Gunsmithing Any thoughts on structured barrels?

[Ledzep]

A question - is it your experience to see SD's flatten as the barrel carbons/coppers back up? Not specific to or barrel. My intuition says "yes". With that: the question becomes how many foulers should be shot?

From a stripped clean barrel, within the first 2-10 shots, sometimes you will see goofy shots related to velocity. More rarely you'll see in the first 1-3 shots after cleaning some accuracy fliers. Suppressors can also cause 1st shots in a string to have low velocity (20-50fps slow). Not sure the physics behind that but I've seen it enough times with various combinations to keep an eye open for it.

Beyond that, I have not really noticed SD's to change unless you change bullet type, powder lot or type, or sometimes primer type (some cartridges are more or less sensitive to this). If you shoot 20-30 shot strings and get the SD on that, it stays within about 1fps pretty much every time until the fouling builds up to the point of significantly increasing peak pressure, at which point SD's and precision both suffer.

 

[JB.IC]

View attachment 8339134View attachment 8339142View attachment 8339149
6xc - Factory rounds
Tubb Gun, Vortex Gen lll, Tubb muzzle brake, Magneto Speed used for data.
60shots- group shown is 56-60- 12minute cycle.
100yds, Phoenix Bipod, rear bag, prone.
69deg ambient. Final barrel temp 110max read with a chamber value of 93deg. Wind 11:00 2-5mph. 34%RH
Stripped clean cold bore shot included.
2 Witnesses.

A question - is it your experience to see SD's flatten as the barrel carbons/coppers back up? Not specific to or barrel. My intuition says "yes". With that: the question becomes how many foulers should be shot?

Yes. I’ll send you a plot here in a few mins.

Edit:
We’ll never mind, I was changing too many reloading variables in the plot to make sense of it.

 

[John Baker]

View attachment 8339134View attachment 8339142View attachment 8339149
6xc - Factory rounds
Tubb Gun, Vortex Gen lll, Tubb muzzle brake, Magneto Speed used for data.
60shots- group shown is 56-60- 12minute cycle.
100yds, Phoenix Bipod, rear bag, prone.
69deg ambient. Final barrel temp 110max read with a chamber value of 93deg. Wind 11:00 2-5mph. 34%RH
Stripped clean cold bore shot included.
2 Witnesses.

A question - is it your experience to see SD's flatten as the barrel carbons/coppers back up? Not specific to or barrel. My intuition says "yes". With that: the question becomes how many foulers should be shot?

max	3175​
min	3164​
Ave	3166.7​
ES	11​
SD	3.743142​

Not the best at inserting charts and data....
Focusing a bit on SD drift. This represents a 30shot string with the shots 21-30 being shown. These are hand loads using Berger 215's. This barrel has north of 2000rds thru it. A Tubb Gun in 300Norma.
We recently had a demo at SHOT in which our MRAD had 30-40rds plus thru it on continuous demonstration/different shooters use. The final rounds were on a 2075yd target with a first round impact and 3 follow up. A stable SD is required to achieve that performance. An "Objective Anecdotal" moment with a couple of dozen witnesses, which was all levels of Mil and LE. The temperature was 49deg and the gun was running a suppressor. The barrel maximum heat was 81deg, chamber 61, suppressor 210degF. I would Hypothesize that a cooler barrel will hold SD's longer.

 

[John Baker]

From a stripped clean barrel, within the first 2-10 shots, sometimes you will see goofy shots related to velocity. More rarely you'll see in the first 1-3 shots after cleaning some accuracy fliers. Suppressors can also cause 1st shots in a string to have low velocity (20-50fps slow). Not sure the physics behind that but I've seen it enough times with various combinations to keep an eye open for it.

Beyond that, I have not really noticed SD's to change unless you change bullet type, powder lot or type, or sometimes primer type (some cartridges are more or less sensitive to this). If you shoot 20-30 shot strings and get the SD on that, it stays within about 1fps pretty much every time until the fouling builds up to the point of significantly increasing peak pressure, at which point SD's and precision both suffer.

It would be interesting to have a conversation with you. We have enjoyed watching the Hornady content.

