RTI ❓ Recommendations for a Low Power .30cal Gun?

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JungleShooter

JungleShooter

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Sep 5, 2018
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Lima/PERU: 11,000,000people +twice as many pigeons
❓ Recommendations for a Low Power .30cal Gun?


😵‍💫 Dozing during a dark drizzly night my mind concocted a semi-crazy idea.
😊 And before I mess up my carefully tuned guns, I thought I'd better ask the collective wisdom at AGN.
I am prepared to take a certain amount of scorn and ridicule for my idea. 👍🏼


➊
If you ever shot quarry with a .30cal slow pellet — say at 500fps:
● How would you describe the hit (especially on a pigeon)?

● Any comments/ recommendations?



➋
My Imagined Scenario:
▪ I'd like to shoot pigeons at 10 to 60y — and scopecam the hits.

▪ I'd like to have a muzzle velocity of around 500fps with either Polymag (44.75gr) or JSB Heavy (50.15gr) — unless you recommend something else!

▪ I'd like the shot noise at the gun very very quiet (with silencer).
(And the impact noise nice and loud.)



➌
Your recommendation —
What gun — and why?

▪ Option (A): RTI Prophet 1 — regular valve

▪ Option (B): RTI Prophet 2 — balanced valve

▪ My barrel is an RTI LW barrel in .30, length 600mm (=regular size), with the large double-transfer ports.



➠ Thanks for any input you might have for me. 👍🏼

Cheers, 😃

Matthias
 
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I can only guess that a slow moving .30 hitting a pigeon would be something like this.
Screenshot_20250309-173746.png

But I don't have any actual experience to answer your question.
 
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Vetmx said:
I wonder if going that slow with a 30 would cause an accuracy issue. Would the gun be just as accurate throwing knuckleballs.
Click to expand...


Yeah, I was wondering about precision, too, Frank....


Cole, thanks for the graphic display of what I hope the result will be. 👍🏼


Justin, tell me more about your 550fps EGgun — do you have one of the rare .30cal models?



I'll make an appointment for a range day tomorrow — where I might do the deed of changing barrels/scopes/power — depending on your recommendations and input.
Of course, you are not liable if it won't work the way I hoped. 👍🏼


Matthias
 
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Sicumj said:
Shooting 60 yards at that speed would be challenging. You will need to be spot on with your distance calculation. Polymags sure will work but I doubt they will deform much at distance.
Click to expand...


● Yes, James, I'm aware that my PBR is rather small...:

For a 1" killzone ChairGun calculates the PBR to run only from 9y to 31y (0'd 28y).


● At 50y the projectiles drop 1/2" (1.4cm) earch yard of forward travel, so yeah, precise ranging is critical.

But... — that is not really a problem — or is it? (I'm new at this slow stuff — I always have been a power hungry in the past....)

Matthias
 
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Motorhead said:
I know how I would set one up ... but as to recommendation of a ready to go rig, got nothing.
Click to expand...


🔶 Scott, 👍🏼

would the Prophet 2 with a balanced valve be better for this —
or the Prophet 1 with a regular valve?

(Why...? 🤔)




🔶 xsarfc9x,

even though I live in the desert — quite literally, and figuratively as there is a dearth of airguns in Peru —
I got the gun/s, and barrel/s, and ammo. Thanks to a very nice AGN member who helped! 😃

Matthias
 
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JungleShooter said:
🔶 Scott, 👍🏼

would the Prophet 2 with a balanced valve be better for this —
or the Prophet 1 with a regular valve?

(Why...? 🤔)




🔶 xsarfc9x,

even though I live in the desert — quite literally, and figuratively as there is a dearth of airguns in Peru —
I got the gun/s, and barrel/s, and ammo. Thanks to a very nice AGN member who helped! 😃

Matthias
Click to expand...
Lets do a look at the requirements to do this and have a low ES while operating low noise ?
Integrity of the valve and air path needs to be air tight ... as in no air leakage past valve stem, no leakage in transfer path or at barrel probe. Your placing a BIG HEAVY Cork of a pellet in there and wishing for low output and consistency so any leaks in getting and keeping air behind pellet is going to hurt doing so. ;)

Knock open valve ( Not balanced ) with a fairly large throat and transfer path so the air pulse AMPLITUDE stays high.
Regulated for sure using a Light hammer & heavy spring. as you want a very low dwell strike which will launch the pellet hard, but not exhibit longer dwell which is required for bigger power & longer barrels.
Barrel for this 12 to 15 inches is likely all required.
Regulator pressure is key as your extracting the launch energy off pressure more so than volume .... SNAP launch of pellet and valves already closed !!!
Set up as such would have consistency high ( Low ES ) Low air use and minimal muzzle report for sure.

JMO ...

