My 6.5 SPR build

[frank]

I'm going to use this thread to document my 6.5 SPR build. If I don't get in a hurry (like I normally do), I'll take lots of pics of the process. My goal is for an SPR-type rifle (think MK12) in 6.5 Grendel.

I'm starting with a Noveske N4 light in 5.56. I will use the lower for both my current N4 carbine and the new 6.5 SPR upper. The lower consists of a Noveske receiver, Geiselle SSA-E trigger, and a B5 Sopmod stock. The SSA-E and Sopmod were recent additions with this build in mind.

For the upper, I've obtained a Satern barrel and bolt purchased used locally. The barrel is 24", SS, heavy profile, fluted to the gas block. Since 24" does not fit the SPR profile, I'm going to send it off to Adco to have them cut/thread/crown, enlarge the gas port, and bead blast the finish. I'm still undecided on the final length (thinking 19 to 19.5").

Other parts that I have obtained for the build include a PRI 14" carbon fiber free float handguard, a Badger low pro gas block, and a PSA blemished upper.

I still haven't decided on a muzzle device yet. I'm considering staying true to style for the MK12 and going with the Ops Inc brake and collar, but I don't really want to spend the money for the contouring needed for the collar install; especially when I don't plan on getting the suppressor. I might just go with the AAC single chamber brake because it won't add much length to the barrel.

Feedback and recommendations are welcome.

[ricsmall]

Welcome! Sounds like you've done your homework on this build. What size are you going to have the port enlarged to? Good to have you here.

Richard

[frank]

Welcome! Sounds like you've done your homework on this build. What size are you going to have the port enlarged to? Good to have you here.

Richard

Depends on what length I have it cut to. I've come up with a formula that I think will get me pretty close. For a 19.5" barrel, I believe that the ideal port size should be 0.098".

[Drifter]

If your gas block seat is 0.875", be careful with the gas port enlargement. The options for an adjustable 0.875" gas block are very limited. PRI and Paladin are the only ones that come to mind.

If the gas port is undersized, you can always enlarge it as necessary if you have something else in mind regarding the gas block.

FWIW, I have a used-up Satern that was cut to 19.5" and it ran fine with the original 0.094" port.

I'm currently running a Satern cut to 18" with 0.091" gas port, and it's a little finicky.

[frank]

If your gas block seat is 0.875", be careful with the gas port enlargement. The options for an adjustable 0.875" gas block are very limited. PRI and Paladin are the only ones that come to mind.

If the gas port is undersized, you can always enlarge it as necessary if you have something else in mind regarding the gas block.

FWIW, I have a used-up Satern that was cut to 19.5" and it ran fine with the original 0.094" port.

I'm currently running a Satern cut to 18" with 0.091" gas port, and it's a little finicky.

Thanks. I measured the gas port on my Satern at 0.094", so it sounds like it will be fine leaving it where it's at if I go with 19.5". My original plan was to have it cut to 19.5 and leave the gas port alone. When I found out that Adco includes enlarging the port (if necessary) when they shorten a barrel, I figured I'd let them do it. After your confirmation that it will work with the current port size, I guess I'll leave it alone and see how it runs.

[m796rider]

I did a very similar SPR-type Grendel. I started with an AA 19.5" barrel and had it cut to 18.25" with no change to the gas port. It functioned perfectly with the Hornady 123gr Amax factory loads but did not like the Wolf Gold 120MPT ammo.

[Drifter]

In part, it will depend upon the ammo. Factory ammo and reloads with slower-burning powders will run better than reloads using light bullets and fast powders.

The barrel that I had cut to 19.5" was 20" to begin with, so didn't really expect any significant reliability issues.

My main point is that an overgassed systems sucks, and the selection of .875 adjustable gas blocks is limited. So if the port is enlarged too much, it's not an ideal scenario.

[frank]

m796- That is a sweet stick! I really like the way the extended gas block and the overlapping suppressor mount minimize the exposed portion of the barrel. I've got the Centurion C4 rail on my carbine, and love it.

Drifter- Do you prefer the 18" or the 19.5"? My rifle will mainly be used for target shooting off of a bench or prone, but I'd still like to be able to hunt with it if the opportunity ever came up.

[Drifter]

Drifter- Do you prefer the 18" or the 19.5"? My rifle will mainly be used for target shooting off of a bench or prone, but I'd still like to be able to hunt with it if the opportunity ever came up.

I don't really notice much difference. To some degree, I suppose it boils down to appearance and what looks right to your eye. That being said, 19.5 is more likely to run reliably without enlarging the gas port.

