Is my Barrel Shot Out

[RIIID]

Putting in a new barrel won't guarantee the velocity will go up, it could go down. Trying to get the same power factor from two different guns and the same load is a matter of luck. Now if the same gun and ammo show a big difference between two chrono tests eliminate all variables before jumping into a new barrel. I'd just bump the powder charge to get the desired PF, when accuracy goes away then start to look at a new barrel.

I once saw the same ammo(new brass, same lot run of powder and primers) used in three different guns with varying round counts, the gun with the highest round count(50K+) had the fastest velocity, the second gun with a round count of(20K+) made major but was 35 fps slower than gun #1, the third gun had a new barrel with less than 500 rounds it was the slowest and went minor.

Rich

[CocoBolo]

Putting in a new barrel won't guarantee the velocity will go up, it could go down. Trying to get the same power factor from two different guns and the same load is a matter of luck. Now if the same gun and ammo show a big difference between two chrono tests eliminate all variables before jumping into a new barrel. I'd just bump the powder charge to get the desired PF, when accuracy goes away then start to look at a new barrel.

I once saw the same ammo(new brass, same lot run of powder and primers) used in three different guns with varying round counts, the gun with the highest round count(50K+) had the fastest velocity, the second gun with a round count of(20K+) made major but was 35 fps slower than gun #1, the third gun had a new barrel with less than 500 rounds it was the slowest and went minor.

Rich

Did another round of side by side crono testing bumping the load up to 10.7gr of AA#7 the weak gun 1345fps 168 pf, the other gun 1401 fps avg or 175.125. So I could shoot it as is, the primers were starting to show signs of pressure but were still ok. With the 125gr BayouBullets .356 at 10.3gr it hit 1350 fps and the faster barrel gun was 1390 fps, this closed the gap by 20fps which is a good indication to me that the barrel is in fact getting a little lose. The best thing about the testing is I found out gun #2 really likes and shoots the 10.5gr load. I was running 10.2 but .3 just flattened it out and softened it up. The Bayou bullets ran as clean as Zeros and grouped just as well. A friend with his gun also did crono on his ammo and mine in his gun and his gun was even faster than either of mine. So I think the facts are self evident.

[CocoBolo]

Here we are 5 month later and I think I have the answer to the questions and all the evidence is yes it was shot out.

Went to test the new barrel to day took both gun and the old barrel.

This is all ammo from the same batch. (125gr Zero 10.5gr AA#7 set 1.140).

Old Briley Barrel 1301 avg fps (10 shots)

Sanity gun - Bull Sti Barrel 1376 avg fps (10 shots) The original gun the first comparisons were made with.

New Clark Barrel 1426 fps avg (10 shots).

I swapped barrel and this as fast as I could so that the light condition didn't have time to change hardly any. I also shot from my elcheapo bench rest aka at the same distance angle and elevation.

I'm convinced that I did the right thing to replace the barrel. Some side benefits came in the process the barrel locks up good and tight and this improved the accuracy of the gun some, it use to string shots but now it doesn't. Also while it was in the shop I had the smith work on the aftec and clean it up and round the bottom edge so it seems to feed smoother. He also smoothed up the breech face.

It looks like I can drop my load a few tenths with the new barrel.

The recoil and flip did not change in my opinion its still what I call sweet shooting. I don't like the term soft and flat, I prefer either Violent or Sweet and this is some muddled up confusion between recoil and flip the jist of it being if I'm comfortable shooting it its sweet, otherwise its violent. Some have said my shorty is violent, well it does tend to flip a bit but its smooth and trackable, I call it fast.

I thought I'd just put the ending on the story. Now I've got two sweet shooting 38 Supers and a ticket to Vegas.

I almost foget the mention the biggest suprise of all, shooting the new 38 Super Barrel and the new 9 major barrel and thowing the shorty on the gun POI and POA was very close with all 3. The old Briley barrel hit about 3 inches right and 2 inches low. I really didn't expect that at all.

Edited August 6, 2010 by CocoBolo

[G-ManBart]

That new Clark barrel is likely going to drop some velocity pretty soon and take something of a "set"...often in just a couple of thousand rounds. That's when you'll really see how much of a difference there is, but two brand new barrels made one right after the other can be 100fps different, so maybe the old one wasn't nearly as shot out as it seems now. Only time and rounds will tell. R,

Edited August 6, 2010 by G-ManBart

[CocoBolo]

That new Clark barrel is likely going to drop some velocity pretty soon and take something of a "set"...often in just a couple of thousand rounds. That's when you'll really see how much of a difference there is, but two brand new barrels made one right after the other can be 100fps different, so maybe the old one wasn't nearly as shot out as it seems now. Only time and rounds will tell. R,

That is true and you see this in load data here on the fourm, its like HOW MUCH?

