Author Topic: Benjamin Franklin 317 RestoMod (Read 10765 times - 3 votes)
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Tack Driver 10 · « **Reply #40 on:** July 27, 2019, 05:48:47 PM »

Drilled and tapped the bolt for the typical 8-32 Crosman bolt handle.
One is SS and the other is the stock handle.
I like them both but there is also a vast plethora of them available on Ebay to choose from.

The long SS bolt handle is p/n 392LE-009, about $10 from Crosman.

Tack Driver 10 · « **Reply #41 on:** July 28, 2019, 03:33:21 PM »

It's hammer time, actually hammer spring time....LOL

Since the heavy valve spring has been replaced with a light version it's time for the hammer spring to follow suit.

The stock spring is .039" wire and 3 3/4" looooong.
Replaced it with a Disco spring with .034" wire and 2 3/4" in length plus a 7/16" Delrin spacer.

Also replaced the tiny ball bearing on the bolt with a Delrin rubbing block.

Can now cock the gun easily with my little finger.

Getting very close to the buttery smooth cocking experience we all dream of.
Personally I can't believe it's not butter!
How buttery smooth is it?

After cocking the gun a few times my phone rang.
It was my doctor.
I said what's up Doc?
He said your cholesterol!
He advised me to cut back on the butter....LOL

USAFANG6799 · « **Reply #42 on:** July 28, 2019, 06:40:56 PM »

Someone snitch on your using too much butter again 😄
The 317 (now know as 317 Express) is looking and shooting like a Twenty Century model had Crosman kept it updated.
Maybe Crosman would take your idea and run with it?
A carbine with this much power should be a hit!

Many thanks for the updates.

Tack Driver 10 · « **Reply #43 on:** July 28, 2019, 07:51:26 PM »

Quote from: USAFANG6799 on July 28, 2019, 06:40:56 PM

Someone snitch on your using too much butter again 😄
The 317 (now know as 317 Express) is looking and shooting like a Twenty Century model had Crosman kept it updated.
Maybe Crosman would take your idea and run with it?
A carbine with this much power should be a hit!

Many thanks for the updates.

Can't a guy have at least some guilty pleasures?
What's next, take away the bacon and ice cream?....LOL

avator · « **Reply #44 on:** July 28, 2019, 07:55:52 PM »

Bacon and ice cream are bad? I'm doomed.

USAFANG6799 · « **Reply #45 on:** July 28, 2019, 08:48:29 PM »

Ron & Bill....you are not here in this world to think and feel you are on some kind of cruise ship. Ya here to work for da Man till ya drop or until he dismisses U by throwing you overboard in these shark infested waters.
Think of this as being on a Roman Galley as that is the closest thing you’ll experience to a cruise ship.
Today’s entertainment will be demolition derby with possible fireworks/flaming arrows.

Now back to it and put your backs into it girly men😜😭

avator · « **Reply #46 on:** July 29, 2019, 08:16:42 AM »

Quote from: USAFANG6799 on July 28, 2019, 08:48:29 PM

Ron & Bill....you are not here in this world to think and feel you are on some kind of cruise ship. Ya here to work for da Man till ya drop or until he dismisses U by throwing you overboard in these shark infested waters.
Think of this as being on a Roman Galley as that is the closest thing you’ll experience to a cruise ship.
Today’s entertainment will be demolition derby with possible fireworks/flaming arrows.

Now back to it and put your backs into it girly men😜😭

Such a fitting post to read on a Monday morning before starting the work week..
Thanks for the reality slap....

Tack Driver 10 · « **Reply #47 on:** July 29, 2019, 05:05:42 PM »

The pump arm had about .020" side play in the main pivot.
The pump arm was .250" and the slot in the front cap was .0270".

Cut two .010" brass shim washers to take it up.
The main pivot bushing and the link rivet looked good.

Andrew · « **Reply #48 on:** July 29, 2019, 06:53:38 PM »

I love this thread, been watching and enjoying.

You are so talented Ron and so funny with it too.

Tack Driver 10 · « **Reply #49 on:** July 29, 2019, 08:42:32 PM »

The good, the Bad and the Ugly.
This ain't no spaghetti western pardner!
How's a cowboy gonna shoot straight with a crooked tootsie roll?

The tootsie roll on this gun is a wee bit off kilter to say the least.
Possibly a rough day in the wood shop, a Monday/Friday gun or too much Tequila....LOL

Tack Driver 10 · « **Reply #50 on:** July 30, 2019, 05:19:19 PM »

Made a new test piston using a 392 style cup seal.
I was surprised the the dead air space is actually about 10% less in the cup seal.
Diameter measured .790" mounted in the piston vs .770" for the original seal.
I'll get it in the gun and chrony it post haste.

