New barrel slowing down?

[Freebore221]

So I am breaking in a new 6.5 CM barrel from P2 precision...
Pre-fit for BAT TR 26" and it seems to be slowing down?
Using some cheap Barnes Match Burners 140 grain and 40.0 grains of RL 16 with CCI #200 seated to 2.800 COAL.
Accuracy is fine and stable around 1/2 MOA. Speeds measured with Garmin Xero sitting on bench. TBAC Magnus was used as well.
First 20 rounds average velocity was 2713 FPS.
Second 20 rounds average velocity was 2706 FPS.
Third 20 rounds average velocity was 2696 FPS.
Fourth 20 rounds average velocity was 2696 FPS again.
Fifth 20 rounds average velocity was 2689 FPS.
I cleaned with Eliminator every 20 rounds using patch/jag and a few strokes of a nylon brush.

100 rounds down the barrel so far...

Any thought on why this seems to be slowing down?

 

[rustyinbend]

(a) You might be cleaning too much ... it takes a few rounds after a cleaning to settle down.
(b) Have you run any copper remover through it, or just the Eliminator?
(c) I know others will cringe at this ... but have you looked at it with a bore-scope?

I've experienced something similar a while back with a new barrel, and it ended up being about copper, not carbon.

 

[Freebore221]

No copper remover, just eliminator. Loaded up another hundred and going out tomorrow. I am thinking I won't clean for these last hundred rounds and see how it acts. Didn't want to look at a brand new barrel in the borescope and psyche myself out, it shoots acceptably, just puzzled that it seems to be slowing down, and not speeding up.

 

[straightshooter1]

So I am breaking in a new 6.5 CM barrel from P2 precision...
Pre-fit for BAT TR 26" and it seems to be slowing down?
Using some cheap Barnes Match Burners 140 grain and 40.0 grains of RL 16 with CCI #200 seated to 2.800 COAL.
Accuracy is fine and stable around 1/2 MOA. Speeds measured with Garmin Xero sitting on bench. TBAC Magnus was used as well.
First 20 rounds average velocity was 2713 FPS.
Second 20 rounds average velocity was 2706 FPS.
Third 20 rounds average velocity was 2696 FPS.
Fourth 20 rounds average velocity was 2696 FPS again.
Fifth 20 rounds average velocity was 2689 FPS.
I cleaned with Eliminator every 20 rounds using patch/jag and a few strokes of a nylon brush.

100 rounds down the barrel so far...

Any thought on why this seems to be slowing down?

Did you load up those 100 rounds all at the same time?

How to you handle your powder during and after charging cases?

Was ambient temperature pretty much the same for each 20 round session?

 

[Freebore221]

Did you load up those 100 rounds all at the same time?

How to you handle your powder during and after charging cases?

Was ambient temperature pretty much the same for each 20 round session?

All loaded at the same time with the same canister of powder, first 40 rounds shot on Wednesday morning, last 60 rounds shot Thursday morning. Thursday was about 10 degrees cooler than Wednesday. Possible temp variation but RL 16 is pretty temp stable and 10 degrees is not much of a difference. Headed out to shoot the next hundred I loaded last night, will report back.

 

[rustyinbend]

No copper remover, just eliminator. Loaded up another hundred and going out tomorrow. I am thinking I won't clean for these last hundred rounds and see how it acts. Didn't want to look at a brand new barrel in the borescope and psyche myself out, it shoots acceptably, just puzzled that it seems to be slowing down, and not speeding up.

Actually ... bore-scoping a new barrel is kind of important, at least IMHO. It's always good to know what you've got, and also scoping a new barrel gives you a comparison baseline as it ages.

 

[Freebore221]

After 200 rounds total the speed is up a little bit at 2717 FPS. Probably the slowest and lowest speed up in any barrel I have owned.
Still shooting about 1/2 MOA so that is good!

 

[straightshooter1]

All loaded at the same time with the same canister of powder, first 40 rounds shot on Wednesday morning, last 60 rounds shot Thursday morning. Thursday was about 10 degrees cooler than Wednesday. Possible temp variation but RL 16 is pretty temp stable and 10 degrees is not much of a difference. Headed out to shoot the next hundred I loaded last night, will report back.

