unexpected results with some JSB .177's

[shooter r]

My R7 really likes the 8.44 gr. JSB. It only goes 542 fps, but it's accurate within the range ability of the gun. I decided to try some JSB 7.33's, for a little more speed. I bought two tins. The first one had a bunch of pellets with what I'll call "flat spots" on the skirts, i.e. they were not perfectly round. So... I culled out 10 of the most obvious ones, to more or less "use them up", and for some reason, I decided to put forth my best effort to shoot a good group (standing at 18 yards), thinking: "just how big is this group going to be ?". Well... it was almost as good as any of my "better" groups. Under an inch with NO flyers. When I seated those "pellets", there was a definite "space" where a section of the skirt was not in contact with the beveled area of the breach.

Since I like experiments, especially those that debunk, or at least put into perspective, my current mind set of: "this is how it must work", I am going to try a few groups with some "perfect" looking pellets, and some that I will put a little dent in the skirt with my fingernail. They will be subtle dents, not crushers. I would like to know if anyone who shoots enough to wonder if there is a difference, and actually tries this little test, to post their results here. I'll post my results in a day or two. Good Shooting! Randy       

[Smaug2]

I'm betting they shoot the same as the perfect ones.

The 7.33s have thin skirts, to keep the weight down. But they are the favorite pellet in my HW30s. (either JSB or Air Arms Falcons)

Air arms 7.9s shoot the same, and so do 8.4s, but I've got to believe that in a low powered gun like this, the spring will last longer with lighter pellets.

CPLs also shoot well, and so do RWS Meisterkugeln Pistol. (which also cut a nice clean hole, most of the time!)

We should get together and shoot some time; we're only an hour apart. Maybe split the difference and meet in the Bristol airgun range this spring?

[Oldgringo]

FWIW, my Hw30S' and R7 all three like the 7.33 gr. pellets.  Nobody seems to like the CPLD's?

[nervoustrigger]

The logical consequence of bent skirts is varying amounts of blow-by resulting in velocity variations.  With the thin skirts and soft lead of the 7.3gr, one would expect them to obturate easily and seal against the bore before there has been much blow-by.  Perhaps that's why those with slightly deformed skirts still group well for you at 18 yards.  At longer distances, that velocity variation would tend to become more noticeable.  Putting a few bent pellets and good pellets over the chronograph would tell the story.

To share a recent experiment with the same pellets, I was shooting test groups with a new Crosman 2400KT with a 14" LW barrel.  Of all the pellets I tried, it grouped best with the tin of Air Arms 7.3gr.  By flaring the skirts ever so slightly with the end of a 1/4" phono plug, the average velocity jumped up from 670fps to 700fps.  That is almost a 10% increase in energy (8.0fpe vs 7.3fpe).   Because they were grouping well at 25 yards (ragged hole 5-shot groups), I could pick out about a 1/4" vertical shift.  As I recall, the Chairgun prediction was a pretty close match. 

To be clear, this scenario was a little different than yours--comparing flared skirts to otherwise unbent skirts--but hopefully gives some perspective.

[Smaug2]

FWIW, my Hw30S' and R7 all three like the 7.33 gr. pellets.  Nobody seems to like the CPLD's?

My HW30s likes CPLs almost as much as the 7.3 gr. Air Arms Falcons or JSB Exact RS.

I don't like them as well though, because they cost as much as the JSB/Air Arms and I have to buy them 1250 at a time, instead of just 500.

AND they have crummy packaging. AND they need to be lubricated when shot over 750 fps so they don't foul the bore. They're good pellets, just a more work in all respects.

[Hoosier Daddy]

Nothing to add that already has not been said, I bet the initial air plast expands the skit easily on the lighter pellet.
But I gotta ask...

Nobody seems to like the CPLD's?

What pellet is that?
Crosman Premier _ _

[shooter r]

I'm thinking "Crossman Premier Light Domed" at 7.9 grs.

[Hoosier Daddy]

Thanks... never saw the "lights" before.

