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Author Topic: B30-1 .177 teardown  (Read 238 times)

Offline xyon

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B30-1 .177 teardown
« on: February 27, 2019, 07:02:13 PM »
Hi,
I  bought a B30-1 from guncity a couple of days ago after seeing that they have them for $199. I got the .177 as I have a Diana 52 in .22 which this gun is a copy of, mostly that is.

This is what it looks like straight out of the box.



I was going to shoot a group with the open sights, but after a couple of shots I saw the rear sight was wobbling from side to side. When I got back inside I noticed the screw holding the sight in place was loose, so nothing to drastic there.

The finish on the wood is reasonable with no major flaws,  I have the Diana stock next to it for comparison


B30-1 above, Diana 52 action below

Quite similar as you can see.

First surprise for me, the trigger is not a T05 or T06, also the lack of washer on the cocking arm pivot has caused the paint to wear off after just a few shots.


On a positive note, the rear of the piston has a plastic bearing. The other surprise is the piston diameter is 26mm where as the Diana 48/52 is 28mm


The spring ends were ground a bit, but not enough, to stop them gouging the washer a bit.


Next I will clean up the spring, trigger and seal and reassemble for some testing.

Offline Mintie

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Re: B30-1 .177 teardown
« Reply #1 on: February 27, 2019, 07:38:42 PM »
Look forward to hearing more about this, Always fancied one!
Lots of airguns

Offline Pauly5

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Re: B30-1 .177 teardown
« Reply #2 on: February 28, 2019, 10:51:18 PM »
Me too. Doesn't Hidayat have one of these with a chopped barrel? Opposum slayer.

Keep us posted.
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Offline Novagun

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Re: B30-1 .177 teardown
« Reply #3 on: March 01, 2019, 12:51:07 AM »
Waiting on the next installment.

Offline xyon

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Re: B30-1 .177 teardown
« Reply #4 on: March 03, 2019, 09:36:31 AM »
Done a bit more with this. Since the last pic was of the spring, I'll mention that first. You can see the spring is quite dirty, it looks like they didn't wash it after heat treatment or something like that, a bit poor.

The trigger is interesting (to me at least) as it is not a t05 or t06. I'd be interested to know where the design came from. It has 2 claws, one on each side, that hold the piston latch rod. It has 2 screws that can be adjusted to give a 2 stage pull, which I have done. When I got it, the first stage screw (hmm or was it the second) was wound all the way in meaning there was only 1 stage. I have disassembled the trigger an de-burred and polished the sears. From the few shots I have made the pull weight is not too bad, but it's no t06. It is unusual in that the pull weight decreases as you pull the first stage.

Sorry no pics of it disassembled, forgot to take any.
The other thing to note about the trigger design, is the auto safety engagement happens as soon as you lift the cocking arm. This means the rifle cannot be de-cocked as the Diana can. The trigger is blocked when the cocking arm is not in its home position.
« Last Edit: March 03, 2019, 09:41:02 AM by xyon »

Offline xyon

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Re: B30-1 .177 teardown
« Reply #5 on: March 03, 2019, 09:52:44 AM »
Before reassembling I checked the piston and breech seals were holding pressure, I did note the piston seal is quite a tight fit, but I though I would test it as-is first.

Now the bad news, First thing I did was chrony it. 676 fpe with 8.44gr JSB exacts :-)
That is disappointingly less than what I had hoped for. I tried a couple of H&N FTT, but they were slower.

Question now is, what is wrong???

Should I take it back to gun city, or try to fix it myself?

Offline Pauly5

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Re: B30-1 .177 teardown
« Reply #6 on: March 03, 2019, 11:44:58 PM »
Maybe the piston seal has too much friction? What about the breech seal, is that good?
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Offline Akzle

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Re: B30-1 .177 teardown
« Reply #7 on: March 04, 2019, 02:55:47 PM »
The other thing to note about the trigger design, is the auto safety engagement happens as soon as you lift the cocking arm. This means the rifle cannot be de-cocked as the Diana can. The trigger is blocked when the cocking arm is not in its home position.

