Is my barrel worn out? Chrono data enclosed

[Fullauto_Shooter]

Finally got a chance to chrono some loads the other day and got some interesting results with 2 of my pistols.

Pistol #1 is a G35 with new Storm Lake barrel

Pistol #2 is a P16-40 with a well-worn factory barrel (at least 40K rounds thru it)

After compiling all the data, I noticed that Pistol #1 shoots about 60 fps faster than Pistol #2 with Precision 185gr "black bullets", and about 45 fps faster with 180gr MG bullets. Chrono data is shown below for a few of the loads:

185gr Precision "Black Bullet" / 4.5gr W231

P16 - 886 fps

G35 - 938 fps

185gr Precision "Black Bullet" / 4.7gr W231

P16 - 902 fps

G35 - 970 fps

180gr MG / 4.5gr W231

P16 - 815 fps

G35 - 857 fps

180gr MG / 4.7gr W231

P16 - 844 fps

G35 - 893 fps

All velocity data is based on the average of 10 consecutive shots with each load. Is this much velocity variation normal or is it an indication that my P16 barrel is excessively worn? Given these chrono results, I'd have to load right about 5.0 to 5.1 gr of W231 to make major with a 180gr MG FMJ bullet out of my P16 - that just seems a bit excessive to me. Any thoughts??

[Mick]

They sure don't get any faster once you start shooting them!!!

I've had two new barrels shoot that far apart, both 5" Schuemanns.

Different cutter, different day...

I would expect that new barrel to be faster. I shoot 4 different 40s often. I load for the SLOWEST barrel. They all make it then.

[HSMITH]

Your barrel is worn out when bullets still tumble after a good cleaning.

Glocks are almost always faster than a conventionally rifled barrel, what you are seeing is perfectly normal in my experience.

[Carlos]

Your barrel is worn out when bullets still tumble after a good cleaning.

Glocks are almost always faster than a conventionally rifled barrel, what you are seeing is perfectly normal in my experience.

Same here. A friend's P16 was that much slower than my SV w/ KKM bull barrel, with the same load. As long as its still accurate, you don't need to replace it.

[racerba]

Glocks are almost always faster than a conventionally rifled barrel, what you are seeing is perfectly normal in my experience.

He doesn't have a stock Glock barrel - it's a new Storm Lake barrel.

[HSMITH]

Ahhh, thanks. I missed that.

New barrels are usually a lot rougher than a well used barrel and consequently faster also. My theory is the bullet is riding on the tops of the roughness and doesn't have as much drag as a very smooth barrel.

[G-ManBart]

That's totally normal. Take two identical barrels built one after the other, put them in the same gun and you will frequently see that much difference between them. Nobody knows how or why, but it happens.

[mike cyrwus]

para=apple

glock=orange

[racerba]

para=apple

glock=orange

No no no...

Para=oranges

Glock=apples

[mike cyrwus]

para=apple

glock=orange

No no no...

Para=oranges

Glock=apples

Actually,

Para=apples

M&P=oranges

Glock=lemons

[Fullauto_Shooter]

Thanks for the info, guys. This was my first trip to the range with my new Chrono (CED M2) so I'm a definite Chrono "Newbie". I had no idea that different guns could routinely produce such drastic velocity differences. Guess I'll just load my rounds hotter than I have in the past.

Thanks again for your input.

[Joe4d]

Let your group size decide, only thing you are looking for is consitency of velocity, with a decent load combo you should have standard deviations below 20, when a previously good load starts giving wide SD's it could be time for a barrel change.

[jerseyglock]

para=apple

glock=orange

No no no...

Para=oranges

Glock=apples

Actually,

Para=apples

M&P=oranges

Glock=lemons

Actually,

Para=apples

M&P=oranges

Glock + KKM = apples

[grandbagger]

will these variations in barrel speed affect felt recoil?

[XRe]

will these variations in barrel speed affect felt recoil?

To a small degree, possibly. Basically, the slower the barrel, the more powder you have to use. More powder means more gas and ejecta coming out the front of the pipe. That translates directly into more recoil energy. However, its likely a non-issue... In other words, I wouldn't try hunting down a slow barrel for lower recoil. Powder choice has a much bigger effect, in the end....

[ahtsay]

Let your group size decide, only thing you are looking for is consitency of velocity, with a decent load combo you should have standard deviations below 20, when a previously good load starts giving wide SD's it could be time for a barrel change.

How many shots, more or less would it take to shoot out a barrel? Recently I've noticed my gun giving me a wider range of velocity on the chrono as well. I've shot maybe 10-12K rounds through it, I'm not sure if this is enough to wear it out. Its a stock STi Edge. I'm not sure if its the ammo or the gun though.

[Paul Burtchell]

Full Auto,

Thanks for letting me shoot that "wore" out gun Saturday. I definitely think it's a gonner and you need to sell it to me REAL CHEAP

[G-ManBart]

Let your group size decide, only thing you are looking for is consitency of velocity, with a decent load combo you should have standard deviations below 20, when a previously good load starts giving wide SD's it could be time for a barrel change.

How many shots, more or less would it take to shoot out a barrel? Recently I've noticed my gun giving me a wider range of velocity on the chrono as well. I've shot maybe 10-12K rounds through it, I'm not sure if this is enough to wear it out. Its a stock STi Edge. I'm not sure if its the ammo or the gun though.

The real answer is "it depends" but that's not very helpful! Each barrel will be a little different and the exact load you're using and how hot you let it get when you're practicing factor into how long it should last. Unless you're really getting it hot on a frequent basis, it should last a lot longer than 10-12K. I'd be ticked off if a stock STI barrel was shot out after 50K.

[Smokecloud]

Dont forget that the glock 35 has a 5.3" barrel and the Para has a 5.0" barrel, that is enough to make 30-50fps difference alone with some powders. Then you have to consider that if all things were equal, even from the same manufacturer, different barrels just simply give different velocities, it all depends on how smooth it is and what the actual inside diameter is, depth of the groves, etc. barrel makers use the same cutters for making lots of barrels, tools wear out and have to be changed, so there are some differences in tolerances out there.

when you chrono your para with the same load in the same conditions and you lose another 50 to 100fps, it will probably be safe to say that your barrel is shot out, but it will probably also be accompanied by a loss of accuracy.

[HSMITH]

As long as it is accurate enough and pressures are under control keep stuffing powder in it to make major. To thrash a barrel that fast it was either junk to begin with or was abused badly (shooting it until it is just ludicrously hot, etc).

Before worrying about SD's get some KNOWN once fired or new brass, and reload them carefully with the same lot of powder you started with. Otherwise it is an apples to oranges comparison.

[Buzzdraw]

If your rifling is burned out forward of the chamber, to the point its pretty much non-existent for 1/2 inch or more, then maybe you need a new barrel. If the accuracy goes to heck, then maybe you need a new barrel. Regular cleaning, using good practices, will extend the life of any barrel or the whole gun for that matter. Rifling will first start to go at the 12 o'clock position in the leade. A given barrel should last longer with lead vs. jacketed bullets. Another trick is to go to slightly larger diameter bullets, if they are available. For worn .355 barrels, you can go to .356 bullets.

A pistol barrel may last 150,000 rounds with mild loads and good cleaning. It may go in a few thousand rounds of high-velocity "screamers". In short, it depends.