6.8 SPC II barrel from Blackhole weaponry


August 12, 2010, 06:48 PM
I recently acquired a 6.8 gun that had the older SAMI spec chamber and 9:5 twist .

I have been looking for a new SPC II chambered barrel and had been searching for an 18" with mid or rifle length gas system.

Well, after searching the various major makers I decided to give black hole weaponry a call since they had a good looking product and very good pricing.

Spoke with Carl from Black hole (the guy that actually makes the barrels) and while going over options and then wait times he said he had some over runs from an order for a major gun maker and they would be able to ship now with no wait time, only catch was that they were enfield rifling and not the 3 poly rifiling.

So for $150 plus $12 shipping I now have a barrel on the way (he bead blasted it to a satin finish for free instead of the normal fee).

Specs on the over run barrels are as follows

standard enfield rifling with 1:10 twist and SPCII chambers and 1/2x28 threaded muzzles (I think he had some unthreaded). standard HBAR profile with .750 under the gas block. I got the rifle length gas system on my 18", but I think he had some carbine and mid-length ones left.

Carl said he has 10 or so more of these over run barrels in stock if anyone else would like to try one out. They didn't have them listed on their site as of today and was a call in only deal.

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August 12, 2010, 07:42 PM
Blackhole weaponry???

Are all the non goofy buisness names taken nowadays?

That's right up there with super sniper or BOHICA

August 12, 2010, 11:20 PM
they are respected in the barrel making business for semi-auto custom builds (i use kreier or hart for all my bolt or bench guns).

August 12, 2010, 11:28 PM
What exactly is Enfield rifling? I haven't known Lee Enfields to be inaccurate, so if you are getting a good deal then why not? I haven't heard of them but you said they are reputable and you talked to the barrel maker himself so at least they work on a personal level.

August 13, 2010, 12:20 AM
enfield rifiling is industry standard way of doing rifiling for many barrels. tried and true method.

poly rifiling is a newer style of rifiling.

The idea behind the poly rifleing is less drag on the bullet due to less surface area of the rifleing cutting into the jacket. Instead of a square notch with 2 points (enfield style rifiling) cutting into it you have a rounded hump making one smooth low profile surface, applying lower pressure at that same point.

here is a comparision of enfield vs. poly


poly is better at not cutting the bullet too much (better FPS) but maintaining or improving accuracy (especially with the 3 poly).

I took the enfield rifled barrel instead of the poly rifled barrel, well because of the cheap price. (the poly barrels from black hole are some of the top 6.8 barrels out there). of course AR performance makes excellent barrels as well as white oak.

so basically i will probably loose 40 to 100 fps out of an enfield rifled barrel versus a poly rifled barrel, but I will save $125 and still have an excellent match grade barrel for hunting and varmint shooting.

August 13, 2010, 01:18 AM
So enfield rifling is essentially cut or button rifling? Please correct me, but I have never heard this term before and I have done science projects on rifling.

Is this poly rifling, polygonal rifling? Such as found in Glock's and H&K's?

Either way based on the article you linked I don't have enough conclusive evidence that poly rifling is better to justify the cost.

I got a BCM 5.56 Upper with the CHF barrel. I have heard that the BCM Hammer forged barrels are more accurate than the standard BCM barrels so I went with that, it was only like $40 more and I had money to burn at the time. Is it more accurate than the cut (iirc) barrels? I have no clue until I build the exact same gun (except different type barrel of same length and profile) and shoot the exact same load through both. But, I don't have the funds now and I prefer not to have two identical guns.

August 13, 2010, 08:52 AM
The claims that I have heard for polygonal rifling are more for lower pressures and less fouling. Accuracy is more a product of consistancy in the bore. A poorly produced poly barrel will never outshoot a quality barrel of any type rifling. Pretty good depiction below:


August 13, 2010, 10:26 AM
68 , thanks for the diagram. I was looking all over for it (my google skills were not good last night...lol)

August 13, 2010, 12:38 PM
Oh okay thanks for the diagram. So Enfield rifling is 5R, which is very good. Honestly, I would probably flip a coin and decide.

Well, I woke up later than I wanted, time to hit the range.

Float Pilot
August 13, 2010, 07:25 PM
Hmm, maybe time to replace my 16 inch 6.8mm barrel with an 18 or 20.
I am bored with the 16 and nobody wants to buy the rifle as is...

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