jam on the gamo sits further forward than the xl so you are extending the xl jam. Stretch the Jam spring and install the jam.
9) mount complete xl barrel on the gamo. Check that the receiver is level with the top of the barrel block when you close the barrel. It should be very tight and level. Mine wasn't the first time and I had some barrel drop. I had to remove a little more (step 7) to get it level. Mine ended with just up just a little upward slant to the barrel that can only be scene with the levels.
10). Polish the areas you filed. round the area at the base of the barrel block so you don't tear up your seals when closing.
11) install the seals and make any adjustments needed to create a good seal.
I put a .25 xl barrel on the gamo. I got ave 800fps using 19.9 grain h&n greens. I'm quite happy with the results.
The actual filing and installing took about 8 hours.
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USA, Mckees Rocks, PA
Bullpuppy
Shooter
Posts: 51
yes
Real Name: Tim Eastman
Re: Does anyone have the benjamin trail np xl and the Gamo Magnum
«
Reply #2 on:
March 23, 2018, 02:13:37 PM »
Just a update. I finished the fitting and had some barrel droop. I got rid of it by filling the area of the barrel block the contacts detent pin until I ended up with a very slight upward direction. I tested this by putting a level on the scope mounts and the top of the barrel block without the alive jam installed. When I reinstalled the xl alive jam the gun would not open. The xl jam worked until I got rid of the barrel droop. Now the xl alive jam extends further, there is some play on closing and the gun will not open. I made a new alive jam pin and angled the two cuts to match the angle of the cuts on the original gamo .177 barrel alive jam and it works perfectly with no barrel slop. The alive Jam on the gamo is different than than the XL. The gamo alive jam is wider in diameter and is positioned closer to the barrel block and extends almost to the breach while on the XL the alive jam does not extend as far because the detent pin is in a different position on the Xl receiver. The angles of the cuts on the alive jam are also at different angles. The alive jam on the Gamo magnum almost matches the alive jam on my Trails NP2. The alive jam I made is the same diameter as the XL and is a bit shorter but the angles are the same as the gamo.
I did just one round of testing on the new barrel. It sighted in fine after 4 shots. The only .25 pellets I have on hand are the 19.9 gr H&N field target trophy green. They chrono today at 837 fps. I shot just 1 group at 20 yards and got .7 inch ctc group. I am next going to shorten the barrel, laminated it and add a shroud.
Just a note. based on my one test I got 30.96 foot pounds in .25 cal
the same gun shooting in .177 got 23.32 foot pounds using 10.5gr Crosman Premiers at 1000 FPS (the best shooting pellet at the highest sub-sonic velocity). An example of the efficiency gains by going to a larger caliber on the same gun (of course we are using different barrels and pellet brands) . My impressions so far is the gun likes the .25 cal over the .177. The heaver barrel block of the xl makes it handle better.
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USA, Mckees Rocks, PA
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Does anyone have the benjamin trail np xl and the Gamo Magnum