GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: lloyd-ss on April 14, 2011, 09:32:06 PM
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(A long post, I got into it :P )
I posted some pics the other day in the Pellet Review gate, shooting 22 cal pellets into plastic grocery bags inside a piece of 2" PVC pipe. You can recover the pellets pretty much undamaged for testing.
Nathan HNT5 asked how many more bags and pipe length it might take to capture higher powered pellets.
I've got the sickness, just like so many of you poor souls out there, so, of course, I had to find out. Was there another option? I don't think so.
I have a 28" 9mm barrel I've been working with, lapping the rifling, doing some power mods, plus added a shroud. It's the one I blew the end cap off of in the Shoptalk and Mods gate ("Next time, a sturdier shroud end cap"). I've since then fixed it.
I've got some 200 gn bullets I've been trying. I pulled the copper gas checks off the bottom and the bullet weighed 196 gn. I am getting decent power, and right before I tried this test, I did a shot at 2561 PSI and got 791 fps which is 272 FPE.
I have to say that the setup was a major pain. I took a 4 foot long piece of 3" PVC pipe and stuffed lightly wadded plastic grocery bags, 2 bags in each wad. 13 wads filled the pipe. I taped and tied the pipe in place in front of the muzzle, and left an air gap between the muzzle and pipe. I taped a 1" wood dowel on top of the pipe so that I could get the alignment right. Experience has shown that if the bullet hits the inside of the pipe, it will take off like a ruptured rubber duck right out the other end. Alignment is critical. I braced a thick poplar board over the far end, just in case.
I set the gun up to get another 272 or so FPE shot. The pictures pretty much tell the story.
Bottom line is, plastic grocery bags work pretty good for retrieving bullets for examination.
A side view of the setup with everything tied and taped down.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/1-272.jpg)
Sand bag and rope securing the PVC in front of the muzzle.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/2-272.jpg)
A view for the left handed shooter.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/3-272.jpg)
A view for the right handed shooter.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/4-272.jpg)
Ready to fire.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/disp.jpg)
Blasted a few of the bags back out of the pipe.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/5-272.jpg)
Carefully pushed the plastic bags out of the tube to disturb them as little as possible, even though they were pretty dead.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/6-272.jpg)
By putting the bags in in separate wads you can find the bullet pretty easily. The little pigtails showed the bullet passed thru pretty quickly.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/7-272.jpg)
This bag is all stretched out like a bad hernia. The bullet is in there.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/8-272.jpg)
A little ripping of the plastic......Ta - Dahhhhh.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/9-272.jpg)
Here it is, pretty much unscathed. This barrel has very shallow rifling, in need of polishing, and if you zoom in you should be able to see the rifling witness marks. You can also see from the rub marks that the nose of the bullet is slightly off center from the main diameter of the the bullet.
(http://i226.photobucket.com/albums/dd79/loyd500/272FPE/11-272.jpg)
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Fantastic slightly historical post Lloyd, kudos to you.
Fellas.. all make sure to take a gander at Lloyds amazing airmachine, your about the first to see that one and i'll bet most of us will never see it again. 270+ftlbs out of your creation, is very impressive in itself Lloyd and even if your experiments are a little scary ;D i sure like hearing about your newest and latest. Once this post makes it's way down the 1st page i'll move it with your permission to bigbore gate where we can hold onto it a bit longer ;) J
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Jeff,
This thing has had many pounds of lead thru it in .25 to .510. Yes, we'll have to pick it up on the big bore gate.
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Thats pretty nice setup you have. Like the shop. Cool experiment also. I would have never thought those plastic bags could stop that much force.
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I like it. Not nearly as expensive as ballistics gel, and you are recycling.
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I would have never thought those bags could have possibly stopped a pellet either but seeing how the plastic seems to stretch quite a ways before the pellet passes through, it's like a slingshot in reverse. I have a whole new way of indoor test firing now, ;D Thanks Lloyd!
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........................ I would have never thought those plastic bags could stop that much force.
It took about 30" of loose bags in the pipe to stop that shot, and the bullet compressed the bags pretty well into the end of the pipe. If I hadn't had a board over the end, it would have blown everything out the end of the pipe. And I had the pipe lashed down pretty well.