 

[John Baker]

View attachment 8341031 View attachment 8341032

max	3175​
min	3164​
Ave	3166.7​
ES	11​
SD	3.743142​

Not the best at inserting charts and data....
Focusing a bit on SD drift. This represents a 30shot string with the shots 21-30 being shown. These are hand loads using Berger 215's. This barrel has north of 2000rds thru it. A Tubb Gun in 300Norma.
We recently had a demo at SHOT in which our MRAD had 30-40rds plus thru it on continuous demonstration/different shooters use. The final rounds were on a 2075yd target with a first round impact and 3 follow up. A stable SD is required to achieve that performance. An "Objective Anecdotal" moment with a couple of dozen witnesses, which was all levels of Mil and LE. The temperature was 49deg and the gun was running a suppressor. The barrel maximum heat was 81deg, chamber 61, suppressor 210degF. I would Hypothesize that a cooler barrel will hold SD's longer.

22 Shots #25-46 on new 416 Hellfire.
300 yards - 7 different powder charges - load testing.

Love this tacomHQ Structured Barrel. No weird harmonics between loads sending bullets every which way.

I probably should have let my string continue upwards with the different powder charges, but I knew I didn't load any with enough powder to get me where I wanted, so I dropped them down to save paper

Cutting Edge 550 grain lathe turned solid copper projectiles, Bertram brass, BAT Machine Company Inc.ne EXS action, Athlon Cronus scope, Era-tac adjustable scope base, Jewell trigger, Ryan Cheney ELRn Cheney ELR . com Airfoil bag!

 

[John Baker]

• Vudoo .22

“The first 10-rounds with the SK were one hole. One thing became very obvious to me is the ES/SD impact shows immediately, but that was it. The rifle wants put everything in the same hole. It’s like watching a video game through the scope. No recoil, no movement, nothing just deadness.

Groups at 100-yds | POA 2/10ths high:
+ 1st row CX .001RO | Avg .1675″
+2nd row Midas+ no RO | Avg .268″
+3rd row XACT no RO | Avg .276″
+4th row Tenex no RO | Avg .272″
*RO – Run out

Corollary data:
CX 0.001RO | Avg 1065 SD 6.7
M+ | Avg 1068 SD 11.4
XACT | Avg 1049 SD 8.9
Tenex | Avg 1107 SD 8.1
Δ58 FPS

Honestly, the rifle outperformed every ammo I fed it. It needs to go to Lapua and Eley for testing in their tunnels to find an ammo lot that will deliver the best SD’s. It was amazing shooting across the radar that I could tell based on where the impact went whether the velocity was high or low. I did have some ammo I was testing an Olympic runout gauge on, and the ammo performed best. And it was .001RO. I still need to shoot the .000’s I have, those will tighten up the group even more. Or at least the data of 20 years of research shows that for every .001″ of run out equates to 1/10th group size.

The barrel is outstanding, and shows quickly the weak point is in the ammunition. Even though it’s Olympic ammo.” – Chris Baxter

5-Round Groups from Four Different Manufacturers

View attachment 8314868
An initial look at cool down data- will try to get more from the Cerakote test.

“Small update on MV info and how this barrel shoots. After the lot test I got the rifle back and I ordered 10k rounds for the rifle. Put the rifle back together, zero’d and began gathering data. I like to shoot a couple full boxes for the average. This particular lot was mean averaged by Eley at 1078 MV, I shot 2 full boxes(100rds) with the Garmin mounted to the rifle and after all the rounds recorded I had an average MV of 1140.5, an extreme spread of 18.8, and an SD of 4.8….and this barrel is about 5-600 rds away from being broken in by my usual standard. Crazy result over 100 rds IMHO.

I chose the lot that had a 14mm 50M average. I wasn’t sure that was ‘good’ and he said it was very good and olympians shoot 13-14mm average ammo.

This rifle is HAMMERING for a .22 in terms of repeatability, consistency and potential….and it hasn’t reached its full potential yet which is the most important part for me thus far. It’s this good now and will only get better.“ - @76.binder

 

[RTH1800]

 

[Randy Fox]

The “holes” on the outside of the barrel might not move enough air to make a difference.

It wouldn't be hard to integrate a forced air system to cool the barrel while shooting.