"Anti-bear-trap" "safety".
I remove that shit from any guns that have it, It's unsafe to have to fire a rifle to make it safe.

Offline xyon

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Re: B30-1 .177 teardown
« Reply #8 on: March 04, 2019, 06:59:22 PM »
I left out the auto trigger safety part when I reassembled it for testing. But I would not remove the anti bear trap from one of these as the sliding compression cylinder is well capable of severing any digits  left in the breech.  :P

Offline xyon

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Re: B30-1 .177 teardown
« Reply #9 on: March 04, 2019, 07:04:42 PM »
Maybe the piston seal has too much friction? What about the breech seal, is that good?

I think the tight seal could sap a bit of power, but I'm not sure how much. Gamo's often have very tight seals and they don't loose too much power over it.
From what I have read on the internet, these B30's often seem to have a weak spring, People have seen quite a large increase in power from replacing the spring.

Offline Pauly5

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Re: B30-1 .177 teardown
« Reply #10 on: March 05, 2019, 05:01:30 PM »
And from a couple of reviews I have read, there seems to be quite a variance in power output, so that would be a big factor, especially if the springs are of a lesser quality.
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Offline Novagun

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Re: B30-1 .177 teardown
« Reply #11 on: March 06, 2019, 02:00:56 AM »
Couple of observations.

You bought a $199 gun and that is what you got. At least it works.

Having dismantled it, I doubt Gun City would be interested in any claim.

The test with this project is to see if you can get it to shoot well, with little extra money added to the purchase cost. Just the tinkering you can do yourself.

Looking forward to the next instalment.

Offline xyon

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Re: B30-1 .177 teardown
« Reply #12 on: March 08, 2019, 07:56:33 AM »
Maybe I got a Friday afternoon "special".  The breech lead in was not sufficient, so when you closed the compression tube up to the breech it was shaving a ring off the back of the pellet. I decided to fix that myself rather than return it. The power has not increased with that fix, so I'm suspecting the breech seal and/or the main spring.

Offline Dvlnme

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Re: B30-1 .177 teardown
« Reply #13 on: March 08, 2019, 09:52:05 AM »
dont be too disapointed mate its bit like expecting a Lada car to be as good as as BMW car,you get what you pay for thats just the way things are,its never going to be the eqaul of the Diana 52,it is what it is,bout all you can do really is polish all the moving and essentual parts possibly replace spring and seals with better ones get it so its funtioning smoothly and shooting consistantly as accuratly as possible at whatever power level that may end up being,and just shoot and enjoy it for what it is mate.as the old saying went you cant make a silk purse out of a pigs ear eh!!many budget chinese made airguns and firearms are made to look good on the outside and not so good on the inside,thats just the way it is with them,there are large numbers of gun factorys in china many making the same guns,some factorys are just better at it than others and its pretty much the luck of the draw as to which factorys the guns are sourced from by the exporter who will proberly buy the guns at the cheapest price they can,the fine up standing gentleman who owns gun city is very much a busseness man looking for bargain deals mate for himself that he can then sell for a decent profit at as cheap as possible retail prices,thats just the way he runs his busseness,personally i wouldnt buy a roll of toilet paper off him.
 As my other half tells me mate sorting this rifle out will keep you in the workshop and out of the pub and getting into trouble lol,its a project gun just enjoy the project for what it is and dont expect too much from it,like novagun says thats half the fun of it too.
 cheers mike

Offline Novagun

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Re: B30-1 .177 teardown
« Reply #14 on: March 08, 2019, 11:26:13 AM »
Right on. A good project. Once you have sorted out the breach seal it might be a good idea to try a decent spring. Ron Young might have something that will fit.  If not there is a bloke in Christchurch that makes one off springs at a very reasonable price.

brian@metal springs.co.nz.  0276937252  or 03 4544569. Good to deal with.