Just as a plain pellet trap, I've used the plastic grocery bag method for a long time (and some other folks have too), mainly stuffed solid into a plastic milk crate, with a back-up board in the bottom. It works really well for low energy stuff and is light and easy to move around. For that, you can compress all the bags with a piece of cardboard cut to fit inside the milk crate, and then slip a few thin sticks thru the holes in the side of the crate to keep the cardboard from popping out. You can really just stuff a cardboard box with grocery bags and tape it shut. Somebody else was using that method, too.
For big bore, you have to re-stuff the bags fairly regular so that you don't hit the same hole too often and get a pass-thru.
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Love hearing about your adventures, Lloyd, but I also find it a bit scarey..... CAUTION!!! MAD SCIENTIST AT WORK!!! ;) ;D ;D ;D
PV
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Cool stuff!
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Cool, thanks. I may have to go get me a length of PVC pipe and try it out. I would have thought that 272 ft. lbs w/ 196 grain bullets would have tore right through those plastic bags and the wooden back plate. Amazing stuff.
Nathan
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hahaha Paulie nailed it! Mad scientist is right! So Lloyd the first time you tried this, did you hold your breath and say a little prayer? hehehe very very cool stuff Mr. Lloyd....please keep us posted on your laboratory ...Bart
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Hey Bart and Paulie and all,
Mad Scientist, ehh, OK, I'll take that as a compliment. My wife just rolls her eyes and shakes her head. But she really does understand.
You asked about more mad scientist stuff. You can see some of that in the thread for..... Let's use this as an opportunity to get a plug in for............ the {{{ BIG GTA RAFFLE }}} still going on until the end of this month. Good prizes and the winning number might still be available. But you won't know unless you put your number in the hat.
You can find it in the Announcement Gate and Bart is ram-roddin' the raffle.
Here's the link. Hope i got it right--
http://www.gatewaytoairguns.org/GTA/index.php/topic,10843.0.html (http://www.gatewaytoairguns.org/GTA/index.php/topic,10843.0.html)
Down in that raffle thread is a picture of one of my very early protos from years ago. (seriously, it really is.) A dump valve arrangement that fired assorted odds and ends thru 1/2" and 3/4" copper pipe. That one didn't have any electronics. Did you know that if you put a few wraps of masking tape around a stack of pennies they will fit perfectly into a piece of 3/4" copper pipe? 13 pennies is about 610 grains in case you were wondering. Now THAT is a wad cutter. Just about 10 gauge, I think.
Lloyd
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Always like to see "Arkansas Tumbleweeds" used for more than letting your groceries fall out the bottom. On the way to a car. In a thunderstorm. At night. With no parking lot lights.
Good move!
EDIT: BWAAHAA! A penny-pincher, too!
Charles
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Interesting post Lloyd,
Surprised to see the big rub mark
forward of the rings. Looking forward
to another phone conversation.
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...............Surprised to see the big rub mark
forward of the rings....................
Hi Bill,
This was shot through the barrel that I lapped the breech-to-muzzle taper into using the method you instructed me on. I also sized the bullet ( it was originally .358 dia) in a die with a sharp cornered entrance hole that sheared the lead off instead of just squeezing it smaller. The front 2 bands were .355, and the last band is .358 after the sizing process. The bullet may have entered the die a little off center and that would have accounted for the rub mark it got in the barrel. That certainly wouldn't help accuracy either. I will think about how to fix that issue. Also, judging by the bullet when I looked at it under magnification, the shallow rifling still spun the bullet without shearing the lead, but it looks like the bore needs to be polished.
Any thoughts... Bill or anyone?
Thanks,
Lloyd
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I've been using a large wad of plastic grocery bags as a trap for a year now. Backed by a steel plate, in the basement, I have yet to heard even a thunk. Don't have a PCP but they soak up .177's from a Diana 54 with ease and no splash back. Haven't dissected it yet. Been hoping to recycle them but not so sure if I will be able to get all of the bits of bag out. Anyway, cheaper than plumber's putty.
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After enlarging the photo of the bullet.
