Is my Barrel Shot Out

[CocoBolo]

My favorite open gun, I'm having trouble making power factor. Both guns are 5" no holes one with Brazos Comp and the other had a Bedell.

Last year when I would Crono the difference in pf between the guns was 3 pf now the gap has widened to 10 pf with the same load.

Satudays Crono Results win 10.5gr AA#7 125gr Zero Gun in question Avg 1331 fps, the other Avg 1394 fps. These results were fired with 10 shots on the same crono same time and same batch of ammo.

I'm shooting .355 bullets, and I am guessing that .356 might help the gun that is down of fps. The Briley the down level gun was making 166pf with 10.2gr and the other 169 pf last summer but there have been a few thousand rounds down the tube since them may 10K or so.

Both guns are as accurate as I am capable of shooting. Notice I'm a "C" so I hit something once in a while. Actually I dont' have to slow down like the fast guys I'm already going slow so I make mostly A's with either.

Is it time for a new Barrel?

[caspian guy]

I would not normaly have thought 10k rounds would cause that much difference. Have you shot it for group off bags? If it still groups ok I have used the .356 trick in the past and it did seem to help with the velocity. Is this the same batch/lot of powder you were using before.

[9supercomp]

I know you said the same load, but are you using the same lot of powder, they do varies form lot to lot.

[G-ManBart]

Is the faster gun much newer than the slower gun? How many total rounds down the barrel for both?

How many rounds were you shooting per string over the chrono? If it's less than 20 you might not have gotten the most accurate results. Did you shoot them one right after the other, or could the lighting have changed at all between guns? Sometimes on partially cloudy days you shoot one string in bright light and the next with a cloud over the sun and it makes a difference. Some of this is why I always say you should load Major to 173+....the old 169 or 170 just doesn't always cut it since there are so many variables to factor in. R,

[CocoBolo]

The chrono data is from the same batch of 400 rounds I loaded last week all from the same jug of powder. I chroned a couple weeks ago and found that my 167 pf load was now 162 pf so I bumped the load .3 and only picked up 25 fps. I've also been testing 9 major loads in another top end. Ok, so maybe this Briley gun has 20K+ round, the other probably has 10K+. The crono test was done back to back so its the same lighting. Gun 1 the Briley 1331 av the Competitor 1394 av. This is 38 Super Comp 10.5gr of AA#7 125gr Zeros 1.240. I also did some Crono work with 8.0gr of N350 which also had similar results with the Briley down about 60 fps, which was previously major at 7.8gr. With the 10-5gr AA#7 the primers are not looking good and I would have to go to rifle primers or get primer flow so I don't want to push the load up any more.

This Briley gun has never grouped well the slide has a little up and down slop and a bit of side to side but for this game it works rather well, it tends to string down. The other gun shots groups with holes tied together till I changed the comp and bullets are still hitting it so its back to the shope one more time. I shot two stages with it today and had two flyers that cost me 30 points at @ 40 yards.

Cripes 1 am two weeks out from a major match and trying to figure out what to shoot. Looks like I just might have to blow the dust off the old Limited gun. I could shoot minor, just not sure thats a good idea.

Edited March 29, 2010 by CocoBolo

[Tom S.]

I'm curious, could weakened springs create this? Is it possible the slide isn't being held as tightly by the recoil spring causing a slight drop in pressure, compared to the lesser used gun????

[eric nielsen]

I think by "string down" you mean the groups are spread vertically in the Briley. Yes springs can be a factor. Mainspring and/or recoil spring. Probably not a factor in velocities. BUT sometimes changing primer brand and/or hitting them a lot harder will change velocities [and group size].

My Caspian Hicap was so loose that it rattled with the hammer back and you could yank the racker & slide around in a short arc compared to the frame. What matters is what does the gun do consistently with the hammer down and the bullet roaring down the barrel. Pretty sure I had a 19lb hammer spring and 11 or 12 lb recoil spring. Whatever it was it worked: shot-out-looking Nowlin barrel would group under 1" @25y.

You might look at the surfaces of your hammer and FP stop. Hammer face should be flat, hammer pin and its pin-hole should be round, FP stop should have a nice curve at the bottom with no flat spots. Locking lugs are something to have a smith or a very good Open shooter look at.

Also: do your primers have nice round strikes, or oval? Are both holes in your barrel link round & is your slide stop pin round?

Velocities are something that can change with the weather and at different rates in different guns. OR go down for good as the barrel gets shot. Depends. You may have heard the very very old debate about whether AA7 is unusually abrasive to barrels; that one I don't know.

