Paradigm Carbon is a fairly new contender in the ultralight rifle barrel market. They are not new to carbon fiber, having developed methods for it across other industries for quite some time. One of their sales reps reached out to us regarding their barrels, and we ordered a 7mm blank to test out. After all, half the fun of building custom rifles is testing out new technology as it evolves!
The Paradigm barrel blank has some design features that are different from other carbon barrel makers. The obvious first difference is the lack of any steel capping the carbon fiber on the muzzle end! Due to their wrapping process, the company states that the extra steel material there is not required. This of course means that on most bore sizes, 5/8-24 TPI muzzle threads are out of the question. The steel barrel liner is large enough to thread 1/2-28TPI, and Paradigm supplies a 1/2-28 to 5/8-24 thread adapter for common muzzle device use. An advantage to this wrapping method is that according the Paradigm, their barrel blanks can be cut to any desired finish length, rather than being limited to a pre-determined length. This could be very helpful for rifle builders, as it cuts down on the number of different blanks needed in stock to maintain inventory.
The steel portion of the barrel blank is produced by Rock Creek barrels, and is rifled using the button cutting method. Our initial borescope inspection showed the bore finish to be average. Slight tool marks from the rifling button were still visible, but not in a serious enough condition to cause concerns about excess fouling or accuracy problems. There were no major defects in the bore, and overall straightness and concentricity of the bore to OD was very good. Paradigm offers two contours; the 88 and the 95, whose names correspond to each contour’s muzzle diameter. You can find a print with dimensions for each contour here. We went with 95 contour for our test barrel.
Machining the barrel blank was uneventful, just the way we like it! The blank indicated easily, and it was quickly possible to achieve TIR of less than .0005” on an SSG range rod. We chambered this blank with our Manson 7mm SAW II reamer, as this caliber was a perfect choice to test the barrel’s performance. We have mountains of test data from other builds in this caliber, so it makes a great established baseline. The carbon fiber on the muzzle end machined well, and showed no signs of de-lamination.
Barrel Break in and Test Data
Break-in load: 171 Barnes Match Burner, 2.920″COAL, WTO 5x fired brass, 44.8grs H4350, CCI450
2729/13.7SD. Break in shots went into 1 MOA, except two flyers that went 2” left of group. One was a clean shot and one was fouled. All trigger pulls felt good. Cleaning during break in was normal, with excess copper fouling build up. Copper failing began to diminish after shot number 6.
166 Hornady A-Tip, 2.235”BTO/2.960”OAL, 44.5gr H4350, CCI450
2745/22es over 3rds, 2741/11.2SD over 9.
No cold bore shift observed, either shot to shot between cold shots or on successive warm shots afterward.
Group testing with various muzzle devices
Test load: 162ELD-M, 2.945”OAL/2.255”BTO, 44.5 H4350, CCI450, 5x Brass
2736/11.5SD, .529” group
2754/7.0SD, 475” group
POI shift from bare muzzle is 1.4” straight down.
2738/9.6SD, .799” group(wind change and gusty), next group in better conditions was .274”
POI shift from bare muzzle is .25” straight down
Heat stress test
Rifle configured with Tank-ST brake for heat test. Same test load as used for muzzle device testing. Three consecutive 3 shot groups were fired, allowing the barrel to cool 2 minutes in between shots to determine accuracy baseline.
Group 1: .799”
Group 2: .275”
Group 3: .782”
Average MV across all groups was 2748/10.4 SD
Average group size: .619”
Rapid fire test, 10 rounds fired as fast as target could be reacquired. Ambient temp was 101 degrees.
First three shots went into .480” group. Group size increased with barrel heat, but POI did not shift. Total group size for 10 shot string was 1.012”. Muzzle velocity for entire string was 2744/8.5SD.
Conclusions and Final Thoughts
I have to admit that I was skeptical of this barrel when we received the first blanks. The lack of steel on the muzzle end didn’t look right to me, and I had doubts that its performance would live up to the company’s claims. After testing though, I’m very impressed with it. The accuracy potential of this barrel blank is as good as any of the others on the market, assuming its properly chambered and mated to a properly built rifle in all other areas.
The barrel’s performance under heat stress was very good, considering it’s intended use. For high volume shooting such as PRS and NRL competitions, I’d still recommend a heavy contour steel blank for maximum performance. However, our test barrel proved absolutely trustworthy for its intended purpose, and showed itself more than capable of standing up to abuse when needed.
One concern that remains for me is muzzle wear when used with a suppressor. Because of the limitation of 1/2-28TPI muzzle threads, the decreased amount of wall thickness around the bore at the muzzle end could lead to premature muzzle wear, especially on large magnum calibers. We saw no issues with it during this test, but given that less than 100 round were fired I did not expect to. This will be a concern to be re-visited over time, as the barrel continues to wear. Of course, this is a non-issue for the shooter who is not planning to run a suppressor for extended strings of fire.
Our test is too preliminary to make any judgments about barrel life. The barrel does quickly dissipate heat through the carbon and cooled down relatively quickly, especially given that all of our testing occurred at ambient temperatures between 90 and 101 degrees! The barrel has approximately 60 rounds on it at completion of our test, but has yet to show signs of any kind of speed up. We inspected the throat with a borescope after testing, and saw no signs of premature erosion.
In summary, our opinion is that Paradigm barrel blank is an excellent option for reducing overall rifle weight, without sacrificing accuracy. We will be stocking these blanks in certain configurations, and look forward to building more into our rifles in the future!