Looking for info on the workings of springers.

[Traffer]

Hi folks,
I am beginning an experiment which possibly involves using springer air gun components. I know almost nothing about the parameters of these things (bore and stroke of the piston, strength of spring and yada yada)
I am going to try and make a pneumatic depriming rig , especially for berdan primed cases. Offhand I figure that a halfway strong springer mechanism would provide enough power to blow out primers.
I could build the cylinder buy a big spring etc but it would be much more efficient to just mod a junked air rifle for the task.
So i guess a couple of questions...anyone have an old or junk pellet rifle that they could sell cheap?
And do you have any suggestions as to why it would not work (I expect a ton of responses to why it can't be done...hahahah)
Thanks for the consideration.

[georgerkahn]

I'll respond by suggesting it can be done -- to my vision ;). Two things I might note, however. To wit, your sentence -- third from end -- asks for a pellet rifle you wish to purchase. Why not list a WTB in the S&S for one?
Secondly, I have had a few springers through the years, and albeit manufacturers/sellers dispute it, I suggest most are a lot of work! Eighteen to twenty pound force needed to cock one, I would thing, get pretty tiresome after "how many?" primers blown out. (Immediately, I'd look for adapting a PCP airgun rather than a springer for this reason alone.)
Back to your vision -- it would seem pretty basic to securely (weld or thread), say the ends of a PCP fill tube to the top of the die in calibre you wish to decap, along with the other end at barrel's end. With a capped case in die, in a single stage press -- a simple pull of the trigger would send air enough to do "something". This gets "sketchy", though, as air is readily compressed -- I have no idea re physics involved to determine if you'd just compress the air; remove the primer; or, (God forbid) blow something up :(. Years back I heard of a fellow who used a hydraulic system made from a car jack -- using oil (rather than air) as the vehicle to transfer requisite primer-moving force.
Whichever -- best wishes to your success!
geo

[DougGuy]

Pulling a lever on a press to deprime is a TON easier than cocking a springer! You could adapt a PCP airgun which uses a valve that outputs a short burst of high pressure air when the trigger is pulled. The downside of this, you might have to keep increasing the flow from the valve until you max it out then if it still doesn't work you would have to go to a modded valve which will increase the amount of air per trigger pull but severely decrease the number of shots until you refill the reservoir again.

There is also a cautionary note in order here. With compressed air like what you would work with in air guns, ANY amount of oil or flammable lubricant anywhere in the mechanism that would be exposed to high pressure air could detonate and explode, it's called dieseling.

[frkelly74]

Maybe , are you thinking berdan primers by any chance? That might be just the thing if it would work. You would need to keep it pointed in a safe direction, set up a target and do two things at once. Shoot the target and deprime brass at the same time.

[Traffer]

This is rough picture of the concept that I have. I am not familiar with a CO2 powered system but sounds like a better alternative. I would have to figure out how they work...It is it just a metering valve using pressure dumps directly from the cartridge to the pellet or is thee a secondary piston or something in between them?
Anyway this picture just shows the simple concept of how it would work. Seems simple enough to me:
292392

[DougGuy]

If you are going to do all that, just build a die with a spring loaded punch that lifts the punch up, you load a primed case and smack the top of the punch with a soft hammer.

[Traffer]

If you are going to do all that, just build a die with a spring loaded punch that lifts the punch up, you load a primed case and smack the top of the punch with a soft hammer.

That could work... I can give it a try ...my only concern is the volume of air that needs to be compressed to get enough pressure. It would certainly work with hydraulics but with air it may need a much longer throw than would be practical by just smacking with a hammer.

[P Flados]

The pressure required is probably quite high.

Any "free air space" between the air source and the actual primer will "dilute" your available pressure.

A downside will be the speed of primer discharge based on the high input air pressure.

I recently looked at the videos of the "whack a mole" hydraulic de-priming methods for berdan primers. The method is functionally quite elegant, but all videos I saw are also quite messy. I have been thinking through an variation or two that might be less messy.

[rking22]

The primer is likely to exit the case at about 611 FPS too!

[358429]

What about low pressure/simple... a tire cheetah running off an air compressor?

