Small barrel mod to help pellet seating consistency

[K.O.]

I am pretty sure others may do this or in some other form...

Cut and paste from my post at  GTA...


I use a home made plastic pellet seating tool ( a small allen wrench will work) instead of a extended probe to seat my pellets just past the port.  1377/1322/2100 the 853 came with a long probe...

you can definably feel that some seat much easier and a few very hard but for the most part about one in 12 was tighter.




with the my stock 1322

once in a while when I first set up my T.O.F.  chrono and before I was seating my pellets I would get a very high fps that equaled my later seated numbers.

it ended up being that if I pointed my 1322 down while pumping most pellets seated just past the port and a few tighter ones did not seat all the way past the port

well having had accuracy probs with my 1377 because of concentric rings at lead in and burrs at the port,  I took a good look at the barrel of my 1322.

what I saw was close to the below pics and show that there is something that can be done to help the barrels handle the slight inconsistencies in head size  I am getting less fliers and slightly better groups for having done it

I just  put a  14.5 barrel on my 1322 and used the same dowel (Cone shape one end) to sand the barrel bit by bit until my pellets seated just past the port.

in that process I  also removed the hard edges at breech and at beginning of rifling, which is what I did to the stock barrel and that helped reduced the fliers and the size of the fliers deviance from the group.

I think some of the pellets (especially the larger ones) caught on the hard edges and became slightly deformed

seating effort is much more consistent...

the pictures are from   Woody67 (inside harassment with Font size )

pics of  breech end of barrel are in this thread...

http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,12918.0.html

[K.O.]

It was the thread

"Crosman Premiers Tin vs Box" at GTA that prompted the post

I have not  used the boxed Premiers  but it does seem to help my 1322 handle inconsistency in pellet sizing...

[K.O.]

wow am I hard to understand or just annoying?

I read about smoothing the lead in but nothing about easing the hard edges and just wanted to know if it is a common thing done or not...

I am also wondering what most feel is proper barrel prep.

My 1322 stock, the pellets seated past the port with a good tap or shake and it was very accurate  so when I had it apart I made it so that the new barrel did the same by sanding that area till it seated the pellets the same with a light tap...

So I just wondered what every one else does if anything?

What is just right in this area?

[BDS]

wow am I hard to understand or just annoying?
I read about smoothing the lead in but nothing about easing the hard edges and just wanted to know if it is a common thing done or not...

I am also wondering what most feel is proper barrel prep.

My 1322 stock, the pellets seated past the port with a good tap or shake and it was very accurate  so when I had it apart I made it so that the new barrel did the same by sanding that area till it seated the pellets the same with a light tap...

So I just wondered what every one else does if anything?

What is just right in this area?

and... "sanding" ? say it ain't so, you meant lapping/polishing of the breech end and leade right?

[K.O.]

600 grit wet/dry was going to follow with 1200 but did not...

It still is very accurate as it was stock...

I just have not found a write up so I did it my way...

[K.O.]

the only thing I saw about leade in...

http://www.gatewaytoairguns.org/GTA/index.php?topic=37755.0

If you look at the pics in the other thread you can see when they cut the leade in they left the end of the rifling sharp edged.

I turned a dowel down till it just fit the leade and then took it down at the tip just enough more to use a small strip off wet dry at the tip of which the last 1/4" was angled to a blunt cone.

I glued the wet dry to the dowel with it forward just enough to cover the angled part all this to round the sharp edge not to take it al the way down.

The pellets did not seat as well on the new barrel they stopped half covering the port even with a hard tap or shake so I once again made the dowel fit with wet/dry glued and five minutes later it matched the stock barrel.

I used  the dowel then to  just barley ease the hard edge at the o-ring seating area.

I have not done this to my 1377 yet just the 1322.

The 1322 is more accurate and has less fliers.

I guess I will have to do the 1377 also with no this is how I do it from others. 

I can  feel  the pellets catch espesialy the ultra mag 10.5s...

[BDS]

GTA and Rsterne have it technically correct but, your method is fine (and less grief and strife) for what you are trying to accomplish which IMO is deburring and polishing.

As long as you don't create a surface or feature that nicks the lead pellet, your work will only improve the pellet seating which should improve the guns capability to hit zero.

Note, others might argue the point but, it's only the last few inches of good quality rifling and a good crown that matter in airguns. Case in point are the high-end $$$$ FX PCP airguns with their "smooth twist" barrels.

[K.O.]