This was my 19.5 Satern:



The 18 Satern is the top one (camo), and the bottom one is a 20 Shilen with target crown:

[frank]

Thanks. The pictures help. The 18" definately looks best to me, but I also have to consider that I will be running a 14" handguard that will "shorten" the look of the barrel. Maybe I should just split the difference and go with 19"...

[frank]

I sent my barrel off to Adco. I decided to go with 19". I'm also now considering the Barrett M468 muzzle brake; it is small and has the right look that I am going for.

[joker31]

I have a 18" Satern that I had custom profiled for the OPS inc. by Satern. I called someone at OPS and got the profile info (Drawing) and sent it to Satern to have them make my barrel that way from the start. I do plan on using an OPS Can and used them in Afghanistan so I know what a benefit they are. I suggest the OPS inc Brake which looks just like the one that is made for the suppressor but doesnt require the shoulder. I built mine for hunting in my Wounded Warrior group. All ex group guys hunting is scary to Game Wardens, especially when they stopped to talk to me and didn't see the 4 others in Ghillie until I told them to break cover. Anyway, I hunt with the 18" Satern and 2 other guys in my group have them on order, Satern Barrels are the best there is as far as I'm concerned. Also if you dont want to spend OPS inc money you can use a Ross Schuler brake. (Looks good and he will custom profile them to order) I use a Ross for now because Florida won't let us hunt with cans for now. (Hopefully change soon) I am waiting for my can to get here because the can comes with the collar and adapter. BTW the MK12 was way overrated, seen A4's make the MK12's look stupid when Marsoc guys were out on mission with us.
Ross Schuler Brakes [ATTACH=CONFIG]3801[/ATTACH][ATTACH=CONFIG]3800[/ATTACH]

Griffin Armament Brakes[ATTACH=CONFIG]3802[/ATTACH]

OPS Inc Brake[ATTACH=CONFIG]3803[/ATTACH]

[frank]

I have received the stripped upper, bolt carrier, and handguard. I received the handguard last night. It is the 14" raw carbon fiber version without the rails. Sometimes, buying a quality component just gives you a warm and fuzzy. The PRI is a work of art!

Now that all the large components are here, I'm getting really excited about the build. Just need to order some small parts and wait for the barrel to come back from Adco.

[frank]

Got my barrel back from Adco yesterday; they do nice work. I should receive the remaining small parts from Midway on Thursday and be able to assemble over the weekend. Here is a photo of the barrel and handguard as a teaser:

[frank]

Finally got her together and took some pics. The scope and rings are cheapie and temporary- just for functional testing purposes until I can get the scope that I want.

[500]

Looks great!

[frank]

I finally got a chance to shoot my build this weekend. Really just a function check, but I did fire a couple of groups. I am pleased to report that it is 100% functional with all three magazines (two ASC 17 rounders and one CPD 24 rounder). Ejection was about 3:30. About half the brass had a very small dent from the brass deflector (not big enough to worry about).

After sighting it in, I fired two 3 round groups at 100 yds using Hornady 123gr A-max. The first group measured 0.7". The second group sucked (about 1.5"), but I didn't feel very good about two of the shots. The range that I shot at had hanging cardboard backer targets that flapped in the wind. I had to try to time my shots as the target flapped down. I'm also getting used to the two-stage SSA-E trigger; my other precision rifles have extremely light (10 oz and 1.5 lb) single stage triggers. Since I'm sharing this lower with my 5.56 carbine, I needed to compromise on the trigger. The cheapy temporary scope didn't help either. The Viper HS-T will be a huge improvement!

Overall I am pleased. With so many unknown variables (barrel length, gas port diameter, ejector spring mod, etc), I'm thrill that it is 100% functional right off the bat. The first group shows the accuracy potential when I do my part. I'm really looking forward to mounting a real scope on it and stretching its leggs out.

[usmc1371]

nice looking stick frank. im doing my homework on a spr styled upper. looking for the right barrel know.

[MrFrankZ]

I am digging the PRI handguard. What is the weight on that thing? I am bouncing between the Seekins SP3R and the Lancer LCH, but yours just made itself a contender now that I see it actually mounted.

[cory]

I am digging the PRI handguard. What is the weight on that thing? I am bouncing between the Seekings SP3R and the Lancer LCH, but yours just made itself a contender now that I see it actually mounted.

There's a user on here that makes carbon fiber hand guards, if you're looking to go as light weight as possible.