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All Springer/NP/PCP Air Gun Discussion General > "Bob and Lloyds Workshop"

272 FPE in a plastic grocery bag

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Brushy Bill:
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)


Edited for pour spelling

lloyd-ss:
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???

lloyd-ss:
Brushy Bill,
A wealth of information in your post.  Over the next few weeks I hope to apply some of it.
Thank you,
Lloyd

melloroadman:
LLoyd found the picture of the never fired just chambered bullets .Marvin

DaveShooter:
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.

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