Edited March 29, 2010 by eric nielsen

[G-ManBart]

I would be incredibly surprised if it was a spring, hammer or FPS problem. Crazier things have happened, but I still doubt it.

I've seen 60fps difference from one day to the next, so that's something to consider.

At 20K your barrel shouldn't be shot out, but if you do a lot of sustained rapid fire (like multiple bill drills in a row, or a couple of mags without letting the gun cool), it could be starting to erode the throat enough to see on the chrono.

I think Benny Hill runs 12.2gr with a 115, so you might have enough room left to up the charge enough to get 170+ for the match. R,

[Sean Gaines]

like everyone has said there are too many variables that come into play.

weather

different lot of powder

Barrel clean, dirty

changing loads

chrono

primers

etc. etc.

Some guns operate better with more powder working the comp. I say that with caution, do it with acceptable acceptable pressures. as far as your primers, you may try using an extending firing pin, that may help. as far as shooting a barrel out in 20k, I don't think that happend, but like gman said I have seen wierder things. Try it with a different chrono, and see if your results are different.

[CocoBolo]

Guys I don't think its the crono when your setting there with two guns shooting the exact same loads and you are getting 60+ fps difference. I did get slightly slower readings two weeks ago when it was cooler and overcast.

I'm going to bump it +.2gr and test again. I have some bullets in bound I can try and don't start laughing they are BayouBullets, these will have a better seal and while I might get some goop in the comp I think they will do the trick, its just a matter if they can stand the speed. I've seen one guy at a major running cast bullets with red wax on them, when he did ULSC it looked like someone puked in the gun, but it ran till the 12th stage.

I don't do a lot of practice but can get carried away with a couple of plate racks just fooling around and run thu a couple big sticks rather quickly. The round count is a guess, I bought the gun used and I don't track how many rounds I shoot, but I know I average about 1500 a month, so it might be 25k but probably not more. I shot a lot of MTG and they are just a little undersized according to my caliper when compared to the Zero and I run AA#7 its pretty abrasive.

[G-ManBart]

Guys I don't think its the crono when your setting there with two guns shooting the exact same loads and you are getting 60+ fps difference. I did get slightly slower readings two weeks ago when it was cooler and overcast.

I wasn't suggesting that the 60fps difference was a problem with the chrono, just that there are a lot of reasons why you can get 60fps difference. Most people chrono once or twice and call it good, then they chrono again six months or a year later and find things have changed. To really have a good idea what's going on you need to chrono on different days, different conditions a number of times to really have a solid baseline for that load. One partial way around this is probably to build a chrono box and run IR screens, but that still leaves the temperature variable. I've chrono'd my N105 load exactly 21 times since Aug 2008 when I switched to it (really 42 since it's two guns). My max spread from high to low velocity with my primary gun was 66fps (1548 down to 1482) for a change in PF of 8

While it's not likely, you had a comp change somewhere in there too right?

I shot a lot of MTG and they are just a little undersized according to my caliper when compared to the Zero and I run AA#7 its pretty abrasive.

AA#7 isn't really abrasive. They had one bad lot about 15 years ago and they fixed the problem quickly. I ran pounds and pounds of it and Wil Schuemann told someone here that he'd shot some crazy number like 100lbs of the stuff over the years with no problems. R,

Edit because I can't count...lol

Edited March 30, 2010 by G-ManBart

[CocoBolo]

G-man that goes right along with what Marketing says, a bad expierence by a customer lives for ever. I don't have any direct knowledge that it is abrasive but I heard that, probalby some guy that had part of the bad batch, his rant lives on.

[lcs]

I just got my new open for some initial testing. Both of my open guns are 5 inch, no barrel ports and basically the same comp. The new open has a Nowlin barrel and my backup has an STI (no idea on round count, but the gun is tight and groups rather well).

The same load (115 MG CMJ and Silhouette same lot#), same day, same chrono, showed my backup at 166 and my Nowlin at 171. I will be doing more testing to dial-in my new open and hopefully get the backup to a safe chrono margin. Going to the chrono with a 166 PF gun ain't going to fly.

Like CocoBolo I do not have an accurate record of round count on my backup. My spread indicates about 40 FPS difference (Probably acceptable). This spread did not surprise me, but if I were to have a 60 FPS difference on different days I'd be looking to rebarrel.

The whole purpose of a backup, (at Major matches), is to be able to replace you primary gun in the event of a failure. You need to be able to use the same ammo. If my backup and primary gun showed a 60 FPS difference, I would not consider my backup as a viable option.

[CocoBolo]

I just got my new open for some initial testing. Both of my open guns are 5 inch, no barrel ports and basically the same comp. The new open has a Nowlin barrel and my backup has an STI (no idea on round count, but the gun is tight and groups rather well).

