Planet Airgun

General Airgun Categories => Maintenance, Modifications and Upgrades => Topic started by: svendogg on January 07, 2018, 03:53:06 PM

Title: Synsg chrono test and breech seal replacement
Post by: svendogg on January 07, 2018, 03:53:06 PM
After a disappointing night at the range on Friday where my attempt to zero my synsg at 30yards failed disaterously ( it was miles off to begin with and I just shot my s400 instead), I decided to get a bit of data on it while it was nice outside.

Chrono test first, methinks, .22 Superdome 14.5g

First shot - bad
2nd shot- 621

Now I can't do the maths in my head..... But that's a touch high I reckon. Third shot...... Didn't happen, batteries died. Great.

Trip to the shop, new batteries installed. Combro calibrated. Try again.

564fps
567
566
557
566
565

Pretty damn good, averaging 10.25 ft/lbs. When I last owned this gun it was around 9.7, so can only assume the internals have bedded in a bit more now. Anyway, I'd always thought (and research seems to back this) that the breech seal sat a little too flush. I'd ordered some suitable o rings (cheers UKCAF for the info) and a Diana 34 steel breech shim. Installed these after picking out the old seal and cleaning the breech with cotton buds......

571
567
563
572
At this point I wiped a bit of excess silicon grease off the seal with my thumb
567
567
567
569
571
566

So either with or without the first 4 shots, I'm getting a return of 10.39ft/lbs, which isn't a massive increase, but it's an increase nonetheless.

Anyway, a good start point. Got an Aussie seal waiting now, but I'm gonna get it zeroed and shoot it until the summer months as is I think, then strip, deburr, reseal and relube.

I'll keep y'all posted ;)
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on January 07, 2018, 08:02:00 PM
Those are none too shabby power figures sven, and more importantly, the consistency is very good, spesh after wiping the grease off the breech seal. 8)

Do you have any idea why you struggled to zero the SYNXS? :-\


Looking forward to yer further updates. ;)
Title: Re: Synsg chrono test and breech seal replacement
Post by: seagate on January 07, 2018, 08:11:13 PM
  Looks consistent enough.  :)
 What's the firing cycle like?
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on January 07, 2018, 08:53:09 PM
Think the scope was just so far out initially, trying to get a 30yard zero straight away was daft. I'll zero at 10yard first and then push out, was just being lazy
Firing cycles ok, a decent thunk. Hopefully calm down a touch after a tidy up
Title: Re: Synsg chrono test and breech seal replacement
Post by: seagate on January 07, 2018, 09:11:58 PM
 ''a decent thunk''  happy days.
Title: Re: Synsg chrono test and breech seal replacement
Post by: Baggawind on January 08, 2018, 10:41:15 AM
A quick tip for when you strip the rifle. There are two pins that hold the trigger block in place. Get yourself some steel rod the same diameter and make two pins , only 5mm shorter. Then you simply push out the standard pins with the shorter ones. This keeps the trigger assembly and safety in one piece. Then , to re-assemble , you just reverse the process. And make sure you de-burr all the slots and holes in the cylinder to avoid nicking the new piston seal. I bet you,ll find the original seal has been damaged whilst being assembled at the factory.
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on January 08, 2018, 10:08:41 PM
Thanks baggawind, I'd read that before about the drift pins, I've got some sorted ready 👍
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on March 24, 2018, 03:49:21 PM
Finally managed to get a proper test of the synsg since rebuild..... It's a long time but this is how my life is right now. Chrono test first:
509
509
512
512
510
514
516
515
519
513
515
514

Average of 513, for 8.48 ft/lbs. Significantly lower than before. Now I've lost a little spring length due to flattening the rough chopped end, and grinding flat, but maybe only 5-6 mm maximum. Surely the loss can't be due to that alone? Accuracy seems fine still, it was quite happy to stick pellets touching each other time after time (even if it is only about 12 yards), just seems odd to have lost so much muzzle energy
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on March 24, 2018, 05:16:43 PM
I'm assuming you're testing with the same pellets Sven?

That loss could be down to the shorter spring length...........it certainly isn't going to do it any favours (unless it was oversprung in the first place, which is unlikely).

Loss off velocity could also be down to thicker/more lube being used in reassembly, or the piston seal being a bit tight, if it was replaced?

Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on March 24, 2018, 06:17:21 PM
Piston seal is now an Aussie one, didn't seem overly tight so didn't size it, thought beat to leave alone rather than risk cocking it up. Lubed sparingly, last time I had a Springer issue it was due to too much lube, so I learned my lesson with that one
Title: Re: Synsg chrono test and breech seal replacement
Post by: Baggawind on March 24, 2018, 09:58:13 PM
This week I did a full short stroke conversion on my mates 208 using an Aussie seal. I,d already done it to my 208 and he liked the way it performed. Like yours, the seal didn,t need sizing. I reduced the stroke down from 88mm to 80mm, made new guide and top hat and applied very little grease. This resulted in a power output of only 10 fpe. There,s loads of space inside the piston to allow for packing, which is what I did. Including the top hat flange, the packing came to 4mm. This upped the power to 11.5fpe. And is very smooth to shoot. IIRC the spring is 3.05 mm section by 25 coils. That,s a compressed length of 76.25mm. Even with the packing the spring is nowhere near coil bound so you have plenty of space to play with. My advice is to get some power washers 3mm thick and gradually pack the spring out until you reach the required power. If you like I could make some for you , FOC. Pm me and i,ll send you some.
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on March 24, 2018, 11:25:26 PM
Very kind of you baggawind, pm coming your way
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on March 25, 2018, 11:28:20 PM
A very kind offer Mel. 8)

Applauded ;)
Title: Re: Synsg chrono test and breech seal replacement
Post by: IceBlerk on March 26, 2018, 10:39:08 AM
This week I did a full short stroke .........

