Reloading Dev and Muzzle Brakes

[MNtadpole]

I need some help with my load development that I have been doing on my Tikka T3x TAC A1 in 6.5CM. I had previously conducted a ladder-load test to locate my velocity nodes for the rifle, of which the rifle didn't have the it's 6.5mm Precision Armament Hypertap muzzle brake on. Today, I attached the muzzle brake for seating depth testing at the range (100 yards). I started the seating test at the maximum COL that the magazine would allow, which was the same length that my ladder-load test used. Each series of shots during the seating test would increase the seating depth by .003" into the cartridge case, for a total of .036".

Upon conclusion of today's seating depth testing, I feel like the muzzle brake did decrease felt recoil, but at the expense of hurting my group sizes. Prior to ever attaching the brake, this rifle was easily able to bug-hole groups at 100 yards.

A majority of the seating test series were shooting groups .50" - .80". The best group of the whole day measured .20". Overall the characteristics of the groupings without the brake could not be replicated in the groupings with the brake installed. Is this normal?

I do have a suspicion as to a possible influencer of these issues. I did notice, about half way through my test, that my muzzle brake did work itself loose. No baffle strikes though, so that's good! I did use the provided wrenches to tighten it at the range (they are kinda small and crappy. No real leverage). Although the brake didn't become loose again, It still was unable to reproduce the tight groups that I saw without the brake on. SIDE QUESTION: Is there a method of attaching this rifle to a bench vice to support the rifle while I tighten on a muzzle device?

I was hoping someone to offer some advice, besides just taking off the brake. Thanks in advance!

 

[Mauser06]

Could be a host of issues.


Could be as simple as needing to rework the powder ladder.




First thing I'd do is remove the brake and see if it replicates the original groups. Then you know if that's what's causing the groups to open up or not.


IMO, load development should be done with the rifle configured as it'll typically be used. I understand you didn't have the brake.


Was the muzzle already threaded during the last development? If it's new, that could be the issue. The slightest burr on the crow on the crown could do it.


Fouling, different conditions, barrel broke in, could be a number of things. First thing to do is remove the brake and verify.

Could even be a slight reaction from you because of the brake. Some add a ton of noise and muzzle blast. The first could times I blew everything lighter than my ammo box off my bench, I'm certain i jumped. Lol. Could easily develop a "flinch" from an obnoxious brake.

 

[Dthomas3523]

Attaching a brake is the same concept as a tuner. It’s a weight on the muzzle. This will possibly change group size which requires seating depth testing/adjustments. As long as nothing is wrong with the brake, it will eventually tighten back up once you get the right seating depth.

Powder shouldn’t have to be re-worked if you’re not using a POI based load development method. If you are using POI based method, probably best to start over.

If you’re using a chrono ladder test to look for “flat spots” then you’re passing in the wind anyway.

 

[mtang45]

You changed barrel harmonics by adding the brake. You need to start over with a new ladder test.

 

[MNtadpole]

Could be a host of issues.


Could be as simple as needing to rework the powder ladder.




First thing I'd do is remove the brake and see if it replicates the original groups. Then you know if that's what's causing the groups to open up or not.


IMO, load development should be done with the rifle configured as it'll typically be used. I understand you didn't have the brake.


Was the muzzle already threaded during the last development? If it's new, that could be the issue. The slightest burr on the crow on the crown could do it.


Fouling, different conditions, barrel broke in, could be a number of things. First thing to do is remove the brake and verify.

Could even be a slight reaction from you because of the brake. Some add a ton of noise and muzzle blast. The first could times I blew everything lighter than my ammo box off my bench, I'm certain i jumped. Lol. Could easily develop a "flinch" from an obnoxious brake.

Yea I probably should have used the brake during initial velocity testing...

Yes, the muzzle is factory threaded.

I ensured that the barrel was cleaned prior to this range session.

 

[MNtadpole]

Attaching a brake is the same concept as a tuner. It’s a weight on the muzzle. This will possibly change group size which requires seating depth testing/adjustments. As long as nothing is wrong with the brake, it will eventually tighten back up once you get the right seating depth.

Powder shouldn’t have to be re-worked if you’re not using a POI based load development method. If you are using POI based method, probably best to start over.

If you’re using a chrono ladder test to look for “flat spots” then you’re passing in the wind anyway.

I was under this belief too, that the anything added to the barrel would be changing the harmonics...and that it's just a matter of balancing the harmonics back to offer up small groups.

I am using a MagnetoSpeed chrono to locate flat spots in velocity. Is this not a good way to find velocity nodes? What do you mean by "then you're passing in the wind anyway"?

