Home Forums Hunting & Shooting Hunting Rifles Barrel speeding up upon proper breakin?

I posted this on another forum as well, but wanted to see what some of you guys on here thought...

Is it common for a barrel to gain velocity after proper breakin?

Last summer, I put a new Shilen Barrel on my .270. I finished it at 24.75". I put approx 100 rounds down it (Barnes, Accubonds, Partitions) to break it in and develop a load for 2016 fall hunting season.

I ended up settling on 55.0 grains of IMR 4831 W/ 129 Barnes LRX. The book showed this to be around 3150, but my chronograph was showing an average of 3075 - so I ran with that. The velocity was questionable as I had a tad longer barrel than the book, but it wasn't enough for me to care too much and accuracy was what I was looking for.

FAST FORWARD - This spring I have brought out the 270 for two separate range visits - one about a month ago in 50 degree weather and one today in 75 degree weather.
NOTHING HAS CHANGED on the rifle or the loads, in fact I was shooting the same loads I developed last fall that have been sitting in the safe all winter.

In my first range visit a month ago, the velocity average for the 15 rounds I shot was right at 3140 FPS. POI stayed exactly the same and group size was 3 shots in .5-.6 range which is what this load has always done. Overall an average velocity increase of approx 75 FPS over the last time I shot the rifle in the fall.

Today, I get out and I shoot 24 rounds - 6 4 shot groups. POI is same. Was shooting .5-.6 4 shot groups (Super Stoked about that) but Velocity average was 3217 FPS. Highest Velocity was 3240, lowest was 3180.

Will a barrel normally speed up like this? By now I consider the barrel broke in as I can shoot quite a few barnes loads with minimal fowling. Again, these are all the same loads from a batch of 60 I whipped up last fall. I know it was hotter today, but the speed increase has came every range session.

I am mainly curious because I shot today to get a final chrono speed to submit for my Leupold CDS Dial. I was going out to verify 3150 ish, and now I am averaging 3200. I wont be shooting far enough for it to really matter (5-600 max) but I still want to be as accurate as possible.

Thoughts? Do barrels speed up?

Please describe and explain "proper breakin".

Thanks..

Was it hotter - temp effects powder sometimes.

It was hotter today than it was a month ago, but it was same if not cooler then when I did my initial breakin/load development. I have since gained an average of 125-150 FPS under similar temperatures.

Focus on the important stuff - accuracy., and pressure signs.

Trust me- nothing killed cares if it is at 2460fps, or 3500 fps. MV, or 125 fps slower or faster... BTDT... In 68 years, i've yet to chrony a load, and for my purposes, fps is largely meaningless except for paper calculations for drop. Actually shooting at range matters...when it matters, So far, this has come pretty close to book values but then I don't have a Ransom Rest....any errors in data are possibly/likely mine - but they are what I will be using in the feld.

Did the POI is change from initial sight-in. at the "lower" velocities? - that matters! Has it? I bet not, but that is far more important information than fps!

For hunting purposes, you need to know the range, and the drop at ranges for that rifle and load That's it. Temperature/pressure of air isn't going to make a whit of difference for hunting purposes until waaaaay out there! Or 20,000 feet. And then only a matter of a few inches at distances nearly no one of us has business shooting at. On game, anyway. I have yet to find that even a 50 degree drop in temperature makes a significant change for hunting purposes- and I've killed game from 90 to -30, or so. But then, I like to get within 300 yards or less.

If you are focusing on velocity rather than consistent accuracy, you might want to re-think.

IMHO.....

You'd think DURING 68 yrs some people would LEARN :/, "ignorance is bliss" ??

However if you haven't USED a piece of equipment, you DON'T know what you are missing.!

Tell us WHAT pressure signs are 'reliable' indications of pressure,- BELOW too much ?

There is TOO much uh, uh, uh, in the rest of this to try to deal with. There is more horse poop here than in a horse stable.

Suffice it to say - a good CHRONOGRAPH + using it would answer your questions a WHOLE LOT faster PLUS save components AND trips to a range OR some place you can shoot PAST the muzzle.

Once you know your velocity (speed) you'll be CLOSE to knowing what to expect in trajectory!
--------------------------

alright lesson learned, I know not to waste my time.

One thing that can change is,the bullet sometimes can get tighter in the case after it sets over a period of time.I found that out after trying to pull some ammo apart with my collet bullet puller.The necks were lubed with a small amount of case lube before seating the bullet.Had to seat them deeper first to move the bullet before I could pull them.This could cause variation of velocity.I recently switched to powdered graphite to lube my case necks,this seems to work better.Then of course temperature can affect velocity.Another is the direction of the sun on your chronograph.I found if my chronograph was facing into the rising sun shooting east,it apparently was casting a shadow across the windows thus changing how it was seeing the bullet as it passed over it.I moved to a different location where I'm shooting in a northern direction,I now can see a more consistent velocity when I shoot.I recently had a Pac-Nor barrel put on a rifle.I'm about 40 rounds down the barrel now and I have noticed a slight increase in velocity from the first rounds that were fired in it.Looks like around 30-40fps.One thing I did notice too,the standard deviation is really close.What a difference a good smooth bore makes.

Yes, barrels speed-up as they settle in. You need to ask this on precision shooters' forums. In general, a barrel speeds up and settles down after 100 to 200 shots. The better the barrel, the quicker it comes into tune.

or maybe it was just the chronograph?

I would expect some shift in point of impact with a 200 fps velocity difference, specially with arifle that shoots 0.5-0.6"... wouldn't you?

Not in my experience.
If anything a "broken in barrel" having ironed/smoothed out whatever will result in lower pressures/velocity.
I really never noticed a increase or decrease worth going hmmmm over.
Can't say in your case what is going on but would be thinking temps, lighting conditions, distance to chronograh , coal, load building/record keeping process, throat.

A lot of times, particularly on good aftermarket barrels, the first few shots will be lower. I always thought it just took a certain level of fouling to get them there. My last barrel on my .220 AI (Shilen) was like that, but I'm only talking 10-20 shots, and only when new.

Ask the same type of question over on accurateshooter.com. Especially anyone shooting in PRS venues.

They will know from experience. It's common knowledge that you don't set your comeups, etc until after at least 100 rounds, if not 200. The velocity rises little by little until it levels off.