Faced with a situation with subsonic setup when not enough energy for recharge - the case is thrown out, the hammer is charged, but next cartridge is not chambered in 9 of 10 cases.
Disassembled the gas block - the hole in it is wider than the outlet of the barrel, respectively, the installation of an adjustable gas block is unlikely to increase the volume of gas returned to the bolt frame
Perhaps someone has already solved this problem – please advise how optimally (from the financial side) to solve this issue.
DB15 blk 16” twist 8”, full stock
Vectan A0 Subsonic Cycling Issues
Moderators: gds, bakerjw, renegade
Re: Vectan A0 Subsonic Cycling Issues
More information needed.
Did you measure the size of the port in the barrel? it would be helpful to know.
Length of the gas system, pistol or carbine?
Buffer weight?
You mention “full stock”, is that a full size rifle stock, A2 Model?
Is so it requires a special buffer or a spacer to use a carbine buffer and spring.
Load data, bullet and charge weight.
Are you in Europe?
Not many use Vectan powders here, and load data is almost non existent. I think I have data for AO, and maybe still some powder, I will check my notes tomorrow.
Did you measure the size of the port in the barrel? it would be helpful to know.
Length of the gas system, pistol or carbine?
Buffer weight?
You mention “full stock”, is that a full size rifle stock, A2 Model?
Is so it requires a special buffer or a spacer to use a carbine buffer and spring.
Load data, bullet and charge weight.
Are you in Europe?
Not many use Vectan powders here, and load data is almost non existent. I think I have data for AO, and maybe still some powder, I will check my notes tomorrow.
300 Blackout, not just for sub-sonics.
Re: Vectan A0 Subsonic Cycling Issues
Hi
https://diamondbackarmstore.com/diamond ... fle-black/
COAL: 2.25 inch
load: 6,1gr
~0,11 inch
Pistol
3 oz
no, i meant that use carbine in the form in which it is sold, from the box
https://diamondbackarmstore.com/diamond ... fle-black/
I use led bullet very similar to Lyman 311299 but with weight 208gr
COAL: 2.25 inch
load: 6,1gr
Re: Vectan A0 Subsonic Cycling Issues
I am sorry, I confused two powders AO,and AS.
I never tried AO fo subsonic, no data. The data I have is in the thread linked below. Since the Vectan/Noble sport powders are rare here, I use 300 Whisper data. It is close enough for a start.
viewtopic.php?f=141&t=110213&p=1009324& ... r#p1009324
It sounds like the AO may work for you. There are a few things you can try, and questions I forgot to ask.
Are you using a suppressor?, that can add back pressure and help cycling.
What is the velocity with the load you are using?
The AO powder is a bit fast for subsonic, but it may work. One thing to try, is to open the gas port more. This may become a problem later wit a different powder, or shooting supers. Max diameter would be .125”. The gas block and tube are that size, so any bigger is a waste.
Do you have other powders available, it might be easier to change.
A different bullet.
This is not a powder that I used for long, and always for supers, so I’m not much help.
I never tried AO fo subsonic, no data. The data I have is in the thread linked below. Since the Vectan/Noble sport powders are rare here, I use 300 Whisper data. It is close enough for a start.
viewtopic.php?f=141&t=110213&p=1009324& ... r#p1009324
It sounds like the AO may work for you. There are a few things you can try, and questions I forgot to ask.
Are you using a suppressor?, that can add back pressure and help cycling.
What is the velocity with the load you are using?
The AO powder is a bit fast for subsonic, but it may work. One thing to try, is to open the gas port more. This may become a problem later wit a different powder, or shooting supers. Max diameter would be .125”. The gas block and tube are that size, so any bigger is a waste.
Do you have other powders available, it might be easier to change.
A different bullet.
This is not a powder that I used for long, and always for supers, so I’m not much help.
300 Blackout, not just for sub-sonics.
Re: Vectan A0 Subsonic Cycling Issues
Thanks for the link!
max pressure ~ 27600psi
the gas tube is indeed 0.125" inch diameter and it is larger than the port size of the barrel so replacing the gas block with an adjustable one will not help with cycling.
if I understand correctly the solution may be in a less rigid spring?
Yes
316-318m/s or 1036-1043fps
A0 is fast and manages to burn 100% in the barrel, which actually gives high stability, but at the same time, the muzzle pressure is low ~1340psi
max pressure ~ 27600psi
the gas tube is indeed 0.125" inch diameter and it is larger than the port size of the barrel so replacing the gas block with an adjustable one will not help with cycling.
if I understand correctly the solution may be in a less rigid spring?
Re: Vectan A0 Subsonic Cycling Issues
If the gas block and tube diameter is .125”, and the port is .110”, the port in the barrel is a restriction. Opening the port will help.
The muzzle pressure is very low, probably too low to work without either less spring pressure, or weight in the buffer and bolt carrier. You might take the buffer apart and remove the weights. You can always put them back. Less spring tension can also help, but remember that it is the spring tension that is required to load the next round from the magazine. It needs to provide enough force to strip the next round and force the bolt closed.
Something else you can try, but the powder might just be too fast, is a lighter bullet, or less powder. It is a balancing act.
A lower fill ratio or lighter bullet, will drop the peak pressure, which will raise muzzle pressure. Muzzle pressure is what cycles the action. Moving the bullet out, longer length will do the same, but you are almost at maximum length. I like to see at least 6000 psi at the muzzle.
I personally do notlike to have to make so many modifications to a rifle to make a single powder work. Then if you change powders, you may have to change things again.
Hope that is some help.
Edited to clarify in bold. Thanks BJK for catching that.
The muzzle pressure is very low, probably too low to work without either less spring pressure, or weight in the buffer and bolt carrier. You might take the buffer apart and remove the weights. You can always put them back. Less spring tension can also help, but remember that it is the spring tension that is required to load the next round from the magazine. It needs to provide enough force to strip the next round and force the bolt closed.
Something else you can try, but the powder might just be too fast, is a lighter bullet, or less powder. It is a balancing act.
A lower fill ratio or lighter bullet, will drop the peak pressure, which will raise muzzle pressure. Muzzle pressure is what cycles the action. Moving the bullet out, longer length will do the same, but you are almost at maximum length. I like to see at least 6000 psi at the muzzle.
I personally do notlike to have to make so many modifications to a rifle to make a single powder work. Then if you change powders, you may have to change things again.
Hope that is some help.
Edited to clarify in bold. Thanks BJK for catching that.
300 Blackout, not just for sub-sonics.
Who is online
Users browsing this forum: No registered users and 22 guests