I wanted a U.S. MK 12 Mod 0 SPR rifle, but then added the cost up of all the options: my wallet said ouch; my fireman salary laughed at me.  It was shameful, I tell you.

So, I built an SPRish rifle.  I went with a Stag lower, A2 upper, NM sights front and back, B/BC/CH, early A1 stock from Moore Militaria, a Clark carbon fiber free float tube, a SPR barrel from White Oak Armament, and a RRA 2-stage trigger.  I can hit a 6" diameter plate at 300 yards with the iron sights using 69 and 77 grain home loads or other match ammo.

Quoted: some thoughts on timing, dwell and all of that....

That is very interesting and I can see where in full auto there might be a problem but if this is so bad than how come out of all the thousands and thousands of rounds I have fired through not only my personal carbine but my issued (several different ones) carbine also, I have never once had a malfunction at all?

Quoted: Quoted: some thoughts on timing, dwell and all of that.... That is very interesting and I can see where in full auto there might be a problem but if this is so bad than how come out of all the thousands and thousands of rounds I have fired through not only my personal carbine but my issued (several different ones) carbine also, I have never once had a malfunction at all?

Many of the carbine problems have been solved by things like M4 feed ramps and heavier buffers.  And some guns just plain run.  I watched 2K rounds go downrange on a 10.5 with a carbine buffer (the lightest), no o-ring and no other methods used to correct timing- it worked great.  Similarly, my personal guns have not always worked, even when using many of the proper parts.

WOW that was a great info quote!  I have to go back to link and see more!

One question though - author states that one out of two factors affecting dweel is barrel diameter.  IS this since a larger diameter means that the gas has a 'longer' gas port to flow through or is it some other reason/  If so, in essence, both factors are the same - the gas port.  

That info about hte bullet 'stops' is downright fascinating.

tag 4 SPR info

I have nothing special in mine or any of the ones I have been issued except for M4 feedramps and we all at ARFCOM know that those are worthless right But the bushmaster I had when I was an LEO had no feed ramps and it worked great too, all of ours did.

What rifle is ALL KAC stuff???  I know I have seen it...not the 308 one either.

Quoted: WOW that was a great info quote!  I have to go back to link and see more! One question though - author states that one out of two factors affecting dweel is barrel diameter.  IS this since a larger diameter means that the gas has a 'longer' gas port to flow through or is it some other reason/  If so, in essence, both factors are the same - the gas port.   That info about hte bullet 'stops' is downright fascinating.

yes... the flow through a tube is based on the dia and length of the tube... it does make enough of a difference that the port *should* be different sizes on a .625 and .750 barrel...

Quoted: Quoted: WOW that was a great info quote!  I have to go back to link and see more! One question though - author states that one out of two factors affecting dweel is barrel diameter.  IS this since a larger diameter means that the gas has a 'longer' gas port to flow through or is it some other reason/  If so, in essence, both factors are the same - the gas port.   That info about hte bullet 'stops' is downright fascinating. yes... the flow through a tube is based on the dia and length of the tube... it does make enough of a difference that the port *should* be different sizes on a .625 and .750 barrel...

dia and length of tube or port.  I'm talking bout the port from this line in quote:

Pressure from the port is regulated only by the size of the gas port and the diameter of the barrel.

Quoted: What rifle is ALL KAC stuff???  I know I have seen it...not the 308 one either.

SPR Mark 12 Mod 1 (Mod 0 has the PRI tube)

I think this one is by MSTN:

Is the basic advantage of a SPR rifle vs a Varminter type rifle that the varmit is typically more accurate but gives up mobility(due to weight) where the SPR gives up accuracy yet has more mobility.  Really I don't know but I would like to learn more about SPR's(allready read the wikipedia) link.

Quoted: Quoted: Quoted: WOW that was a great info quote!  I have to go back to link and see more! One question though - author states that one out of two factors affecting dweel is barrel diameter.  IS this since a larger diameter means that the gas has a 'longer' gas port to flow through or is it some other reason/  If so, in essence, both factors are the same - the gas port.   That info about hte bullet 'stops' is downright fascinating. yes... the flow through a tube is based on the dia and length of the tube... it does make enough of a difference that the port *should* be different sizes on a .625 and .750 barrel... dia and length of tube or port.  I'm talking bout the port from this line in quote: Pressure from the port is regulated only by the size of the gas port and the diameter of the barrel.

sorry... I should have not used the term tube, as it is confused with the "gas tube" proper... I ment the hole that is the gas port... I was just thinking about the tables that list the maximum flow through a *tube* based on source pressure, diameter and length of the tube... should know better than to think and type at the same time -- not at all the arfcom way

The port size *should* be adjusted for the smaller or larger barrel diameter at the port location... as this is not much of an issue anymore, with the defacto standard being .750 -- naturally, the larger dia barrel will have a larger hole...

