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Tested my Bulldog .308 conversion today. For slugs only. 3000psi, 171gr at 920fps (320fpe). That’s with the hammer adjuster flush with the receiver. I’ll try some other settings, but it’s close to what I want. Changes: 49” barrel, .295 dia transfer port in valve and barrel thimble, .120 dia pin probe. I ran it tethered today, but should get 5 shots from the attached bottle once it’s hooked up.

IMG_3326.jpeg
 
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Tested my Bulldog .308 conversion today. For slugs only. 3000psi, 171gr at 920fps (320fpe). That’s with the hammer adjuster flush with the receiver. I’ll try some other settings, but it’s close to what I want. Changes: 49” barrel, .295 dia transfer port in valve and barrel thimble, .120 dia pin probe. I ran it tethered today, but should get 5 shots from the attached bottle once it hooked up.

View attachment 516565
@Scotchmo Can you post some shot-string data? Is that something you built? What is a barrel thimble?
 
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@Scotchmo Can you post some shot-string data? Is that something you built? What is a barrel thimble?
I started with an M257 and did the conversion myself. A post of the shot string will be more pertinent once I get the bottle hooked up. Today’s testing was done tethered and every shot was at 3000psi.

If you want to know what it would do strictly from the plenum/air-tube, I might try that next time, but it will be a severe decline after two shots. It seemed to drop from 3000psi to about 2600psi after each shot.
 
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I started with an M257 and did the conversion myself. A post of the shot string will be more pertinent once I get the bottle hooked up. Today’s testing was done tethered and every shot was at 3000psi.

If you want to know what it would do strictly from the plenum/air-tube, I might try that next time, but it will be a severe decline after two shots. It seemed to drop from 3000psi to about 2600psi after each shot.

@Scotchmo Yes please keep us posted.
 
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@Scotchmo Yes please keep us posted.
I reoriented the bottle and hooked it up to the fill port threads (rather than make a front connection). It’s a 400cc bottle from a Gauntlet 2. It can go to 4500psi, but 4000psi is a more practical fill pressure while at the range. Even if I take a purge shot, it looks like I’ll get 5 good shots for target shooting at a match while untethered.

The old Ninja bottle reg needs some attention as it is inconsistent and creeping some. Pressure readings are approx psi with small gauges.

Arsenal .308, 171gr BT
Bottle(psi), plenum(psi), FPS
4000psi, 3100psi, 943fps
3900psi, 2900psi, 932fps
3700psi, 2900psi, 910fps
3500psi, 2900psi, 911fps
3200psi, 2800psi, 940fps
3000psi, 2750psi, 916fps
2900psi, 2600psi, 897fps
2800psi, 2500psi, 881fps

This thing is light enough and kicks hard enough to make it hold sensitive. I managed some decent 5 shot groups, using a bipod, on a bench, at 100yds. 3/5 inside the 10 ring on the first group (some good luck).

IMG_3335.jpeg


IMG_3339.jpeg
 
@Scotchmo I wasn't expecting to read that the .257 (.308 mod) is also hold sensitive. The M357 certainly is. Thank you for sharing what appears to be honest groups.
The M257 probably isn’t, but I’m not surprised that this .308 is hold sensitive.

Big difference between 140fpe and 320fpe. Also, long barrel and slow acceleration of the heavy for caliber projectile. That makes it more difficult to keep a light weight rifle on target.
 
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In the All Things Bulldog thread, I've got a basic bulldog question. I ordered my M357. I would like to order a couple spare magazines.

I've looked, and asked (ChatGPT 4o) and have learned that the .357 and M357 (allegedly) use different mags. Can't seem to find a PN, or in-stock for the M357. Are they that hard to come by? And, is there a PN for them? Found one on Amazon that Amazon says is for my M357, but the listing says it is for the .357. Different model numbers for the platforms leads me to believe the listing, and not Amazon, is right.

Does the M357 take the RC357 Auto Indexing Magazine?
If not, what is the part number for the M357 Magazine?


I'm guessing the information I'm requesting MIGHT be answered when my M357 arrives. I'd like to have those mags on the way before then... And, it could be handy (from my day 1 perspective) to have a list of Caliber/generation::Magazine, here in the Bullpen!

Thanks to whoever answers (and doesn't call me out on my greenness. :ROFLMAO:;))
 
In the All Things Bulldog thread, I've got a basic bulldog question. I ordered my M357. I would like to order a couple spare magazines.

I've looked, and asked (ChatGPT 4o) and have learned that the .357 and M357 (allegedly) use different mags. Can't seem to find a PN, or in-stock for the M357. Are they that hard to come by? And, is there a PN for them? Found one on Amazon that Amazon says is for my M357, but the listing says it is for the .357. Different model numbers for the platforms leads me to believe the listing, and not Amazon, is right.

Does the M357 take the RC357 Auto Indexing Magazine?
If not, what is the part number for the M357 Magazine?


I'm guessing the information I'm requesting MIGHT be answered when my M357 arrives. I'd like to have those mags on the way before then... And, it could be handy (from my day 1 perspective) to have a list of Caliber/generation::Magazine, here in the Bullpen!

Thanks to whoever answers (and doesn't call me out on my greenness. :ROFLMAO:;))
@air_raid_abq They use the same magazine. If they don't, the old .357 mags work in the M357. You can grab new ones cheap from Pyramyd AIR or just about any airgun retailer.
 
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