[shooter r]

I agree with the above. The 7.3 JSB's (which are  shorter than the 8.44's) have skirts that are thin, and soft. That seems to be a good thing for a lower powered "pellet gun".

Crossman pellets seem hard, and are probably made that way to survive the trip to the consumer via Wal-Mart, etc. I once waited to look at the selection, when the person in front of me gave a tin a really good shake, I presume to check if it was full?

The head on the Crossman pellets seems to kind of "crunch" into the chamber of my R7, and they do not group as well. Oh, well... believe it or not... At Wal-Mart today (2/3/17), online: Crossman .177 cal 7.9 grs. 500 ct. Hollow Point for $6.28, FREE shipping on orders over $35. If so inclined... Go For It!

[Oldgringo]

Thanks... never saw the "lights" before.

Crosman Premier Light Dome.  They can be ordered through Walmart, PA et al.  They are lousily packaged by Crosman 1250 to the box.  The box will run you $30 (+/-).  I thought my Blue 97K might like 'em but the jury is still out on that. 

[Smaug2]

Thanks... never saw the "lights" before.

Crosman Premier Light Dome.  They can be ordered through Walmart, PA et al.  They are lousily packaged by Crosman 1250 to the box.  The box will run you $30 (+/-).  I thought my Blue 97K might like 'em but the jury is still out on that.

Hoosier, Gringo: The ones you get from the big box stores aren't the same as the ones you order in the 1250 box. The ones in the tins from the big box stores seem to have some kind of coating on them now, but they're as dirty as ever. The 1250 ct. boxes' packaging is &^^&, but the pellets are more consistent. They're from the same die lot. Try them sometime, if you haven't before. Guys in my club used to buy the CPH's, wash them, dry them and lube them manually. Word is that they're not as good these days; I bet the machines are just getting old. They must be or (must've been) good pellets to be worth going through all that. They were pretty consistently the most accurate pellet out of my high power .177 rifles. It was discouraging too, since they were more work. I'd have rather bought JSBs and not had to do any more, but they just didn't shoot as well.

[anti-squirrel]

Thanks... never saw the "lights" before.

Crosman Premier Light Dome.  They can be ordered through Walmart, PA et al.  They are lousily packaged by Crosman 1250 to the box.  The box will run you $30 (+/-).  I thought my Blue 97K might like 'em but the jury is still out on that.

Amazon often has them on sale.  I picked up a box for < $20.  Just gotta keep an eye on them as they usually sit right at $29.99

[Kernbigo]

try the 10.34 they are my best shooting pellets in my ruger air hawk

[LAalex]

The logical consequence of bent skirts is varying amounts of blow-by resulting in velocity variations.  With the thin skirts and soft lead of the 7.3gr, one would expect them to obturate easily and seal against the bore before there has been much blow-by.  Perhaps that's why those with slightly deformed skirts still group well for you at 18 yards.  At longer distances, that velocity variation would tend to become more noticeable.  Putting a few bent pellets and good pellets over the chronograph would tell the story.

To share a recent experiment with the same pellets, I was shooting test groups with a new Crosman 2400KT with a 14" LW barrel.  Of all the pellets I tried, it grouped best with the tin of Air Arms 7.3gr.  By flaring the skirts ever so slightly with the end of a 1/4" phono plug, the average velocity jumped up from 670fps to 700fps.  That is almost a 10% increase in energy (8.0fpe vs 7.3fpe).   Because they were grouping well at 25 yards (ragged hole 5-shot groups), I could pick out about a 1/4" vertical shift.  As I recall, the Chairgun prediction was a pretty close match. 

To be clear, this scenario was a little different than yours--comparing flared skirts to otherwise unbent skirts--but hopefully gives some perspective.

I would also recommend flaring your pellets.  Velocity in my 22 cal. Diana 48 with 13.4 AA went from 775 avg. fps to around 825.  Not quite 10% but still substantial enough to justify the effort.  You can make a flaring tool out of almost anything.  I use these (see link) just because I have them for touching up crowns but an ink pen barrel or a sanded wood dowel will work just as well.  Good luck.

http://www.squirreldaddy.com/category-s/324.htm