MarauderAirRifle.com

[FuzzyGrub]

Started thread here on my Prod SSG progress:


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.

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:

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.

[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 dropped 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.

[screwwork]

Nice looking wood on the Prod..
Great job on the SSG keep up the good work and I would be interested in seeing your SSG with heavier spring results.

Thx Randy

[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.

[FuzzyGrub]

I saw this string posted on the yellow for the FFH/SSG. String is not as good as typical BSB o-ring at same power level.

http://www.network54.com/Forum/79537/message/1455773248/Performance+test-+Prod+drop-in+FreeFlight+Hammer+kit+vs+stock...

[Roger]

I agree John, my prod also has the BSB tune with a stronger spring and larger tp and my string starts at 697fps the middle part of string is in the upper 740s ending at 695. This is a 24 shot string on a 2700psi fill. I am very happy with my prod as it is set up now!

Roger

[FuzzyGrub]

After a post on the YF decided to try a combined BSB/SSG. I changed out the spring to a 20lb/in one. Left the existing hammer in, that was already adjusted to BSB tune. Quick testing showed that I can't quite get back to the same power just shy of coil bind. Not that surprising giving that is the same rate spring I use for the BSB tune. If I back off on the stop, then it does get there but no SSG in play. Looks like MC has a 26lb/in in 0.300" OD I could try.

[oldpro]

Ran a few strings today Fuzzy heres one by the way you just got thread jacked LOL. Heres a pic installed http://airgunguild.com/index.php/topic,200.0.html



Created: 02/22/16 05:45 PM
Description:
Notes 1: 2500-1500psi
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 14.30
Temp: N/A °F
BP: N/A inHg
# FPS FT-LBS PF
16 725 16.69 10.37
15 729 16.88 10.42
14 737 17.25 10.54
13 738 17.30 10.55
12 740 17.39 10.58
11 742 17.48 10.61
10 749 17.82 10.71
9 742 17.48 10.61
8 743 17.53 10.62
7 744 17.58 10.64
6 739 17.34 10.57
5 732 17.02 10.47
4 727 16.78 10.40
3 735 17.16 10.51
2 729 16.88 10.42
1 724 16.65 10.35
Average: 735.9 FPS
SD: 7.5 FPS
Min: 724 FPS
Max: 749 FPS
Spread: 25 FPS
Shot/sec: 0.1
True MV: 736 FPS
Group Size (in): 0.00