Do chrome lined barrels speed up?

[sjbryan65]

Do chrome lined barrels speed up like stainless barrels?

About to start loading for a new geissele super duty...

Just wondering if it should be stable velocity wise right off the bat or if it will need some rounds through it before it settles down?

Thanks!

 

[Near miss]

I would never start developing loads right away for any new barrel. But I guess you could start trying what bullets it likes the best at min charge if you must get things going.

 

[simonp]

I would never start developing loads right away for any new barrel. But I guess you could start trying what bullets it likes the best at min charge if you must get things going.

Agreed; break the barrel in with at least 200 rounds before developing a load - least in my experience

 

[sjbryan65]

Yea that is my process with stainless barrels. Shoot 200 either factory ammo or load up some factory seconds at a lower charge.

Then break out the bergers and start testing. Thanks for the advice guys.

 

[FredHammer]

I don't think anybody has answered the question yet. I am curious.

 

[sjbryan65]

Yea still interested on whether they speed up or not.

I will test mine and report back. Might be a while though before I get 200 rounds through it.

 

[Ex E6]

Speed up ?. As increasing velocity over a standard Chrome moly ? YES .

Let ME explain ANY bore which has been hard coated WILL increase bullet velocity to an extent . One is sealing the porosity of the metal ,so less friction jacket shedding would stand to reason . Right

I've been attempting to get a particular company to perfect BAM coating inside a narrow cylinder Dies and eventually BARRELS .

It requires precision Laser vacuum vapor deposition , unlike cutting tools and such which are readily done as the surfaces are already exposed .

Imagine a Diamond Hard bore and chamber High heat resistant ,half the friction of Teflon applied in microns fused too the metal .

AlMgB14

https://www.nanotrun.com/ternary-bo...magnesium-boride-almgb14-powder-p00270p1.html

We report a new industrial application of aluminum magnesium boride AlMgB14 (BAM) coatings to enhance the hardness of tungsten carbide ceramic (WC-Co) and high-speed steel tools. BAM films were deposited by RF magnetron sputtering of a single dense stoichiometric ceramic target onto commercial WC-Co turning inserts and R6M5 steel drill bits. High target sputtering power and sufficiently short target-to-substrate distance were found to be critical processing conditions. Very smooth (6.6 nm RMS surface roughness onto Si wafers) and hard AlMgB14 coatings enhance the hardness of WC-Co inserts and high-speed R6M5 steel by a factor of two and three, respectively. Complete coating spallation failure occurred at a scratch adhesion strength of 18 N. High work of adhesion and low friction coefficient, estimated for BAM onto drill bits, was as high as 64 J/m2 and as low as 0.07, respectively, more than twice the surpass characteristics of N-doped diamond-like carbon (DLC) films deposited onto nitride high-speed W6Mo5Cr4V2 steel.

 

[Ex E6]

With respect to barrel break in , I've gone a different route . Manufacturing today isn't what it was 40 years ago ,thankfully it's MUCH BETTER !.

Quality Barrels as well as receivers are done much more precisely ,IMO . So Now I wet patch out a New barrel always going from chamber too crown , I then remove the patch put a cap on Dewy rod thread pull it back . When it's clean I switch too a Swab mop and try using slightly larger than bore IF it will go down wet . Now using JB bore paste ,I stroke same as with wet patch down bore ONLY ,removing mop as with wet patching every time . repeat #20 times applying a little paste here and there down the bore with a ( I use a plastic 1/8" rod but a wooden dowel works as well ) and reapply Bore paste too the Mop . Wet patch clean bore until Every thing is Spiffy . Shoot #1 wet patch shoot #2 wet patch repeat until reaching #5 shots . Your bore is as conditioned as it will ever be and saves Time as well as ammo .
Try it You will be impressed .

 

[M4orturnate]

I can't believe nobody knows if they speed up or not. I admit I've never tracked velocity in a chrome lined barrel like I do with my precision guns.

 

[ZA206]

With respect to barrel break in , I've gone a different route . Manufacturing today isn't what it was 40 years ago ,thankfully it's MUCH BETTER !.