When I had my SPR built it had to be a Mod0 because none of us had heard of the Mod1 yet. If I could do it all over again, it would be a Mod1 with LaRue parts. KAC parts are too hard to find and expensive, plus the LaRue parts are just a hair better quality anyway

Steve at Adco built a Mark 1 Mod 0 SPR for me. You asked about accuracy. How's this:



Bomber

Quoted: When I had my SPR built it had to be a Mod0 because none of us had heard of the Mod1 yet. If I could do it all over again, it would be a Mod1 with LaRue parts. KAC parts are too hard to find and expensive, plus the LaRue parts are just a hair better quality anyway

Do you have a pic of your SPR? And where can I get more info on Larue stuff? Thanks

Quoted: Quoted: When I had my SPR built it had to be a Mod0 because none of us had heard of the Mod1 yet. If I could do it all over again, it would be a Mod1 with LaRue parts. KAC parts are too hard to find and expensive, plus the LaRue parts are just a hair better quality anyway Do you have a pic of your SPR? And where can I get more info on Larue stuff? Thanks

Wes built my SPR several years ago.

This is the picture from his industry forum:


I payed a bundle for it at the time, but it did shoot sweet as hell. You could build one for way cheaper nowdays.

LaRue parts needed for a sweet Mod1:
(1.)LaRue 12.0
(2.)LaRue low profile gas block
(3.)LaRue bipod mount
(4.)LaRue SPR or SPR-EER scope mount

Just add a set of Troy flip-up sights and it would be damn near complete.

Quoted: Quoted: Quoted: When I had my SPR built it had to be a Mod0 because none of us had heard of the Mod1 yet. If I could do it all over again, it would be a Mod1 with LaRue parts. KAC parts are too hard to find and expensive, plus the LaRue parts are just a hair better quality anyway Do you have a pic of your SPR? And where can I get more info on Larue stuff? Thanks Wes built my SPR several years ago. This is the picture from his industry forum: photos.imageevent.com/smglee/mstn/large//SPRCrane.jpg I payed a bundle for it at the time, but it did shoot sweet as hell. You could build one for way cheaper nowdays. LaRue parts needed for a sweet Mod1: (1.)LaRue 12.0 (2.)LaRue low profile gas block (3.)LaRue bipod mount (4.)LaRue SPR or SPR-EER scope mount Just add a set of Troy flip-up sights and it would be damn near complete.

Would the larue rail allow me to maintain the FSB. I would like to keep the configuration as similar to my concept illustration as possible and I wont need to buy flip down front sights either

VB, what we are trying to tell you is that the FSB/Gas port setup you are talking about is inferior.  The timing is off.  The 18 inch is marginal as it is.  Why not look into a Recon from Global Tactical.  It is a 320 dollar 16 inch mid length.  Run a 12.0 Larue and you are in business, and the product is shorter, lighter, and cheaper than an SPR/Whatever that Hybrid thing is, and sacrifices only a few feet per second.

Quoted: Would the larue rail allow me to maintain the FSB. I would like to keep the configuration as similar to my concept illustration as possible and I wont need to buy flip down front sights either www.mstarmetro.net/~acouret/SPR%20custom.JPG

If the Larue is anything like the DD 12.0 then yes you could use the FSB.

From the illustration it looks like you would need:

Dissy Upper (your choice)
KAC M5 RAS (You should go with the free-float RAS instead) / DD 12.0 / LaRue
KAC 11 Rib Panels x 3 (if you didn't purchase the KAC RAS)
KAC MWS Rail Sling Mount
ARMS PEQ 2-3
ARMS #40L
ARMS #22 Medium Rings
ARMS #22TRC
ARMS #22TRR
Leupold Mark 4 LR/T 3.5-10 Illuminated with M3 Dials
Leupold Alumina 2.5" Sun Shade

If you do free-float you'll need a Action Block and a Vice to hold the upper in place, a Drift Punch to remove the FSB, and a Barrel Wrench to remove the A2 flash suppressor and remove the barrel nut / delta ring / etc.

