PC77 pellets limit or mine? possably spiraling

[K.O.]

I pick up  lightly used PC77

It was shooting all over, I was pretty sure it was not me...

same range with just out of package 1322($40 wow had to get it !!!!) was getting  1-1.25 groups (stock peep) at 20 & 25 yards

took a close look at the pc77, lead in had concentric rings and had burrs at port, did a quick clean up and reassembled.

pics of groups  after  that  are in my intro thread  (do not have to read but the pics are there)

http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,12647.0.html

Looking at the movement of group and the fact things go to cr@! at 30 yards  make me suspect ---  Spiraling just further down range now...

So  are the 7.4 field pointed hunters just prone to spiraling, or do I need to look a the barrel and breech again...


OR  do ya suspect its just the rusty operators doing???

[K.O.]

I was going to run some more 10.5 Ultra Mags thru  today and see how they would do but was 15- 20 mph winds all day...

[quickster47 †]

I would be trying several different pellets as your barrel could just be one of those that is very pellet picky.

Carl

[K.O.]

I would be trying several different pellets as your barrel could just be one of those that is very pellet picky.

Carl

yep that's the plan,  but another gusty day fun for a challenge but ruins it for tune,

right now I need a few more choices  like some  exact domes and premier domes,

but my air gun budget this month is going towards a couple barrels and a  steel  .22 breech.



right now                                                        853       PC77       2100
__________________________________________________________
1/2 tin of H&N hollows  7.1g                                                   
1  tin Premier Ultra  10.5g                                                              
1 tin  Crosman Hunting points 7.4g                                                   
1 tin  Destroyer ex  7.4g                                                          
1/4 tin Destroyer  7.9                                                            
1 tin   Daisy precision max points 7.8g                                          

[WyoMan]

^^^ too funny...love the chart 
I would try some JSB Exact domes, sounds like you plan to, the soft lead and 4.52mm help to make sure the pellet spins
and doesn't strip in the shallow rifling...some crosman barrels are that way
also, if you get good groups at 30 yds then thats awesome....domes have better BC for longer range 

[1377x]

bc makes a world of difference for long range shooting
not surprised the regular destroyers and daisy pointed dont fly
the daisy .22 flathead was one of the best pellets i shot . they are very soft and very dirty. if i could still get them locally i would have some

[K.O.]

bc makes a world of difference for long range shooting
not surprised the regular destroyers and daisy pointed dont fly
the daisy .22 flathead was one of the best pellets i shot . they are very soft and very dirty. if i could still get them locally i would have some

yep  B.C. definatly helps that is why it is my goal to get the 1377 shooting Premier heavies at  about 625 fps or so (with only  14.5 barrel? )


But B.C. is not every thing these 7.4  I got are pretty uniform,

the 853 at 400 fps or so was giving quarter size groups( little 4x15 scope) @ 20 yards and that is with the pellet on its way back down by about 1/4"

and barrel pointing about 2" high (according to chair gun.

BUT...

All this is trumped by your tools acting like a problem child which both my PC77 and 2100b are doing...


yup I got the 77 down to decent groups with the 7.4s  I (as a wag) figure B.C. about .18 and was going to try to further tune but then roll pin  started

moving and groups went back to pre breech end  barrel work...

I was like "What the hockey  " till the pin really migrated noticeably.

I am done with the brat until to pin gets here other than modding the band to float the barrel.

I could do a slightly better job(I just did a quickie) on the lead in, but

that will wait for the long barrel as will most of the work.

I do think 1/2 (+/- a tad) groups @ 20 yards are very doable...

Oh yeah it could be that he  got jealous, Fed ex delivered the 1322s 1399...

2100  tune saga in next post (a teaser though, got a .25" and two .5" groups @ 20 yards before going back to misbehaving. but do KNOW why Q.C. issues again).

[K.O.]

Ok so now the 1377 has a temp pin till the good one get here,

Turned down a drill bit shank slightly, held in place with tightly wrapped rubber bands.

will shoot later today to see if group size comes back down.


I  held off posting because I could not find the plastic cutting board I need to (hopefully) fix the 2100s accuracy issues.

I have  a small collection of wood because one of my hobbies is making dulcimers and acoustic lap slides,

so I guess temporarily I will use hard maple barrel stabilizers.

changes in size with R.H. and temp would be down in the thousansd of inch range,

beside I just want to know the fix will work.

I am pretty sure it will.


I still have the opinion that the 13xx and 2200/2100 series are great values and realize to keep prices low some compromises are necessitated.

But come on, to long of screws on the sights is an easy Q.C. fix  as are the rough lead in and port burrs in the 1377. they are still a tuners delight but

could also  the leaders when it comes to accuracy and power for the price point.  Just a very small  Stupid Q.C. fix....

But not the only prob on my 2100,

If I had bought new it would have gone back...

The barrel is pointed some what down towards the pump tube...

Hoping to tighten up my groups I pull the shroud to do the plumbers tape thing.

I see the screw marks on the barrel and shorten them.

Reassemble...

Shoot heavies big groups  a bit low switch to hunting points  and it is shooting them about 4.5" higher,

I bet most of you can figure out why...

got my bore light out and yep barrel is bowed

pulled shroud and used it to straighten barrel,

reassembled...

got the sweet grouping  (especially in comparison to starting point).

Four hours later look down barrel and yep back to bowed.

well the day was full of fits and start and set backs...

setting up a time of flight chrony  that day using my spare comp went the same way.

Well the day ended on a high note thanks to my oldest daughter,

an early B-day present...

a 1399 for the 1377, and now he and big brother look like twins agin...