Quality Barrels as well as receivers are done much more precisely ,IMO . So Now I wet patch out a New barrel always going from chamber too crown , I then remove the patch put a cap on Dewy rod thread pull it back . When it's clean I switch too a Swab mop and try using slightly larger than bore IF it will go down wet . Now using JB bore paste ,I stroke same as with wet patch down bore ONLY ,removing mop as with wet patching every time . repeat #20 times applying a little paste here and there down the bore with a ( I use a plastic 1/8" rod but a wooden dowel works as well ) and reapply Bore paste too the Mop . Wet patch clean bore until Every thing is Spiffy . Shoot #1 wet patch shoot #2 wet patch repeat until reaching #5 shots . Your bore is as conditioned as it will ever be and saves Time as well as ammo .
Try it You will be impressed .

You should look into VFG pellets…

 

[Ex E6]

You should look into VFG pellets…

I've got so many bore mops I could open shop . Some outfit years back folded and I must have bought #4 cases of various sizes .

The ones I use for Bore polishing ,I rinse them in acetone after using them . What's even funnier is I've got abrasive powders from 12-3500 grit .

Still have 2 gal. of super fine Mt Saint Helen's ash also . I shouldn't laugh , I used it on a UGLY 03 bore with bronze brush and groups actually shrunk nearly in half .

 

[Ex E6]

I can't believe nobody knows if they speed up or not. I admit I've never tracked velocity in a chrome lined barrel like I do with my precision guns.

They DO . However proving that to any degree is gonna raise skepticism . Take Two Identically manufactured barrels and see if they give Identical velocities with same charge . I'll save you the trouble THEY WON'T !.

The Only way one can actually prove it is by taking their KNOWN load in their Known Rifle firing #10 rounds of #20 made same day and average that velocity . Against their Rifles New Chrome lined bore or Salt bath Nitrided bore with the same loads made same day .
Guaranteed velocity will increase , now by how much is anybody's guess .

I've #2 Older Bushmasters and tried getting consecutive serial #'s ,was only able to get within #6 serial #'s of 1 st. one .
They DON'T shoot same loads but both are TACK DRIVERS ,with their respective loads . Both are chrome lined 5.56 and do register higher velocity than a couple of unlined I also have . Yet that's hardly concrete proof is it .

 

[sjbryan65]

The question is whether they speed up as you shoot them.

So for example my brand new chrome lined barrels first 10 rds average 2650fps.

What will rounds 200-210 average? Will it still be around 2650 or will it have gone up?

Traditional stainless barrels are known for speeding up from new, sometimes as much as 100fps. Was curious if a chrome lined barrel would behave similarly.

 

[Ex E6]

The question is whether they speed up as you shoot them.

So for example my brand new chrome lined barrels first 10 rds average 2650fps.

What will rounds 200-210 average? Will it still be around 2650 or will it have gone up?

Traditional stainless barrels are known for speeding up from new, sometimes as much as 100fps. Was curious if a chrome lined barrel would behave similarly.

Doubtful ,reasoning all projectiles cause a degree of wear over time . Reason SS speeds up is Bore Burnishing and it too will pass .

As bore wears more gas leaks until eventually loss of velocity and accuracy . Don't sweat what You can't control .

Powder lots vary as do primers and there's NOTHING which can compensate that monkey , so bottom line Reloading as shooting is variable .

 

[M4orturnate]

They DO . However proving that to any degree is gonna raise skepticism . Take Two Identically manufactured barrels and see if they give Identical velocities with same charge . I'll save you the trouble THEY WON'T !.

The Only way one can actually prove it is by taking their KNOWN load in their Known Rifle firing #10 rounds of #20 made same day and average that velocity . Against their Rifles New Chrome lined bore or Salt bath Nitrided bore with the same loads made same day .
Guaranteed velocity will increase , now by how much is anybody's guess .

I've #2 Older Bushmasters and tried getting consecutive serial #'s ,was only able to get within #6 serial #'s of 1 st. one .
They DON'T shoot same loads but both are TACK DRIVERS ,with their respective loads . Both are chrome lined 5.56 and do register higher velocity than a couple of unlined I also have . Yet that's hardly concrete proof is it .

That's not what we mean. In a stainless barrel the first few shot will be slower and it will get progressively faster until it's stabilized somewhere between 60 and 200 rounds depending on cartridge. I've had a few that didn't speed up and some that gained almost 100fps in 50 rounds.

