I have heard people speak of fast and slow rifle and pistol barrels.I know the slow barrels are out of spec but I've always wondered were they generally too tight and causing extra friction or too loose and letting some of the expanding gases pass by the bullet?Thanks in advance for your help.

Brair .

I was given 5 Mannlicher rifles, identical in every respect, brand new in their boxes, and 5 scopes to install and site.

All were in 270 Winchester, ammo with them was Norma.

I was amazed at the difference in velocity between them.

The fastest was 150 fps faster than the slowest!

Should we assume that those 'fast' barrels have tighter dimensions and would be frustrating to reload for because pressure signs would appear with lower loadings?

quote:

I know the slow barrels are out of spec

They are most likely all with in spec.

Just different

Interesting thread. I've often wondered about this. Some in depth
research is required to accurately answer this question.

Not really sure how would one go about researching this.

I posted the example above because it is very easy to see.

I have had many rifles, using the same cartridge, the same length barrels, and give different velocities.

This is one of those phenomenon that, although a real thing, has never been scientifically researched. Saeed is the only one who has any real data that I have seen; everything else is random observations based one barrel.
Out of spec barrels; unlikely. And to do a real study it would take $299K and three years to do it; take a sample of ten barrels from each maker, including factory ones. All in the same caliber, and all identical in length. Do a rigorous test protocol. All ammo from the same lot of course.
Then when you are done wasting all the money, you will have some data over which to ponder. I predict, useless practical data, but testing is like that. Decisions can then be made from the data gained.
I will initiate the test once the sponsor sends me a check.
Note that it happens, is not due to out of spec barrels because accuracy does not suffer, and you can't control it.
Shoot them. It doesn't matter.

In order to investigate the relative speed of projectiles in various barrels one would have to remove the variability of the cartridge = find a way to launch the projectile at a pressure/speed that is consistent shot to shot.

If the variant factors would be understood it might be possible to design and build barrels that are 'faster' - a good thing, I would think.

I have an ole mauser that is slow and low. It is old new stock military...unknown maker. Velocities are 200 fps slower than listed, but adding more powder brings the velocity back to standard.

But my load is unsafe to use in other old 7x57s, it will lock the bolt up.

Never have slugged the barrel for diameter.

With the right powder, gun shoots better than some new ones.

I have two factory rifles.

One is supposed to have higher velocity than the other, because it uses a bigger case and more powder.

But the smaller ones is actually faster???

These are a Weatherby Mk V in 30/378 Weatherby, and a Remington Sendero in 300 RUM.

I get more velocity from the 300 RUM than the 30/378??!!

It would be interesting to see a test with strain gauge pressure readings, and laser measured bore and groove diameters along with chamber dimensions to .00005 or so. How to go about that, I have no clue, but as DPCD says, its just a matter of money. I'm not THAT interested...

My suspicion is that its relatively minute differences in the machining caused by multiple factors.

I would think it would be a slightly less tight bore with smoother/sharper rifling to reduce friction is the cause of the faster barrel.

I just would find it interesting if it is more a materials sciences issue or if it is an engineering issue.

Neither; it is sorcery.
However, I know a 100% reliable way to get more velocity, and we use it on the M256 Tank Cannon; we get over 5000 fps from them.
Make them Smooth Bore!. That pesky rifling slows down bullets more than you realize.

This isn't an apples to apples comparison but interesting none the less:

Bro and I built two 6.5 Creedmoors and his sports a 24" Lilja tube while mine proudly wears a much faster 26" Bartlein barrel. Reality is that with the identical load, his 24 is faster than my 26!!!
Hand weighed brass, powder, bullets, you name it, we do it.

Is mine or is his out of specs? I suspect neither and since they both shoot so damn well, we'd never change a thing.

I'm a believer that some barrels are just faster while some are just slower and I don't care to spend the money to find out why.

Maybe it's the same reason guys will buy several barrels, chamber them all, shoot them, and only keep a couple of them out of the pile they bought. Some shoot better than others!

Zeke

Throat, Throat and Throat.
Did I mention the Throat?

Same barrel, 2 chambers. 26" with throat .004 over bullet diameter and 25" with throat .0005 over bullet diameter. Same batch of reloaded ammo (RP case, WLR primer, 61.5gr ReL-19, 150gr NBT), 26" 10 shot average 2675fps, 25" 10 shot average 2995fps.

Of course; if everything is not the same, including the throat, no comparison is valid. One of your barrels is an apple; the other a tomato.

Over 300 FPS more.Wow.
I remember Ray Atkinson once said he had never seen a slow custom barrel.

quote:

Originally posted by Tailgunner:
Throat, Throat and Throat.
Did I mention the Throat?

Same barrel, 2 chambers. 26" with throat .004 over bullet diameter and 25" with throat .0005 over bullet diameter. Same batch of reloaded ammo (RP case, WLR primer, 61.5gr ReL-19, 150gr NBT), 26" 10 shot average 2675fps, 25" 10 shot average 2995fps.

quote:

Originally posted by dpcd:
Of course; if everything is not the same, including the throat, no comparison is valid. One of your barrels is an apple; the other a tomato.

