Barrel tuning.

[martin_b]

I'm picking up my rifle tomorrow after its had a new barrel fitted. 

The old barrel went south pretty quickly, ( operator error and old age it turns out), so my problem might be I have 500 rounds of identical hand made rounds ready and waiting, what if my new barrel doesn't like the load? Can you use a barrel tuner to tune a barrel to a specific load, or if the 2 aren't a match do I have to pull all the bullets  and start again?  (obviously I give the barrel a chance to break in first)

[Geezedtee]

A Barrel Tuner can tweak a good load, but it won't turn a bad load into a tack driver.

 

[Popsbengo]

2 hours ago, martin_b said:

I'm picking up my rifle tomorrow after its had a new barrel fitted. 

The old barrel went south pretty quickly, ( operator error and old age it turns out), so my problem might be I have 500 rounds of identical hand made rounds ready and waiting, what if my new barrel doesn't like the load? Can you use a barrel tuner to tune a barrel to a specific load, or if the 2 aren't a match do I have to pull all the bullets  and start again?  (obviously I give the barrel a chance to break in first)

It's a controversial subject, some say "works a treat", some say "snake oil" and then views in-between.

Barrel break-in is another subjective view, at least for a quality target barrel like Sasson or Bartlien.

😑

[martin_b]

5 minutes ago, Popsbengo said:

It's a controversial subject, some say "works a treat", some say "snake oil" and then views in-between.

Barrel break-in is another subjective view, at least for a quality target barrel like Sasson or Bartlien.

😑

Thanks, lets just hope 42grains is perfect!

incidentally Old barrel was a Sasson is now a Bartlien.  

[No i deer]

The chambers vary and the ammo that fitted the old chamber may not fit in the new one

[Big Al]

The first issue you have is one of safety, knowing for sure that the old ammo you have wont cause pressure in your new barrel. The second is will the old ammo fit the new chamber?

I would load a few pressure testers up for the new barrel starting at least 2.0gr lower than your old ammo currently is and creep up to your old ammo charge weight and then beyond by another 1.0gr if possible. Go out and do a pressure test and if it reveals that your old charge weight is safe in the new gun then your safe to use the ammo assuming it fits the new chamber. If it doesnt then your pretty much scuppered without stripping that ammo and resizing it, whatever you do dont try to resize loaded ammo.

 

As for a barrel tuner, if you have a good tuner than has been fitted/balanced by someone who knows what they are doing and they give you comprehensive instructions on how to use the tuner you might be able to improve the old load should it not shoot so well in the new barrel. My experience is tuners will tune any load so some degree, even bad loads. A well balanced tuner can usually half group sizes from worst case scenario. By that I mean if you keep adjusting the tuner until the groups are the largest then with correct tuning they will go to about half the worst group size, so 2" down to 1" or 0.5" down to 0.25" if you have a good barrel and load combo. Ive seen so many examples of this with both home loads and factory ammo Im confident in what I say. If when the tuner has been fitted by coincidence an optimum is reached before moving the tuner then all moving it will do is increase group sizes then bring them back to where they started again.

 

The biggest issue I have found though regarding tuners is actually getting one that is the right weight for the barrel and that has the right level of adjustment in terms of thread pitch and increment size to give you half a chance of it being useful. Long thin barrels have different requirements to short fat barrels, the same tuner wont work the same on each. As I see things now its a bit pot luck with tuners because nobody Im aware of has made different spec (weight) tuners to work with different barrel profiles and there is very little published info that is any use to allow users to get the best from the tuner assuming its the right spec for the barrel. The same weight tuner could work across all barrel specs but it would need to be treat very differently on a stiff barrel to a flimsy one.

 

If I was going to produce barrel tuners for general sale I would probably make at least three different weights to cover the spectrum of CF barrels out there from hunting to competition and again a couple of different ones for rimfire, its definitely not an easy one size fits all thing.

 

A lot of the tuners out there are just far too heavy and as a result the adjustments are too coarse often creating POI shifts rather than shifts in tune, I think this explains why many people have been sceptical because they havent been able to get the best from the barrel with the wrong type of tuner fitted and very poor instructions for use.

 

If nothing else and you dont use a tuner then if your old ammo is safe to use you can use it to run the new barrel in.

 

Every new barrel needs to be run in but not for the reasons many think. For me running the barrel in has nothing to do with extending its lifespan or improving its accuracy. Every barrel Ive ever chrono'd from new (of which there are many) has always sped up by anywhere from 80-150fps after around 100-150 shots. If you develop a load for a new barrel before it stops speeding up then your tune will shift as your speed does. Thats why diligent competition shooters dont develop a load for a new barrel until it has stopped speeding up. Of course this only matters when looking for optimum accuracy, many people just require acceptable accuracy which can be very different from optimum.

