BORESCOPE TERROR

[searcher]

I hadn't checked a .20 Practical A/R rifle on paper in several years of fairly heavy round count varmint shooting on it. Before going to the range, I bore-scoped it and the throat was just plain gone. Smooth rifling for a few inches. Yikes! So went to range to see what it was doing on paper, as I had already loaded up another 1,500 rounds for the upcoming spring shooting. I was thinking that was not such a great idea. I use two bullets, mainly - the 32 V-Max and 40 V-Max in that rig. The 32 V-Max shot .318" and the 40 V-Max .285" 5-shot groups @ 100 yards in 5-10 MPH wind conditions. I find it fascinating that the bore and throat could change so drastically and the barrel shoots as good as it did 6,000 rounds back. I never altered the bullet seating depth or changed the powder charge through three lots of powder (Accurate LT32). It just keeps ticking.... Makes me wonder how many of you out there have rifles that keep shooting - and how many rounds you were able to get on them before they took a dive.

 

[pacificman]

Yep...Seems the target will always tell you what you need to know. I had a .17 Remington with a pac-nor barrel that went south at about 3000 rounds...but I was shooting well over 4000 fps. with better than 1/2 MOA. I always let the barrel cool when shooting sage rats. I decided to shoot a different bullet and use a different powder for an additional 600 rounds with about 600 fps. velocity loss. The accuracy was about MOA at that point.
I decided then to re-barrel to 20 practical ...which I'm still shooting. I remember when the 17 Rem. barrel was worn out that you could drop a bullet in that 17 Rem. and it would go about an inch down in the barrel before it would touch any lands...LOL. The way I found out the barrel was toast was it just would not shoot tight groups anymore when checking my target. I did have a 204 with I'll bet more than 6000 rounds out of that one. I'm shooting a 223 with has to be more than 7000 rounds and like you it's still shooting 1/2 MOA...but my velocity has been only 3100 fps. with the good accuracy...maybe that's why it has lasted so long...I don't know....LOL.

 

[jpx2rk]

I hadn't checked a .20 Practical A/R rifle on paper in several years of fairly heavy round count varmint shooting on it. Before going to the range, I bore-scoped it and the throat was just plain gone. Smooth rifling for a few inches. Yikes! So went to range to see what it was doing on paper, as I had already loaded up another 1,500 rounds for the upcoming spring shooting. I was thinking that was not such a great idea. I use two bullets, mainly - the 32 V-Max and 40 V-Max in that rig. The 32 V-Max shot .318" and the 40 V-Max .285" 5-shot groups @ 100 yards in 5-10 MPH wind conditions. I find it fascinating that the bore and throat could change so drastically and the barrel shoots as good as it did 6,000 rounds back. I never altered the bullet seating depth or changed the powder charge through three lots of powder (Accurate LT32). It just keeps ticking.... Makes me wonder how many of you out there have rifles that keep shooting - and how many rounds you were able to get on them before they took a dive.

Any pics of the barrel/throat?

 

[varmintshooter]

I think we want a barrel to look a certain way and if it doesn't we think it won't shoot. Makes me wonder how many have been trashed because they didn't pass inspection with borescope. I'm not talking competition but minute of groundhog

 

[1raggedhole]

I like the borescope to confirm reason of what I am seeing on paper. I have shot out a few barrels on prairie dogs. In my experience, they will shoot good for very long time if you keep them cool. When they are nearing the end, a string of more than 20-30 rounds and the bullets will start to wander a lot (Meaning inches). At that point I usually find no rifling for the first inch or two, and/or severe fire cracking. You can also notice this when cleaning, as the fire cracked barrels will take much longer to remove the copper.
If you run em hot like I do, my 20 cal barrels are usually toast by 4000 rounds. You can get much more if you are shooting slow with a bolt gun.

 

[dantiff2]

Yep...Seems the target will always tell you what you need to know.

^^^100%^^^

 

[justinp61]

I hadn't checked a .20 Practical A/R rifle on paper in several years of fairly heavy round count varmint shooting on it. Before going to the range, I bore-scoped it and the throat was just plain gone. Smooth rifling for a few inches. Yikes! So went to range to see what it was doing on paper, as I had already loaded up another 1,500 rounds for the upcoming spring shooting. I was thinking that was not such a great idea. I use two bullets, mainly - the 32 V-Max and 40 V-Max in that rig. The 32 V-Max shot .318" and the 40 V-Max .285" 5-shot groups @ 100 yards in 5-10 MPH wind conditions. I find it fascinating that the bore and throat could change so drastically and the barrel shoots as good as it did 6,000 rounds back. I never altered the bullet seating depth or changed the powder charge through three lots of powder (Accurate LT32). It just keeps ticking.... Makes me wonder how many of you out there have rifles that keep shooting - and how many rounds you were able to get on them before they took a dive.

How is the velocity compared to when it was newish?

 

[K22]

I am not against bore scopes; I just don't use them because I am a dinosaur. Also, I am not smart enough to correlate a specific bore scope image to performance. Instead, I use shots on target as my guide to cleaning and barrel performance adequacy. This has always worked for me for a very long time.

Because of my shooting discipline (varmint and predator hunting), I do not shoot sustained round sequences so my barrels rarely if ever become hot and never over heated even during range practice which, weather permitting, is usually 2 to 3 times a week. My "money shot" is the cool / cold barrel shot and that is the way I practice.

I began keeping an exact round count many years ago. However, because the conditions in which I shoot my round counts probably doesn't relate to others based on what I see at the range. The vast majority of fellow shooters I encounter at the range shoot sustained round sequences. While other factors contribute to bore wear, the most significant is heat which can change the metallurgical properties of the steel. Sustained fire creates a lot of heat and heat accelerate barrel wear.