PS.
Doing such a tune on a longer barrel or a detuned High output set up ... likely will have a higher ES value and more noise. Likely would find needing to run really low reg pressure which would have valve dwell longer and resulting muzzle noise greater. * We already KNOW that small sips of HP is more efficient than big sips of LP when equal output is tuned for each configuration.
Reason in eyes viewpoint is that the long barrel push of the air moving pellet needs to keep happening or the DRAG of the pellet within barrel will slow the pellet down and speeds will be hard to keep consistent.
This especially true with any sort of balanced valve, as they want to FLOW and don't work that well making them take small sips of air.
 
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Motorhead said:
Lets do a look at the requirements to do this and have a low ES while operating low noise ?
Integrity of the valve and air path needs to be air tight ... as in no air leakage past valve stem, no leakage in transfer path or at barrel probe. Your placing a BIG HEAVY Cork of a pellet in there and wishing for low output and consistency so any leaks in getting and keeping air behind pellet is going to hurt doing so. ;)

Knock open valve ( Not balanced ) with a fairly large throat and transfer path so the air pulse AMPLITUDE stays high.
Regulated for sure using a Light hammer & heavy spring. as you want a very low dwell strike which will launch the pellet hard, but not exhibit longer dwell which is required for bigger power & longer barrels.
Barrel for this 12 to 15 inches is likely all required.
Regulator pressure is key as your extracting the launch energy off pressure more so than volume .... SNAP launch of pellet and valves already closed !!!
Set up as such would have consistency high ( Low ES ) Low air use and minimal muzzle report for sure.

JMO ...
Click to expand...

When the pro's answer, I listen in silence.

Thank you very much for such a helpful explanation — and it shows me with such clarity that internal ballistics is where my ignorance shines the most.
➠ The realm of the pro's like you....


● So, using the P1 with the regular valve, not the P2 with the balanced valve.

● A short barrel is enough for this (you mention 12"-15" [30-38cm]).
My barrel is 23" (60cm), and your comments makes me wonder if a much shorter gun would be worth the barbaric deed of chopping an RTI barrel.

● Lighter hammers and stiffer springs are out of reach for me, just have the factory setup.

● I take it I should tune the HST to 5% below the maximum velocity at a given regulator setting?



What a great forum — because of such great people.... 🤝🏼

Matthias
 
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JungleShooter said:
❓ Recommendations for a Low Power .30cal Gun?


😵‍💫 Dozing during a dark drizzly night my mind concocted a semi-crazy idea.
😊 And before I mess up my carefully tuned guns, I thought I'd better ask the collective wisdom at AGN.
I am prepared to take a certain amount of scorn and ridicule for my idea. 👍🏼


➊
If you ever shot quarry with a .30cal slow pellet — say at 500fps:
● How would you describe the hit (especially on a pigeon)?

● Any comments/ recommendations?



➋
My Imagined Scenario:
▪ I'd like to shoot pigeons at 10 to 60y — and scopecam the hits.

▪ I'd like to have a muzzle velocity of around 500fps with either Polymag (44.75gr) or JSB Heavy (50.15gr) — unless you recommend something else!

▪ I'd like the shot noise at the gun very very quiet (with silencer).
(And the impact noise nice and loud.)



➌
Your recommendation —
What gun — and why?

▪ Option (A): RTI Prophet 1 — regular valve

▪ Option (B): RTI Prophet 2 — balanced valve

▪ My barrel is an RTI LW barrel in .30, length 600mm (=regular size), with the large double-transfer ports.



➠ Thanks for any input you might have for me. 👍🏼

Cheers, 😃

Matthias
Click to expand...

Hi Matthias,

I have two P1s and .177, .22LR, .25LR and .30 barrels for them.

i have also made a number of custom hammer springs for them.

The P1 hammers are HEAVY - 30.65g !
The P2 used a hollowed out, much lighter hammer.

The P1 also used a very stiff 2.63” hammer spring (.38 OD and .24” ID). The P1 also had a delrin guide inside the hammer, you could remove it to help reduce hs pre-load if you wanted to shoot lighter weight pellets.

Interesting that your .30 barrel 600mm barrel has the big dual “slug” port. All my P1 barrels across all calibers use round “pellet” ports.

For your “low power” .30 experiment , it might be easier to use a P1.

With the P1, you can play with reg pressure and hammer spring preload to try to dial in your low power tune. You can also easily swap out to a lighter hammer spring or cut a coil or two off the stock spring.

My understanding of the P2 and P3 with balanced valves is that you primarily manage velocity solely with regulator pressure - so you have fewer variables to “tune” with.

I’m not certain whether your large barrel port will help or hurt your “low power” objective vs. the smaller round port on my .30 P1 barrel - I’d defer to Motorhead on that topic.

Hope this helps,

Ed
 
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