[martin_b]

9 hours ago, No i deer said:

The chambers vary and the ammo that fitted the old chamber may not fit in the new one

That i did think of..  I made up a couple of dummy rounds and left them with the builder.

[martin_b]

Thanks for all the advice chaps.. 

The rifle is chambered in 6.5CM and I'm currently running 42g of RS62 with a 140g,bullet  which from my research seems to be a very conservative load (2650fps), but it worked well  so I'm hopeful this will be OK for the brake in process but I will load a few test rounds first and check the current load is safe, then after 100 or so rounds reassess the situation and see where i go from there. 

[Ronin]

I’m sure with a quality barrel - if fitted by a competent rifle smith you should be able to develop a load that returns single hole accuracy at calibre diameter or just slightly larger without resorting to a tuner

You don’t say if the brass you’ve loaded is brand new or left overs from the old barrel

 

If the new barrel was chambered and headspace’s to the same dimensions as the old barrel then it should fit 

 

The issue will be the bore diameter of the Bartlein will likely be different to the Sassen it replaced and if tighter land diameter will manifest in higher pressure 

 

something to bear in mind from the onset

 

A tuner may help with a generic load but doesn’t replace good practice load development 

👍🏻

 

[Scotch_egg]

So what exactly happened to the first barrel? 

[No i deer]

6 hours ago, Ronin said:

I’m sure with a quality barrel - if fitted by a competent rifle smith you should be able to develop a load that returns single hole accuracy at calibre diameter or just slightly larger without resorting to a tuner

You don’t say if the brass you’ve loaded is brand new or left overs from the old barrel

 

If the new barrel was chambered and headspace’s to the same dimensions as the old barrel then it should fit 

 

The issue will be the bore diameter of the Bartlein will likely be different to the Sassen it replaced and if tighter land diameter will manifest in higher pressure 

 

something to bear in mind from the onset

 

A tuner may help with a generic load but doesn’t replace good practice load development 

👍🏻

 

Hi Andy..

He said he had 500 rounds already made up 😳.

I hope they fit as that's alot to redo 😬

[martin_b]

4 hours ago, Scotch_egg said:

So what exactly happened to the first barrel? 

Well over 2000 rounds (I bought the rifle used) and a stuck cleaning rod,  which in my ham fisted efforts to remove it seems to have marked the lands. One or both of the above has seen groups opening up and the odd unexplained flyer.

Neil McKillop has fitted the barrel and diagnosed the old one.

[Scotch_egg]

30 minutes ago, martin_b said:

Well over 2000 rounds (I bought the rifle used) and a stuck cleaning rod,  which in my ham fisted efforts to remove it seems to have marked the lands. One or both of the above has seen groups opening up and the odd unexplained flyer.

Neil McKillop has fitted the barrel and diagnosed the old one.

2000 rounds isn’t too bad. The stuck cleaning rod is something I have to admit to also doing with my first centrefire. It also ended up in a re-barrel. 
 

as per the replies above. You might struggle with the brass if the chambers differ too much. Worth taking the firing pin out and checking the chamber. 
 

I would also do some pressure testing. Load up some rounds from 40gr in .5gr steps to make sure the rifle will be safe with the load you have in your 500 rounds  fingers crossed for you, because pulling 500 rounds will be no fun at all.

 

 

[martin_b]

I'm delighted to say the dummy rounds I've made up all fit, so thats the first hurdle over.

Im less delighted to report my exhaust back box and the rest of the system parted company on the way home, so it may be a couple of days before I can commence firing!

 

As to pulling rounds, I do have a Frankford Arsenal pile driver puller, which in my opinion is b****dy marvelous.. and must have paid for itsself several times over.

[Big Al]

Another very simple option you have is to try some seating depth tuning with the old rounds, if groups aren't quite where you want them.

I appreciate you can only easily seat the bullets deeper into the case but your accuracy nodes will repeat. By going 0.005" deeper into the case over a 30-40 thou span or as far as is safe and practical you might find something if you didn't want the faff of a barrel tuner or pulling all 500 rounds to do a new load.

Just watch out for indications of pressure increases as those bullets get considerably deeper into the case, they should be easy to see/feel.

[Ralpharama]

If the barrel had 2000 rounds through it, I would have thought the likelihood would be that the bullets would be out further than a new barrel without throat wear? My guess would be that the bullets would be more likely to need to go deeper into the case the back out? 

[martin_b]

Put 25 down the new barrel this morning at Bisley.   Started off low but got to my current load with no pressure issues.  I'll probably shoot another 25-50 and then get in Chrono'ed on the next club shoot,  after that shoot my best ever 4 rounds of O/T so a good morning all round. 

Edited Wednesday at 04:51 PM by martin_b
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