Benji 392. Best number of pumps?

[Tallbald]

Just pondering at 2;15 A.M. (shouldn't have taken a late nap) the concept of diminishing returns as it relates to my new Benji 392, .22 caliber  pumper. Is there an optimal number of pumps I should start at when using my gun to eliminate a combination of squirrels/birds/rabbits raiding our garden 50-60 feet out? If each pump gets harder yet  less productive in the number of FPS it adds to the pellet velocity, what lowest  number of pumps will give the best velocity return for my effort? I hate to pump 8 times for every shot if only 4 or 5 pumps would make for a humane head shot kill.  Knowing the lowest number of pumps I can use, and always using that number would simplify things for me a lot. I could use that number for pest elimination as well as paper punching, and maybe save a lot of wasted effort. OK., so I'm middle-aged fat man lazy lol. What's your all's experience? Thanks. Don

[lillysdad621]

5 pumps. all that is needed. my sheridan is the same. shoots mid 500s. learn trajectory and lay down the law.

[TimmyMac1]

Power is adjustable. Trajectory is inevitable. I would set it up to go three pumps at 10 yards and add more pumps the farther you reach out to stay on target. That is the most practical use of a MUlti is to pump only as much as you need or "shoot more pump less" as I like to say. On a stocker 4 pumps is 500 fps (on a Steroid that is 3 pumps). The gun action will flex upward the more pressure is in the system so it will shoot HIGHER with More pumps in it. You need to lesarn to use that feature to your advantage.
Pretty soon you will realize the true advantAGE of a Multi. Spring gun familiar shooters are always looking for the perfect Number but it is up to the application and distance which is not always the same. It's versatility is it's multiple pump freature so why hogtie the possibilities with a One power setting mentality?
Pump enough to get the job done. Know where it will go if you pump more.

TimmyMac1

[lillysdad621]

Tim... you mean zero at 10 yards with 3 pumps and then see how much higher would then 4 pumps do, then 5... and so on and so forth? or set then cards out to your chosen range and see how low 3 pumps will shoot and then adjust? I chose 5 pumps always because it gets tiring pumping pass that and i have found and learned the trajectory while zeroed at 15 yards... even at 50 yards i know my rifle (a sheridan) will hit 4 inches low. average squirrel height? 4 inches. so aim 3 high and count him for the pot. Plus it gets too noisy pass 5 pumps... heck, if plinking in the yard i stop at 4 and hit targets within 30 yards more often than not. i see no point in pumping 8 to 10 times. Also, a steroid treatment will allow me to get that same velocity at lower pumps??? i thought it gave more of a " magnum power " advantage at full 8 pumps... like allow for a flatter shot at long distances, with a lot more power. if i can get the 5 pump power at 3 pumps, i am very interested. will it make the pumping harder???

[Tallbald]

I myself am disabled due to spinal damage. I also have carpal tunnel syndrome in both wrists, and neck problems. These things sort of limit my pumping strength. Yes, I purposely bought a pumper though because of build quality for my dollar (I got a good one I believe), nostalgia (Sheridan pellet guns in my youth) and I am not the only shooter who will be using the gun (my robust children sometimes shoot with me and can pump more times). I like the idea of learning power and trajectory for a fixed number of pumps with one accurate pellet too. Mac1's proposal has a lot of merit and does indeed utilize the full capability of the gun, but my physical limitations dictate I go with the minimum number of pumps to get the job done  .

Please share with me advise about the style and weight pellet my 392 likely prefers too. I'm hoping it's a weight and style that's not too pricey....
Thanks all. Don

[cwlongshot]

As Tim said its variable. The alterations allow more air to be more efficiently compressed into the valve. So it stand to reason that each pump from a steroid gun, would provide additional velocity over a stock setup.

Yes it is harder to pump with successive strokes.

But that's only part of the steroid build. The other part is the gun is built/rebuilt to take the additional strains pumping more exerts on the action.

If you have a cronograph. Or have use of one you can also get good idea of power needed based on foot pounds of energy and the 2x rule of thumb. Say your gun produces 7 fpe at 15 yards. That's good for a 3-4# critter. Stay a bit lo for margin of error. At 17-20fpe that a fully pressurized steriod 'Dan should reach your should be good for about a 10# critter! So I would shoot it at X pumps, read velocity, figure FPE AT IMPACT DISTANCE and decide by2 for animal weight. Now you have educated guess at a humane kill.

CW

Edit, many folks like the JSB pellets and I am hearing good things about the ACCU-pells from Webly Scott too!

[lillysdad621]

on the 392 i would pass some crosman premiers 14.3 gr pellets... they should do acceptably well. 1 inch groups should be doable out to 25 yards. And you should be able to get those everywhere. My dan shoots jsb better and predators into a small ragged hole... but i still use the cylindricals ... they have acceptable hunting accuracy and pack a wallop. even at 565 fps.

