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Old 04-05-2020, 01:40 PM   #16
Fynn64   Fynn64 is offline
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With a longer slot you will also lose cylinder volume. While the sorbo will reduce the volume, it will also make the gun quieter.
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Old 04-05-2020, 02:22 PM   #17
Vsr10   Vsr10 is offline
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First i try to make piston shorter, then we will see what next to do,only i don't understand how yours short piston works but mine short plastic piston won't catch sear with pps cylinder
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Old 04-05-2020, 02:59 PM   #18
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My spring guide has a pretty thin base. Also depending on your spring guide/stopper, there can be a nipple/cut out. I shaved the nipple off all of my spring guides mainly because it can cause latching issues with the Bulltrigger. The sear is moved back but depending on your parts, that could be the latching issues. Try more sorbo for the process of elimination as well.
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Old 04-05-2020, 03:49 PM   #19
1tonne   1tonne is offline
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-I think some bull trigger have the sear slightly further back than a standard trigger.
-The piston o-ring should not catch on the port as it goes past. If it does, use a round file and be careful
-Do not extend the port. You will lose critical air volume and that is more important than the initial acceleration of the piston. You will get more fps with air volume than a fast piston but to maximise your cylinder volume you need to correct length inner barrel for the bb weight you are shooting.
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Old 04-05-2020, 04:43 PM   #20
Vsr10   Vsr10 is offline
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Quote:
Originally Posted by Blind Sniper View Post
My spring guide has a pretty thin base. Also depending on your spring guide/stopper, there can be a nipple/cut out. I shaved the nipple off all of my spring guides mainly because it can cause latching issues with the Bulltrigger. The sear is moved back but depending on your parts, that could be the latching issues. Try more sorbo for the process of elimination as well.
I will investigate why isn't catching tomorrow
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Old 04-05-2020, 04:46 PM   #21
Vsr10   Vsr10 is offline
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Quote:
Originally Posted by 1tonne View Post
-I think some bull trigger have the sear slightly further back than a standard trigger.
-The piston o-ring should not catch on the port as it goes past. If it does, use a round file and be careful
-Do not extend the port. You will lose critical air volume and that is more important than the initial acceleration of the piston. You will get more fps with air volume than a fast piston but to maximise your cylinder volume you need to correct length inner barrel for the bb weight you are shooting.
Am using 0.43,and have 430mm inner barrel
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Old 04-05-2020, 05:39 PM   #22
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Quote:
Originally Posted by 1tonne View Post
-I think some bull trigger have the sear slightly further back than a standard trigger.
-The piston o-ring should not catch on the port as it goes past. If it does, use a round file and be careful
-Do not extend the port. You will lose critical air volume and that is more important than the initial acceleration of the piston. You will get more fps with air volume than a fast piston but to maximise your cylinder volume you need to correct length inner barrel for the bb weight you are shooting.
So my question is, if you get more fps with air volume, and matching your barrel to bb weight maximizes air volume, then shouldn’t a 370mm with a .48 give more fps than a 430mm with a .48? I know all of your testing is for efficiency, but what would you say are the advantages of a 370mm barrel for a .48 over a 430?
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Old 04-06-2020, 05:42 AM   #23
Vsr10   Vsr10 is offline
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One off topic question, is the stock vsr buckings same for bridged and unbridged barrel? I want to open bridge on my steel barrel so i can use ML buckings, hope that will not make problem if i want to put back stock bucking
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Old 04-06-2020, 03:59 PM   #24
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Quote:
Originally Posted by Vsr10 View Post
Am using 0.43,and have 430mm inner barrel

That sounds about the correct ratio. So all good

Quote:
Originally Posted by Blind Sniper View Post
So my question is, if you get more fps with air volume, and matching your barrel to bb weight maximizes air volume, then shouldn’t a 370mm with a .48 give more fps than a 430mm with a .48? I know all of your testing is for efficiency, but what would you say are the advantages of a 370mm barrel for a .48 over a 430?

The shorter 370mm barrel should give more fps than the 430mm inner barrel when shooting 0.48gm bb's and when measuring with 0.48gm bb's.
If you were to use a 430mm inner barrel and 0.48gm bb's there is not enough air to push it out 100% effectively. It will still shoot out but there will be a little bit of the suck back effect (negative pressure) behind the bb once all the positive gas is used up. This will lessen the energy that the bb would have had and will make it just slightly less accurate (probably not really noticeable). Normal energy loss is about 0.3 joules between the 2 barrel lengths when using an M170 spring and standard weighted piston.
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Old 04-07-2020, 01:49 AM   #25
Vsr10   Vsr10 is offline
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I will using 0.43,or maybe 0.45 for now..
Just need good spring to get 3.5j or 4j,rapax 3+ lost about 20% strength, need to find strong spring but it's must be shorter than rapax to not lose to much strength over time

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Old 04-08-2020, 09:17 AM   #26
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everyone saying about loosing cylinder volume and in both occasions volume is the same as piston go fare as grove on cylinder then no advantage to go this 1 cm as this will not compress air ( air go off through grove ) in first cm but maybe you get some advantage due to when start compressing piston have some acceleration already
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Old 04-08-2020, 03:43 PM   #27
1tonne   1tonne is offline
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Originally Posted by matikmat View Post
but maybe you get some advantage due to when start compressing piston have some acceleration already

That is where the advantage is. The initial speed of the piston.
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Old 04-09-2020, 03:31 AM   #28
Vsr10   Vsr10 is offline
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Quote:
Originally Posted by 1tonne View Post
-You will get more fps with air volume than a fast piston but to maximise your cylinder volume you need to correct length inner barrel for the bb weight you are shooting.
Whats is the correct lenght for 0.43?
I mesure my pps cylinder, it's have about 90mm x 22mm (o ring isn't visible when bolts is pulled)

90x23mm is the stock cylinder (o ring is visible when bolt is pulled back)

According to this i have more volume on stock than a pps cylinder
I maybe can get 95mm x 22mm on pps if i shorten the piston, (o ring then will be visible when bolt is pulled back)
But not sure that the sear can catch piston after that
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Old 04-09-2020, 04:12 AM   #29
1tonne   1tonne is offline
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The difference is minimal. I would still just get the 430mm inner barrel.
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Old 04-09-2020, 05:10 AM   #30
Vsr10   Vsr10 is offline
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Quote:
Originally Posted by 1tonne View Post
The difference is minimal. I would still just get the 430mm inner barrel.
I have 430 mm barrel already, 6.03mm
So that part is ok
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