Benjamin Franklin 317 RestoMod

[Tack Driver 10]

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

I'm going to make the decision easy for you.
Going with the last 90 duro poly seal.
De-tuned it should get around:

3 pumps 550 FPS
5 pumps 650 FPS
7 pumps 750 FPS

Won't know for sure until the deed goes down.
Should be able to get er done in the morning.

[USAFANG6799]

Going with the last 90 duro poly seal.

That what I was hoping for but didn't know how this would effect the longevity of the 312 since they were never designed to shoot that hot.

Should be quiet the interesting rifle to shoot now.
It will be a basement or range only since I'm sure it will be pretty noisy now 

While I'm thinking of it......what is that number stamped on the bottom of stock on the 312?
It looks like a date code but not sure. I didn't think Crosman did that when they made them.

I did contact Bill this AM to request a refund of $140 which he promptly credited me this AM.
He said he was going to send you the $ to ship it back to him.
I said to him that I would pay to have the sights sent back to him so not to worry about the $10.

Matt

[avator]

Ron, I sent you a PM.

[Tack Driver 10]

Made the new 90 duro poly seal and cleaned the felts.
I'm always amazed at how much gunk comes out of them.
Put a new Big Fat American Felt up by the piston....LOL

Adjusted the piston to just under 7 3/8" and installed it.
It fully clears the breather hole with the pump arm open.

Chrony with 7.9 CPHPs:

1 pump  360 FPS 02.27 FPE
2 pumps 465 FPS 03.79 FPE

3 pumps 548 FPS 05.27 FPE
5 Pumps 672 FPS 07.92 FPE
7 pumps 732 FPS 09.40 FPE (full dump)
7 pumps 767 FPS 10.32 FPE (oiled)

About what I expected and gained 35 FPS when oiled with 7 pumps.
Possibly some wear in the tube bore but normal for an older gun.
If it's like my first gun, it got shot a lot more than it got oiled....LOL
 
The number stamped on the butt end of the stock is 361.
So March 1961.

[USAFANG6799]

Those numbers are the best this 317 has seen even when it was new I'm sure. It should outlive me now for sure.
That's a mighty fine piston and rod assembly. Too bad the tube is not made of glass so it could show off it's stuff.
I'm saving the pictures as you update your progress. It will make a really great scrap book to go along with Resto Mod.
I have to figure a way to put this all together for a scrap book.

Many thanks for the update!

[Tack Driver 10]

I was thinking I was close to finishing this gun but it threw me a curve.
That's what I get for thinking....LOL

After the first pump the arm would spring open some.
It would pump up but something was amiss.
Looks like the poly check valve got smoked and was leaking.
Time to put on my Teflon Ron hat and fix this once and for all.

First thing I did was polish the check seat with 400 grit paper on the end of a dowel.
It had a weak area between the 1-3 o-clock position.
Then made the Teflon check valve and seated it using the PA and a wood dowel.
Installed the check valve, dowel and PA then tightened the PA screw and left it sit for a bit to form fit.
You know what they say, you never have a second chance to make a first impression....LOL

Now the only original parts in the valve are the washer and check valve spring.
The Teflon check should last the life of the gun as well as the Delrin seat.

[USAFANG6799]

Is this going to turn out to be the "Million Dollar 317" 

If it is I'm glad it's in the right hands to work out the bugs before it goes back on duty.

[Tack Driver 10]

Put the gun back together and it held air overnight.

With the smaller blue spacer in the valve it will have more volume and lower velocity.
It will also be easier to pump up to 8.

Final chrony with 7.9 CPHPs:

3 pumps 516 FPS
5 pumps 606 FPS
7 pumps 690 FPS
8 pumps 723 FPS

I like this pump curve.
500, 600, or 700 FPS without pushing the gun too hard.

Stick a fork in it, it's done.
Like sand through an hour glass, so go the guns of our lives.

I really have to say, I'm going to miss this old gun.
It was a fun project........now back to my Crosmans....LOL

Before the curtain closes, one last picture of the tools.
The valve seat in this gun has a 14-28 thread vs the stock 9/32-32 thread so made 2 brass ends for either seat, SS hardware.
The valve nut tool is made from an old Crosman barrel.
 

[USAFANG6799]

Put the gun back together and it held air overnight.

With the smaller blue spacer in the valve it will have more volume and lower velocity.
It will also be easier to pump up to 8.

