Started a Prod SSG

[FuzzyGrub]

I have been busy but trying to keep up on Bob's SSG thread: http://www.gatewaytoairguns.org/GTA/index.php?topic=102095.0

This weekend I got a chance to throw some parts together to figure out lengths and spring options.  The main piece for a non lathe or mill owner was the crosman challenger RVA.  It threads into the degasser threads on the Prod endcap.  The RVA does have some internal threads in the thumb wheel section (10-32).   For a standard SSG:

you need to drill out these thread.  I went slightly larger than the guide ID to prevent threads from scrubbing. 

The prod has about 3/8" cocking distance, but with using a set screw vs sticker, that will be about 1/2".  The hammer has about a 1/2" recess, but will lengthen that to also try the "Guide Fixed at Rear" version:  
In that case, you don't drill out the treads but thread the rod into them.

I have some parts on order, and it will be a slow process for me, but wanted to post the info on the RVA incase there was some others out there how to go about without machine tools.

[BigTinBoat]

Thanks John - will be watching with as the other guns I have (S510, At44, QB's and Hammerli 850) would take some more complex machining to make. Your Prod should be the same as my 1720T.

[FuzzyGrub]

Thanks John - will be watching with as the other guns I have (S510, At44, QB's and Hammerli 850) would take some more complex machining to make. Your Prod should be the same as my 1720T.

Yes, parts are the same.  I may end up testing the 1720T before Prod.   The Prod has a M4 stock on it that is not compatible with a SSG. 

[FuzzyGrub]

Received crosman end caps and additional RVAs.

Note: Going with "Standard SSG" for now, so don't have to drill out hammer.

Placed a parts order with McMaster-Carr on Sunday:

Guide: http://www.mcmaster.com/#91251a085/=10y5dtg
Stop Nut: http://www.mcmaster.com/#93298a109/=10y5ejs
Stop damper: http://www.mcmaster.com/#90131a101/=10y5f1c
Pinch Protector: http://www.mcmaster.com/#9056k75/=10y5fkr

I am starting with a longer than stock (2" vs 1.5") hammer spring. It is from parts drawer and don't have a part number.

Note: The RVA will need to be locked down with a side set-screw/fishing line friction stop.  Initially, I plan to just use some VC-3.

[cilami]

The first attempt with the SSG in my Prod was not very encouraging. I am happy with my current tune so I think I did not try hard enough. My fault. A few more shots at 20 fpe would be appreciated. I am following this with interest. Thanks John.

[FuzzyGrub]

As some of you might have noticed, I ordered the wrong thread bolts.   I meant to order 10-32.  That's what happens when you add/delete parts at the last minute!  Now, for a standard SSG the thread size is not important.  10-32 would be needed if you tried the guide captured in end cap version.  So, will continue on. 

The SHCS head fit the Prod hammer slot without the need of any "machining".   The RVA needed to be opened slightly with a number 10 drill, and the SHCS feels fairly smooth. 

I need to pick-up some new nuts on the way home tomorrow. 

I plan to baseline my 1720T which has a .110 TP, heavy hammer, spring, and o-ring buffer.  It should be 15FPE for 23-24 shots on a 3K fill.

Initial testing coming soon after.

[FuzzyGrub]

I ran a string for the baseline tune, and found it not performing as expected. It started at the expected 800fps at 3K, but peaked early at 2.7K and dropped to 760 by shot 24 at 1.8Kpsi. That is with AA 10.3g pellets. I didn't bother replacing O-rings or trying to retune it.

Installed the SSG with the set-screw hammer striker 0.050" below the hammer face. Installed one o-ring for "bottom out" protection. Adjusting the SSG, found that I could not get back to 800fps at 3K. At just below coil bind, was getting 775fps, Others have reported similar on their first attempts. ie couldn't get back to original power level. I did run the string out and fps hit 800 at 2.6K and peaked 835 at 2.2K and droped back below 800 at 1.8K on shot 30. The curve clearly has moved lower.

The gun was already very quiet with a grafted mrod shroud, but you could still hear a difference, especially on the bottom end of string. I'd say that the SSG is working, I'll probably run another string before pulling it and changing to a heavier spring.

[BigTinBoat]

 I did run the string out and fps hit 800 at 2.6K and peaked 835 at 2.2K and droped back below 800 at 1.8K on shot 30.

The shot string sounds real nice, especially at the lower pressure, sounds like more power to be had


I'm thinking I see more parts here then on your list.
Is that a knurled nut? or is that those cushion washers stacked up?