 

[TonyTheTiger]

I can't believe nobody knows if they speed up or not. I admit I've never tracked velocity in a chrome lined barrel like I do with my precision guns.

Kinda wish I could answer. Every time I've gotten a CL barrel, or any AR barrel really, I spend at least 100 rounds blasting cheap ammo before I even think about getting out the chrono.

 

[M4orturnate]

Kinda wish I could answer. Every time I've gotten a CL barrel, or any AR barrel really, I spend at least 100 rounds blasting cheap ammo before I even think about getting out the chrono.

I'm similar. The only time I even Chrono a cl barrel is if I'm making a load for it. Even then it's usually just a few to make sure it's safe and around what I expected

 

[Ex E6]

The ONLY reason any bore speeds up is projectiles are smoothing or polishing the bore to an extent . Slap some PTFE or dry moly inside the bore and measure velocity increase . Same principle essentially lubricity decreases friction .

That's WHY I JB Mop swab MY bores as part of their break in process and fore go shooting all that plinker ammo .

By Shot #5-10 I'm dialed in with normally excellent repeatable accuracy . So I saved 190 rounds

 

[MSTN]

JB Bore Paste is 600 grit. I like it for chrome lined barrel prep and belt-fed barrels:

KG-2 is 1200 grit. I prefer it for today's premium SS barrels.

 

[M4orturnate]

The ONLY reason any bore speeds up is projectiles are smoothing or polishing the bore to an extent . Slap some PTFE or dry moly inside the bore and measure velocity increase . Same principle essentially lubricity decreases friction .

That's WHY I JB Mop swab MY bores as part of their break in process and fore go shooting all that plinker ammo .

By Shot #5-10 I'm dialed in with normally excellent repeatable accuracy . So I saved 190 rounds

So I guess every competition shooter and gunsmith is wrong. I use bore paste and a mop to and absolutely won't trust velocity for at least 100 rounds. More like 200 on something low pressure like a br. Hand lapping plays a part for sure but running a mop and iossi ain't getting it done.

 

[Coffee_and_Pipes]

This sounds like a research project for Molon. I’d be interested to see his findings.

 

[Ex E6]

I don't know of a single premium barrel manufacturer that doesn't LAP their barrels before sales ,so knowing that I simply try polishing the bore to a finer degree and having abrasive grit 12-3500 allows ME to pick MY preference . I use JB bore paste as the carrier ,mainly because I have an abundance of it . Making base paste is easy enough Binder carrier and abrasive .

IF I choose to do it quicker I run an oil solvent carrier and with SS barrels chromic oxide abrasive . Generally starting at 360-400 and finishing out around 800 . Anymore than that is pointless in MY view . Chrome bores are totally another animal and IF I polish it's far finer and less abrasive .

 

[bfoosh006]

I can't believe nobody knows if they speed up or not. I admit I've never tracked velocity in a chrome lined barrel like I do with my precision guns.

I'd bet the reason why "no One knows" is because it isn't enough of a FPS difference to matter.

 

[Pappasniper]

With current manufacturing I would believe it is not going to be significant. I would clean the barrel then maybe I would shoot 25 rounds then would consider that good to go. I doubt 25 rounds will matter that much but if it gives you peace of mind, do it. And I would start load development right away. Its going to take a few round to get it perfect anyway. I do not believe in the break in barrel concept anymore. Even with CL AR barrels shooting MOA, it just is not a thing IMHO.

PB

 

[VegasKyle]

I can't believe nobody knows if they speed up or not. I admit I've never tracked velocity in a chrome lined barrel like I do with my precision guns.

My sample size of one says yes.

I shot my SCAR 20s over the chrono when it was brand new and got some good dope in AB that was getting me hits out to 1100yds. Shot various ammo for groups at 100yds(mostly without a chronograph) and then next time I shot long range was a little local match without a chrono. The targets were big but I started needing a couple tenths less drop than the dope I had when we got out to 7-800yds. I added 50fps MV to the ballistic calculator and was back on track out to 1300.

The next range trip I shot the same lot of M118lr over the same chrono as I did when I first got the gun and the MV avg was about 40fps higher. Probably 400 rounds after the initial velocity numbers.