Reliving the past: a smooth bore .177 post

[Ribbonstone]

What can you do with a "BB" smooth bore?

HAd been thinking (as old folks are likely to do) if the old days were kind of miss-remembered".  Remember shooting pretty small critters, from pest birds to squirrels, out of the tops of trees with a smooth bore "BB" gun.

Was I full of "it"?


Revisited the old home. It's changed over 50 years, but the back door is still where it always was and the rear fence line can still be made out (the fence has moved, but the old fence line can still be found).

The scrub land is still there, although the trees have grown.  The old Live Oaks tend to grow "out" (wide) about 60-75%  more than than "up" (tall) but can estimate the heights and the sistances between the oldest trees.

Came up with something more like 45-50 feet as "dead on" and a max of about 60-70 feet.

So...20-22 yards with a smooth bore?  Is that really possible?

Guess there are lots of old smooth bore Benjamin 310's and 340's still out there able to be shot.  It's not like those old MSP's wore out easy, and it seems the old ones were quite often smooth bores.

The bottom on is a 310, which is what I bought as a "kid" from the local hardware store (that let a kind pay a bit per week until the rifle was paid for).



Made some economic sense as a kid. Minimal $ on hand at any one time (yep...grass cutting and paper route), being able to shoot cheap steel BB's seemed a plus.

Old smooth bore 310's/ 340's (not so much the 3100 or 3030 co2 rifles as they are pretty much  BB/ball rifles are nothing).

Some years back bought a Benjamin 340, which would have been the last smoothbore model I'm aware of.

DSCN1120 by Robert Dean, on Flickr


TESTING:

Can pretty well sum up a few years of off-on testing with one target shot at 30 feet.



So a try for 4 X 5-shot targets at 33 feet:



And a try at 60 feet with the "winner" of the above test:



RESULTS:  Was a full of teenage "long eyes" that made feet into yards?

Maybe not.

Certainly was full of "it" if I calimed steel BB's did the job at 60 feet.

Possible (but unlikely) if I used lead ball.

LIKELY if I used  the right pellets. And as I remeber it, the cheapest back then were the Eunglish made "Bulldog" pellets, that did have a large round head and a really thin deep hollow skirt.


IF you want to try on old Benjamin smooth bore (310/340):

UNDERSTANDING THE BOLT:

There is no bolt probe o-ring. Evidently they lapped the bot to a metal-to-metal fit. reminded of ground glass stoppers in lab bottles.

Probe is a hollow probe "trumpet".  Idea is that a lead ball will just barely fit into the trumpet, and be friction tight enough not to roll down the barrel.
Do not "jam" the ball too tight in the "trumpet".  Makes for a variable release, which makes for variable velocity, and vertical stringing.



Steel BB will fit deeper in the trumpet as it is smaller.  DO NOT jam it in there hard, or you're likely to have the air port bolocked and the BB go no where when you try to fire it.




WORST CASE: Steel BB's
Mistake #1. The bores are too large to use steel BB's well.   It's a .170-.171" ball in a .176-.178" hole.

Mistake #2: The high precison BB's aren't any bigger...they are just more uniform in size...which doesn't help much.

What seems to happen is that air finds it's way around that gap, randomly more on one side of the BB than the other, forcing it to spin in some random direction as it's pressed up agains the bore more on one side than the other.

So, in baseball terms, it's either a curve ball or a knuckle ball.

BETTER CASE: Lead Ball.

It's closer to bore size, so more uniform in barrel contact.

Will eventually pick up a random spin, just not as drastic a spin.

Best fit is one that just won't quite fall down the barrel from gravity.  JUST large enough to slightly "stick".  Can "whack" the barrel with your hand and the vibration will get it to slide down, but it's the best fit a ball is going to get.





I still have some of the old Benjamin Lead ball....seems to work everry bit as good as H&N lead ball.



BEST CASE: Pellets.

Not just any pellet. A round nosed pellet with a deep thin hollow base.  The weight forward/hollow base gives it some "shuttle cock" type of stability.

The odd thing with smooth bores and pellets is that they do NOT seem to like being shot too fast.  COULD BE the balst of exiting air (and there is a lot of air/lot of noise in one of these old guns) upsets the non-rotating pellet.  Might be that without rotation, high speed upsets the balance of nose-drag to base-drag.  MIght be just about anything, but the more I pump the rifle, the worse it shoots pellets (although lead ball doesn't seem to care).

The DUHHHH? moment.

Have had rifled airguns that won't do as well, even at this short range.  Lets assume the rifling actually spun the pellets...why couldn't they do as well or better than a smooth bore?

 Am going to guess that either the disruption of the firing cycle (read that as "tool truck gun" springers) defeated your hold and sighting....or that a pock-marked, unevenly rifled bore is actually worse than a clean smooth bore.

[HunterWhite]

I have wondered what would happen if you put some teeth on the bottom of the barell. This would cause a forward spin, which should cause the BB to climb, but it should be consistent.
I considered just putting some sand and superglue on the bottom of the barell.. what do you think?

[Ribbonstone]

Had thought about a "hop up" system (like used in air soft)....maybe it would work (and actually have BB's "climb" after exit)...but found pellets worked bertyter than I expected and just let that thought go (am not that married to round ball).

