Something Different

[SkyScrapin]

Back in 2012-2014, it seemed impossible to get a Surgeon 591r. Granted I didn't look all that hard, but when I saw one for sale at CS Tactical, I quickly jumped on it with the idea of building a coyote rifle in 22-250ai, but that never happened. Like most of you, my collection has grown over the years and all of my 'purpose built' rifle needs have been met. Back to the Surgeon... With the previous administration's NFA gun trust reform, I decided to go ahead and Form 1 the 591r for a truck gun or similar. Fast forward a couple more years and this is the result:

.308 Win
Surgeon 591r
KRG Whiskey 3 Gen4
Bartlein Barrel
BarLoc
SAS Resistor
Mod22 Trigger
SPUHR
S&B US 5-20

It's a quick mock-up as it's not yet bolted to the chassis. Of all my rifles, this one just might be my favorite. Plan is to hand load 135g SMK supers and 185g Juggernaut subs. Interested to see what sort of velocity it will be bring.

 

[Massoud]

That looks superb!
Justin

 

[Boltfluter]

Very cool truck gun. Should be lots of fun.

Paul

www.boltfluting.com

 

[SkyScrapin]

That looks superb!
Justin

@Massoud Looking at the side profile, do you have a part that would allow me to clip-on a PVS-30?

 

[Shrubjr]

Looks Awesome! What barrel length is that?

 

[SkyScrapin]

@Shrubjr With the barrel removed, it's 11" from end-to-end. Installed it's like 10".

I took some muzzle velocity readings with my 135g SMK loads and H322 powder. Suppressed shooting at 546ft, no wind, hot @ 96F, 43% humidity, and 29.98inHg.

Results:
41 - 2338
41.5 - 2394
42 - 2478
42.5 - 2422
43 - 2489
43.5 - 2545
44 - 2548
44.5 - 2612
45 - 2590
45.5 - 2666
46 - 2679
46.5 - 2704 (compressed)
47 - 2712 (compressed)

43.5-44 seems to be a sweet spot for common velocity. 46, 46.5, and 47 were in a very tight cluster. Going to load up 5 rounds of each to check SDs.

I shot some loads of Trailboss and 185g Juggs for stability in this 11.25" twist Bartlein with amazing results. 10.6g stacked the Juggs at 100 yards. No idea if it's subsonic because checking stability was the only goal.

 

[Shrubjr]

Wow! Those are some impressive results! Thanks for takin time to share 'em with us! Your gonna make me second guess the 10" bolt action 300blk I'm doin.

 

[SkyScrapin]

IMO, caliber is less important than form factor.

The BarLoc makes barrel swaps easy and all you’d need is a new bolt. I originally intended to utilize the West Texas Ordanance Switch Lug, but after talking with @LongRifles Inc., the BarLoc loads the threads where as the Switch Lug does not. I couldn’t be happier with how this rig turned out.

 

[Roadkill4us]

That is SEXY!!

 

[Lionsbreath]

Sexy doesn’t adequately describe this rig! Awesome project, I dream of stuff like this... someday...

 

[Sinocopa]

Looks sweet!

 

[lead ƒarmer]

Very cool! I'd love to have something like that. I love how the suppressor and barrel are basically the same length! Might look good with a Brevis II on there....

 

[Dirty D]

Drop that BA into a folding chassis and you can use a tennis racket case to carry that thing around in (very low profile).

 

[Diablo]

Looks like fun

 

[SkyScrapin]

Drop that BA into a folding chassis and you can use a tennis racket case to carry that thing around in (very low profile).

The Wiskey 3 is a folding chassis. I envisioned riding my motorcycle to the range with the rifle in a backpack. Unfortunately, timing sucks because I just sold the bike. I see myself picking up a new set of wheels over the fall/winter months. We'll see.