Nothing to say about that, Gambo?
Title: Re: Synsg chrono test and breech seal replacement
Post by: Baggawind on March 26, 2018, 02:45:17 PM
Just spotted my mistake. The total packing came to 10mm not 4. Sorry  ::)
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on March 26, 2018, 04:15:22 PM
This week I did a full short stroke .........

Nothing to say about that, Gambo?

Missed that one!!!


Maybe you ought to put yerself forward as an OPAM-QS? ???

(Official Planet Airgun Mis - Quote Spotter)
Title: Re: Synsg chrono test and breech seal replacement
Post by: IceBlerk on March 27, 2018, 09:34:30 AM
Maybe you ought to put yerself forward as an OPAM-QS? ???

(Official Planet Airgun Mis - Quote Spotter)

Ooh! I like ANY title with "Official" in it.

Will I get a badge?
Title: Re: Synsg chrono test and breech seal replacement
Post by: Baggawind on March 27, 2018, 10:57:05 AM
I reckon you guys should form a boy band called TWISTED MINDS. 
Title: Re: Synsg chrono test and breech seal replacement
Post by: IceBlerk on March 27, 2018, 11:06:40 AM
A band reformed from the members of Simple Sister?
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on March 28, 2018, 07:24:59 PM
That means one of us will have to be Dee Snider, and the other Jim Kerr. :-\ :-\
Title: Re: Synsg chrono test and breech seal replacement
Post by: Baggawind on April 01, 2018, 10:35:33 AM
Svendogg, have your washers arrived yet ?
Title: Re: Synsg chrono test and breech seal replacement
Post by: Baggawind on April 02, 2018, 06:30:33 PM
Still waiting for an answer. Did you receive them ? if so did they work ?
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on April 03, 2018, 06:59:47 PM
May get chance to get these fitted tonight, not 100% sure if I'll have the time but I'll try. Will keep you posted on progress 👍
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on May 01, 2018, 07:49:01 PM
Ok, so after finally getting round to fitting some of the power washers, kindly supplied by baggawind (thanks again), I'm now Upto an average of just under 10ft/lbs, so it's a gain of about 40fps on average from about 6mm preload. I'm not too fussed by power, and it'll no doubt rise a little as it beds in, but I had one surprise.....
It's so mild mannered now! It wasn't a hefty recoil before I started but when I was doing the chrono test I thought "not much kick", and after I proceeded to shoot the heads off 2 dandelions in the garden from about 12yards, with ease, the cross hairs barely twitched. It's incredible. I think sacrificing power to get such a gentle shooter is a good tradeoff. Max spread was 14fps over 10 shots so not bad at all for a newly reassembled gun with a new seal!
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on May 01, 2018, 09:04:01 PM
I think sacrificing power to get such a gentle shooter is a good tradeoff.

I totally agree.

Good to hear you are pleased with it sven. ;)
Title: Re: Synsg chrono test and breech seal replacement
Post by: Baggawind on May 02, 2018, 10:14:20 AM
The previous , nasty recoil is probably down to the original piston seal. All those i,ve seen have been nicked when being pushed into the cylinder , causing the piston to crash against the breech end. Like all springers, the various slots and holes need careful de-burring before fitting a new seal.  Like you say, it should bump up a little after a tin full of pellets have gone through it. And, you can always add another washer if needed. Glad it,s worked out OK mate.
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on May 02, 2018, 04:41:39 PM
The recoil wasn't harsh as such before, I have a hatsan 60s that feels much harsher than the synsg ever did, but the transformation is extremely noticeable. Once it's had a tin or two through I might consider another washer but I'd be loathe to upset it now!
Thanks again for the washers, another great gesture by guys on this forum
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on May 02, 2018, 08:53:58 PM
another great gesture by guys on this forum

That's nice of you to say so sven. ;)

applauded
Title: Re: Synsg chrono test and breech seal replacement
Post by: svendogg on May 07, 2018, 09:03:13 PM
Update for anyone whos interested, managed to get 20mins with the synsg tonight (moving house in a few weeks so time is at a premium). 15 yards, nice soft rest, loose hold...... Resulted in 1 hole groups of around 12mm with Superdome, bisley long range gold and AA diabolo field.
Needless to say, happy boy me :)
Title: Re: Synsg chrono test and breech seal replacement
Post by: Gambo on May 08, 2018, 09:30:28 PM
Tidy like sven. ;)