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PostPosted: Mon Oct 04, 2021 11:51 pm 
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Joined: Wed Jan 08, 2014 2:48 pm
Posts: 118
I sanded the sear where it contacts the hammer and bent the spring a little bit to give a slightly lighter pull...

Got about 3/4" group mostly rested with stoeger wad cutters....at about 38' indoors... 6 pumps which is about 400fps on my 760

The target in the pic is 25mm accross.

Image

Sent from my SM-G975W using Tapatalk


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PostPosted: Tue Oct 05, 2021 1:57 am 
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Joined: Sat Oct 02, 2021 1:43 pm
Posts: 8
killercrow wrote:
Do these guns have the smaller front valve half?
I have a Remington airmaster 77 which has this smaller valve. If I were to cut it for a flat top piston I'll also need to cut the check valve too.
Anyway, that 760 could use a flat top piston :wink:


I don't remember for certain but the 'short' front half style may not have enough material to remove to make a flat style ie. you could cut into cavity in the 'nose' area. Iirc they are smaller for some single stroke mainly, and some others, in order to build pressure quickly. Anyway seems prudent to examine dimensions before any cutting.

I agree about the need for a FT piston on the 7760.

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PostPosted: Tue Oct 05, 2021 3:53 am 
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Joined: Thu May 07, 2015 8:30 pm
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Location: Eastern Townships
Phantom Payne wrote:
killercrow wrote:
Do these guns have the smaller front valve half?
I have a Remington airmaster 77 which has this smaller valve. If I were to cut it for a flat top piston I'll also need to cut the check valve too.
Anyway, that 760 could use a flat top piston :wink:


I don't remember for certain but the 'short' front half style may not have enough material to remove to make a flat style ie. you could cut into cavity in the 'nose' area. Iirc they are smaller for some single stroke mainly, and some others, in order to build pressure quickly. Anyway seems prudent to examine dimensions before any cutting.

I agree about the need for a FT piston on the 7760.


Except for the grip front screw hole and TP seat, the 760 valve is identical to the 13xx valve (same length). The TP seat on the 760 valve is recessed, on the 13xx it's just a flat machined on top of the valve body, like on a 22xx valve.


Attachments:
Crosman_valves.JPG
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PostPosted: Tue Oct 05, 2021 9:23 am 
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Joined: Sat Oct 02, 2021 1:43 pm
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airmec wrote:
Phantom Payne wrote:
killercrow wrote:
Do these guns have the smaller front valve half?
I have a Remington airmaster 77 which has this smaller valve. If I were to cut it for a flat top piston I'll also need to cut the check valve too.
Anyway, that 760 could use a flat top piston :wink:


I don't remember for certain but the 'short' front half style may not have enough material to remove to make a flat style ie. you could cut into cavity in the 'nose' area. Iirc they are smaller for some single stroke mainly, and some others, in order to build pressure quickly. Anyway seems prudent to examine dimensions before any cutting.

I agree about the need for a FT piston on the 7760.


Except for the grip front screw hole and TP seat, the 760 valve is identical to the 13xx valve (same length). The TP seat on the 760 valve is recessed, on the 13xx it's just a flat machined on top of the valve body, like on a 22xx valve.


I'm very confident you are correct airmec, what I was thinking of was that the 'nose' of the short front half might be hollow ie. inner shape mimics outer shape (if that makes sense) and that attempting to make it a FT could cut into an empty space as opposed the the 760 valve being solid in the 'nose' area with the inlet valve rearward far enough to allow converting to FT.

I could be wrong, just ask my wife, I was referring to the "Remington airmaster 77 which has this smaller valve" above.

A 7760 mf'd in 2014 I once had apart (Canadian market) had a simple flat washer sitting in the recess you mentioned airmec, as a detune method I presume, it sat below the transfer port and rubber seal. If I remember from back then it was ~ .025 H and .083 i.d. and the o.d. was snug but not tight in that recess.

I don't have a "Remington airmaster 77 which has this smaller valve" to examine here...

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PostPosted: Tue Oct 05, 2021 10:12 am 
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Posts: 118
Petee_c wrote:
I sanded the sear where it contacts the hammer and bent the spring a little bit to give a slightly lighter pull...



I should add, I also wrapped a thin layer of prestretched black electrical tape where the receiver holds the barrel and pump tube. That may add a touch to the accuracy as well....

This is with the cheap 4x15mm scope that came with my 760 kit.... My 760 is circa 2015ish.... The pump handle mold isn't quite as long as what appears to be on the current ones...

The bleed hole was filled with a bit of solder.

I'm thinking of shaving a bit off the sear to get a slightly shorter trigger pull as a possible next mod.

The extended probe may also be on the list. However, I want to mock up the base one and print out a spare with my 3d printer and mod that and then insert a slightly longer metal probe, but I am just learning tinkercad now, so that may be when I have more time.


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PostPosted: Tue Oct 05, 2021 5:46 pm 
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Location: Eastern Townships
Phantom Payne wrote:
I'm very confident you are correct airmec, what I was thinking of was that the 'nose' of the short front half might be hollow ie. inner shape mimics outer shape (if that makes sense) and that attempting to make it a FT could cut into an empty space as opposed the the 760 valve being solid in the 'nose' area with the inlet valve rearward far enough to allow converting to FT.

I could be wrong, just ask my wife, I was referring to the "Remington airmaster 77 which has this smaller valve" above.

A 7760 mf'd in 2014 I once had apart (Canadian market) had a simple flat washer sitting in the recess you mentioned airmec, as a detune method I presume, it sat below the transfer port and rubber seal. If I remember from back then it was ~ .025 H and .083 i.d. and the o.d. was snug but not tight in that recess.

I don't have a "Remington airmaster 77 which has this smaller valve" to examine here...


I see what you mean Phantom Payne and I agree. I remember there's not much material in the short front valve half of the AM77 (I have one). I don't think the AM77 valve can be flat-topped, but the 760 definitely can be.

Yes there are restrictor washers in the de-tuned rifles, they also use them in the M4-177 pump rifle among others. In my M4 it's used along with a venting hole in the back of the valve.

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