Be sure to report the SD and ES for all shots rather than just the averages. It helps paint a better picture.

 

[viking78]

(a) You might be cleaning too much ... it takes a few rounds after a cleaning to settle down.
(b) Have you run any copper remover through it, or just the Eliminator?
(c) I know others will cringe at this ... but have you looked at it with a bore-scope?

I've experienced something similar a while back with a new barrel, and it ended up being about copper, not carbon.

I would say that A is the reason.
I have seen a 100fp difference on speed, with dirty and clean barrel.
It might take a long time to get back to the velocity it was before cleaning the barrel all the way to the metal.
That´s why i do not remove all the copper from my barrels no more, just boresnake after every shooting time.
Cleaning rod when the accuracy is not the level it should be.

 

[Freebore221]

Be sure to report the SD and ES for all shots rather than just the averages. It helps paint a better picture.

Ok, here is what I have. First 50 rounds of the day is the 40.0 grains RL16 the last 50 rounds was kind of a ladder going up 0.3 each load 5 rounds each.

Shots/mv/sd/es 40.0 gr RL16
1-10/2691/20.8/58.3
11-20/2715/16.6/46.1
21-30/2722/12.9/58.2
31-40/2714/15.6/43.4
41-50/2717/8.7/30.9

Shots/mv/sd/es
51-55/2751/9.6/25.7 40.3 gr RL16
56-60/2761/6.3/15.2 40.6 gr RL16
61-65/2774/7.7/17.5 40.9 gr RL16
66-70/2792/11.0/33.0 41.2 gr RL16
71-75/2804/11.8/30.5 41.5 gr RL16
76-80/2826/18.9/53.7 41.8 gr RL16
81-85/2835/12.3/34.4 42.1 gr RL16
86-90/2879/13.2/38.1 42.4 gr RL16
91-95/2895/10.6/24.8/ 42.7 gr RL16
96-100/2916/4.4/12.0 43.0 gr RL16

 

[BuildingConceptsllc]

It's not slowing down. You are cleaning a lot in between and likely within your ES for the same charge weight. Keep shooting it and pick your load and then get your cleaning regiment figured out.

 

[nn8734]

Ok, here is what I have. First 50 rounds of the day is the 40.0 grains RL16 the last 50 rounds was kind of a ladder going up 0.3 each load 5 rounds each.

Shots/mv/sd/es 40.0 gr RL16
1-10/2691/20.8/58.3
11-20/2715/16.6/46.1
21-30/2722/12.9/58.2
31-40/2714/15.6/43.4
41-50/2717/8.7/30.9

Shots/mv/sd/es
51-55/2751/9.6/25.7 40.3 gr RL16
56-60/2761/6.3/15.2 40.6 gr RL16
61-65/2774/7.7/17.5 40.9 gr RL16
66-70/2792/11.0/33.0 41.2 gr RL16
71-75/2804/11.8/30.5 41.5 gr RL16
76-80/2826/18.9/53.7 41.8 gr RL16
81-85/2835/12.3/34.4 42.1 gr RL16
86-90/2879/13.2/38.1 42.4 gr RL16
91-95/2895/10.6/24.8/ 42.7 gr RL16
96-100/2916/4.4/12.0 43.0 gr RL16

Any pressure signs anywhere between 42.1 and 43 grains? If not, I'd do some initial development somewhere in that range and see how it shoots, go from there.

 

[Freebore221]

Any pressure signs anywhere between 42.1 and 43 grains? If not, I'd do some initial development somewhere in that range and see how it shoots, go from there.

I was amazed there were no signs of pressure with any of these loads, 2900 FPS+ with 140's is pretty darn fast.
Definitely looking at load development there as well as the lower node @ 40.6 grains.

 

[nn8734]

I was amazed there were no signs of pressure with any of these loads, 2900 FPS+ with 140's is pretty darn fast.
Definitely looking at load development there as well as the lower node @ 40.6 grains.

I never start load dev on any of my barrels before 150 rounds or so for .473 stuff and 100 or so for magnums...I've noticed too may oddities over the years when round counts were below that...I either shoot some factory ammo or load a nominal charge weight and shoot those (sometimes I'll get lucky and the nominal charge weight will end up being the final load).