 

[blbennett1288]

That thing is slick...i want a shorty now lol

 

[Boltfluter]

Those are some amazing speeds for such a short barrel. Looks like you picked the correct powder. Nicely done. Looking forward to group
shots when you have a good load.

Paul

www.boltfluting.com

 

[savagepc.223]

Very cool. I’d love to see some groups out of it

 

[Massoud]

@Massoud Looking at the side profile, do you have a part that would allow me to clip-on a PVS-30?

With that can being so close, our INVR and NVMC both won't fit as they won't clear the can. The Enclosed Forend might fit around that can. Actually you might be able to run the INVR backwards so it's only inside the barrel channel and not sticking out forward of the forend. I'll see what I can find out. Thank you for your business!
Justin

 

[SkyScrapin]

Those are some amazing speeds for such a short barrel. Looks like you picked the correct powder. Nicely done. Looking forward to group
shots when you have a good load.

Paul

www.boltfluting.com

No doubt - the velocity spread shocked the hell out of me too. There isn't much if any data on SBR bolt guns and thus it was a shot in the dark as far as starting points. I have to give @Zak Smith credit for that. We discussed this project several months back, right when I was deciding to run either the Resistor or Ultra 9.

 

[SkyScrapin]

I’m still fireforming brass until starting the load development process, and while I’m by no means shooting groups with this rifle, it has been quite interesting to shoot at distance. With a 100 yard zero, it takes me 19 mils of elevation to get to the 1036 yard gong. By contrast, my 6x47L takes 7.5 mils elevation at the same distance. TOF for the short 308 seemed to be around 2 seconds, but will need to run the numbers to see if that’s accurate. Wind was blowing the 135g SMK another 5 mils off Target.

 

[jordan0317]

That thing is baller as fuck

 

[SkyScrapin]

@Massoud Hey Justin, any feedback on measurements to allow a PVS to mount up over the short barrel without interference?

 

[Dougie308]

Back in 2012-2014, it seemed impossible to get a Surgeon 591r. Granted I didn't look all that hard, but when I saw one for sale at CS Tactical, I quickly jumped on it with the idea of building a coyote rifle in 22-250ai, but that never happened. Like most of you, my collection has grown over the years and all of my 'purpose built' rifle needs have been met. Back to the Surgeon... With the previous administration's NFA gun trust reform, I decided to go ahead and Form 1 the 591r for a truck gun or similar. Fast forward a couple more years and this is the result:

.308 Win
Surgeon 591r
KRG Whiskey 3 Gen4
Bartlein Barrel
BarLoc
SAS Resistor
Mod22 Trigger
SPUHR
S&B US 5-20

It's a quick mock-up as it's not yet bolted to the chassis. Of all my rifles, this one just might be my favorite. Plan is to hand load 135g SMK supers and 185g Juggernaut subs. Interested to see what sort of velocity it will be bring.

Nice hardware!

 

[m6z]

Nice.

I keep going back and forth on barrel length on my build. Think I'm leaning towards 16.5" now.

 

[SkyScrapin]

Nice.

I keep going back and forth on barrel length on my build. Think I'm leaning towards 16.5" now.

If you have multiple rifles or the capability to switch barrels, do it. I have a handful of .308 rifles in 22", 16" and now this 11". It's every bit as accurate as the others, and certainly handier with a suppressor.

Did some shooting last week and found a subsonic load with 185g Juggs that print .5-.6" at 100 yards. My expectations were blown away... Think load development for subsonics is all but done at this point.

Still working on my 135g SMK supersonic load. When it's pushed to 2700 fps, there are light ejector marks. Probably going to dial it down to 2650 fps and try to find a node after I'm done fireforming brass.