IF I AM READING TAILGUNNERS POST CORRECTLY(?????) he is talking about a single barrel that was chambered with a lose throat and tested, then rechambered with a tighter throat and tested again.

If I read that correctly(he did say “same barrel”) then it is pretty darn interesting.

I would love to see someone do that same procedure, but in reverse: start with a tight throat and test, then cut a looser throat and retest.

quote:

Originally posted by dpcd:
Of course; if everything is not the same, including the throat, no comparison is valid. One of your barrels is an apple; the other a tomato.

dpcd
JBrown has it, right. The barrel was shortened 1" at the breach end and re-chambered.
I didn't do it as an experiment, it was a new 26" barrel to replace a shot out 21". Only way to salvage the tube was to chop off 1" and re-thread/re-chamber.

quote:

Originally posted by brair:
Over 300 FPS more.Wow.
I remember Ray Atkinson once said he had never seen a slow custom barrel.

1st guy was a "run in a rental reamer and take the money and run" guy.
2nd guy was a "take pride in my work" gunsmith.

I'd bet money that Ray A was also dealing with / is the second type of gunsmith.

Sorry; I don't actually read the questions before posting answers; it is quicker that way.
However, It still does not show that the "barrel" was fast or slow; relative to other barrels; it proves that the chamber throat has an impact on the velocity; different scenario entirely.
Again, of course, if you change a parameter, the comparison takes a path other than barrels. Interesting though.

I shoot two .358 STA’s both customs, one from Winchester Custom Shop the other with a Lilja custom barrel. The Lilja barrel is consistently 50-75 fps faster than the Winchester with the same loads. I also shoot two .223 Remington’s preparing them for Pdogs, both Savages with same length barrels, one is 50-100 fps faster than the other with same loads. I also shoot four .270 WSM’s, all Model 70 Winchester’s, one has a stainless barrel, the others have blue barrels and are all Limited Editions. The stainless barrel is consistently faster than the others and they all have different speeds. In my experience all barrels have their own personality and will reveal it if shot enough. My son and grandsons and a great grandson hunt with these rifles each fall. I gather the rifles up each winter and load and play with those loads spring and all summer with my Oehler 35-P and we are ready for the new hunting season. I show them on the targets where the bullets should hit with my shooting and their shooting is close enough to mine that we don’t have any problems in the field. This is how we do it for what it is worth. Good Shooting.

Sorry to be like a dog returning to its vomit, but do you guys find those fast barrels show pressure signs sooner when working up loads?

quote:

Originally posted by brair:
Over 300 FPS more.Wow.
I remember Ray Atkinson once said he had never seen a slow custom barrel.

After Ray owns them they always shoot faster and more accurately.

quote:

Originally posted by sambarman338:
Sorry to be like a dog returning to its vomit, but do you guys find those fast barrels show pressure signs sooner when working up loads?

I think that is a great question. I would also like to hear the answer.

quote:

Originally posted by p dog shooter:

quote:

Originally posted by brair:
Over 300 FPS more.Wow.
I remember Ray Atkinson once said he had never seen a slow custom barrel.

After Ray owns them they always shoot faster and more accurately.

HAHAHHAHHAHHAH

quote:

Originally posted by JBrown:

quote:

Originally posted by sambarman338:
Sorry to be like a dog returning to its vomit, but do you guys find those fast barrels show pressure signs sooner when working up loads?

I think that is a great question. I would also like to hear the answer.

i would expect that a fast barrel has less friction, from either being larger or smoother, or both - there's several dimensions to deal with in this, bore diameter, groove diameter, groove depth, steel surface finish, steel compounding, and all the angles and corners ...

but, that's just a guess on my part, leveraging smooth bore 22 and TANKS as mentioned above, to bracket the guess

Thanks jeffeosso,
that's an angle I had not thought of.

I was thinking that a tight barrel might give higher pressure, which could cause the powder to burn more efficiently, leading to higher velocity at the muzzle. But rather than signifying the best possible, such barrels could result as the tooling wears down.

Maybe you're right, though, as hopefully the barrels on custom rifles would be best quality and just right in dimensions.

Anyone, anyone?

P-dog,
Be glad to give you and Jeffe some lessons in improving a barrel for accuracy! called breaking in a barrel, polishing the bore out properly, and a few other magical tricks you probably wouldn't understand!

But in reply to the poster, there are fast and slow barrels, Ive seen a bit more than 100 FPS in calibers of all kinds..Does it effect accuracy is determined by the barrel in question just like it would in a perfect barrel, for lack of a better word..

My personal take on the situation is: It is what it is and acceptable..If it makes any difference I don't know how you could tell because some barrels just shoot better than others not matter whatcha do..