With all that, you’ll have an upper that looks like the illustration, but whether you’ll get the performance you expect out of a standard barrel is another question.

Does anyone make an 18" barrel with a rifle length sight raduis? Since many here seemed very concerned about the dissy gas system and loss of velocity and accuracy I will consider a more proven gas system but with a minor loss of compactness

I've evolved my concept a bit to reduce cost even more, but at this point it is turning from an SPR into more of a DMR. New rail, removes the need for a ARMS PEQ, and Ive gone with an 18" barrel with rifle length gas system.

Quoted: VB, what we are trying to tell you is that the FSB/Gas port setup you are talking about is inferior.  The timing is off.  The 18 inch is marginal as it is.  Why not look into a Recon from Global Tactical.  It is a 320 dollar 16 inch mid length.  Run a 12.0 Larue and you are in business, and the product is shorter, lighter, and cheaper than an SPR/Whatever that Hybrid thing is, and sacrifices only a few feet per second.

You are wasting your time. VB knows pretty much nothing and bases his decisions on second hand bad info and goofy airsoft pictures. This thread is just further evidence of what a clown he is. Just watch, VB will get plenty of good advice but he will ultimately ignore it because it will contradict what a movie prop gun looks like.

Ok now I'm playing with you...

I took from the ARMS rail up from my SPR Mod 0 build and put it on a dissy.

You can decide if its really worth it for you, but at this point I would suggest just getting something like an MRP and a few barrels of various lengths to see what you like.

Quoted: Ok now I'm playing with you... I took from the ARMS rail up from my SPR Mod 0 build and put it on a dissy. www.hunt101.com/img/380702.jpg You can decide if its really worth it for you, but at this point I would suggest just getting something like an MRP and a few barrels of various lengths to see what you like.

OMFG, that is my concept!!! I hate you.

Go shoot it please and tell me what your groups are like at 300 yards. And have you had any cycling issues with the Dissy. Many here are concerned about the config

Speaking of SPR style rifles.

Here is Jason at JTAC SUPPLY's latest build.
Many thanks for a flawlessly beautiful upper.

Quoted: VB, what we are trying to tell you is that the FSB/Gas port setup you are talking about is inferior.  The timing is off.  The 18 inch is marginal as it is.  Why not look into a Recon from Global Tactical.  It is a 320 dollar 16 inch mid length.  Run a 12.0 Larue and you are in business, and the product is shorter, lighter, and cheaper than an SPR/Whatever that Hybrid thing is, and sacrifices only a few feet per second.

WOW, engineering brilliance.

Quoted: OMFG, that is my concept!!! I hate you. Go shoot it please and tell me what your groups are like at 300 yards. And have you had any cycling issues with the Dissy. Many here are concerned about the config

Like I said I'm playing with you, I took parts off of my SPR Mod 0 to show you what your design looks like in reality - I have no plans on keeping the rifle like this.

This is what it will look like after tonight:


In the pseudo SPR configuration the thing is over 10 lbs unloaded, a little much for a 16" if you ask me.  You'd save a lot more money if you went with something similar to the Dissy with ACOG vs. SPR-Dissy.

If you’re still planning to convert your RRA into SPR-Dissy how does it perform now?  Putting all the extra weight on the rifle will only make it heavier, and while the scope will help you keep your group size down, if your rifle isn't already accurate it won't be after you've poured all that money into it (unless your upgrading your barrel, then it should improve).

What size groups do you / your rifle obtain at 300 yards?  Because how mine performs and how yours performs isn't related.  I have put a 10x scope on a 16" before and they do fine out to 200 yards (max size of my range), though I only shoot for groups at 100 yards (too hard to see those small holes at 200, that and the weeds are too high).

Do you have any cycling issues now with the rifle you intend to convert?  If not then you won't after you FF and add the scope, etc.  It will be exactly the same, but with a lot more gear on it.  If you were to grind down / replace your FSB, install a FF tube over it, and add a new FSB in front of that you then have a Dissy (amazing I know ).

If you have your heart set on an SPR-Dissy and you think what you have now performs well then by all means go ahead.  I’m presently building a 18” SPR Mod 0 (almost exactly like Va_Dinger’s, but in 6.8) and it is so freaking heavy.  The next rifle I’m going to purchase will be an MRP, which will retain the advantage of the single upper rail, but cut down on the weight (of the SPR Mod 0).  Something to consider.

