New project: .177 slug gun

[rsterne]

I wonder if you can get the GC bullets Tim linked WITHOUT the gas check.... That is what usually works best in airguns.... That NOE 27 gr. GC without the gas check (and hollowpointed) is what Cedric was using....

Bob

[Dairyboy]

10 shots at 55yds with the 21gr. Interesting though...first 4 shots were the 4 high one's, next shot was the low right flyer no idea what that was. Next 5 shots were the ones just lower than the group of 4. What I don't understand is they were all shot at the same POA

[skorec]

10 shots at 55yds with the 21gr. Interesting though...first 4 shots were the 4 high one's, next shot was the low right flyer no idea what that was. Next 5 shots were the ones just lower than the group of 4. What I don't understand is they were all shot at the same POA

Dillon,   Which barrel and velocity ?

Bought  my .177 LW ( choked or polygonal - NCH  ) barrels   shot them similarly or little  bit  better at 950 FPS .  20% of flyers is adequate for too slow TR.
We definitely need .177 barrels with faster twist rate.   

Only Hatsan barrels are different  see the video?
https://www.gatewaytoairguns.org/GTA/index.php?action=profile;area=showposts;u=25374

[KnifeMaker]

“Cedric is always chasing the leading edge, or setting it. such a shame we lost him here on the GTA. A real loss for those interested in longer range hunting and AirGunning in general   As nice a person you will ever know. We've been friends for many years now.  “
I’ve been wondering where he went . My ideas where he’s hanging out these days ?

No Sir I don't. We talk on the phone, and I watch his videos on youtube.   

[KnifeMaker]

30 bucks for them is mighty expensive!

[rintafile]

Here's some .17  casts at a pretty good price.

https://shop.reedsammo.com/Cast-Bullets_c281.htm

Hard cast and lubed bullets....Maybe not best option..Always can try but if those are hard as .22 bullets which are on same page. 15 and 22 BHN is pretty darn hard for airgun. Just my opinion.

[Dairyboy]

10 shots at 55yds with the 21gr. Interesting though...first 4 shots were the 4 high one's, next shot was the low right flyer no idea what that was. Next 5 shots were the ones just lower than the group of 4. What I don't understand is they were all shot at the same POA

Dillon,   Which barrel and velocity ?

Bought  my .177 LW ( choked or polygonal - NCH  ) barrels   shot them similarly or little  bit  better at 950 FPS .  20% of flyers is adequate for too slow TR.
We definitely need .177 barrels with faster twist rate.   

Only Hatsan barrels are different  see the video?
https://www.gatewaytoairguns.org/GTA/index.php?action=profile;area=showposts;u=25374

Peter, these were shot from a standard crosman barrel and were in the 850fps range

[Nvreloader]

Dillon

Was this group shot thru a magazine?

Try a group with a single shot block, or hand fed and see what happens.

I know my Mrod mags cause fliers, which I can't find out the reason why.

Tia,
Don

[bandg]

I currently don't have any magazine fed air guns but I've mentioned elsewhere that I have seen similar issues in a .17 HMR Taurus revolver that I own.  One chamber has noticeably more play than do the others, apparently due to the indexing cut being slightly wider for that chamber.  If I avoid that chamber the gun shoots great groups.  But if I include that chamber the groups opened noticeably and using only that chamber produces quite large groups.  If the magazine in question is free of burs that could damage the pellet, it would seem to probably be related to magazine indexing and possibly some type of impact to the pellet upon chambering. 

[Dairyboy]

Hand fed, rarely use a magazine in any gun.

[bandg]

Shot without magazine and assuming the scope is good and mounts are good, the way the clusters of shots seem to shift downward, is it possible it is related to change in reservoir pressure causing change in pressure on the barrel? 

[Motorhead]

Along that thinking .... The SS valves really can shift speed in my testing if the hammer strike is a tad to much.  If over striking it fully lifts poppet and stem goes flush with body having the hammer bouncing off the face of valve body.

Not that this is the issue ... just something to look at

[oldpro]

 Shoot a string and look at the FPS for any speed changes If its pretty steady measure all the bullets OD or use a sizer to get them all uniform.

[K.O.]

