Bull pup SBR project

[yoni]

I am going to do a super short X95 SBR, like a 9,5" barrel.

My question for the wise people of M4, is do I build it in 5.56 or 300 blackout? Or do I in time just do both?

I of course will drop in the Geissele trigger pack and trigger.

Last question is does anyone know what happened to the bullpup forum?

Someone posted at bullpup forum a few years back the SBR build they did on a X95 and it was IIRC only a shade over 17inches in overall length.

https://www.thefirearmblog.com/blog/...tavor-x95-sbr/

[mig1nc]

Bullpup forum is dead and gone.

I don't think the X95 would have enough dwell time to drive a 300blk that short.


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[yoni]

Bullpup forum is dead and gone.

I don't think the X95 would have enough dwell time to drive a 300blk that short.


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Do you know what happened to it? Why did it die?

How can the 300 drive a 9 inch AR but not a X95?

[Todd.K]

Have you tried the 13” factory option for your requirements?

It really come down to how short you can make the gas system, and how much energy the system needs to function. Some multiple part piston systems have a practical minimum too long for ultra short barrels.

[georgeib]

Do you know what happened to it? Why did it die?

How can the 300 drive a 9 inch AR but not a X95?

A 300 AR barrel uses a super short pistol length gas system which gives it sufficient dwell time, whereas (presumably, as I am not super familiar with the x95) the x95 uses a longer gas system which doesn't allow sufficient dwell time to reliably cycle.

[yoni]

I am tired and I am major pissed at a client, so this may be a stupid question.

In the link they got a 9 1/2 barreled 5.56 X95 to run and run great, would it not be the same in a 300 blk?

[georgeib]

I am tired and I am major pissed at a client, so this may be a stupid question.

In the link they got a 9 1/2 barreled 5.56 X95 to run and run great, would it not be the same in a 300 blk?

Not a stupid question. The reason 300blk needs more dwell time is because in subsonic varieties, it is much lower pressure than 556. All things being equal, a higher pressure cartridge requires less dwell time. I'm sure @lysander can explain the physics, but I think you get the idea.

[yoni]

So I was not thinking of subsonics in the gun.

So the question is will regular 300 blk work in the gun?

[georgeib]

So I was not thinking of subsonics in the gun.

So the question is will regular 300 blk work in the gun?

At the risk of setting off a 556 vs 300 debate, I would ask you what advantage you see to 300 supers over 556? Energy wise, in a 10" barrel, they will be very similar with the edge going to 556, and 556 will shoot flatter due to higher velocity. And then there's availability.

[mig1nc]

At the risk of setting off a 556 vs 300 debate, I would ask you what advantage you see to 300 supers over 556? Energy wise, in a 10" barrel, they will be very similar with the edge going to 556, and 556 will shoot flatter due to higher velocity. And then there's availability.

In a 10" barrel a 300blk super will have about as much energy as a 16" 556. And much better penetration. I'm not sure where you got that information.


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