TOO many variables with my 6 BR-AI ???

[jamesdmock]

Being a simple man (or maybe simple-minded), I have made tuning the 6 BR-AI more complicated than it should be. First, let me thank those who have been very helpful via this forum..... Bart Sauter, Alex Wheeler, Tom Mousel, Mike Ezell, Tim Claunch, and Jim O'Hara. Saturday is our final match of the season, and I have been struggling to get that perfect load. To add to my frustrations, last Sunday, I got the flu.

I have shot a Dasher since 2009 and have done fairly well with it, but I decided to give the BR-AI a try. Mine is a 30" barrel with a Ezell tuner. My early practice sessions featured several bullets, powders, and charges were varied and seating depth was all over the place. I had too many variables and a helter skelter method of finding the right load.

With the big match coming up Saturday, I decided to get serious. I had mostly shot the hotter loads of Varget and H4895 and shot mostly Bart's bullets (103's, 105 Infinities, and 105 Gungnirs). After seeing that Alex stated that many had found that a good node with 30.6 grains of H4895, I decided to give that a try. I first tried this charge with the 105 Infinity seated just off the lands and loaded them with Federal 205 primers. I have a 100 yard range at my house so I put on my heavy coat (still have a touch of flu) and shot a three group with the tuner set for the last load I tested. This first group was a triangular group that was a large .2xx. Okay but not great. Maybe I would have to go with this load???

Since this was with a cold, clean barrel, I decided to shoot another. For this group I moved the tuner out 1 mark (~.001") and also dialed in 11.25 MOA elevation in the scope (the amount needed to get from 100 to 600 yards). EUREKA ! This group was a zero and I quit. With only 6 rounds on the barrel, I don't believe that I will clean it before Saturday's match. Good shooting....James

PS- Sometimes we waste components trying to save them by taking short cuts in the tuning process.

Let me correct the record. Yesterday, I was so cold that I didn't go to the target and measure the "zero" group, but through the scope it certainly appeared to be a zero. After some warming today, I went down to the target and measured the group and it had a little "wing" that caused it to measure ~0.140". This is still a great group for a 105 VLD bullet, but I wanted to correct the record. I have been a skeptic of many claimed 'zeroes" in the past and I didn't want to be a maker of false claims. Good shooting....James

 

[tclaunch]

Way to go James, perseverance sure goes a long way. I shot my 6BR Ackley today myself, and was getting real close. H4895 outshot Pulldown RL15 this test but still had half bullet vertical at 31 grains. Looks like this barrel will want the 31.1 load.

Good luck Saturday!!

I don`t have the patience to test a tuner ....yet!!! I understand the need for rimfire, no way to change loads.

 

[Alex Wheeler]

I was just talking about the different loads I am seeing with the barrels I have done. It seems like guys are either at 30.6 or 31 with H4895. I dont know why. They are too close to be different nodes. I am starting to think its powder lot related. I experienced something similar in the dasher too. It seems like if a guys is using 31 it works in all his BRA barrels which makes me think its not barrels. 31 seems a little more common but 30.6 is close. Most of the time guys seem to have luck with br4 or 400s with H4895. Let us know how it works at the match. I wouldnt clean it either

 

[Dino]

I was just talking about the different loads I am seeing with the barrels I have done. It seems like guys are either at 30.6 or 31 with H4895. I dont know why. They are too close to be different nodes. I am starting to think its powder lot related. I experienced something similar in the dasher too. It seems like if a guys is using 31 it works in all his BRA barrels which makes me think its not barrels. 31 seems a little more common but 30.6 is close. Most of the time guys seem to have luck with br4 or 400s with H4895. Let us know how it works at the match. I wouldnt clean it either

Don’t think it’s powder lot, I have 2 Krieger’s one Will shoot 31.1 no problem the other I would need a hammer to open the bolt at 31.1 of h4895. Both barrels.237, both barrels chambered with the same reamer. Same lot of powder for both.

 

[Shynloco]

Don’t think it’s powder lot, I have 2 Krieger’s one Will shoot 31.1 no problem the other I would need a hammer to open the bolt at 31.1 of h4895. Both barrels.237, both barrels chambered with the same reamer. Same lot of powder for both.

Although I'm not convinced that it isn't the powder lots, I have started to believe that ambient temp plays a significant role in how well it shoots one day and how that same load tends to open up on a colder day and at a different hour of testing. Not really sure which it is. But I do know the colder the temps the lower the pressure of my load, hence less velocity. It's always a challenge to find the answers that obviously JD did find.

BTW JD, good luck on your final shoot of the year!

Alex

 

[moondog]

31.0 H4895 271/2' Chanlynn barrel,105 Hybrids, CCI BR4 -.010"
seems to be what mine wants too.

 

[500Stroker]

All rifles shoot differently.
I no longer waste time and components tying to shoot someone else's load, been there done that.

