New barrel advice

[starman]

MoonBogg:
The "optimal" CB really isn't controversial or even all that difficult to understand. What is difficult is wading through all the BS and stuff that is misleading or irrelevant or flat-out wrong.

Moonbogg was asking about a silent solution, not about c:b optimization. We covered that in other threads recently.

[john bunsenburner]

We are gettign way of topic...
You needs a quiet gun there are two ways(of the top of my head) to get that.

1. You builds a gun where the energy is so efficiently used that there is no extra energy left over that can be converted from kinetic into sound energy.

2. you builds something the attach to his gun that absorbes the sound acting like an insulation, simply put a silencer.

Personly the second idea is what I would choose but living in a big town having a spud gun with an illigal piece of equiptment is definately not the way to keep away from police...
I my self am not a combustion cannon person but as I see it the gun that is most efficient(having the least extra energy at the end, thus having a quiet shot) will have a C:B ration of 0.8:1. If you have a ratio like that then your gun should be very quiet, if you make the chamber volume lower your shot could have less than optimal velocities(still could be a nice shot) but will definately be fairly quiet.

[jimmy101]

MoonBogg:
The "optimal" CB really isn't controversial or even all that difficult to understand. What is difficult is wading through all the BS and stuff that is misleading or irrelevant or flat-out wrong.

Moonbogg was asking about a silent solution, not about c:b optimization. We covered that in other threads recently.

No, he was asking about CB ratios and mentions 1.5 and 0.8 and the differences between the two. 1.5 is oft quoted as being the "best". 0.8 is oft quoted for the same thing. I'm aware it has been coverred in other threads, I posted in'm.

[starman]

Yes, here's his original post...he wants a silent barrel...

I am making a silenced barrel. My chamber is 4" SCH40 x 17" long. I currently have a 1.5:1 C:B: ratio with a 43" long, 2" SCH40 barrel, and its LOUD.
I was thinking about lengthening the barrel to 60", making it closer to 1:1 and having the last 17" of barrel the silenced part, using 4" SCH40 as the silencer. This would leave me an effective barrel section with no holes in it at 1.5:1 still, with the remaining section used basically for gas and pressure dispersion. What you think? Sound about right?

His secondary question:

About the ratio, from what i've read 1.5:1 is optimal, going with .8:1 seems to be too little. Won't the spud drag at the end of the barrel?

He's worried about "spud drag"...

[Moonbogg]

His secondary question:

About the ratio, from what i've read 1.5:1 is optimal, going with .8:1 seems to be too little. Won't the spud drag at the end of the barrel?

He's worried about "spud drag"...

Yes, spud drag is not good. However, unreasonably loud noise isn't good either, and since actual silencers will send us all to federal prison, its best to find a compromise. I am thinking (mostly guessing) that a 1:1 ratio offers a good compromise between velocity and sound. What I need is the best compromise ratio between noise and velocity. If 20 or 30 yards is lost for a 10-20 decibel reduction, then its well worth it. But if the only way to tone down the noise a bit is to lose 100 yards or have an underpowered gun, then its not worth it.

Compromise is the target, velocity is paramount.

PS..note on common spud silencers. All they do is reduce muzzle pressures, so you might as well do away with the bulk and weight and use a lower C:B ratio (IMO)

[jackssmirkingrevenge]

An effective suppressor is not hard to build and if made permanently attached to a large bore spudgun, extremely unlikely to get you into trouble with the law.

I would go with a longer barrel if compactness isn't an issue, if not porting the end of the barrel, sleeving it and packing it with steel wool will work just as well.

[Xxplosive42o]

In alot of cases keeping your C:B around .8 will serve you best. It should give you great velocity and quiet down the beast. I have a 45" barrel for a 1.5:1 ratio and a 75" for a .9:1 ratio. In all honesty, the 75" barrel performs better and is alot quieter. It might differ for you like it does with everyone, but I'm sure you'll find whats best for you.

G'luck Moon!

[jackssmirkingrevenge]

In alot of cases keeping your C:B around .8 will serve you best.

Not in all cases of course, this beast had its C:B ratio cut down significantly below 0.7 and it still sounded like a 12 bore going off, to the extent that I barely used it more than 5 times.

[ALIHISGREAT]

In alot of cases keeping your C:B around .8 will serve you best.

Not in all cases of course, this beast had its C:B ratio cut down significantly below 0.7 and it still sounded like a 12 bore going off, to the extent that I barely used it more than 5 times.

to be fair, alot of the sound would have been bounced back because you were shooting up against a wall/shipping container.

[jackssmirkingrevenge]

to be fair, alot of the sound would have been bounced back because you were shooting up against a wall/shipping container.

Trust me, I fired it outside and it sounded even louder

[Moonbogg]

In alot of cases keeping your C:B around .8 will serve you best. It should give you great velocity and quiet down the beast. I have a 45" barrel for a 1.5:1 ratio and a 75" for a .9:1 ratio. In all honesty, the 75" barrel performs better and is alot quieter. It might differ for you like it does with everyone, but I'm sure you'll find whats best for you.

G'luck Moon!

Thanks for the post. I believe the 75" barrel gun performs better in terms of velocity simply because it is a larger gun.

[ALIHISGREAT]

to be fair, alot of the sound would have been bounced back because you were shooting up against a wall/shipping container.

Trust me, I fired it outside and it sounded even louder

ok... thats wierd?!?! i wonder what makes it so lound, you wern't using an actual spud as ammo were you? maybe if you shot a tight fitting projectile like a spud... it would be quieter?

[jackssmirkingrevenge]

Thanks for the post. I believe the 75" barrel gun performs better in terms of velocity simply because it is a larger gun.

The mixture in a given chamber will only expand to a certain volume. as long as the barrel volume is below this level, the projectile will continue to be accelerated as long as it is in the barrel. Once you skip this value however, this will cause drag and actually slow down the projectile on account of the outside pressure being greater than internal pressure.

[raptorforce]

An effective suppressor is not hard to build and if made permanently attached to a large bore spudgun, extremely unlikely to get you into trouble with the law.

I would go with a longer barrel if compactness isn't an issue, if not porting the end of the barrel, sleeving it and packing it with steel wool will work just as well.

uhhh so if the silencer is removable its illegal?