Barrel Speed during reloading

[jrock]

I usually break in with about 10 to 20 rounds. Then shoot a couple ladders with a couple bullets and powders. By time that is done, I've usually fire formed enough brass and bullets down the barrel that I'm ready for the fine tuning ladder test. I might shoot a couple times a year to do this work so I have never bother to try and find a point where the barrel speeds up. By time I'm done basic load workup, my velocities don't change much.

 

[jdmecomber]

It depends on the barrel. my experience as follows:
Benchmark 6.5 WSM 120 FPS
Rock Creek 28 Nosler 70 FPS
Broughton 7 saum 0 FPS
Proof 30/28 Nosler 15 FPS
Broughton 338 edge 60 FPS
Broughton 30/28 15 FPS

I start working on things right away after break in and cleaning. You can find seating depth. You may or may not have to reduce powder charge. I haven't noticed it happening right away, but more gradual. I shoot every shot and record velocity over a Labradar. I believe that cleaning the rifle well and removing copper after each 20-25 rounds seem to bring on any velocity change faster. Depending on how your headspace was cut during rifle chambering determines how much your virgin vs fired brass velocity will change. I measure volume of virgin and fired to see the difference and load accordingly. Biggest difference that i have seen is with belted magnums and velocity increase on fired brass..

Do you have notes on how many shots it took the benchmark to level out?

 

[Rhovee]

It was about 100-120 rounds.

 

[jdmecomber]

It was about 100-120 rounds.

thanks

 

[jdmecomber]

Well
112 rounds in and it appears the barrel has settled.

We settled on a node in the 2940's. It has produced three groups now with 7,12 and 15 ES. This gun with Reloader 26 hasn't produced a group over .75 moa with 3.5 grains of powder around 190 fps in total spread. I think once I get prone these groups will get better. We have multiple groups under .20 moa.

We tried some other powders around the same node of 2940 and it was a failure. The other powders were very unstable in the same node. H1000 and Retumbo were used.

Imr 7828 SSC had around an moa in group size and about a 15 ES with new brass. I think this could really improve with fireformed brass and some lands movement, but this is a hunting rifle. The customer should be happy.

 

[tbrice23]

Well
112 rounds in and it appears the barrel has settled.

We settled on a node in the 2940's. It has produced three groups now with 7,12 and 15 ES. This gun with Reloader 26 hasn't produced a group over .75 moa with 3.5 grains of powder around 190 fps in total spread. I think once I get prone these groups will get better. We have multiple groups under .20 moa.

We tried some other powders around the same node of 2940 and it was a failure. The other powders were very unstable in the same node. H1000 and Retumbo were used.

Imr 7828 SSC had around an moa in group size and about a 15 ES with new brass. I think this could really improve with fireformed brass and some lands movement, but this is a hunting rifle. The customer should be happy.

What barrel and cartridge are you shooting?

 

[J E Custom]

There are a lot of variables that can effect velocity, and different barrels can contribute to this greatly,

In my opinion, if it takes 100+rounds for a barrel to settle in it was not broke in properly. Some barrels take longer to break in, especially factory barrels. They don't have the bore finish that custom barrels do
and I have seem them take up to 60 or 70 rounds to settle in and some realy never did, but they shot as good as they ever would.

Most High quality barrels will break in with anywhere from 10 to 30 rounds through them if the clean and shoot method is used and will settle in to an average velocity. The quality of the ammo or reloads
has a lot to do with how fast you start getting stable velocities also.
so I use the same load to reach this point because it shows the difference from shot to shot. I start load development only after the barrel settles down and consistent velocities and SDs for that load are achieved.

This can sometimes be a very boring process but it is well worth the effort. And even though the load may not produce the desired results, It is an apples to apples comparison to show the state of the barrels brake in and can tell you when you should/can start load development. the fact that we start loads on the low side and work up has a lot to do with increase velocity as we go but I have found that the barrel will reach consistent velocities much sooner if the load doesn't change.

A while back I did a velocity test while breaking a barrel in to see the effects on velocity. and after the test, the velocities have not changed enough to consider it significant except when I increase the powder charge or burn rate. (Pressure) I have verified this by using the leftover break in loads that at some point are used for fouling shots before a hunt to check on the barrel condition. A good bore scope will give you an indication of the bore condition, but a velocity test using the same load as you started with will give you proof.

Here is the results of the velocity test during brake in.
https://www.longrangehunting.com/threads/new-barrel-break-in-and-cleaning-methods.160450/page-2

Just My opinion based on my experience with new barrels.

J E CUSTOM

 

[jdmecomber]

What barrel and cartridge are you shooting?

Benchmark 7 Rem mag

 

[jdmecomber]

There are a lot of variables that can effect velocity, and different barrels can contribute to this greatly,

In my opinion, if it takes 100+rounds for a barrel to settle in it was not broke in properly. Some barrels take longer to break in, especially factory barrels. They don't have the bore finish that custom barrels do
and I have seem them take up to 60 or 70 rounds to settle in and some realy never did, but they shot as good as they ever would.

Most High quality barrels will break in with anywhere from 10 to 30 rounds through them if the clean and shoot method is used and will settle in to an average velocity. The quality of the ammo or reloads
has a lot to do with how fast you start getting stable velocities also.
so I use the same load to reach this point because it shows the difference from shot to shot. I start load development only after the barrel settles down and consistent velocities and SDs for that load are achieved.

This can sometimes be a very boring process but it is well worth the effort. And even though the load may not produce the desired results, It is an apples to apples comparison to show the state of the barrels brake in and can tell you when you should/can start load development. the fact that we start loads on the low side and work up has a lot to do with increase velocity as we go but I have found that the barrel will reach consistent velocities much sooner if the load doesn't change.

A while back I did a velocity test while breaking a barrel in to see the effects on velocity. and after the test, the velocities have not changed enough to consider it significant except when I increase the powder charge or burn rate. (Pressure) I have verified this by using the leftover break in loads that at some point are used for fouling shots before a hunt to check on the barrel condition. A good bore scope will give you an indication of the bore condition, but a velocity test using the same load as you started with will give you proof.

Here is the results of the velocity test during brake in.
https://www.longrangehunting.com/threads/new-barrel-break-in-and-cleaning-methods.160450/page-2

Just My opinion based on my experience with new barrels.

J E CUSTOM

I like it, Lots of good information in there. Intersting how the same load might get you there faster.