“Slow” barrel vs. “Fast” barrel

[elk wallow]

So I see people talking about a barrel being slow or being fast. What makes a barrel either slow or fast? I have a Sauer 100xt in 6.5 prc that seems to be slower than what I see others getting for velocity.

Thanks,Kevin

 

[Jud96]

The internal finish of the bore and bore diameter are the two things that mainly make one barrel faster than another.

 

[elkaholic]

So I see people talking about a barrel being slow or being fast. What makes a barrel either slow or fast? I have a Sauer 100xt in 6.5 prc that seems to be slower than what I see others getting for velocity.

Thanks,Kevin

Consistent bore diameter and finish from end to end. tightness of bore. Land configuration and # of lands can also have an affect.
Twist rates also affect velocity, but I think you're looking more at apples to apples. Throat diameter too.

 

[elk wallow]

Consistent bore diameter and finish from end to end. tightness of bore. Land configuration and # of lands can also have an affect.
Twist rates also affect velocity, but I think you're looking more at apples to apples. Throat diameter too.

So is a tight bore faster or the opposite? I think I've read that you mention in other threads that Brux barrels have tight bores.

 

[elkaholic]

So is a tight bore faster or the opposite? I think I've read that you mention in other threads that Brux barrels have tight bores.

depends on how tight. Just right is fastest.
Too tight raises pressure with more friction and too loose may not seal the bore well losing velocity. Bullets are normally very close to bore size.
A tighter bore may get more velocity with the same charge than a looser one but may over pressure before full potential is reached.
Whether too tight or too loose, its measured in .0001"
Generally speaking, a little tight will be more accurate and a little loose will be a little faster.

 

[L.Sherm]

The grooves matter more than the bore as far as velocity sealing up to a bullet.

 

[J E Custom]

Consistent bore diameter and finish from end to end. tightness of bore. Land configuration and # of lands can also have an affect.
Twist rates also affect velocity, but I think you're looking more at apples to apples. Throat diameter too.

Exactly right

The reason some barrels are faster is that the manufacture has found the right combination of all these elements and their barrels will always be I little faster.

There is also a connection between accuracy and with these barrels because of their consistency. Barrels without these consistent traits, normally don't shoot that well.

J E CUSTOM

 

[elkaholic]

The grooves matter more than the bore as far as velocity sealing up to a bullet.

My bad, I often say that backwards!
Thanks Sherm

 

[josip89]

1. I dont know how new is barrel.
Because some barrel speed up after 100 or 200 rounds.I think that shooting polished barrel inside and because it speed up.

2.I know from experience if You clean barrel to the metal ,it need few bullet to speed up to the normal speeds.(but i dont think that is your problem)

 

[AaronSkipDavidson]

Interesting topic.

A SAAMI spec barrel will shoot slower (25 to 35fps) than a barrel that runs a few tenths larger in bore and a few thousands wider in groove.

Same chamber and loads.

We've just done an extensive test with a statically significant number of barrels.

I was surprised at the result, my instinct told me the result would have been the opposite.

 

[Mc Fraser]

Is a 5R barrel faster or slower than a 3R barrel? Everything else being equal.

 

[vancewalker007]

So I see people talking about a barrel being slow or being fast. What makes a barrel either slow or fast? I have a Sauer 100xt in 6.5 prc that seems to be slower than what I see others getting for velocity.

Thanks,Kevin

The quality, groove design and spec's can affect the speed of a barrel. Also, a lot of barrels will speed up after 200-300 rounds. As a recent example my 26in Proof Sendero 6.5 PRC jumped about 45fps around 253 rounds. Your new rifle may do the same.

 

[aalyea]

I built a 358 Norma using Hart air gauged barrel 25" that with midrange powder charges routinely was 150fps faster than max charges posted in manuals. Never any pressure signed or short brass life.

 

[elkaholic]

Is a 5R barrel faster or slower than a 3R barrel? Everything else being equal.

Id say 3r but it depends on the total width of the land surface. i.e. 3 groovers normally have wider lands but 3 vs 5.