The same load (115 MG CMJ and Silhouette same lot#), same day, same chrono, showed my backup at 166 and my Nowlin at 171. I will be doing more testing to dial-in my new open and hopefully get the backup to a safe chrono margin. Going to the chrono with a 166 PF gun ain't going to fly.

Like CocoBolo I do not have an accurate record of round count on my backup. My spread indicates about 40 FPS difference (Probably acceptable). This spread did not surprise me, but if I were to have a 60 FPS difference on different days I'd be looking to rebarrel.

The whole purpose of a backup, (at Major matches), is to be able to replace you primary gun in the event of a failure. You need to be able to use the same ammo. If my backup and primary gun showed a 60 FPS difference, I would not consider my backup as a viable option.

Unfortunately the backup gun has the fast barrel, my #1 love to shoot it gun is the one with the issues. Both 5" one Cone and one bull but otherwise equal in most ways. In this case the STI Barrel is much faster than the Briley barrel, go figure.

[lcs]

Sux when you have these issues right before a major match. It should not take long to ream the comp on your backup.

My new open is a Brazo's cone comp also. Like you, I like the way the Brazo's comp'd gun shoots.

Good luck!

[G-ManBart]

Like CocoBolo I do not have an accurate record of round count on my backup. My spread indicates about 40 FPS difference (Probably acceptable). This spread did not surprise me, but if I were to have a 60 FPS difference on different days I'd be looking to rebarrel.

Out of my newer Open gun I posted results taken over 19 months and my biggest spread was 66FPS with the same lot of powder, bullets and cases (not sure about primers). The only thing is that it's not consistently higher or lower, it just depends on the conditions (light, temp etc). The barrel has around 11K on it now (I have an exact log, to the round, but I haven't updated the total lately). I've avoided getting it hot, it hasn't lost any velocity or accuracy, and it certainly doesn't need to be replaced, but it has shown that much variation on different days. The barrel in my slightly older Open gun has a bit more through it...maybe 20K max, still gives the same basic velocity and hasn't lost any accuracy, but it also shows a similar amount of variation from day to day. R,

[CocoBolo]

G-man - The first time I chronoed my load it was 167pf about 2 years ago, then a few month ago it was 165.7 pf, then next time 160 pf, The other gun has always been higher but abut 3 pf 20-30fps, I wish I had cronoed it with the other one on these other occasions. What we are talking about here is bumping that load .3 gr same jug as last crono both guns side by side same conditions now 63fps. So something is up, and I'm positive its not crono, all other factors are equal except for the gun. The slow gun has a cone comp Brazos, the other a Bedel Ti and an STI Bull Barrel, same brass, same primers, same powder, same bullets all loaded in the same run. Gun #2's numbers are about what they were before with the same load. The slow one is down. My 9 majors are runnning good numbers for the load, and no problems hitting major+.

Desperate times call for deprate measuresI just got a shipment of 125gr .356 BayouBullets from Donnie Miculek, http://www.bayoubullets.net. Now these will seal better and they will achieve higer velocity with the same charge. I got about 20fps over precision moly bullets in my limited gun which was down .4 gr from a jacketed bullet load. So I'll drop down from 10.5gr to 9.8gr and work up to see where I hit 170pf. I might get a little goop in the gun but I think it will run well with them if they can stand the heat and speed, if not they will work fine in my 9 mm limited gun.

[GrumpyOne]

G-man - The first time I chronoed my load it was 167pf about 2 years ago, then a few month ago it was 165.7 pf, then next time 160 pf, The other gun has always been higher but abut 3 pf 20-30fps, I wish I had cronoed it with the other one on these other occasions. What we are talking about here is bumping that load .3 gr same jug as last crono both guns side by side same conditions now 63fps.

What was the temperature difference between the "few month ago", then the "next time"?

[eric nielsen]

Summer to winter can easily be a drop of 40fps or more. Elevation [above sea level] changes can go either way. Some magnum-primer/slow-powder combos can have a noticeable effect @ chronograph. Most guys shoot small rifle primers in Open.

Brand of brass can easily drop 30fps or more. Example [38 super]:

Winchester: 1300

RP brass: 1330

RP nickel: 1345

PMC: 1375

I would load for Winchester with my chrono, usually shoot RP nickel in a tournament, and throw out every PMC case I ever found. Not that it's bad stuff, it's just made with a thicker cross-section and less powder capacity. SuperComp shooters probably have a similar situation.