[Sean Gaines]

I had the opposite effect with my Briley barrel compared to my sti barrel. Same load in my sti barrel had a PF of 168 or 169, the new briley barrel I was getting 174-175PF, granted it had 1" more barrel but that is alot of PF for 1". Its the most accurate pistol I have shot, besides my open setup.

I agree with Rich, you are lucky if the same load can give you the same results from different barrels. Depending on who is cutting the lands and groves for the company you are buying from. alot of people think that companines cut the lands and groves for thier barrels. That is incorrect, there are a handfull of barrel companies out there that are cutting the lands and groves, and making blanks, then they goto the various companies in the form of a barrel blank, and then they cut the barrels to thier specification. so in essesence if you get a barrel blank from lothar walther who cuts the lands and groves, it may or may not be faster then lets say Wilson, not to be mistaken with wilson combat. So it really depends on the the company who makes the barrel blanks, that is going to determine the speed of the barrel, and even then you will probably see some fps difference.

[G-ManBart]

That new Clark barrel is likely going to drop some velocity pretty soon and take something of a "set"...often in just a couple of thousand rounds. That's when you'll really see how much of a difference there is, but two brand new barrels made one right after the other can be 100fps different, so maybe the old one wasn't nearly as shot out as it seems now. Only time and rounds will tell. R,

That is true and you see this in load data here on the fourm, its like HOW MUCH?

I'm not looking at my data (but I did rough PF calculations), but I saw roughly 40fps drop on my newest gun (keeping an exact round count on it)...maybe a touch more. It started off right around 174PF and dropped to 169PF, so I went up .2gr in powder to get it back to 173+. R,

[G-ManBart]

I had the opposite effect with my Briley barrel compared to my sti barrel. Same load in my sti barrel had a PF of 168 or 169, the new briley barrel I was getting 174-175PF, granted it had 1" more barrel but that is alot of PF for 1".

Actually, that's exactly how much difference the stock answer would be for a 1" longer barrel...roughly 50fps. 50pfs with a 115gr bullet equals 5.75PF, with a 125gr it's 6.25PF, with a 147gr it's 7.35PF, and with a 180gr it's 9PF.

So it really depends on the the company who makes the barrel blanks, that is going to determine the speed of the barrel, and even then you will probably see some fps difference.

If you take two barrels off the line, made one right after the other, they'll often show quite a bit of difference. In rifles it's not unusual to see 100fps difference in otherwise identical barrels...and nobody seems to be able to explain it!

[Aircooled6racer]

Hello: I think your accuracy would be your final telltale sign if the barrel is shot out. The ones I have seen either start to scatter the bullets at 25 yards or they start to keyhole. Some barrels are just faster than others even from the same manufacturer. If you get a fsat one that's great if not add powder and make it fast Thanks, Eric

[CocoBolo]

Just so no one gets the wrong message the Briley Barrel in this post is of unknown round count and came in a used gun I bought very cheap. I put probably close to 25k more rounds on it.

Some indications of high round count were the cone comp being lose in the slide and the slide being a bit lose on the frame so this old girl had seen lots of action.

Fate brought me to the Clark barrel, fate acted by putting a classified add for a threaded barrel with the right ramp cut in front of me for less than half the cost of others. It was not a concious selection based upon any merit or lack of merit for any other brand.

Since these Clark's are my first ever new barrels in an Open gun I can't make any comparison to other mfg barrels.

The effectiveness of any barrel will be materially affected by the skill of the smith that fits it.

[G-ManBart]

Checked my data and it was in the 30-40fps range that it dropped off (with the same lot of powder). An earlier lot was a little bit hotter, so I lost maybe 20fps with the new lot, then 30-40fps when the barrel seemed to take a set and that dropped me 6-7PF....added .2gr and it's back where it should be. Bad part is I'm almost out of the current lot and have 12lbs of an even newer lot, so I'm hoping it's the same as the last one.

My ancient Open gun has way over 100K through it, and it's still accurate, but I always tried to avoid getting it too hot, which makes a big difference. R,