Geissele Cut Rifled SPR Build and Barrel Evaluation. (Part 3 Completed 10MAR25)

[Bigjake83]

Hello Snipershide!

Geissele Automatics has been offering Single Point Cut Rifled Barrels for close to two years now but they've been restricted to the 6 ARC Stratomatch or blanks that the end customer could have custom turned from barrel manufacturers like White Oak Armory.

Two weeks ago Geissele proudly released thier new 18" SPR Cut Rifled Barrels to the public.

At the time of their release I purchased 3 of the new SPR Barrels for testing and evaluation. Geissele seems to have paid close attention to the features customers want today.

Barrel description:

18" Single Point Cut Rifled
5 Right Hand Lands and Grooves
Geissele 3 Port Phased Array Gas System
416 Stainless Steel
1-7 Twist
.223 Match Chamber
5/8x24 Threads
Rifle Length Gas
.750 Gas Block Journal
M4 Feed Ramps
Bead blasted finish

The quality and the machine work on these SPR barrels are as good as they Come, truly impressive.

The SPR Barrel has a precise and clean cut 11° Taget Crown the is chamferred, delivering exceptional accuracy and greater protection.

The Geissele Proprietary Phased Array Gas System utilizes a unique 3 Gas Port Design. Each Gas Port is .063" in diameter and is located at varying distances from the Gas Block Journal Shoulder with a milled spiral cut that Channels the gas from all three Gas Ports, equally dispersing gas pressure for a smoother recoil impulse resulting in faster Sight Recovery and Target Acquisition.

Each gas Port has a forward facing Teardrops Style Chamfer eliminating any possibility for developing a Burr at the Gas Port which can be detrimental to accuracy.

internal View:
Each Gasport is perfectly centered in a Groove.

As I stated above the machine work on these Cut Rifled Barrels are truly a work of art, I've performed a Side-By-Side Borescope Comparison between a Craddock Precision Bartlein .223 and the new Geissele SPR barrel.

Geissele:

Throat:

Neck:

Base:

Shoulder:

Tenion Face:

Craddock Precision Bartlein:

Throat/Neck:

Base:

Lands and Grooves:

Gas Port:

Tomorrow  Part 2, Upper Assembly.

Jake.

 

[oldrifleman]

So standard gas blocks work?

 

[Bigjake83]

So standard gas blocks work?

Yes Sir, I'll cover that tomorrow in Part 2 with the Upper Assembly Tutorial.

But in short I pressure tested multiple gas blocks and the Clamp On was the most efficient in eliminating unwanted gas leaks.

 

[Gasgun]

Is this a Wylde chamber?

 

[max1840]

Very nice rundown. Looking forward to part 2 and waiting on barrel restock

 

[346ci]

Really nice to see 5/8-24 threads on a .223, hope more follow.

Crazy gas port design, did they do that to keep them out of the lands?

 

[Maelstrom]

I would love to see these offered in a couple other calibers like .22 ARC, 6.8 SPC II, and 6 ARC.

 

[TheOE800]

I would love to see these offered in a couple other calibers like .22 ARC, 6.8 SPC II, and 6 ARC.

I’d love to see this with a KAC E3 extension and Mod 2 (or Ridgeline) gas system. Best of all worlds.

 

[Bigjake83]

PART 2

Due to the success and phenomenal accuracy with my SOLGW / Geissele Heavy Contour Chrome Lined Barrels Builds,
I thought it best to build the SPR Rifle with the exact same parts and features for the side-by-side comparison and range report for the Geissele SPR Cut Barrel Vs Heavy Contour Chrome Lined.

Every aspect of the two builds will be identical to keep everything Apples to Apples, with the exception of the barrels.

BUILD PARTS LIST FOR BOTH RIFLES.

SOLGW BROADSWORD BUILD KIT

Tuned Geissele SSA-E X (2lb - 6oz)
(Haven’t forgotten you @j-moose32 )

VLTOR A5 H2 Buffer / JP Polished Rifle Length Spring / Dark Hour 13 Position Receiver Extension.