[Jack D]

My C9, .20 cal., with 6 pumps, will go clear through both sides of a can of spray paint at 20 yards with pressure in the can, or a squirrel. Trajectory is also quite flat at the range with 6 pumps. Less would probably be good, too (five?). Anything more than 6 just makes my arms hurt.

Edit.
But it's good exercise for the old arms. I've emptied a 500 tin in the last couple of weeks and my arms are feeling it.

[D14Jeff]

I myself am disabled due to spinal damage. I also have carpal tunnel syndrome in both wrists, and neck problems. These things sort of limit my pumping strength. ............   

this video might be something you want to try ....



this one will show you how to disassemble it and explain what the different parts are and what they do .



and this mod to the valve reduces pumping effort .

http://www.network54.com/Forum/275684/thread/1179020046/Not+that+there+was+much+doubt%2C+but+replacing+the+front+O-ring%2C+did+cure---

 

[OleTomCat]

I took the Blue Demon to the fun shoot this past weekend and as luck would have it someone actually had a chrony there....

With 8 pumps it averaged just under 700fps with ~14gr pellets, with 14 pumps it was knocking on 800fps with those pellets and sounded like a .22lr going off without the sonic crack....

I can pump to 14 pumps if I need to but it is uncomfortable to do, 8 is enough for just about everything I shoot, I am thinking I need to try Timmy's idea of 3 at 10yds then work my way out and up to the back fence...

[Jack D]

I took the Blue Demon to the fun shoot this past weekend and as luck would have it someone actually had a chrony there....

With 8 pumps it averaged just under 700fps with ~14gr pellets, with 14 pumps it was knocking on 800fps with those pellets and sounded like a .22lr going off without the sonic crack....

I can pump to 14 pumps if I need to but it is uncomfortable to do, 8 is enough for just about everything I shoot, I am thinking I need to try Timmy's idea of 3 at 10yds then work my way out and up to the back fence...

Steriod conversion?

[cwlongshot]

I took the Blue Demon to the fun shoot this past weekend and as luck would have it someone actually had a chrony there....

With 8 pumps it averaged just under 700fps with ~14gr pellets, with 14 pumps it was knocking on 800fps with those pellets and sounded like a .22lr going off without the sonic crack....

I can pump to 14 pumps if I need to but it is uncomfortable to do, 8 is enough for just about everything I shoot, I am thinking I need to try Timmy's idea of 3 at 10yds then work my way out and up to the back fence...

Steriod conversion?

YUP it is.

See Al's sig line.

CW

[OleTomCat]

I took the Blue Demon to the fun shoot this past weekend and as luck would have it someone actually had a chrony there....

With 8 pumps it averaged just under 700fps with ~14gr pellets, with 14 pumps it was knocking on 800fps with those pellets and sounded like a .22lr going off without the sonic crack....

I can pump to 14 pumps if I need to but it is uncomfortable to do, 8 is enough for just about everything I shoot, I am thinking I need to try Timmy's idea of 3 at 10yds then work my way out and up to the back fence...

Steriod conversion?

Timmy at Mac1 Airguns in Ca. (he posted his responce in post #3 above) rebuilds the old Streaks and can upgrade the internals of the pump to give you vastly superior power with much fewer pumps....

[Jack D]

I took the Blue Demon to the fun shoot this past weekend and as luck would have it someone actually had a chrony there....

With 8 pumps it averaged just under 700fps with ~14gr pellets, with 14 pumps it was knocking on 800fps with those pellets and sounded like a .22lr going off without the sonic crack....

I can pump to 14 pumps if I need to but it is uncomfortable to do, 8 is enough for just about everything I shoot, I am thinking I need to try Timmy's idea of 3 at 10yds then work my way out and up to the back fence...

Steriod conversion?

YUP it is.

See Al's sig line.

CW

Ah. Yes. I see. Was curious since he said 8 pumps was just under 700fps and the published velocity of the stock version at 8 pumps is 685 fps....just under 700......but weight of pellet for the published velocity is unknown. I would assume it is the Benjamin cylindrical since it is their own. Curious.

[cwlongshot]

I took the Blue Demon to the fun shoot this past weekend and as luck would have it someone actually had a chrony there....

With 8 pumps it averaged just under 700fps with ~14gr pellets, with 14 pumps it was knocking on 800fps with those pellets and sounded like a .22lr going off without the sonic crack....

I can pump to 14 pumps if I need to but it is uncomfortable to do, 8 is enough for just about everything I shoot, I am thinking I need to try Timmy's idea of 3 at 10yds then work my way out and up to the back fence...

Steriod conversion?

YUP it is.

See Al's sig line.