BrushPopper · « **Reply #51 on:** July 30, 2019, 05:22:44 PM »

Should take less pumps to max it, but wasn’t it retaining pressure @ abt 7pumps before?

Valve cap. Prolly still the same..

USAFANG6799 · « **Reply #52 on:** July 30, 2019, 06:41:31 PM »

Guessing a gain of about 10 more fps with the new cup seal?

Tack Driver 10 · « **Reply #53 on:** July 30, 2019, 07:56:05 PM »

Adjusted the piston to a strong 7 3/8" and when installed in the gun due to the seal compression just cleared the breather hole.
So this version is at max length as tested.

With CPHP 7.9 g

3 pumps 575 FPS 05.80 FPE
5 pumps 675 FPS 07.00 FPE
7 pumps 750 FPS 09.87 FPE
8 Pumps 775 FPS 10.53 FPE

Performance wise, comfortably nestled in the bosom between the stock (worn) seal and the poly seal.
Realistically I believe this is the best alternative.
It pumps nice and smooth and the power is linear, very strong right out of the gate.
Replacement seals are available and inexpensive from Crosman.

I'm giving it the Tack Driver Good GunKeeping seal of approval....LOL

BrushPopper · « **Reply #54 on:** July 30, 2019, 08:21:15 PM »

Sounds like a winner, good job!👍

Tack Driver 10 · « **Reply #55 on:** July 31, 2019, 01:07:10 PM »

Made a new piston seal from high end 90A cast polyurethane.
This one has 18 smaller holes spaced at 20 degrees and closer to the perimeter.
Adjusted the piston to 7 13/32" which is max while clearing the breather hole.

With CPHP 7.9 g

3 pumps 595 FPS 06.21 FPE
5 pumps 710 FPS 08.84 FPE
7 pumps 780 FPS 10.67 FPE
8 Pumps 796 FPS 11.11 FPE (full dump)

The low dead air space builds high power at the low end.
I ran it twice because I thought there might be a quirk, second time 3 pumps=593 FPS.

This version performed better than the cup seal and similar to the purple 80A poly seal.
It got harder to pump the last 2 strokes as it topped out but that is to be expected.
De-tuning the gun by adjusting the piston to 7 3/8" should be a good setup.
I'm also thinking of removing the spacer in the valve to gain more valve volume.

I think a good plan is to make a piston that will take either the cup seal or a poly seal.
That way either seal can be used.
A few more piston seal versions and you can have one for every day of the week....LOL

Tack Driver 10 · « **Reply #56 on:** July 31, 2019, 06:19:10 PM »

So, if someone were to take the bull by the horns and make a piston that would accept either the stock cup seal or a poly seal.......
It might look something like this:

USAFANG6799 · « **Reply #57 on:** July 31, 2019, 07:14:02 PM »

Quote

A few more piston seal versions and you can have one for every day of the week....LOL

And or for what ever game ya going after

Those are some very interesting designs Ron!
What a talent ya got!

Many thanks for infusing it into the 317!

USAFANG6799 · « **Reply #58 on:** July 31, 2019, 07:16:27 PM »

Quote from: Tack Driver 10 on July 31, 2019, 06:19:10 PM

So, if someone were to take the bull by the horns and make a piston that would accept either the stock cup seal or a poly seal.......
It might look something like this:

Would this work for/on other air rifles that use piston or spring?

USAFANG6799 · « **Reply #59 on:** July 31, 2019, 07:25:30 PM »

Decisions ,Decisions , Decisions

90A cast polyurethane:

With CPHP 7.9 g

3 pumps 595 FPS 06.21 FPE
5 pumps 710 FPS 08.84 FPE
7 pumps 780 FPS 10.67 FPE
8 Pumps 796 FPS 11.11 FPE (full dump)

Tack Driver Good GunKeeping seal of approval....LOL:

With CPHP 7.9 g

3 pumps 575 FPS 05.80 FPE
5 pumps 675 FPS 07.00 FPE
7 pumps 750 FPS 09.87 FPE
8 Pumps 775 FPS 10.53 FPE

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Benjamin Franklin 317 RestoMod

Author Topic: Benjamin Franklin 317 RestoMod (Read 10765 times - 3 votes) )

Author Topic: Benjamin Franklin 317 RestoMod (Read 10765 times - 3 votes)
)