Progressive Velocities from break in of new Bartlein in 284

[ecomeat]

I thought some forum members might be able to make use of the following Chart, showing the velocities achieved for different powder charges of 2213sc. It shows the velocities getting progressively faster as the number of shots fired through the barrel increases.
These are the velocities achieved in the Bartlein 5R barrel that Frank Green kindly gave to me, and that Craig McGowan from 7mm.com.au kindly arranged delivery of.
All velocities, except those single shots in the "350+" column were measured with my own MagnetoSpeed V2. I had issues with a cable this week, and borrowed a V3 from Mike Samuels . There appears to be a discrepancy between the two measurements of 15-20 fps, as though they belong back at around the 100 shot mark. If my Labradar turns up in early May as promised, i guess we will know then which one has an error.
In the meantime, some members might be able to make use of the following data.


My chamber has a 0.313" neck, with cases neck turned to 0.013" and a 0.310" loaded round measurement.
My current batch of AR2213sc is MEM5195, and it is a VERY slow one, compared to MEM5096, and the preceding MEM4989

[Frank Green]

It's possible the difference is between the two chronographs. That being said though I know some barrels can change a little velocity wise but usually have settled down by the 100 round mark.

I feel how the throat polishes and breaks in is the reason why.

The other thing I would be curious about is...are you starting your chronograph testing with a clean barrel? If so sometimes the first couple to few rounds can be slower than the rest. I'll record the data for the first 5 rounds and see what I get to see if there is any variation but I'm more concerned with the rounds after that. Also what temperatures was the testing done at? If one day is colder than another that can explain your velocity pick up as well. Also as the barrel wears you usually see velocity loss over the course of time.

Hows the barrel shooting accuracy wise?

Later, Frank
Bartlein Barrels

[ecomeat]

Frank,
vastly experienced guys like Rod Davies have said that they expect all barrels to "speed up" by 60-80 fps somewhere between 150-250 rounds fired, causing them to re-check their velocities around that region.
These results seem to indicate that it may be a more gradual process than I had expected, no doubt due in the main to the throat "breaking in" and polishing gradually, as you noted.
All of these sessions were preceded by 4 shots first, to warm and foul the barrel as recommended by Williada.
Our temperatures on days i have shot have "in the main", been best described as bloody hot . Throughout summer, and in this early part of our Autumn, most days I have shot it have been 30-32 even up to 36 deg C
The barrel is a very, very good one, thank you. Bartlein can be fairly proud of their workmanship !!
It has a long tuning window, and i am quite excited about its potential for future performances. After shooting in a City Vs Country Teams event in ten days time, i will put it back in the gunsafe, to save it for major events such as our National Queens in June, and then our big QRA (Queensland) Queens in September.
I have asked Craig to send another Bartlein down to Matt Paroz in Sydney for chambering, to help me to recover emotionally from having to put this one away !!
Tony

[Frank Green]

Glad the gun is shooting great for you and back on track!

Yes I do agree that some barrels can pick up speed and like I said up to about a 100fps is normal. Some guys do get more.

Again though every barrel is a individual. My .284win. hasn't picked up any speed at all. My last .260 Rem. hasn't on my tactical rifle. My 6 Creedmoor and my last two .30cal (7.5x58mm) guns haven't either.

My 6x47 Lapua did pick up some but less than a 100fps.

Later, Frank

[williada]

Tony, the barrel seems to be following the predicted path of velocity increase. Frank is right in that the throat can take a while to polish; but in addition, my understanding is that during the work hardening process the micro surface of the bore swells effectively decreasing bore size to marginally increase pressures for up to a couple of hundred rounds before it starts to wear and the downward slope of velocity begins. What we have seen is velocity gradually increase as denoted by reducing amounts of copper on the patch with the traditional break in of the throat, and thereafter the increase in velocity still can occur with a short period of bore swelling on the surface due to work hardening and chemical fouling from residues.

As some of us say over here, its getting your barrel over the hump before meaningful work can be done for a while before things taper off over time. Of course not all barrels react the same way. That's why it is important as Tony has done to keep track of the velocities in order to revisit tune. Its really just being aware of the possibilities.

My process for working the hump period is not to use lubricants such as moly but let the bullet do the lapping assuming the barrel has been lapped correctly in the first instance. It is important during this period to keep your barrel clean so the jackets can do their work of lapping.

Its a bit off topic, but there is another school of thought, that once the barrel is cherry ripe the decision to clean it thoroughly is based velocity variances as a guide rather than after every so many rounds in order to conserve the internal surface from errant cleaning. David

[BATattack]

Very interesting Tony and a question I've been thinking about myself! I've got a new tube as well and haven't done ANY load development and it's shooting better (like almost twice as good!) than any of my others ever have after development so I'm wondering what to do!