What is the piece that looks to be threaded into the end cap?
Is that piece drilled in the center?
Would like to see those parts un-assembled.

Thanks

[cilami]

So your efficiency should be close to 1.40 now, correct?.  Seems to be a significant improvement to me.

Maybe 24 shots at 20 fpe are a possibility?

[BigTinBoat]

So your efficiency should be close to 1.40 now, correct?.  Seems to be a significant improvement to me.

No not 1.4.........30 shots from 2600 down to 1800 with a 65cc tube pushing 15.2fpe (Avg) is 2.08

Just with the BStaley it is like 1.33 on my gun. 23 shots from 3k down to 2K with 10.3 avg 830fps (15.8fpe)

[cilami]

So your efficiency should be close to 1.40 now, correct?.  Seems to be a significant improvement to me.

No not 1.4.........30 shots from 2600 down to 1800 with a 65cc tube pushing 15.2fpe (Avg) is 2.08

Just with the BStaley it is like 1.33 on my gun. 23 shots from 3k down to 2K with 10.3 avg 830fps (15.8fpe)

2.o8! Great.

[YEMX]

Once all these prototypes are finalized and such- will the SSG look better?  I love the added benefit of the SSG, but not so much the looks.  I'm weird, I know.

[FuzzyGrub]

The shot string sounds real nice, especially at the lower pressure, sounds like more power to be had

No shot strings are no good yet, and would not try calculating out efficiency, until then, ie 30 shots included more than what was within the 800 range.

I'm thinking I see more parts here then on your list.
Is that a knurled nut?
or is that those cushion washers stacked up?

It is a cushion washer, followed by two standard nuts.   See my thread size screw-up above.  Also, if you use nyloc, need to slot the end of the guide to keep it from turning.

What is the piece that looks to be threaded into the end cap?

That is the crosman challenger RVA.


Is that piece drilled in the center?

It is, but you need to drill it slightly more for the guide rod.  See drill size in above posts.


Would like to see those parts un-assembled.

Thanks

See above.

[FuzzyGrub]

Once all these prototypes are finalized and such- will the SSG look better?  I love the added benefit of the SSG, but not so much the looks.  I'm weird, I know.

Looks, well not sure if you can get all of the SSG parts inside a Prod/1720T and still make enough power.   I have some alum tube that will cover and protect fingers, but "looks" won't improve much. 

[FuzzyGrub]

I added a jam nut to the crosman challenger adjuster along with nyloc one to the stop nuts. So far, I'm getting the same power level at lower pressure (2250 - 1750) and quietter, but my shot count within 4% is not as good as with the BSB.

Maybe tomorrow I'll be able to try a heavier spring, but that should just move the peak to a higher pressure. or I might finish up my 1st attempt at Mrod SSG.

Anyone else testing a SSG in Prod or 1720T with any result data they would like share?

[FuzzyGrub]

Swapped back to BSB set-up. I was able to quickly retune to 22 shots 788 - 820 -789 on a 3.1k to 2.1K fill.

Compared to my SSG which was 17 shots 784 - 815 - 783 on a 2300 - 1700 fill.

The SSG is considerably more efficient, but couldn't get comparable shot count. It could be my implementation. Don't know. I'll wait to see some other SSG Prod or 1720T at equivalent power levels.

[cilami]

I added a jam nut to the crosman challenger adjuster along with nyloc one to the stop nuts. So far, I'm getting the same power level at lower pressure (2250 - 1750) and quietter, but my shot count within 4% is not as good as with the BSB.

Maybe tomorrow I'll be able to try a heavier spring, but that should just move the peak to a higher pressure. or I might finish up my 1st attempt at Mrod SSG.

Anyone else testing a SSG in Prod or 1720T with any result data they would like share?

With both my deficient SSG,  and current tune, I get 17 shots@ 20 fpe from 3,100 to 1,800 psi with HUMA regulator set at 1,900 psi.  I say deficient because I tried the original SSG with 0.035., 0.039., 0.042, and 0.047" springs, but only in 1.5 and 1.75" lengths. I know I need to try longer springs, but I could not find them locally. So my tests are basically meaningless.

For now, I'll also wait and see what others report...and hope Travis will came out with a good, worth, functional SSG for the Prod.    

[FuzzyGrub]

...and hope Travis will came out with a good, worth, functional SSG for the Prod.

He told me he has made one for Prod.  I haven't seen any data yet, though. 

[cilami]

...and hope Travis will came out with a good, worth, functional SSG for the Prod.

He told me he has made one for Prod.  I haven't seen any data yet, though.

Good. We should be seeing some positive results pretty soon.