Author Topic: Synsg chrono test and breech seal replacement  (Read 1541 times)

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Offline svendogg

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Synsg chrono test and breech seal replacement
« 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 ;)

Offline Gambo

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Re: Synsg chrono test and breech seal replacement
« Reply #1 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. ;)

Offline seagate

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Re: Synsg chrono test and breech seal replacement
« Reply #2 on: January 07, 2018, 08:11:13 PM »
  Looks consistent enough.  :)
 What's the firing cycle like?
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Offline svendogg

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Re: Synsg chrono test and breech seal replacement
« Reply #3 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

Offline seagate

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Re: Synsg chrono test and breech seal replacement
« Reply #4 on: January 07, 2018, 09:11:58 PM »
 ''a decent thunk''  happy days.
I plink , therefore I am.

Offline Baggawind

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Re: Synsg chrono test and breech seal replacement
« Reply #5 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.

Offline svendogg

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Re: Synsg chrono test and breech seal replacement
« Reply #6 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 👍

Offline svendogg

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Re: Synsg chrono test and breech seal replacement
« Reply #7 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

Offline Gambo

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Re: Synsg chrono test and breech seal replacement
« Reply #8 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?


Offline svendogg

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Re: Synsg chrono test and breech seal replacement
« Reply #9 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