Assuming your groups are to your liking and SD is under control, you should have a nice shooting rifle once you settle on a final load recipe.

 

[Freebore221]

I never start load dev on any of my barrels before 150 rounds or so for .473 stuff and 100 or so for magnums...I've noticed too may oddities over the years when round counts were below that...I either shoot some factory ammo or load a nominal charge weight and shoot those (sometimes I'll get lucky and the nominal charge weight will end up being the final load).

Assuming your groups are to your liking and SD is under control, you should have a nice shooting rifle once you settle on a final load recipe.

I just realized that it might be confusing if someone only read a couple of posts on here. I actually fired 150 rounds of the 40.0 grain load of RL 16 before performing the ladder loads. I agree with you about rounds down the barrel before any load development attempts.
200 rounds total on this barrel so far, it is solidly in the 1/2 MOA camp. I was just confounded on how the first 100 rounds the barrel seemed to be slowing down a little...

 

[nn8734]

I just realized that it might be confusing if someone only read a couple of posts on here. I actually fired 150 rounds of the 40.0 grain load of RL 16 before performing the ladder loads. I agree with you about rounds down the barrel before any load development attempts.
200 rounds total on this barrel so far, it is solidly in the 1/2 MOA camp. I was just confounded on how the first 100 rounds the barrel seemed to be slowing down a little...

Yea, sometimes odd patterns show up in the data in those first 100 rounds or so...Nothing to worry about.

 

[straightshooter1]

Ok, here is what I have. First 50 rounds of the day is the 40.0 grains RL16 the last 50 rounds was kind of a ladder going up 0.3 each load 5 rounds each.

Shots/mv/sd/es 40.0 gr RL16
1-10/2691/20.8/58.3
11-20/2715/16.6/46.1
21-30/2722/12.9/58.2
31-40/2714/15.6/43.4
41-50/2717/8.7/30.9

As I suspected your numbers suggest to me your original 100 only seemed like it was slowing down, but was just a matter of you ES's being large and the way you split it up, you just happened to see a lower averages in subsequent sets. With the kind of SD's and ES's you're getting, that can easily happen. The new numbers suggests to me you're barrel has settled down and those speeds are what you can expect from 40.0 grs of RL-16.

As far as your ladder numbers, it's how each of those groups relates to each other on paper that'll tell you which load is the better one. Then you'll have to test that "better load" again to confirm that it really is.

 

[RegionRat]

Ok, here is what I have. First 50 rounds of the day is the 40.0 grains RL16 the last 50 rounds was kind of a ladder going up 0.3 each load 5 rounds each.

Shots/mv/sd/es 40.0 gr RL16
1-10/2691/20.8/58.3
11-20/2715/16.6/46.1
21-30/2722/12.9/58.2
31-40/2714/15.6/43.4
41-50/2717/8.7/30.9

Shots/mv/sd/es
51-55/2751/9.6/25.7 40.3 gr RL16
56-60/2761/6.3/15.2 40.6 gr RL16
61-65/2774/7.7/17.5 40.9 gr RL16
66-70/2792/11.0/33.0 41.2 gr RL16
71-75/2804/11.8/30.5 41.5 gr RL16
76-80/2826/18.9/53.7 41.8 gr RL16
81-85/2835/12.3/34.4 42.1 gr RL16
86-90/2879/13.2/38.1 42.4 gr RL16
91-95/2895/10.6/24.8/ 42.7 gr RL16
96-100/2916/4.4/12.0 43.0 gr RL16

What this tells us, is that only the first 10 shots are out of family.
When you mentally extend the centerline of the ladder test back down to the 40.0 grains where you ran the first 50 shots, by the time the first ten are done, the rest behave very well.
So, you may just need to watch how many it takes to reset after a scrub, but I don't see anything to worry over in terms of the barrel.
In general, you may want to work on the decision to stick with this recipe if it serves your purpose, or punt and see if something else shoots tighter.
I think it really depends on your experience level and if you can shoot better to the point where this load holds you back or not.

If you use your imagination and extend that dotted line down to your first 50 shots, it is only the first 10 that don't behave, and I assume you started the session with a clean barrel.
My advice is like the above, just keep rolling and keep up the good work. Shoot more, worry less.
Good Luck and in for the progress report.