 

[Charger442]

To the OP, wrote this up on another forum a few years ago when talking about the speed of sound. i noticed you gave a bunch of atmospheric readings and wanted to drop this equation here for you. The actual speed of sound, on a given day, is only dependent on temperature. Thats not to say tone doesnt change with other variables but the sound barrier is calculated based on temperature being the only variable.

everyone thinks that atmospheric pressure has something to do with it but that falls out of the equation before you get to the final equation. your specific gas constant is calculated using the universal gas constant and the molecular weight of air. Molecular weight or molecular mass is the mass of one molecule of that substance, air, and that weight doesn't change with density.

for those wondering, here are a few equations and a refresher on calculating speed of sound.

we'll use U.S. Customary Units.


Ss = sqrt[k*gc*R*T]


Ss= speed of sound
k= specific heat of air = 1.4
gc= gravity = 32.2 ft-lbm/(lbf-sec^2)
R= specific gas constant for air
T= absolute temperature in Rankine= degrees in F plus 460 (or 459.67 to be exact)


1st, calculate the specific gas constant:

R= R* / MW

R* = universal gas constant in Rankine units = 1545.4 ft-lbf/lbmol-Rankine
MW = molecular weight of air = 28.967 lbm/lbmol

R= 1545.4 / 28.967 = 53.35 ft-lbf/lbm-Rankine

Temperature at my shooting time: 37 deg F = 497 Rankine


Therefore:


Ss = sgrt[ (1.4)*(32.2)*(53.35)*(497)]

Speed of sound on Saturday was = 1093.3 FPS




so to simplify this down, to calculate speed of sound for a given temperature (x in Fahrenheit), use this equation:

Ss = sgrt[ (1.4)*(32.2)*(53.35)*(x+460)]


obviously, these equations treat air as an ideal gas.

 

[spife7980]

To the OP, wrote this up on another forum a few years ago when talking about the speed of sound. i noticed you gave a bunch of atmospheric readings and wanted to drop this equation here for you. The actual speed of sound, on a given day, is only dependent on temperature. Thats not to say tone doesnt change with other variables but the sound barrier is calculated based on temperature being the only variable.

everyone thinks that atmospheric pressure has something to do with it but that falls out of the equation before you get to the final equation. your specific gas constant is calculated using the universal gas constant and the molecular weight of air. Molecular weight or molecular mass is the mass of one molecule of that substance, air, and that weight doesn't change with density.

This is easier, just plug in the temp

 

[Charger442]

This is easier, just plug in the temp

of course, just giving everyone a little background.

 

[SkyScrapin]

To the OP, wrote this up on another forum a few years ago when talking about the speed of sound. i noticed you gave a bunch of atmospheric readings and wanted to drop this equation here for you. The actual speed of sound, on a given day, is only dependent on temperature. Thats not to say tone doesnt change with other variables but the sound barrier is calculated based on temperature being the only variable.

everyone thinks that atmospheric pressure has something to do with it but that falls out of the equation before you get to the final equation. your specific gas constant is calculated using the universal gas constant and the molecular weight of air. Molecular weight or molecular mass is the mass of one molecule of that substance, air, and that weight doesn't change with density.

Solid insight - had no clue. I'm targeting about 1050fps< which means my bullets will be under the sound barrier from 0+ degrees Fahrenheit. Pretty dope. I still haven't chrono'd the Subsonics, but I'd venture to guess I'm right around 1,000 fps. I'll go chrono a few next time I have the rifle out testing 135g SMK loads.

 

[Dendro]

Oh yeah that’s cool, not something you see everyday

 

[Charger442]

Solid insight - had no clue. I'm targeting about 1050fps< which means my bullets will be under the sound barrier from 0+ degrees Fahrenheit. Pretty dope. I still haven't chrono'd the Subsonics, but I'd venture to guess I'm right around 1,000 fps. I'll go chrono a few next time I have the rifle out testing 135g SMK loads.

1050 is always a good, easy rule of thumb. and its why i dont understand (yeah i know this is kinda off topic because its about rimfire) the need for the CCI suppressor ammo doing 970 fps or the CCI Quiet ammo doing 710 fps. CCI standard does 1070 and thats subsonic as long as its above 16 F outside.