GTA and Rsterne have it technically correct but, your method is fine (and less grief and strife) for what you are trying to accomplish which IMO is deburring and polishing.

As long as you don't create a surface or feature that nicks the lead pellet, your work will only improve the pellet seating which should improve the guns capability to hit zero.

Note, others might argue the point but, it's only the last few inches of good quality rifling and a good crown that matter in airguns. Case in point are the high-end $$$$ FX PCP airguns with their "smooth twist" barrels.

"smooth twist" barrels was one of the things I was thinking about the other day... 

It seems that the ultra mags have a slightly larger head size ( I have not actually checked though) and I was thinking about getting a couple barrels to experiment with

one of the things was  to ream out about 13" of a 16.5" barrel very slightly to make  a dedicated ultra mag barrel  and see how it affected velocity and accuracy...   (sort of a smooth twist thing)

I had even done a  "smooth twist 1377" search,
http://www.gatewaytoairguns.org/GTA/index.php?topic=27339.0

are the smooth twist barrels  Hammer forged?  I just assumed never checked...


thanks for the feedback  I am not super anal about my shooting so it is easy to fool yourself that some thing helped.

for tuning purposes I really should make a good rest/cradle is stead of just using the door frame as a side rest.

[bgmcgee]

Yup if you really want to get serious about barrel accuracy you need to clamp it down .You have to take yourself out of the equation.

[K.O.]

I ran time of flight chrono today all  fps is average over 15'  premier hollow points.

10 pumps 491 fps
12 pumps 508 fps
15 pumps 533 fps

not bad for a stock 1322 other than steel breech and 14.5 barrel

[K.O.]

Yup if you really want to get serious about barrel accuracy you need to clamp it down .You have to take yourself out of the equation.

yup

Thanks to you I had an extra barrel band /end plug

one is now just an end plug  so I can see how the 14.5 barrel likes free floating.

but I should  build something like this this tomorrow have the clamp and wood. (its just much more fun to shoot)
http://teotwawkiaiff.com/2011/11/13/homemade-gun-vise/

then I could see any real difference easier...

I have had good luck trusting my gut,

but...

I just hit over the hill...

[woody67]

Note, others might argue the point but, it's only the last few inches of good quality rifling and a good crown that matter in airguns. Case in point are the high-end $$$$ FX PCP airguns with their "smooth twist" barrels.

Excellent point.
Have you seen the barrels that wrap completely around the gun in a spiral? I think the first and last inch or 2 is straight, thats it. The rest is just a spiral. Yhe gun i am talking about is a match/competition gun, so you know it is dead on accurate.
I think someone had it as their avatar on this forum.

[BDS]

"smooth twist" barrels was one of the things I was thinking about the other day... 

It seems that the ultra mags have a slightly larger head size ( I have not actually checked though) and I was thinking about getting a couple barrels to experiment with

one of the things was  to ream out about 13" of a 16.5" barrel very slightly to make  a dedicated ultra mag barrel  and see how it affected velocity and accuracy...   (sort of a smooth twist thing)

I had even done a  "smooth twist 1377" search,
http://www.gatewaytoairguns.org/GTA/index.php?topic=27339.0

are the smooth twist barrels  Hammer forged?  I just assumed never checked...


thanks for the feedback  I am not super anal about my shooting so it is easy to fool yourself that some thing helped.

for tuning purposes I really should make a good rest/cradle is stead of just using the door frame as a side rest.

Here's the FWB pistol that Woody mentioned, it's as accurate as any of their other 10 meter pistols.

As far as HF barrels vs conventional button rifling processes, it really doesn't matter for airguns. The powder burner guys argue the merits all the time based on material density and a bunch of other factors but, they are using very high powered and high pressure, high heat rounds where it can make a difference about barrel life more than any near-term accuracy issues. On the smooth twist concept, it's all about the quality of the leade and the crown because the pellet enters the rifling at a pretty good speed so, pellet deformation (or lack of) is critical. The last few inches of rifling provide the spin to the pellet and the crown allows it to leave the muzzle on a path perfectly parallel to the rifling. Actually, the crown requirement on airguns is mostly just the polishing of the lands and grooves at the point where they meet the crown face. The face of the crown looks better when polished but, other than that small diameter near the rifling, the rest is mostly cosmetic. For powder burners, the face IS important due to the explosive gases and how they interact with the face.

[woody67]

That's the one!!!

Amazing.

[crossliner]

Dang I thought that serpentine barrel was some sort of a joke