Geissele reliability enhanced BCG

Superlative Arms .750 Adjustable clamp on Gas Block

Dead Air Xeno Muzzle Device

Along with the New Complete SOLGW / Geissele Cut Rifled SPR Barrel I assembled a Complete Upper that will eventually go to the PX.

Unfortunately the barrel extension on the new Cut SPR barrels aren't oversized so thermofiting wasn't an option so I went with the Loctite 620 for bedding the barrels.

The Heavy Contour Chrome Lined Barrels have a tighter fit because of the Manganese Phosphate coating on the barrel extension.

The Upper Assembly process is pretty generic, but there's a few specific steps I want to touch on. I'll briefly run down the steps I take during Assembly.


ASSEMBLY
Reaction Rods have thier place in the Tool Box but I prefer the AR Upper Receiver Jig for Assembly. I apply painter's tape to take out any tolerance variation between the Jig and the Upper Receiver mounting points to eliminate any flex when torque is applied.

Whenever Assembling anything new with various fresh parts you always want to carefully perform a mock-up assembly to make sure each part plays well with others, before the Loctite comes out to play.

(1) After you secure your Upper Receiver with your preferred method you want to SEASON the Upper Receiver and barrel nut threads by repeatably torquing the barrel nut to 70 Ft-lbs, make sure to apply Anti-Seize to the upper receiver threads before working the threads.

Once you've seasoned the threads you want to lightly sand the mating surfaces with 400 Grit Sandpaper then clean with a Contact Cleaner like Carb Cleaner then wipe with a sterile cloth, Evenly apply a liberal amount of 620 inside the Upper Receiver Barrel Extension Channel same with the Barrel Extension itself.

When Inserting the barrel you want to directly aligned the barrel to the upper receiver so that you keep the coating of 620 even to eliminate any voids or air bubbles.

Apply direct pressure with the barrel to the Upper Receiver Face taking care not to tilt the barrel keeping the barrel extension and receiver face true.

With your free hand wipe away any excess 620 so it doesn't get worked into the barrel nut threads, firmly hand torque the barrel nut on. Use a quality Torque Wrench for accurate torque specs, between 55-60 Ft-Lbs seems to be the sweet spot for dampening Barrel Harmonics.


Basically apply the same steps when pinning the Gas Tube to the Gas Block.

Make sure to apply 620 to only the end of the gas tube and the aft end behind the gas port of the tube so that the 620 doesn't get into your Gas System. Insert a Q-Tip into the Gas Port of the Gas Block and clean, it will give you a visual indication if any 620 made its way inside the gas tube, when using a AGB perform these steps with the adjustment screw wide opened and after a few minutes work the adjustment screw to rule out any contamination.

Insert a properly sized punch through the gas block roll pin hole and tube for proper gas tube alignment while the 620 cures, applying some low heat from a heat gun will expedite the curing process.
Allow both the barrel and gas system a couple hours to cure.

( I know these steps seem like a pain in the ass but when assembling a quality build these tedious steps make a huge difference in long-term reliability, performance and OPERATIONAL CONSISTENCY)

Operational consistency, proper parts installation/selection and quality ammo are the basic foundation of producing a exceptionally accurate rifle.

This next part is something I think is worth going into detail with.


Proper Gas Tube alignment is one of the most looked over steps that can dramatically affect accuracy.

When using a low profile fixed Gas Block it's very common for the standard off the shelf contoured gas tubes needing to be recontoured for proper alignment over the barrel nut.

The pictures below are a Before and After that perfectly illustrates this issue and the alignment after being recontoured. Because of the Geissele low profile fixed Gas Block neither a straight or "standard" contoured gas tube will have perfect alignment. I'm sure Geissele has rifle length tubes that are specifically made for thier gas block height.