I clean on a regular basis (about 50 rounds) with a simple solvent and bronze brush. Most of my varmint rifles are running over 2,000 rounds, some over 3,000 rounds and they still shoot within my standards. My old 243 Win Rem 700 which has over 3,000 rounds still hold sub 1 moa. with tuned reloads.

The bottom line is I believe it is more about the manner in which one shoots rather than a round count that affects barrel life because of the heat factor. Of course, I am not an expert so I could be wrong.

 

[gunsandgunsmithing]

I hadn't checked a .20 Practical A/R rifle on paper in several years of fairly heavy round count varmint shooting on it. Before going to the range, I bore-scoped it and the throat was just plain gone. Smooth rifling for a few inches. Yikes! So went to range to see what it was doing on paper, as I had already loaded up another 1,500 rounds for the upcoming spring shooting. I was thinking that was not such a great idea. I use two bullets, mainly - the 32 V-Max and 40 V-Max in that rig. The 32 V-Max shot .318" and the 40 V-Max .285" 5-shot groups @ 100 yards in 5-10 MPH wind conditions. I find it fascinating that the bore and throat could change so drastically and the barrel shoots as good as it did 6,000 rounds back. I never altered the bullet seating depth or changed the powder charge through three lots of powder (Accurate LT32). It just keeps ticking.... Makes me wonder how many of you out there have rifles that keep shooting - and how many rounds you were able to get on them before they took a dive.

Yes, there seems to be almost no rhyme or reason why some barrels just shoot and shoot while others lay down in short order, often going away dramatically. I actually prefer that over gradual loss of accuracy though as it leaves no doubt about needing replacement. All that said, the ones I've seen that went way longer than the norm were well maintained and showed very little fire cracking, just worn looking. So, I just guess from that that things like how hot we load, how we keep the bbl from over heating and keeping them cleaned does matter a lot.

Still haven't used it yet but I recently got a reamer where I spec'd it to be a bit different than what's typically done. The area at the very end of the neck typically uses a pretty abrupt 45° angle at the end of the neck of the chamber. On this reamer, I laid that 45° angle down the 15°. The idea being a smoother transition there, less turbulence and a far larger heat sink at that critical point. Time will tell is all I can say. I hope to see much improved bbl life without losing any accuracy. Again, time will tell.

 

[searcher]

Any pics of the barrel/throat?

No - I have older bore scope without camera function.

 

[searcher]

How is the velocity compared to when it was newish?

About 80 fps slower

 

[Clancy]

I pull most of mine when they won’t shoot very small. 3 shot groups in the .1s and 5 shot groups in the .2s. Life’s too short to shoot worn out barrels.

If I wanted to get the most out of one, I’d look more at the shape of the groups than the overall size. Globs are a lot better than a vertical or horizontal group. [that’s assuming you’ve done all you can to tune it.] In the past when I really tried to drain the life out of a piece of steel, it was always the spitting of single shots that got them sent to the scrap pile. Some call it a flyer.

 

[Bronsin]

So THAT'S why you were questioning me a while back when I said that LT can chew on the throat.

 

[ebb]

6000 rounds from a 20 caliber rifle, WOW I had no idea that something like that was possible. Is this normal???? What is the expected life of one of these??? I had assumed that with the little bore they would be way over bore in just about any case you could chamber one in and have never looked at them seriously.

 

[NorCalMikie]

Don't go looking for trouble. But, but, but the bore scope says my barrel is SHOT!!
5 shots that can be covered with a dime and your barrel is junk?
That's what you get for looking.

 

[7315br]

6000 rounds from a 20 caliber rifle, WOW I had no idea that something like that was possible. Is this normal???? What is the expected life of one of these??? I had assumed that with the little bore they would be way over bore in just about any case you could chamber one in and have never looked at them seriously.

Interesting comment ebb. I'm partial to .20 cals...no doubt, but 6,000 plus rds of .20 caliber normally depends entirely on the case size driving it. The Squirrel series and the Mink series based off a shortened .22 Hornet case make the 6,000 rd barrel life easily under normal conditions. Shortened .223 and TCM cases will also (I'm sure there are others). Rounds like the .204 Ruger,.20 Practical, .20 JI, .20 Bobcat, .20BR, .20PPC, and .20/.250..."don't" (just some of the ones I've had). Some of those don't make a 1,000 rds in my opinion. As far as the borescope I use it for cleaning checks almost entirely. I let the rifle from shooting lead the way.

That's why I still like the .20 Vartarg so much. It will go 4-5,000 rds of bbl life in my opinion. To me, it's still like the best of both worlds. You should try one.

 

[Kevin Taylor]

I think we want a barrel to look a certain way and if it doesn't we think it won't shoot. Makes me wonder how many have been trashed because they didn't pass inspection with borescope. I'm not talking competition but minute of groundhog

I have been shooting for decades, all without a bore scope. I shot great groups and was happy. When a barrel went south I replaced it. No need to insist the bore be Perfect.

 

[Tommie]

I don’t own a bore scope and don’t keep track of round count.
Never will.

 

[searcher]

I think we want a barrel to look a certain way and if it doesn't we think it won't shoot. Makes me wonder how many have been trashed because they didn't pass inspection with borescope. I'm not talking competition but minute of groundhog

I agree 100%. I have scoped a few bores that resemble the surface of the moon, craters and deep machine marks thrown in- yet shoot amazingly well.

 

[rockhound78]

Friend had a 7mm TCU barrel he used in IHMSA. He bought it used and don't know how many rounds he put thru it. Finally sent it back to T/C and they sent him a new barrel. Old 10" barrel only had about half its rifling left, but still shot respectable but would throw one or two shots out of a 40 round match, so back to the factory it went.