Barrel life

[Sako man]

I have a general question about barrel life. I have two Tikkas 6.5 Tac A1s. The second one I just acquired, it's second hand. Shooting the same identical ammo the velocities in general are 75 to 100 FPS slower on the used Tikka I just purchased. So theoretically identical guns but second hand one is slower.

Question: Are the slower velocities due to a worn out barrel or other issue?

 

[Steel head]

Barrels differ as well from one to the next.
Tikka is well known to often have slow barrels.

When I see speed loss in a barrel (if it’s still shooting good and they usually do) I at first adjust my load to get back up to speed maybe doing that 1-4 times.
eventually it starts loosing speed fairly rapidly and you can’t keep up and usually by then ES becomes noticeable as well at that point.

 

[1moaoff]

Can be....
Can be just the barrel.

 

[Sako man]

Barrels differ as well from one to the next.
Tikka is well known to often have slow barrels.

When I see speed loss in a barrel (if it’s still shooting good and they usually do) I at first adjust my load to get back up to speed maybe doing that 1-4 times.
eventually it starts loosing speed fairly rapidly and you can’t keep up and usually by then ES becomes noticeable as well at that point.

Ok, didn't know that about Tikkas, good to know. Hard to say, today the ammo had a pretty big ES and the SD was like 27, so not great. Hard to say what's going on. Did get some good accuracy however.

 

[Steel head]

Ok, didn't know that about Tikkas, good to know. Hard to say, today the ammo had a pretty big ES and the SD was like 27, so not great. Hard to say what's going on. Did get some good accuracy however.

I’d just shoot it.
If it’s dying it will noticeably continue to slow down
If it’s just a slow one it won’t.

 

[Sako man]

I’d just shoot it.
If it’s dying it will noticeably continue to slow down
If it’s just a slow one it won’t.

Humm, probably good advice. Ok, i'll see how she does next few sessions.

 

[rustyinbend]

Do you have a bore-scope? I've found mine invaluable in situations like this. I got THIS ONE for less than $50, and it works great and answers questions like this that you just can't answer without a visual reference.

 

[psdan000]

Do you have a bore-scope? I've found mine invaluable in situations like this. I got THIS ONE for less than $50, and it works great and answers questions like this that you just can't answer without a visual reference.

+1 on the borescope, I bought the same one and it's a great tool to have. It will tell you everything you need to know about the condition of your used barrel.

 

[Shoots 700's]

I would just shoot it after a good cleaning. If you buy a bore scope, do you know what to look for once
you start poking it down the barrel?

 

[DownhillFromHere]

O lord the keg o' worms wrt bore scopes is cracking open. A bore scope isn't going to tell you when a barrel's cooked. I have a Bartlein 6.5CM barrel with 2100+ rounds on it; the throat is noticeably eroded and the fire cracking looks like a frozen windshield somebody hit with a brick. But I got 4 hits out of 5 shots on a 24" plate with it at 1270 yards two weeks ago. I also have an AR that shoots sub-MOA groups with 77SMKs and the barrel bore looks like it was pounded out with a hammer & chisel.

A bore scope newbie would be wailing and gnashing teeth... they post "OMG WHAT DO I DO" here all the time. Yes, a bore scope is a valuable tool. But just because a bore isn't shiny pristine doesn't mean it's no good.

 

[CK1.0]

The closer you seat your bullets to the lands, the higher the pressure, the faster they go. To an extent. The same load with a .100" jump vs a .020" jump will be slower.

Most common 6mm and 6.5mm cartridges erode the lands at a rate of 2 to 6 thou per hundred rounds. You'll read on this forum people talking about only losing .002" over 1000rds, etc. It is surprising how many people can't maintain an accurate track of their throat erosion.

^^^ this is good stuff that most people either don't know or just plain forget folks.

I use the Deep Creek method to find the lands (the method I've come to really like/prefer and that is really easy to use if you've got a CRF/fixed-ejector action like an Origin or something):




Using the exact same powder charge (41gr StaBall):

I've found my 6CM will cook off .003-.006" off the lands per 100rds when bullets are seated to the ubiquitous .020" off, and MV averages ~2950-2975fps.

When seated .100" off the lands it's a little slower and only gets me ~2900fps, but over a 1000rds I've only lost a legit/documented .006"!

I've also found the larger bullet-jump makes the gun's waterline at 600+ yards a lot more consistent and predictable, so I won't be going back to seating close to the lands. No reason to smoke my barrel prematurely trying to turn .3" groups into .25" groups at 100 yards when I don't even really shoot at 100 yards unless I'm checking my zero...

FWIW I don't have a bore-scope and don't want one.

 

[Solo 43]

FWIW....back when I was shooting slinged up prone, with irons at 1000 yds (Palma), I had an interesting experience with a barrel at 600 and later that day at 1000. Now, I'm shooting .308/155 grn'ers and shot a 200-15X at 600...hammered it. Later that day, it wouldn't hold the 9 ring @ 1000!!!! Nothing was on call...looked like a buckshot pattern. Now, everything was the same....nothing had changed, even the conditions. At the BBQ, I mentioned it to another Palma team member and he said 'barrel is gone', as he experienced the same thing a few weeks before at a match. BIG difference between 600 and 1000 yds. So, I took the barrel off, set it back, and put it on one of my departments sniper rifles. It shot dots out to 400 yds. I was surprised, but learned something. Now, before anyone pipes in about vels/ES and it changing due to barrel wear, the ONLY thing I based barrel life on (after this incident) was how it shot at 1000. If shots were 'on call!' and it would hammer the X ring in good conditions, I'd leave it alone. I got nervous at the 4000 rnd mark and usually changed barrels, but other then that.....

 

[DownhillFromHere]

...understanding where you're barrel is in it's life doesn't happen from botescoping it once. It's an accumulation of context that informs your holistic understanding.

The pure one-sided "Fuck the borescope" attitude is naive

Truth. Bore scope is one more tool in the box, potentially a very valuable one. But one pass through a barrel, examined in absence of any other data (especially accuracy at distance), is more likely a source of confusion than useful info. "Context" is an excellent word.

 

[Solo 43]

Again, FWIW...I NEVER bore scoped a barrel. The few I did had already come off one of my rifles.

Reloading ammo: got some stories on that as well. Some of them hilarious.....not so much!

 

[CK1.0]

The pure one-sided "Fuck the borescope" attitude is naive

That's not my attitude at all.

For me, it's just sort of like a bore-scope would make me paranoid, or like you said, try to eek out more rounds instead of just spinning on a new barrel when I should.

For some guys bore-scopes might be helpful, but for me, I have enough OCD already when it comes to reloading and all the other stuff... I just choose to avoid that rabbit hole is all (well, until something so wonky happens that I can no longer avoid it).