[CocoBolo]

G-man - The first time I chronoed my load it was 167pf about 2 years ago, then a few month ago it was 165.7 pf, then next time 160 pf, The other gun has always been higher but abut 3 pf 20-30fps, I wish I had cronoed it with the other one on these other occasions. What we are talking about here is bumping that load .3 gr same jug as last crono both guns side by side same conditions now 63fps.

What was the temperature difference between the "few month ago", then the "next time"?

Temp was 55 degrees on the prior occasion and 88 this past Saturday. Then again it was the same temp for both guns. Overcast on the prior sunny on Saturday. This picked the fps up about 10 fps on both guns, but the spread remained 63 fps or 10pf. Certainly the Brass used in both is well used I do have new brass but I am reluctant to drop it at a lost brass match. With new brass the faster gun would be hitting 180 pf, but would the other pick up, interesting question I have those Bayou Bullets loaded to test so I'll try some new brass as well to see what happens. The BayouBullet profile requires it be loaded a little long min 1.260 optimum for crimp is 1.275, both appear to fit the mags and cycle the gun. I'ver run 1.260 a lot in round nose with no problems.

[G-ManBart]

Something to consider is that the more brass gets used, the lower the velocity you're going to see with it. I'm not sure why (mostly neck tension, I think), but it's pretty consistent. New brass is pretty much always going to give you the highest velocity. Even once-fired drops off considerably. I compared new, used, once-fired, Case-Pro'd, U-died, you name it and new was always clearly faster.

The other thing is that guns don't always react the same to temperature/conditions changes the same way. One gun simply might slow down or speed up more than another with all other things being equal. R,

[G-ManBart]

So I'll drop down from 10.5gr to 9.8gr and work up to see where I hit 170pf.

Trust me, I know I harp on this one, but 170PF simply isn't enough. I've repeated it like a broken record, but my batch of 2008 Nationals ammo went 173-173 many times, including two big matches right before Nationals (one sectional and I can't recall the other), and it promptly went 166.1PF at Nationals. That very same lot of everything loaded on the same press, with no changes to it, went 173PF at the 2009 Nationals (yes, I buy in crazy large quantities!). R,

[CocoBolo]

So I'll drop down from 10.5gr to 9.8gr and work up to see where I hit 170pf.

Trust me, I know I harp on this one, but 170PF simply isn't enough. I've repeated it like a broken record, but my batch of 2008 Nationals ammo went 173-173 many times, including two big matches right before Nationals (one sectional and I can't recall the other), and it promptly went 166.1PF at Nationals. That very same lot of everything loaded on the same press, with no changes to it, went 173PF at the 2009 Nationals (yes, I buy in crazy large quantities!). R,

BART - I see your point and may go past 170 depending on pressure signs and if I think this cast coated bullet will stay together long enough to get out of the comp and own range to the target. I've seen some cast and moly coat bullets shot in open guns and also seen them tumble etc, but some worked well.

[G-ManBart]

BART - I see your point and may go past 170 depending on pressure signs and if I think this cast coated bullet will stay together long enough to get out of the comp and own range to the target. I've seen some cast and moly coat bullets shot in open guns and also seen them tumble etc, but some worked well.

I had good luck with cast bullets in an Open gun back in the dark ages...at the old PF, so there's a good chance you'll be okay. Definitely let us know what happens. R,

[lcs]

Like CocoBolo I do not have an accurate record of round count on my backup. My spread indicates about 40 FPS difference (Probably acceptable). This spread did not surprise me, but if I were to have a 60 FPS difference on different days I'd be looking to rebarrel.

Out of my newer Open gun I posted results taken over 19 months and my biggest spread was 66FPS with the same lot of powder, bullets and cases (not sure about primers). The only thing is that it's not consistently higher or lower, it just depends on the conditions (light, temp etc). The barrel has around 11K on it now (I have an exact log, to the round, but I haven't updated the total lately). I've avoided getting it hot, it hasn't lost any velocity or accuracy, and it certainly doesn't need to be replaced, but it has shown that much variation on different days. The barrel in my slightly older Open gun has a bit more through it...maybe 20K max, still gives the same basic velocity and hasn't lost any accuracy, but it also shows a similar amount of variation from day to day. R,

I've never had a spread of 60+ FPS with the same barrel, but if it was only once in 19 months I would not be to concerned either. I chrono 4 or 5 times during the spring and summer as that is the bulk of my shooting. If my backup was consistently 60+ FPS delta from my primary I would rebarrel. Why? When your primary gun is at 172 PF (BTW-I agree with you on loading to 172-175PF) and the same amount of powder is only getting 167 in your backup your pushing the envelope should you have to use you backup at Nationals or any majors. A lot of time and money is wasted if you go minor after having spent large $$$ to attend a major event. JMHO.