Beautiful gun Edwin! Is that the WOA 18" SPR barrel?

Quoted: Beautiful gun Edwin! Is that the WOA 18" SPR barrel?

No, actually it is a Krieger 1/7 18" SS.

Quoted: Quoted: Beautiful gun Edwin! Is that the WOA 18" SPR barrel? No, actually it is a Krieger 1/7 18" SS.

Nice - SPR profile? Any idea on what the over all weight of your rifle is?

ETA - I might have asked you this before but what camera do you use? You take the cleanest\sharpest photos I've even seen on the net. Stickman may poise and photoshop his photos a little better but the detail and color of your pics is just un-friggen-real!

Quoted: Quoted: Quoted: Beautiful gun Edwin! Is that the WOA 18" SPR barrel? No, actually it is a Krieger 1/7 18" SS. Nice - SPR profile? Any idea on what the over all weight of your rifle is? ETA - I might have asked you this before but what camera do you use? You take the cleanest\sharpest photos I've even seen on the net. Stickman may poise and photoshop his photos a little better but the detail and color of your pics is just un-friggen-real!

It's a Krieger SPR profile 18" barrel, and the overall weight with an empty 30 round mag is about 10.25 lbs by my best estimate from digital bathroom scales.

Many thanks for the compliments on my photos.
I use an Olympus 5MP E-1 DSLR usually with the 14-54mm f2.8-3.5 Zuiko lens and when I employ a flash it's the Olympus FL-50.

I could greatly improve the technical side of my photography by employing my Gitzo tripod, this would allow greater depth of field and sharper photos, custom white balance although the Olympus has a terrific white balance sensor, multi-flash lighting as I have several other flash units, custom exposure settings with my spot, light, and flash meters, a proper "studio" setup rather than just using the floor of the garage or computer/exercise room, shooting the photos in RAW for greater dynamic range instead of JPEGs, and of course extensive post processing of RAW images and my multiple software plug ins in Photoshop CS2 instead of the simple if needed Neat Image noise reduction/levels/shadow & highlight/sharpness/resize/sharpness/save for the web routine I employ with JPEGs.
However, that would be too much like work, and I've been very pleased with the results from a simple hand held approach and simplified workflow.

For instance, the photo of the SPR was taken with the E-1 at 14mm 1/50sec f3.5 TTL flash ISO 200 2560X1920 JPEG 3.51MB 0.0 EV compensation standing directly over the rifle & case with the flash bounced upwards with a Stofen Omni-Bounce.   The file was then cropped, levels adjusted, slight shadow adjustment, resized, mildly sharpened, and saved for the web in Photoshop CS2.

Pleasing photos are all about the light, Stick is a master with this and his results definitely show it.
Many of the photographers posting photos here are giving us amazing results, and all of them are using light to it's best effect.  Nothing competes with natural indirect light for a good photo, but for those using flash, bounced diffuse flash works extremely well.

I built my Mk12 Mod0 myself. I bought the barrel, matching bolt and correct Ops Inc brake with collar from Wes at MSTN when he had them. It was made using a Douglas premium blank (I think, I forget the specifics).

I put it together using the following:
-LMT M4 upper
-PRI tube,
-ARMS rail
-PRI flip up front sight
-ARMS medium rings
-Leupold VariX III 3.5-10 w/ M3 knobs
-RRA lower w/ RRA 2 stage trigger
-A1 stock
-Harris swivel bipod w/ PodLoc

I used the Harris because I find it to be much superior to the VersaPod that was on the originals. I also added an anti-cant device on the scope, and a sling stud to the stock so I can use my Tactical Intervention sling. I do have an old PWA lower, which is A1 style (doesn't have the reinforced buffer threads) that I want to use, but will wait on using it until I can get it bushing'd by G.A. Precision to take out the slop.




Here is a target I shot at 700yds with it using 77grn Noslers, Winchester Brass, CCI BR primers and 24.3grns of Varget.



The day I shot this, the wind on the firing line was absolutely horrible! The first 3 shots are in the cluster under the "point" of the daimond. The 4th shot was a called flyer due to a gust of wind blowing me off target and is the shot on the right side of the daimond. My fifth and 6th shot (6th shot to redeem myself for the f-up on shot 4) are directly under the first 3. Discounting shot 4, the group measures 3.5" across.

No, I can't do that all the time-but it does show what the rifle is capable of.