If fps is steady and other causes are ruled out and it continues to make two seperate groups over the fill... it can suggest at a certain fill pressure  the harmonics  of the  skinny choked 7/16 barrel are effected...

[oldpro]

If fps is steady and other causes are ruled out and it continues to make two seperate groups over the fill... it can suggest at a certain fill pressure  the harmonics  of the  skinny choked 7/16 barrel are effected...

Might need to tension the barrel.

[Dairyboy]

Good suggestions guys. Will look into them. Issue is I no longer have the 21gr slugs. Will be trying the 18gr to see how they fair.

I know tune is solid it was when I did the 10.3gr chrony run but maybe not with slugs. Will chrony with the 18gr while shooting groups.

Scopes good have used it on many other guns with no shifts and good BKL mounts.

Pressure change in reservior maybe but idk it's free floated with soft foam around so has some movement and haven't seen any issue of it before.

Would love to tension the barrel but not sure how hard that is on a 7/16" barrel.

[K.O.]

as fill drops the nature of how it gets the round to  x fps changes  along with the changes in the air tube... can see how it would/could alter a set of resonances sometimes....  a skinny barrel is more susceptible to those resonances...

[oldpro]

 Carbon sleeve it Dillon.

[bandg]

Dillon, I have no experience with the platform you are working with and had only looked at a picture to see the mechanical setup.  Picture showed a barrel band from tube to barrel.  If yours is free floated then pressure change in the tube should not be involved unless it is velocity related.  Chronograph all shots for the group?

[Ribbonstone]

Am NOT SAYING these are "slugs"...they certainly are not (although the 21gr.Piledriver kind of crosses the "slug" line).

But as this has sometimes migrated into that area....

Found some of the missing pictures (OK...were filed under HIPAc rather than "targets","QB's", or "pellets").
Have mentioned it often...but worth repeating rather than have someone think it's something other than just blind-luck.


It's blind luck.

 Was built and restocked for one particualr job: fast handling and shooting pest birds at an "up"angle (like they they are in trees), and spent most of it's life down around 8-9 foot pounds for a longer shot count. Was converted to air by way of a HiPac uint (he sold QB verions at one time) to make it more useful in winter.



No twist difference I can see, cut and recrown to carbine length (is 16.6" if the LDC is removed), nothing specail about the bolt probe, and it is not shooting fast....which is kind of a disapointment, as there really isn't a whole lot of great uses for a slug this heavy and slow.

Like many of the older QB 78 barrels, once you cut it, often find the bore is not quite on center. Doesn'tseem to hurt anything, other than making a good LDC harder to arrange.




Last outing, to get sighted in was at 20 yards.  Can tell how long I've been testing various rifles by how rusty the last tin has gotten.



Which isn't bad for 20 yards.


So I tried the two other heavy weight pellets that had shown promise in this rifle (there were more tried...but in the reeally heavy weights (15+ grains) the three  on the left worked better.



 Better day....could get to 25 yards.

URL=http://s157.photobucket.com/user/ribbonstone/media/HiPaC/70f5e451-bc58-473f-8143-95deb7175c6c.jpg.html][/URL]

(BTW: in this case, really never did carry out the 75 yard tests with the 3).

By now, considering the tiny air volume (that's like 72-75CC of air) was getting something like 12-13 good (being 3% or under in velocity varation) shots. So limited my self to the best of the sweet spot...so a refill for each pellet.

Might have taken a few shots to get it "on" at 25 yards, one it was pretty much "on"at 25,then 5 shots for record on the same target.  Lot of moving back and forth, but at least pump filling the little tube wasn't a problem.



About this point,decided that this rifle really wasn'tgoing to be real userful as a heavy-weight shooter.  Accurate enough, but  the slow speed/low energy didn't really offer any advanatge at 50 yards...so I just used up the 21gr.Piledrivers in this rifle (although I still think there is a 1/2 tin of them lurking about the place, hiding).


MAy not seem like it...but I really do appreciate the idea of a really high BC slug in .177.All the benifits of windage/range without the "extra" energy if you can launch them at a decent speed. 


Just my luck that the one rifle that shot them best was slow(but one slower, the same speed, or way-faster didn't shoot them wellenough for me....just "blind luck".