How deep should I expect to do seat depth testing to? During my test, from max COL to the deepest seating, there was a .036" difference. Let me know what you think! Thanks

 

[Dthomas3523]

I was under this belief too, that the anything added to the barrel would be changing the harmonics...and that it's just a matter of balancing the harmonics back to offer up small groups.

I am using a MagnetoSpeed chrono to locate flat spots in velocity. Is this not a good way to find velocity nodes? What do you mean by "then you're passing in the wind anyway"?

How deep should I expect to do seat depth testing to? During my test, from max COL to the deepest seating, there was a .036" difference. Let me know what you think! Thanks

Do your velocity flat spot test 10 times. See if the flat spots stays the same. Think about the logic behind this. You’re adding powder, but velocity (and pressure) doesn’t increase? Explain how that works unless you’re at the point where you can’t get anymore velocity (and then you’ll be at a higher than safe/functional pressure).

Here’s an example of three different 10 shot velocity ladders on the same rifle. Depending which order you shot them in, you would see two “flat” spots. But, if you keep shooting the test, all of a sudden the flat spot is gone.

And then there’s a graph with all three combined, when you take the average velocity of this 3 shots each, all of a sudden (see the red line) there are no flat spots and velocity increases with every change in powder charge (which is what really happens).

Chrono tests that identify “flat spots” are nothing more than a product of Extreme Spread overlapping and statistical variance. When you shoot enough shots to be statistically significant, they don’t exist.

 

[MNtadpole]

Do your velocity flat spot test 10 times. See if the flat spots stays the same. Think about the logic behind this. You’re adding powder, but velocity (and pressure) doesn’t increase? Explain how that works unless you’re at the point where you can’t get anymore velocity (and then you’ll be at a higher than safe/functional pressure).

Here’s an example of three different 10 shot velocity ladders on the same rifle. Depending which order you shot them in, you would see two “flat” spots. But, if you keep shooting the test, all of a sudden the flat spot is gone.

And then there’s a graph with all three combined, when you take the average velocity of this 3 shots each, all of a sudden (see the red line) there are no flat spots and velocity increases with every change in powder charge (which is what really happens).

Chrono tests that identify “flat spots” are nothing more than a product of Extreme Spread overlapping and statistical variance. When you shoot enough shots to be statistically significant, they don’t exist.

So basically what you're saying is that velocity nodes don't exist under a large enough test sample? If that is the case, then how does one settle on a given charge weight?

 

[spife7980]

So basically what you're saying is that velocity nodes don't exist under a large enough test sample? If that is the case, then how does one settle on a given charge weight?

It shoots the best.
Yes, you have to actually shoot at a target to see what it actually does on target.

 

[MNtadpole]

It shoots the best.
Yes, you have to actually shoot at a target to see what it actually does on target.

Please excuse my ignorance, since I have only been at this game for a little under two years. But this seems to be the difference between load development using optimum charge weight vs ladder-test.

 

[spife7980]

Please excuse my ignorance, since I have only been at this game for a little under two years. But this seems to be the difference between load development using optimum charge weight vs ladder-test.

No, a real ladder test also involves shooting paper.

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It’s the stupid fucking velocity “ladder” abomination of a test that don’t correlate to any real world results.

Edit: there are no shortcuts. You may luck into something early but if a person wants to know what effect their changes have actually testing is the only way to know. Anything else is just a guess.

 

[Dthomas3523]

Please excuse my ignorance, since I have only been at this game for a little under two years. But this seems to be the difference between load development using optimum charge weight vs ladder-test.

What spife said.

“Ladder” tests were (still are) very common. They entailed what was mentioned above. Shooting targets at whatever distance deemed suitable for the individual. And looking for charge weights that exhibit the same or very close to the same POI. This was done without a chrono. Either due to chronos at the time not being great or the belief you didn’t need one (still a common theory).

What then happened was people came along when chronos became more popular (mainly due to quality being much better) and incorrectly reasoned “well, if it has the same POI, it must obviously have the same velocity.”

Thus the pipe dream of shooting 10 shots over a chrono came from. The incorrect assumption that for a round to have the same POI at distance it must have the same velocity.

And then you get the the general response from the older or other discipline community “ladders absolutely work” when they are not even aware that most PRS shooters now think of a velocity ladder. So, the other shooters think of POI ladders when they back up the claim of ladders working. Most of the time when they realize what’s being asked they laugh at the idea that more powder = same velocity.

But, don’t just take my word. Load up your velocity ladder and shoot it time after time. You’ll find that each time or several times in your strings of fire, had you done that individual test you would have come up with a different “node”. And our equipment (loading and shooting) is good enough now that most everything shoots better than all but the best shooters. So it appears that it “worked.”