Bought a Lyman Borescope due to a problematic barrel and a guess that it had to do with issues with gas port. So I photographed 6 barrels with various round counts.
First, try to guess the approximate round count of each barrel and second, put them in order from most to least consistent/accurate. Answer guide with round count wayyy down below pictures.
List of Barrels (no particular order)
B:
C:
D:
E:
F:
.
.
.
.
.
Answers:
A - Milspec chromemoly 14.5"
At least 1000+ rounds (unknown exactly)
2-2.5MOA (not consistent)
B - Dracos 6.5CM -
50 rounds -
.3-.5MOA
C - Rainer UltraMatch 224V
1250+ rounds
.5 -.6 MOA
D - Savage MSR10 18" factory barrel -
1,200+ rounds
.5-.6 MOA
E- AeroPrecision 6.5CM -
~120 rounds
.75- 1MOA with random flyers
F - Compass Lake Krieger Blank 223 Match - <250 rounds
.75-1.5 MOA with random crazy flyers
If you visually rank the gas ports based on uniformity, erosion depth and erosion length, presence of any copper vs clean edges, they line up in nearly perfect order of precision.
The factory Savage barrel has over 1200 rounds through it and still shoots 1/2 moa. It put nearly every group over 35+ 5 round groups of multiple loads and bullets in a back to back test on the same day. There is a thread with results somewhere here and I'll link here later.
The Dracos (one of the cleanest) shot this group: (only three shots but lost other pictures from last testing session when phone crapped out). This is second Dracos barrel I've owned and the last one was a drill also, mirroring below for 5 shots groups. SDs are around 8-10fps.
The Aeroprecision shot pretty well (.75-1moa) with slight flyers. I didn't spend much time timing before going back to Dracos. I think it would tuned well though if I shot it more.
The Rainer UM Mod2 shoots regularly to .5-.75 for 5 shots. Here is example of typical 10shot group and it has SDs of around 10-12.
The worst part of this is that one of the most expensive barrels in this test, using a Krieger blank looks is easily the worst barrel in terms of erosion and the inconsistent grouping and SD shows. It will shoot 77TMKs to about .75MOA avg but 69TMKs are 2-3 shots into about 1/2" but then flyers .5-1"+ out of group randomly, making 1-1.5moa group. SDs are sometimes around 10 but next string will be 20-30. My guess I that the longer bearing surface of the 77 keeps it somewhat "square" in bore wheras the 69s get joseled around and become off axis when they hit that massive pot hole of a gas port.
Below is the load testing Target with 77TMKs, Target and LC/Hornady brass (top row is my 22LR at 100yds shot same day in same conditions; not the MSR10, I didn't have time to shoot it.) 1/2" orange aiming stickers:
Here are 6 groups shot at 300yds with CLE Kreiger 223. They average .8MOA (~2.5") shooting at 1" dots.
The only barrel to shoot worse is the milspec but I've never fired tuned loads through it so it may actually shoot around 1-1.5mo if I tried. No photos of there groups.
While it's only 6 barrels and it's anecdotal, it certainly fosters my opinion that a clean gas port (with no shitty erosion, burrs from bad drilling etc) fosters better precision.
If you get inconsistent SDs or random flyers from an otherwise tight gas gun, regularly, it may be (in part) the barrel and not the shooter. When in doubt shoot someone else's tackdriver to see if it's you.
Anyone else surprised/not surprised by this? Thought it was kind of cool.
First, try to guess the approximate round count of each barrel and second, put them in order from most to least consistent/accurate. Answer guide with round count wayyy down below pictures.
List of Barrels (no particular order)
- AeroPrecision 6.5CM
- Dracos 6.5CM
- Compass Lake 223 Match
- Milspec chromemoly 14.5"
- Rainer UltraMatch 224V
- Savage MSR10 18" factory barrel
B:
C:
D:
E:
F:
.
.
.
.
.
Answers:
A - Milspec chromemoly 14.5"
At least 1000+ rounds (unknown exactly)
2-2.5MOA (not consistent)
B - Dracos 6.5CM -
50 rounds -
.3-.5MOA
C - Rainer UltraMatch 224V
1250+ rounds
.5 -.6 MOA
D - Savage MSR10 18" factory barrel -
1,200+ rounds
.5-.6 MOA
E- AeroPrecision 6.5CM -
~120 rounds
.75- 1MOA with random flyers
F - Compass Lake Krieger Blank 223 Match - <250 rounds
.75-1.5 MOA with random crazy flyers
If you visually rank the gas ports based on uniformity, erosion depth and erosion length, presence of any copper vs clean edges, they line up in nearly perfect order of precision.
The factory Savage barrel has over 1200 rounds through it and still shoots 1/2 moa. It put nearly every group over 35+ 5 round groups of multiple loads and bullets in a back to back test on the same day. There is a thread with results somewhere here and I'll link here later.
The Dracos (one of the cleanest) shot this group: (only three shots but lost other pictures from last testing session when phone crapped out). This is second Dracos barrel I've owned and the last one was a drill also, mirroring below for 5 shots groups. SDs are around 8-10fps.
The Aeroprecision shot pretty well (.75-1moa) with slight flyers. I didn't spend much time timing before going back to Dracos. I think it would tuned well though if I shot it more.
The Rainer UM Mod2 shoots regularly to .5-.75 for 5 shots. Here is example of typical 10shot group and it has SDs of around 10-12.
The worst part of this is that one of the most expensive barrels in this test, using a Krieger blank looks is easily the worst barrel in terms of erosion and the inconsistent grouping and SD shows. It will shoot 77TMKs to about .75MOA avg but 69TMKs are 2-3 shots into about 1/2" but then flyers .5-1"+ out of group randomly, making 1-1.5moa group. SDs are sometimes around 10 but next string will be 20-30. My guess I that the longer bearing surface of the 77 keeps it somewhat "square" in bore wheras the 69s get joseled around and become off axis when they hit that massive pot hole of a gas port.
Below is the load testing Target with 77TMKs, Target and LC/Hornady brass (top row is my 22LR at 100yds shot same day in same conditions; not the MSR10, I didn't have time to shoot it.) 1/2" orange aiming stickers:
Here are 6 groups shot at 300yds with CLE Kreiger 223. They average .8MOA (~2.5") shooting at 1" dots.
The only barrel to shoot worse is the milspec but I've never fired tuned loads through it so it may actually shoot around 1-1.5mo if I tried. No photos of there groups.
While it's only 6 barrels and it's anecdotal, it certainly fosters my opinion that a clean gas port (with no shitty erosion, burrs from bad drilling etc) fosters better precision.
If you get inconsistent SDs or random flyers from an otherwise tight gas gun, regularly, it may be (in part) the barrel and not the shooter. When in doubt shoot someone else's tackdriver to see if it's you.
Anyone else surprised/not surprised by this? Thought it was kind of cool.