[Mod90]

Ribbonstone, welcome to my world.
Just one thing to mention though, & that's that you can shoot pellets at high speeds (up to 1080 fps as far as I know) & have them be accurate, but it depends on a few things, such as pellet design (usually thin skirted, shallow based & head heavy domed pellets work best), weight & speed & type/condition of your barrel's choke & crown.
With a smoothbore, a choke is necessary, & an as close to perfect as possible crown is the key to accuracy.

[Ribbonstone]

Not in my experience with smooth bores (and here I mean actual smooth bores, not the FX type paradox rifling)  With no spin at all, they tend to just go completely stupid/tumbling...shot slow, and still getting round holes at 40-50 yards (the groups are &^^&...but the holes are round, so the pellets aren't tumbling).

Only one rifle I would shoot at +1000fps.  Admit it did shoot well out to 90yards (the farthest I paper tested it)..  An old 5mm Sumatra could manage 1030fps with 23gr. 5mm EunJin pellets.  IF it were any other caliber, I'd have switched to something heavier and gone a bit slower...but there isn't anything heavier in 5mm and I wanted the +50foot pound power for Nutria.

If I had to make a blanket statement about high pellet speeds (over 1000fps), it would be that the pellet quality becomes increasingly critical....a little flaw that might land an 850fps pellet 2/3" out of a group will often land a 1030fps pellet a foot away.

[gendoc]

i've had a 1960 model 312 since 1969, it was new when my father bought it and he gave it to me when i could handle it properly.
itsa smoothie as you know and its accurate as can be @ 25yrds.
no tell'n how many squirrels, rabbits, robins and dove its taken....its still hammering on
@ 575fps with CPDUM's.
dennis baker overhauled it last year for its first time.

[Ribbonstone]

  Will work some more when it gets windy....have a suspion that a non-spinning pellet (see not #1) does odd things in a side wind that a spinning pellet mostly avoids.

Note: Smooth bores are "knuckle balls". The travel pretty straight over the short haul, but randomly pick up spin as they travel  No rotational stability, so a little nudge here or there by wind or surface irregularites seems to  make a much bigger difference after 20-30 yards.

[Mod90]

Will work some more when it gets windy....have a suspion that a non-spinning pellet (see not #1) does odd things in a side wind that a spinning pellet mostly avoids.

This is true, but depends on the amount of wind & it's direction, & heavier cylindrical pellets are a somewhat less affected than lighter wasp waisted ones.

Note: Smooth bores are "knuckle balls". The travel pretty straight over the short haul, but randomly pick up spin as they travel  No rotational stability, so a little nudge here or there by wind or surface irregularites seems to  make a much bigger difference after 20-30 yards.

To a degree, this is true as well, but IME you should be able to make it out to about 40 yards before things start going haywire & becoming unpredictable.


I'll try to start making some scope cam vids with these smoothbores at different distances with different pellets, & let's see what we can come up with.

[Ribbonstone]

Pretty close to an average day...sitting in a patio chair, cross legged, with just a 10 yard target.

Which is absolute accuracy terms "suxs"; doen't really know whow much better I'd have done if I transplanted those "basic" iron sights to a more accurate rifled airgun.




Ran out of iron-sight day-light, but I'll give even heavier pellets a try...but what I suspect from other shooting sessions, is the LESS a pellet balances like a "rock in a sock"  (weight foreard/deep hollow base) the less stable it's going to be in smoothbore flight.

Then again I could be dead wrong..but isn't that we bother to shoot pepaer rather than just  guess?

[Mod90]

Got some time this morning to make a short scopecam vid of a 10 shot group out of my unregulated power tuned smoothbore BT65, shooting H&N sniper magnums @ 990fps at a range of 10 yards. Gun is zeroed at 22 yards.
Things to note-
This group was shot in a hurry
These are not the most accurate pellets out of this gun, but I ran out of JSB Monster 13 grain pellets a long time ago. When I get those in hand I'll try with those & we'll see what happens.
This is my first time using both this scopecam setup & this scope shooting for groups, even though I've had them both for a few months. So I suppose with time & practice I may get better results with this setup.

[cobalt327]

Shame- looks like they pulled the video...

[Mod90]

No they didnt

[cobalt327]

¯\_(ツ)_/¯

[cobalt327]

Do you have the access limited in some way?

[Mod90]

Don't think so. I'l try something else & we'll see if it's viewable after

[Hoytwon]

Brings back old memories i shot 1 of those benjamin air rifles when i was a kid it was my dad's at the time, not sure what ever happened to it or what model it was i know it had the ribbed style fore grip! Thanks for the pics and trip back in time!

[cobalt327]

That fixed it.

[Mod90]

That fixed it.

Nice.

Thing is though as I mentioned, that was a really rushed group, with not the gun's preferred diet, & through a scope & scopecam setup that I'm not used to yet, & it still managed to be under a 1/2". Now, that group doesn't really surprise me, & I really don't find it very impressive, because I know for a fact that this smooth bore can do a good deal better. And that's because I once shot a group at 30 yards with this same gun but using JSB monster 13 grain ammo, that measured just under 3/8".