I believe that large area on the truncated
cone of the bullet was not done by the bore.
(there are no rifling marks in that portion that I could see,
if it happened in the bore, they would be there just like
in the rings)
It, and the smeared burr that appears in the lube
groove had to be a product of the sizing process.
If that is a chrome moly barrel Lloyd.
Buy, borrow or make a jag that will fit
a tight patch in the bore and hit it again
with the JB's Bore paste, then with the finer
polishing compound you used before, or
some Flitz or Mothers polish.
I think you told me you had a white rubbing compound,
it should be just fine.
If you do not have any JB's bore paste, get some.
It will polish without embedding in the bore and
it breaks down as you use it, giving you a finer finish
in the process.
Start with both at the breech end, using continual
back and forth movement gradually making the strokes
longer until you reach the muzzle. Once you reach the muzzle,
push the patch on through and remove it, and start over.
The patch must be tight enough to rotate the rod you are using.
With the depth of the grooves you told me about, it should not be
any trouble to make sure you are polishing both the land and groove.
You should see the land and groove clearly in the patch on the jag as
it comes through the muzzle. (the patch should look black and glossy)
I would recommend testing a few shots and inspecting the bullets
before trying to make another sizing die after giving it a good polish,
using un re-sized bullets. (you will be slightly increasing the groove
and land diameter)
I can easily see you gaining a half to 7 tenths (of a thou) in the
polishing process which I do not believe will hurt you at all.
This is one of the benefits I thought would be seen by using the rotary
lapping process on the lands was the bore and land diameter could be
tailored to a specific pre sized, off the shelf bullet. (once it is polished)
When we spoke on the phone, I tried to emphasize the polishing.
But in all my other ramblings it may have been lost.
I think your dangerously close since the base of your bullet was
still .358 I believe a good finish polishing of the bore will be all you need.
If you still think you need a sizing die.
Let me know how long the stroke is on the press you are using
(or machine spindle, if that is the case) and I will draw you up a
die you can try to make. (granted, these sizing dies do not look all
that complicated, but they are not easy to make correctly)
You really do not want to shave the bullet, it looks severely galled, the metal
was not shaved, it was torn. You need the bullet to come
from the die with a shiny, burnished finish.
Unfortunately, (and not to hack on ya) I think your resizing hurt
you more than it helped you.
Your welcome to call if you like, anytime.
Pm me if you need the number again.
Wish I could be there to help you, we could scare the heck out of the locals,
and maybe each other. ;D
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Bill,
Thanks very much for the detailed response.
Like all of us, I have my areas of knowledge, and then there are areas where I need some real help. Your profession as a gauge maker shows, and is appreciated.
I will do some pondering and give a more detailed response, but I see a couple of main points in your post. Please let me know if I got them correctly.
1) The work I have done inside the barrel is a good start, but is not finished. The polishing process is an essential part of the modification.
2) The sizing die I am using is not entirely suitable for the task. It might be getting the size right, but the finish it leaves is not right.
3) A quote from your post above, "This is one of the benefits I thought
would be seen by using the rotary
lapping process on the lands was the bore and land diameter could be
tailored to a specific pre sized, off the shelf bullet. (once it is polished)."
Bill, I agree. All I had available was .357/.358 bullets and I was trying to improvise and make them work in a 9mm barrel. Not the best approach, but it served its purpose. After I get the barrel polished and finished, then I think it will be time to find the correct bullets. Using as-cast bullets would certainly be the preferred way to go, and then it will time to address accuracy. Up until know it has just been about the basic functionality.
Am I learning? I hope so, and thanks very much for the help.
Lloyd
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Hi Lloyd,
Liked your post got me thinking --O-no -lol on small cal say in comparison say ex of 17 hmr powder burner round or even jump up to 17 Rem travel at a high rate of speed shooting through a set-up similar to yours. heck even a 243 cal or 6mm at a high rate of speed man oh man the damage someting like the 9mm or 25 cal airgun toys-lol could do on a target. Sort of like a great wind or tornado takes a piece of broom and forces it right through a tree trunk trunk or solid object, again small size but alot of energy when pushed by force say such as air behind object
being pushed or forced. What i'm saying is if I don't make it more tech than need be is with say the right amount of force and power and shot placement on an animal or game even smaller calibers will take 'em game out with no issue or problem at all. I guess it could get into the old arguement by some bigger is better. I myself say not always true depends on target or game at hand. Heck just a simple mans way of thinking I guess. Again I love your set-up.