When you're finished you should be able to smoothly slide the carrier evenly back and forth without making hard contact with the gas tube and the Gas Key of the bolt carrier.
Also when you seal and bed the gas tube to the gas block it increases the gas tube rigidity removing gas tube sag for optimum alignment.

In the pictures below with the handguard and BCG removed you can see how the gas tube is perfectly centered and not making contact with the top or bottom of the Gas Tube Port, but perfectly hovers in the center.

Geissele acknowledges with the release of thier new Cut Rifled SPR Barrel and it's proprietary gas system that there will be gas leaks but it won't detrimentally impact reliability and function.

I ran several Hydrostatic Pressure Test with 3 different types of gas blocks by sealing off both the chamber and muzzle, with the upper upside down laying flat I sprayed carb cleaner directly into the gas tube then shot a pressurized charge of air down the gas tube.

Both Standard Set Screw and the Geissele Set Screw with the pre-drilled pinning holes failed, the only gas block that had 100% retention was the Superlative Arms Clamp On Gas Block with only a few drops of contact cleaner that dribbled out of the bleed off port.

what did this testing prove?? Not much... only that the clamp on gas block produced the tightest seal, in no way did this test prove that set screw gas blocks would be less reliable.

For set screw gas blocks I torque mine to 15 in-lbs and use red thread locker.

If the build permits the use of superlative arms clamp on adjustable gas blocks they are my go-to for precision builds. I torque my clamp on gas blocks between 30-35 in-lbs.

Moving forward to the next steps of completion everything is pretty much basic assembly, just take care to not over torque the gas block set screws and muzzle devices. Most muzzle devices that require shimming should be timed and torqued around 20 Ft-lbs with a drop of thread locker.

Geissele 18" SPR Complete Build.

Part 3 will be initial Set-Up and Range Report.

 

[oldrifleman]

Great build instructions. I am about to do my first full upper build. Need to copy this post!

 

[B Man]

Sub’d

 

[Kadams1563]

Do they make these in 13.9?!?

 

[Bigjake83]

Do they make these in 13.9?!?

Do they make what? In 13.9"... barrel, handguard??

 

[Bigjake83]

I would love to see these offered in a couple other calibers like .22 ARC, 6.8 SPC II, and 6 ARC.

You and me both brother, i wouldn't doubt that the 6ARC Stratomatch with its cut rifled blanks already have it.

Geissele is SERIOUSLY making some big moves in all the right directions.

 

[Bigjake83]

I’d love to see this with a KAC E3 extension and Mod 2 (or Ridgeline) gas system. Best of all worlds.

In a Larue Tactical Smal Frame OBR Receiver Set with full ambidextrous controls...

 

[camotoe]

Chubby.

 

[NHPiper]

Thanks for all the work on this @Bigjake83, appreciate you taking the time to document your assembly process as well.

Will you test these with the SPR Ops12 style collar and AEM5/OCM5 suppressors since they have that capability? I would like to run my OCM5 on the barrel. But have found that reflex cans sometimes have poor harmonics when it comes to barrels, even worse with bolt guns. So I would be curious how these run. I'd be happy to ship over a Otter Creek flash hider and SPR collar if you need one to screw a can on with.

 

[Bigjake83]

Thanks for all the work on this @Bigjake83, appreciate you taking the time to document your assembly process as well.

Will you test these with the SPR Ops12 style collar and AEM5/OCM5 suppressors since they have that capability? I would like to run my OCM5 on the barrel. But have found that reflex cans sometimes have poor harmonics when it comes to barrels, even worse with bolt guns. So I would be curious how these run. I'd be happy to ship over a Otter Creek flash hider and SPR collar if you need one to screw a can on with.

No worries, I enjoy contributing to the Hide and highlighting quality products.

I don't have any reel need to go down the Ops12 AEM5/OCM5 Suppressors hole, it's an iconic design and if I every get the itch for a clone correct MK12 I might entertain the idea.

Jake.

 

[Bigjake83]

Taking the SPR out today

 

[Kadams1563]

Do they make what? In 13.9"... barrel, handguard??