1. Shot a powder ladder, pick a node for the ambient temp you shot the ladder in.
2. Tune the overall length per Bergers recommendations. You can find it on their website.
3. Adjust the tuner to hone the barrel harmonics, follow the adjustments recommendations from the tuner manufacture.
Job over.

I test, practice and compete at 600 yards.
Good luck

 

[urbanrifleman]

All rifles shoot differently.
I no longer waste time and components tying to shoot someone else's load, been there done that.

1. Shot a powder ladder, pick a node for the ambient temp you shot the ladder in.
2. Tune the overall length per Bergers recommendations. You can find it on their website.
3. Adjust the tuner to hone the barrel harmonics, follow the adjustments recommendations from the tuner manufacture.
Job over.

I test, practice and compete at 600 yards.
Good luck

I think those velocities should be 3000? Not 2000ish?

Fine shooting BTW

 

[500Stroker]

I think those velocities should be 3000? Not 2000ish?

Fine shooting BTW

Those velocities shown, are at the target, no at the muzzle and because they are taken done range there are alot of variables therefore not very accurate.

 

[Terry O]

I think those velocities should be 3000? Not 2000ish?

Fine shooting BTW

The velocities listed are at the target from the Silver Mountain Target system.

 

[urbanrifleman]

The velocities listed are at the target from the Silver Mountain Target system.

WOW!! Coolllll....

 

[rardoin]

You need to tune the vertical out a bit...would not have dropped #12 out of the X-ring



Nice!

 

[GSPV]

Cool beans, JM! Don’t you love it when something comes together!

 

[jamesdmock]

Cool beans, JM! Don’t you love it when something comes together!

Greg, not to be negative, but I am not sure that anything has "come together" yet. One 3-shot group at 100 yards does not mean that I am set to win at 600 yards. However, I have a load with which to work and will do any tuning with the tuner per Mike's instructions. I would have shot more loads yesterday, but it was cold and I was sick...so I will go to the match and shoot this load the best I can. I have all of my excuses in order and the big one is ALLGORE"s global warming. In Louisiana, we are not accustomed to having snowfall in early December. Without all of that global warming we would be freezing. Good shooting....James

 

[GSPV]

You have the process. It’s more important than the product.

The only thing that I would do, and I’m just a duffer, is make sure that my current load is one where increasing powder charges yield a lower POI on the target. That’s going to be the most tolerant to the inevitable variations in bullet exit time/point.

I’ve heard tale, can’t verify it myself, that the tuner going out is equivalent to an increasing powder charge. Take it FWIW

 

[sdean]

A lot of tales get repeated on the internet.

 

[gunsandgunsmithing]

A lot of tales get repeated on the internet.

Very true!
Lots of tales out there in regard to tuners but the simplest way to look at what they do is, they time ideal muzzle position with bullet exit. So, as velocity goes up, we need to speed the barrel up accordingly. The way to do this is to shorten it, to speed up its frequency. As velocity goes down, we need to slow the barrel frequency. We do that by lengthening the tuner.

So, as a rule, as temps go up, move the tuner in. As temps go down, move the tuner out.

 

[500Stroker]

Very true!
Lots of tales out there in regard to tuners but the simplest way to look at what they do is, they time ideal muzzle position with bullet exit. So, as velocity goes up, we need to speed the barrel up accordingly. The way to do this is to shorten it, to speed up its frequency. As velocity goes down, we need to slow the barrel frequency. We do that by lengthening the tuner.

So, as a rule, as temps go up, move the tuner in. As temps go down, move the tuner out.

Are you referring to ambient temp or barrel temp or both?

 

[gunsandgunsmithing]

Are you referring to ambient temp or barrel temp or both?

Specifically, ambient, but it's never good for a round to cook in the chamber for long, either.

 

[jamesdmock]

Well, the match has come and gone and let me congratulate Jeff Turner as SOTY. I needed a minimum of 187/5X to catch and pass Jeff. I shot a 185/4X and lost by 0.34 points (average of 6 best targets). I shot the 6 BRA with 105 gr. Bart Infinity and 30.6 gr. of H4895. The conditions were not suited for high scores...it was in the mid-twenty degree range when the sun came up. Also, there was bright sunshine and this produced some horrendous mirage by the 3rd match. I started well with a 49/2X on the first target, and did okay on the 2nd with a 47/1X. I was leading and feeling fairly well about my chances.....but the opera ain't over till the fat lady sings. By the 3rd match the mirage made even seeing the strikes on the gong difficult. I dropped 6 points and got no x's. Now I was up against the wall. Upon examining the 3rd target, I noticed too much vertical. I turned the tuner out one mark (~.001) and planned to shoot a 3-shot group on the gong to see if that helped. I could not clearly see the results on the gong and decided to try with that setting. I shot a VERY vertical group with a 45/1X score and my hopes were dashed.

I have just about decided that I am not smart enough to change tuner settings during a match. I am going to test my new 6 BRA w/out tuner and see what the groups look like. I may shoot the next match sans tuner....we'll see. James