I'm in two minds if I should do a ladder test to find a load Window and record the velocity of that Window and continue to monitor and adjust load to maintain that velocity .

Or

Shoot it for a few 100 and then worry about development after.

[KHGS]

Very interesting Tony and a question I've been thinking about myself! I've got a new tube as well and haven't done ANY load development and it's shooting better (like almost twice as good!) than any of my others ever have after development so I'm wondering what to do!

I'm in two minds if I should do a ladder test to find a load Window and record the velocity of that Window and continue to monitor and adjust load to maintain that velocity .

Or

Shoot it for a few 100 and then worry about development after.

Enjoy it!!!! Some barrels (the good ones) do not require much work. For me those that require lots of work are destined for the bin, life's too damn short (for me anyway) & barrels are really cheap when you think about it.
Keith H.

[Longranger]

On chronographs, we recently did a comparison between the Magnetospeed and a Oehler 35P.

We found that the Magnetospeed averaged around 50fps slower than the Oehler. Both appeared consistent though.

[BATattack]

Very interesting Tony and a question I've been thinking about myself! I've got a new tube as well and haven't done ANY load development and it's shooting better (like almost twice as good!) than any of my others ever have after development so I'm wondering what to do!

I'm in two minds if I should do a ladder test to find a load Window and record the velocity of that Window and continue to monitor and adjust load to maintain that velocity .

Or

Shoot it for a few 100 and then worry about development after.

Enjoy it!!!! Some barrels (the good ones) do not require much work. For me those that require lots of work are destined for the bin, life's too damn short (for me anyway) & barrels are really cheap when you think about it.
Keith H.

Haha thanks Keith! I think this one might go in the cupboard and maybe come out around 2017 but failing that it should be a hell of a OPM barrel!

[ecomeat]

Haha thanks Keith! I think this one might go in the cupboard and maybe come out around 2017 but failing that it should be a hell of a OPM barrel!

Adam,
Yes, in the interests of 2017, put it back in the cupboard. Do the right thing !
Do not even THINK about bringing it to QLD for the National Teams event at Belmont.
We are having our Qld Team selection trials next weekend as part of our City Vs Country, with 2 x 300 and 2 x 1000.
Coach Kielly , that cranky old CRO bloke at Belmont, has a big field of Nominations to choose from this time around, so whoever is fortunate enough to be selected is going to be part of a fairly capable Team.
So save that barrel, Adam. Your country needs it in 2017

[BATattack]

Haha thanks Keith! I think this one might go in the cupboard and maybe come out around 2017 but failing that it should be a hell of a OPM barrel!

Adam,
Yes, in the interests of 2017, put it back in the cupboard. Do the right thing !
Do not even THINK about bringing it to QLD for the National Teams event at Belmont.
We are having our Qld Team selection trials next weekend as part of our City Vs Country, with 2 x 300 and 2 x 1000.
Coach Kielly , that cranky old CRO bloke at Belmont, has a big field of Nominations to choose from this time around, so whoever is fortunate enough to be selected is going to be part of a fairly capable Team.
So save that barrel, Adam. Your country needs it in 2017

don't worry Tony I've got 4 more to play with between now and Belmont . . . . . Even a couple of them bartlines . . . So might fine a couple more cherries

[Norm]

With the Magneto Speed device. Due to the way it works, I think you need to take the Hysteresis effect into account when recording strings of shots.
The first shot should be discounted and the following shots should be at an even time interval, without the time interval being too long.
I find I get better results when this is done.

[williada]

Its obvious that all the shooters gear is first rate. They're only the pawns in the event. They only get to pull the trigger. Anyone can pull a trigger and they should do it when they are told to. . Can they resist the feeling of wanting to bite a four inch nail in half when the masterminds telling them to fire miss an obvious change. . This event is the battle of the coaches and selectors. Don't let them off the hook.

[mike H]

Its obvious that all the shooters gear is first rate. They're only the pawns in the event. They only get to pull the trigger. Anyone can pull a trigger and they should do it when they are told to. . Can they resist the feeling of wanting to bite a four inch nail in half when the masterminds telling them to fire miss an obvious change. . This event is the battle of the coaches and selectors. Don't let them off the hook.

Willada,
Now I know you are human.
Thanks for your freely given knowledge.
Mike.

[RDavies]

With the Magneto Speed device. Due to the way it works, I think you need to take the Hysteresis effect into account when recording strings of shots..

Hysterisis effect, Doh, here is another shooting term I don't have a clue about.
Hang on , no, maybe I can use it as an excuse. yep, I had 5 Xs in a row, then the old Hysterisis came and I got a 5 at 3 oclock.