This thread is about a barrel correct? So yea. That’s what I was asking about. I want a mini SPR type build.

13.7-13.9 with a 1-6 or 1-8 on it.

 

[Malum Prohibitum]

Part 3 will be initial Set-Up and Range Report.

In for Part 3 . . .

 

[oldrifleman]

This thread is about a barrel correct? So yea. That’s what I was asking about. I want a mini SPR type build.

13.7-13.9 with a 1-6 or 1-8 on it.

The answer is no, in the Cut Rifled barrel they only come in rifle length gas 18” length.

 

[atomic41]

I'm only mad that I will be tempted to buy your upper when it goes up for sale. This is not what I needed to spend money on right now dammit.

 

[The Knuckle]

Nice build. I wonder how much of a difference that gas system really marks.
Also I thought that burnishing or seasoning the threads was supposed to be done dry, then lube for final assembly. That’s how I was taught.

 

[Bigjake83]

The answer is no, in the Cut Rifled barrel they only come in rifle length gas 18” length.

I guess that Google search function is still elusive to some..lol

 

[Bigjake83]

PART 3


Initial adjustment and assessment complete.

The rifle fired 100% reliability with no issues whatsoever, I started off with six clicks out from closed on the Superlative Arms Adjustable Gas Block and only needed to add two.

Recoil impulse was definitely softer allowing for me to easily stay on target and not lose any sight picture.

I had absolutely no gas leaks with the SA AGB.

I only about 90 mins, and around 75rds of various types of Ammo.

I stated off with a 10rd groups of 77gr AAC SMK Ammo, I pulled a few but today wasn't about a final accuracy assignment, but barrel break-in l.

The SPR Barrel definitely didn't prefer the 73gr Ammo like the Heavy Contour Chrome Lined Barrels do.

The best accuracy results came from my go-to Handloads of 23.5grs of Tac/77gr SMK and MK262 Ammo.

That's right @JR1200W3 your Ammo likes the new SPR Barrel, put up some respectable number too.

23.5grs RamShot Tac /77gr SMk, /LC Brass / CCI BR4 Primers

FOR A GRAND AVERAGE OF .663 MOA!

Ultimately I have a feeling the Cut Rifled SPR barrels are going to be Handloaders Barrels as all my Bartlein and Kreiger barrels are, they just never seem to reach thier full potential with Factory Ammo.


Next up in part 4 will be the final Accuracy Evaluation and a GEISSELLE BARREL SHOOTOUT 18" CUT RIFLES SPR Vs 14.5" HEAVY CONTOUR CHROMED LINED.

If anyone has any special request in the meantime let me know.

Jake

 

[troupe]

Very nice write up and a great build.

 

[B4forever]

Great work! Love your content.

 

[r.tenorio671]

Jake, ...if it is within your means, I'd appreciate seeing some testing with some of the more "generic" ammo brands that most would find at the more common big box stores. That radial gas porting has really caught my attention.

TIA

 

[Malum Prohibitum]

Ultimately I have a feeling the Cut Rifled SPR barrels are going to be Handloaders Barrels as all my Bartlein and Kreiger barrels are, they just never seem to reach thier full potential with Factory Ammo.


Next up in part 4 will be the final Accuracy Evaluation and a GEISSELLE BARREL SHOOTOUT 18" CUT RIFLES SPR Vs 14.5" HEAVY CONTOUR CHROMED LINED.

If anyone has any special request in the meantime let me know.

Jake

I would be very interested in hearing about how these barrels compare to Bartlein or Krieger generally, but especially with respect to precision.

 

[sheepdog697]

tagged. amazing write up as usual.

 

[Bigjake83]

I would be very interested in hearing about how these barrels compare to Bartlein or Krieger generally, but especially with respect to precision.

All my Bartlein and Kreiger Cut Barrels are Sub Half MOA, so if it finds a load that can average that they'll be on par.

The Chrome Lined Heavy Contour barrels are already meeting that standard.