Taper/bevel my breech

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hw77grey
Posts: 34
Joined: Tue Mar 21, 2017 5:03 pm

Taper/bevel my breech

#1 Post by hw77grey »

I am considering putting a taper on my breech, for better more consistent seating. Think I will try my phantom first, ideas?
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Whitewolf
Posts: 3099
Joined: Thu Feb 02, 2006 11:35 pm
Location: Alberta Canada

Re: Taper/bevel my breech

#2 Post by Whitewolf »

This brings up a pile of questions as to your reasoning.?
If there is no burrs upon the breach, why?
Problem with accuracy?
Have you tried a variety of pellets and noted head diameters to the accuracy your getting?
Just to change things can change the characteristics of how your pellet will behave upon accuracy.

If you feel the breach requires polishing. Use a power drill with a Qtip. Insert a pellet to the full depth of it length. Load the qtip with a fine polishing compound. Autosol is my prefered choice. Slowly polish in both directions the lands of the rifling. With a cleaning rod cleaning patch extract the inserted pellet and check fit of your desired accurate ammo. Little at a time, no serious rrush. Do note that the skirt of the pellet does have to crush and conform to the rifling of the bbl. But it will soften the amout of force required to seat a pellet.

Regards
May the cry of the pack be with you upon your hunt

Whitewolf
hw77grey
Posts: 34
Joined: Tue Mar 21, 2017 5:03 pm

Re: Taper/bevel my breech

#3 Post by hw77grey »

I like your advice Whitewolf. My phantom is very pellet fussy. It also is
Erratic with poi and velocity, and seems to have a very tight breach. I have had success tuning phantoms in the past, and 2240's even got to tune and spare no expense on a hw77 ( that was a treat). By no means am I a professional, just enjoying air guns. I have covered all the bases with this phantom but recently
Watched a UK tuner do this very thing, put a bevel on a breach to help with consistent seating. Wanted to see what others here thought.
Watertown
Posts: 841
Joined: Wed Feb 17, 2010 6:04 pm
Location: Nova Scotia

Re: Taper/bevel my breech

#4 Post by Watertown »

I have put a taper on a breech and it improved accuracy. To see if it will help in your case insert a pellet as usual, close and then open the barrel. Inspect the pellet skirt and see if it is deformed, if it is you may benefit from tapering the breech so the pellet seats better in the barrel.
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Dukemeister
Posts: 4366
Joined: Fri Jan 22, 2010 1:17 pm
Location: Kingston, ON

Re: Taper/bevel my breech

#5 Post by Dukemeister »

It has been discussed many times, I have put a link below to an old thread that may leade :lol: you in the right direction:
http://www.airgunforum.ca/forums/topic4 ... =%20cardew
HIH
:drinkers:

))))----//----------==

Iacio, ergo sum
hw77grey
Posts: 34
Joined: Tue Mar 21, 2017 5:03 pm

Re: Taper/bevel my breech

#6 Post by hw77grey »

Dukemeister wrote:It has been discussed many times, I have put a link below to an old thread that may leade :lol: you in the right direction:
http://www.airgunforum.ca/forums/topic4 ... =%20cardew
HIH
:drinkers:
Thanks!
Chevota
Posts: 1287
Joined: Sat Jan 25, 2014 9:16 pm
Location: United States

Re: Taper/bevel my breech

#7 Post by Chevota »

If it's your 77 I'd check everything else before I did that, and if I did I'd start by just smoothing it and maybe the lands in the breech with 600 sandpaper. I just hate to see people "do" their breeches and go too far with it, which I think is what usually happens. Whatever it is I hope you find the fix.
I doubt the Phantom will be of any help b/c it's barrel is likely so bad I don't think that mod will affect it unless it's breech has an actual sharp edge cutting the pellet. You can check buy pushing a pellet thru with a dowel or whatever and feel all the tight spots and toughness, and examine the pellet to see what's it's been thru. Compare to your 77.
Post before/after pix if you can, along with results :)
hw77grey
Posts: 34
Joined: Tue Mar 21, 2017 5:03 pm

Re: Taper/bevel my breech

#8 Post by hw77grey »

Chevota wrote:If it's your 77 I'd check everything else before I did that, and if I did I'd start by just smoothing it and maybe the lands in the breech with 600 sandpaper. I just hate to see people "do" their breeches and go too far with it, which I think is what usually happens. Whatever it is I hope you find the fix.
I doubt the Phantom will be of any help b/c it's barrel is likely so bad I don't think that mod will affect it unless it's breech has an actual sharp edge cutting the pellet. You can check buy pushing a pellet thru with a dowel or whatever and feel all the tight spots and toughness, and examine the pellet to see what's it's been thru. Compare to your 77.
Post before/after pix if you can, along with results :)
No my 77 is gone :( it was a mistake to let it go! Best spring gun I have ever shot.
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