CW

Ah. Yes. I see. Was curious since he said 8 pumps was just under 700fps and the published velocity of the stock version at 8 pumps is 685 fps....just under 700......but weight of pellet for the published velocity is unknown. I would assume it is the Benjamin cylindrical since it is their own. Curious.

Then you need to factor in the ''fudge'' factor... You know XYZ rifle will do 1000fps  but if you where to crony it... you would be lucky to see high 8's. 

Reading and watching videos generally speaking the streaks you will be luck to see 600fps. So hitting 700 ay 8 pumps is a improvement over the ''norm''. 

CW

[TimmyMac1]

That is about 6-7 FPE depending on the pellet used and the Impact energy will be adequate for, pest birds, rabbits and Crows out to 15-20 yards. I'd add a few strokes for Squirrel & Jack Rabbits as they are a bit tougher critters.
The effort to pump is more in a Steroid except the first few strokes which are lower due to larger internal valve volume/lower pressure built. Once you get to 3-4 pumps the pump action is about the same and then at 6-8 it is 25% greater than factory effort. The extended Billet is meant to counter this with better leverage if you have the height/arm length to pump it comfortably. Most folks over 5' 10" love it and shorter people, not so much. They can use it but not as comfortably as a person with long arms.
The above relates to the Current guns design and would not be the same for a Rocker Safety gun where the valve volume is fixed and the increased Steroid pump effort is immediate from the first pump. Rocker Safety guns and early Transitionals have higher pressure/lower volume valves as well as Racine 342 & 347's. They all benefit greatly from the Extended Billet Lever as long as you are tall enough to make the investment worthwhile.
Pellet speed is a poor choice of measurement for Multi-pump performance as the Energy will be much greater with slower/heavier ammo and they will also have a better BC. You need to give a higher priority to a Heavier pellet selection as that is how multis show their efficientcy. We add air volume to these guns and the only way to use that is with heavy ammo that stays in the barrel for the entire valve duration.
When you have a gun that inherantly loves the pellets with higher BC and max power is had with those pellets in all likelyhood they will hit hardest downrange and group well to boot. Trying to make Speed with Multi Pumps is a pointless exercise as the barrel is factory length and not gonna accelerATE PELLETS ALL THAT FAST BEFORE THEY EXIT. If they exit early you have a recipy for noise, inaccuracy and inefficiency. They seem to always be holding hands.
Heaviest pellet make the most power and retain it best. Speed is ENTIRELY OVERATED! Before Chronos we had the penetration tests to validate power. Steroid went thru both sides of a 55 Gallon Galvanised trash can. Effective Energy is not gonna be fast by merchandising standards. The FPS goal posts are out of Benjamin/Sheridan Reach. Certainly a death sentence for the class along with the build cost. We will know what we lost soon when they are gone forever. Too slow but not gutless by any stretch. Measured in Impact energy downrange there are few springers that can compete with Steroid Multi energy delivered even at moderate pump values. But ignorance pushes speed as the deciding factor as to what guns can get it done at the sales counter. The speed thing is why so many guns are sold in essentially the wrong caliber just to hit the stupid numbers touted as the speed you need. Guys call me all day long and ask for 1200 fps .177/1000 fps in .22 as the minimum they would accept. My reaction is sorry. Can't help you.
When you try all the options and find the accurate sweet pellet, I'll eat dirt if it is also the swiftest. DATA pellets are useless. Without Mass we have no BC worth mentioning. It is basically an insult to the consumers intellegence that has gone on for decades now. Doc BB knew there was always a good bet the Consumer couldn't get his head around Airgun Balllistics. It is pretty simple in that the more power you can make the more pellet mass you need. In a Multi that can mean different pellets for different power levels and applications(Read: Versatility).
The most important factor is the ease that you can shoot recoiless Pnuematics. They are hard to pump, light, powerful and easy to shoot accurately. Self contained accuracy is tough to come by. If you have a Multi that groups well you have a candidate for Steroid. Only a good gun deserves to last for as long as a steroid will.

TimmyMac1

[OleTomCat]

The master speaks.....

Timmy, what weight range pellets do you recommend, I am shooting in the 14gr range with my steroided, Racine, rocker, .20 cal?