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Lloyd I know you have received some good advice on that bullet . I had a barrel that did the same thing to bullets . But it was right were the cambering of the bullet that the problem was . One of the lands had a weak spot in it . The machinist would smooth it down and after a couple of shoots it would lift right back up . That one was easy to find thought . It would be easy to load 1 or 2 bullets then it would become almost impossible to load the next one . Good luck . Marvin
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Yes Lloyd, I think you understand what I was trying to say.
In responce to,
1) Because of the lapping compound used in the lapping
process we discussed and that you have successfully
accomplished. Polishing is a very integral part of the
process. The compound was coarse compared to normal
barrel lapping standards because of the amount of material
that needed to be removed.
While you were only cutting the lands, the grooves were
not really effected. (they still have their original finish, and will
take a polish easier)
The lands on the other hand were cut using a rotary motion.
This motion will leave micro sized grooves in the material
that are cut radially. We need to reduce the depth of those grooves.
This could have been accomplished by using progressively finer grades of
compound on the lap you made. But, as we discussed on the phone,
it would require a separate lap for each grade of compound used.
That did not seem to be an option at the time, you understandably
went with what you had. If you could have done this, you would still
need to polish the bore, but the time and effort in polishing would have been
much less.
If you polish the bore as described in my previous post, using
the JB's bore paste, then the even finer compound you should be fine.
This just will take a little longer than it would have if you were able to
use the progressively finer lapping compounds.
It will be well worth the effort. If it were mine, I would polish until
the finish suited me, hard to describe what that
looks like. You will see the difference as you go. You just want to shine it up.
2) The finish required in a sizing die is incredibly fine. Must be smooth,
any radial marks will cause the lead to tear, and that starts the
galling process. It takes a lot of careful polishing when done outside
of a production manufacturing process. Even then, the bullets must
be lubed.
3) Lets say that you have a good source for .357/.358 bullets
that are sized to .358
Instead of slightly sizing them again to meet your bore size, change the bore
size. You can do this by polishing using the method described
in my previous post.
Even if you reduce the land height in the breech area by this polishing.
remember that the land diameter is tapered. (think of the smooth twist
barrels recently released by FX air guns)
This natural choke that you previously lapped into the land diameter
will work to your advantage.
By starting with short strokes in the polishing process and gradually
making them longer as you work the patch back and forth.
You will maintain this taper. Yes, you will also be increasing the
bore diameter, but this is what you are after. (using out of the box
sized bullets)
It will still have the choke effect. And you will still have sufficient
land contact as the bullet progresses down the bore.
Okay, while I understand you getting rid of the blue lube that is
provided with the bullets, I think you still need to lube them
for shooting. After cleaning the out of the box bullets, place them in
a freezer bag, place a few drops of this lube and gently roll them
around to coat them. Pour them out on a newspaper and let them dry.
This can be found at most big box stores in the bicycle department.
(just shake well before using)
(http://i705.photobucket.com/albums/ww55/BrushyBill/DSCF0125.jpg)
Edited for pour spelling
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Marvin, That's a good point. I've worked this barrel over pretty good, and now that you mention it, the breech block design is kinda unconventional so I will look at that possibility too.
Daveshooter, That .357 bullet had a pretty blunt tip. And I've put some 9mm EunJin pellets into it with similar results, but I bet for a streamlined tip might be a different story. I wonder what a hollowpoint would do in those plastic bags???
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Brushy Bill,
A wealth of information in your post. Over the next few weeks I hope to apply some of it.
Thank you,
Lloyd
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LLoyd found the picture of the never fired just chambered bullets .Marvin
(http://i301.photobucket.com/albums/nn55/melloroadman/IMG_6645A.jpg)
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Lloyd soft-point or even a high-power or hollowout boat tail design lead bullet would be very interesting at least just to see what the end result would be.