Final chrony with 7.9 CPHPs:

3 pumps 516 FPS
5 pumps 606 FPS
7 pumps 690 FPS
8 pumps 723 FPS

I like this pump curve.
500, 600, or 700 FPS without pushing the gun too hard.

Stick a fork in it, it's done.
Like sand through an hour glass, so go the guns of our lives.

I really have to say, I'm going to miss this old gun.
It was a fun project........now back to my Crosmans....LOL

Before the curtain closes, one last picture of the tools.
The valve seat in this gun has a 14-28 thread vs the stock 9/32-32 thread so made 2 brass ends for either seat, SS hardware.
The valve nut tool is made from an old Crosman barrel.

That shot curve does make more sense for this pumper. It will make it more enjoyable to pump up at my age  and my grandson when his dad gives him the go ahead to graduated from BB gun to pumper. Hopefully he won't wait till he's out of college 
I do like those chrony number Ron. Thank U!


I'm very happy to know that you enjoyed your tinker time with my 317. I was hoping you would.
The timing was just right for the project you wanted to experiment with.
Must be destiny.

Hope you hang on to those tools and get to use one on your next project.

I'm going to get a Yellow Ribbon and Tie It Around The Old Lamp Post. I don't have a Old Oak Tree 
Will be waiting for her to come home to Papa.

Don't forget to include your bill for time, labor and parts.
That's the part I'm worried about given how much time and effort you put into this one.

[Tack Driver 10]

How rude, crude and socially unacceptable of me to not allow the guest of honor to have a final word.
Where are my manners?....LOL

Should get it in the mail in the A.M.
I'll send you a PM with the TN.
USPS online says expect it Thursday.

[USAFANG6799]

How rude, crude and socially unacceptable of me to not allow the guest of honor to have a final word.
Where are my manners?....LOL

Should get it in the mail in the A.M.
I'll send you a PM with the TN.
USPS online says expect it Thursday.

I know 
I was really wondering if all the edict your parents, military and your wife taught you were all but forgotten because ya spending too much time with the guys here on GTA

I'm sure you'll do better the next time.

Look'n forward to talk about the good ole days with my RestoMod 317.
Going to be rather difficult keeping my hands off of 'er but I don't think she'll mind.

Looking froward to more of your RestoMods here on GTA.
Will be and staying in touch.

[Relentless Holiday]

Late to this but what a great thread. I read every word and you actually made the process make perfect sense....am just amazed....

Want to take a crack at a Bam B5-10. accurate, rock solid platform, good condition.

 kidding...not kidding. 

Seriously, great work and posting.

Thx for the read.

[Tack Driver 10]

Late to this but what a great thread. I read every word and you actually made the process make perfect sense....am just amazed....

Want to take a crack at a Bam B5-10. accurate, rock solid platform, good condition.

 kidding...not kidding. 

Seriously, great work and posting.

Thx for the read.

Thanks, seems folks take a more traditional approach to these guns leaving them mostly stock.
I also have a Benjamin 312 that I need to upgrade, maybe later this winter.

The next project will probably be a 766-M16 assault carbine.

[USAFANG6799]

Thanks, seems folks take a more traditional approach to these guns leaving them mostly stock.

I'm happy to report that I/we didn't go the more traditional approach.
Performance with 4-5 pumps is more than adequate for basement plinking.
It's in the safe (yep with 2 pumps) building up my anticipation of using it after the holidays when the long hard days of winter here in Maine can be brutal.

Hope all is well!

[Dave S]

Late to this but what a great thread. I read every word and you actually made the process make perfect sense....am just amazed....

Want to take a crack at a Bam B5-10. accurate, rock solid platform, good condition.

 kidding...not kidding. 

Seriously, great work and posting.

Thx for the read.

Thanks, seems folks take a more traditional approach to these guns leaving them mostly stock.
I also have a Benjamin 312 that I need to upgrade, maybe later this winter.

The next project will probably be a 766-M16 assault carbine.

Thanks, seems folks take a more traditional approach to these guns leaving them mostly stock.
I also have a Benjamin 312 that I need to upgrade, maybe later this winter.

The next project will probably be a 766-M16 assault carbine.
[/quote]

I would be curious to see the results of your 312 when your finished. I have a 312 (12 pumper)
 that is clocking at 644.3 fps max using 14.3 gr.Crosman Premeir hunting pellets. Keep us posted on it! BTW, beautiful job on that 317! dave

[Relentless Holiday]

"766-M16 assault carbine"

Hope I come across it.  It's amazing what you and the other real builders do transforming production run guns into custom shooters.  Fun to watch in awe.