That is about 6-7 FPE depending on the pellet used and the Impact energy will be adequate for, pest birds, rabbits and Crows out to 15-20 yards. I'd add a few strokes for Squirrel & Jack Rabbits as they are a bit tougher critters.
The effort to pump is more in a Steroid except the first few strokes which are lower due to larger internal valve volume/lower pressure built. Once you get to 3-4 pumps the pump action is about the same and then at 6-8 it is 25% greater than factory effort. The extended Billet is meant to counter this with better leverage if you have the height/arm length to pump it comfortably. Most folks over 5' 10" love it and shorter people, not so much. They can use it but not as comfortably as a person with long arms.
The above relates to the Current guns design and would not be the same for a Rocker Safety gun where the valve volume is fixed and the increased Steroid pump effort is immediate from the first pump. Rocker Safety guns and early Transitionals have higher pressure/lower volume valves as well as Racine 342 & 347's. They all benefit greatly from the Extended Billet Lever as long as you are tall enough to make the investment worthwhile.
Pellet speed is a poor choice of measurement for Multi-pump performance as the Energy will be much greater with slower/heavier ammo and they will also have a better BC. You need to give a higher priority to a Heavier pellet selection as that is how multis show their efficientcy. We add air volume to these guns and the only way to use that is with heavy ammo that stays in the barrel for the entire valve duration.
When you have a gun that inherantly loves the pellets with higher BC and max power is had with those pellets in all likelyhood they will hit hardest downrange and group well to boot. Trying to make Speed with Multi Pumps is a pointless exercise as the barrel is factory length and not gonna accelerATE PELLETS ALL THAT FAST BEFORE THEY EXIT. If they exit early you have a recipy for noise, inaccuracy and inefficiency. They seem to always be holding hands.
Heaviest pellet make the most power and retain it best. Speed is ENTIRELY OVERATED! Before Chronos we had the penetration tests to validate power. Steroid went thru both sides of a 55 Gallon Galvanised trash can. Effective Energy is not gonna be fast by merchandising standards. The FPS goal posts are out of Benjamin/Sheridan Reach. Certainly a death sentence for the class along with the build cost. We will know what we lost soon when they are gone forever. Too slow but not gutless by any stretch. Measured in Impact energy downrange there are few springers that can compete with Steroid Multi energy delivered even at moderate pump values. But ignorance pushes speed as the deciding factor as to what guns can get it done at the sales counter. The speed thing is why so many guns are sold in essentially the wrong caliber just to hit the stupid numbers touted as the speed you need. Guys call me all day long and ask for 1200 fps .177/1000 fps in .22 as the minimum they would accept. My reaction is sorry. Can't help you.
When you try all the options and find the accurate sweet pellet, I'll eat dirt if it is also the swiftest. DATA pellets are useless. Without Mass we have no BC worth mentioning. It is basically an insult to the consumers intellegence that has gone on for decades now. Doc BB knew there was always a good bet the Consumer couldn't get his head around Airgun Balllistics. It is pretty simple in that the more power you can make the more pellet mass you need. In a Multi that can mean different pellets for different power levels and applications(Read: Versatility).
The most important factor is the ease that you can shoot recoiless Pnuematics. They are hard to pump, light, powerful and easy to shoot accurately. Self contained accuracy is tough to come by. If you have a Multi that groups well you have a candidate for Steroid. Only a good gun deserves to last for as long as a steroid will.

TimmyMac1

[daveb50]

I just did the valve mod on my '97 Streak, very easy to do, with the help of the links I posted about it. I mostly use 4 pumps for target shooting. I like the idea of more pumps will have the same aim point at different distances.
http://www.gatewaytoairguns.org/GTA/index.php?topic=47480.0

[Jack D]

Interesting and informative, Timmy.

It seems much of what I learned about firearms does not necessarily apply to airguns. And that's understandable. With firearms there are a myriad of powders and bullets and barrel lengths available to choose from to from, not to mention calibers, to do the task at hand. With airguns, especially pumpers, you only have one propellant to choose from (air). The only variation in any given gun is pressure and to some extent pellet weight and BC. In the .20 these are limited.

I've seen it written in a few threads in these forums that there are no "heavies" in .20 cal. I did stumble into one. I don't have need for such a heavy weight pellet and doubt it would have much use in a "stock" C9 series, but maybe in a "steriod".  http://www.specialtyshootingsportsoutdoors.com/air-gun-pellets/eunjin/eunjin-20-23-7-grain-pellets-150-count.html. This pellet is much longer than the "normal" pellet and maybe would not perform well in barrels with riflings designed for shorter projectiles. Would be interesting to find out if they are a useful option.

[Jack D]

author=OleTomCat link=topic=47431.msg446124#msg446124 date=1369177029
Timmy at Mac1 Airguns in Ca. (he posted his responce in post #3 above) rebuilds the old Streaks and can upgrade the internals of the pump to give you vastly superior power with much fewer pumps....

I been in contact with Timmy and am still weighing the options. Many factors to consider, my fixed income is the biggest. To justify the change, I'd have to sell something to cover the cost and right now I don't know what that would be. Truth is, 6 pumps in my C9 will kill anything on my property that needs killing and most of the time it is used to poke holes in paper and spray paint cans for recycling. Still, upgrading is compelling. Longgivity is really not a big concern for me. At 73 I'm sure it will outlast me, and my "kids" are in their late 40's and early 50's. Grandkids are all female and not interested. At least not at the moment. Decisions. Decisions.