Imagine a small potato gun to launch your primers into low earth orbit. A shell holder to retain the cartridge in place.

The pneumatic cannon I played with would shoot cold steel blowdarts into treated lumber with such incredible force (air reservoir above 40 psi) that the darts were not able to be removed.

You may be able to assemble one from leftover parts. You only need the pressure vessel and the pressure tube, Some way to fill it like a tire valvestem installed in a drilled hole and some simple valve between the reservoir and barrel. It could be made of brazed pipes, threaded sewer pipe, or pvc pipe.

The next step in scientific progress once you have a functional air cannon would perhaps be attempting to record the velocity of AAA batteries at 150 psi or...[emoji39]

[358429]

Also I have read somewhere?? to place a tight fitting dowel into the berdan case full of water and wacking it with a hammer or placing it in a press or vice to push the primer out, and some other story was theres a secret technique with a dental pick to dig out or pull the primer out? ?? I dont know...I have never reloaded a berdan case..ever.

[georgerkahn]

Also I have read somewhere?? to place a tight fitting dowel into the berdan case full of water and wacking it with a hammer or placing it in a press or vice to push the primer out, and some other story was theres a secret technique with a dental pick to dig out or pull the primer out? ?? I dont know...I have never reloaded a berdan case..ever.

The more I think on it -- the more I better like using water as you suggested rather than air. Seems to me if something goes wrong, operator might only get wet :). My vision would be to mount an aluminum rod -- milled to just fit into case size -- to, say, a 3' piece of angle iron, maybe 6" from it's end -- now hinged to a secure upright. NOT by any means an "artist" ;) -- I attached a sketch. Using, say, an RCBS replacement ram piece/shellholder as used in many single-stage presses on bottom, you'd have the added ability to just replace milled aluminum rod to size required for any shell; and, its required shellholder. Complemented with, say, an Oral Irrigator (the plastic doo-hickey many oral surgeons provide post a tooth extraction for patient to fill with warm water and flush debris from hole where tooth/root used to be) to fill capped case with water before lowering handle to remove the primer...292438.. it might just work?

[W.R.Buchanan]

I doubt you can get enough pressure to knock out Berdan Primers with air pressure. The standard 3rd world way is to fill the case with oil and put a punch in the case mouth and hit it with a hammer. Kind of a mess, but water would work too and be easier to clean up after..
This is obviously Hydraulic, and since liquids don't compress whatever you hit it with with be transferred to the primer.

Air will compress and there in lies the problem with your idea. Geo's idea above would be a simple way to do it.

Randy

[GRid.1569]

Going off course maybe... many years ago there was a product available in the U.K. called Hydropunch that used a drop of water in the case to drive out the berdan primer following a strike of a hammer on a close fitting insert...

[DougGuy]

Heh well, seems like we was all overthinking and overcomplicating things.. Here is a youtube vid of decapping berdan primed cases with nothing but a shellholder. a hammer, a 1/4" nut driver, and enough water to fill the case!

Skip to the 2:00 minute mark.


https://youtu.be/Q0q0E4GtSa4

[P Flados]

Some methods rely on something close to a seal between a punch and the neck of the brass.

This one does not

https://www.bing.com/videos/search?q=hydraulic+berdan+primer+removal&&view=detail&mid=EEE23661B54ED29DBBF8EEE23661B54ED29DBBF8&&FORM=VDRVRV

[DougGuy]

Some methods rely on something close to a seal between a punch and the neck of the brass.

This one does not

https://www.bing.com/videos/search?q=hydraulic+berdan+primer+removal&&view=detail&mid=EEE23661B54ED29DBBF8EEE23661B54ED29DBBF8&&FORM=VDRVRV

That's the exact same thing in the video I posted, using a case full of water and a hammer with a tight (enough) seal in the case neck.

[P Flados]

One method has a plunger that is snug to the ID of the case neck. The case walls are subjected to a pressure pulse when the plunger is hit with a hammer.

The other method has a plunger that is snug to the ID of a sleeve that the case is dropped down into. The pressure pulse at hammer impact only acts across the base of the case in a vertical direction. This method can do 6.5mm, 7mm, 7.62mm, 8mm and bigger with no changes to any tooling.