Borescope Surprise

[Oso]

Recently I bought a lightly used Rem 700 300AAC. It features a threaded 16.5" Heavy Barrel (R5, 1:7.5 twist). It was an extremely clean rifle when I bought it with little to no wear on the bolt face or wear marks on the bolt body. This rifle has seen minimal use and spent the last 10 years is someone's safe.

I have taken it out twice to see how it would perform (50 yards and 100 yards). I know... its a 300BO. I still expect it to shoot 1MOA or better shooting my pet load (125gr TNT with 17.5gr H110 CCI 450). This load is very accurate in my other rifles. However, I can't get it to group consistently. At 100 yards it is a 2"-3" gun. Scope & mount are tight, action is tight, rigid stock with no chance of barrel contact. Doesn't matter if shot off a rest or bag, or with or without a suppressor.

I was out of options/ideas so I finally decided to break out the Teslong borescope. Its been sitting neglected in the corner still in its factory package. After reading enough posts on the darkside of excessive use of the borescope for everything. Until now I have chosen blissful ignorance. I don't have a reference point on what is normal inside a barrel, but I have some common sense. I would characterize the artifacts that I found in the barrel as either (1) lines & grooves or (2) gouges & voids. Both of these were scattered throughout the length of the bore.

I think that I found the culprit - horrible factory barrel. I suspect this is why this rifle wasn't

Pictures to Follow

 

[Oso]

Examples of Lines & Grooves:

 

[Oso]

Examples of Gouges and Voids:

 

[rwj]

I know... its a 300BO. I still expect it to shoot 1MOA or better shooting my pet load (125gr TNT with 17.5gr H110 CCI 450). This load is very accurate in my other rifles. However, I can't get it to group consistently. At 100 yards it is a 2"-3" gun. Scope & mount are tight, action is tight, rigid stock with no chance of barrel contact. Doesn't matter if shot off a rest or bag, or with or without a suppressor.

Perhaps the barrel is the culprit, but it may be worth your time to try a different load in this rifle. I have rifles of nearly the same configuration, but they don’t “like” the same loads to shoot optimally.

 

[RustyInBend]

I had some similar issues with a new barrel, and realized that they weren't gouges or voids, they were "schmootz" stuck in the barrel. I went at it energetically with Iossa paste bore cleaner (some prefer JB Bore Paste) and worked it hard until it was gone. Rifle shot way better after that.

 

[Oso]

Prior to using the borescope, I rigorously cleaned the barrel using Butch's Bore Shine. Upon my first attempt to use the borescope, I realized the barrel was still filthy and there was "Schmootz" scattered about.

I stepped up the cleaning with healthy dose(s) of .30cal patches soaked in Flitz Bore Polish wrapped around 6.5m brass brush. After a dozen or so passes down the length the patches stopped coming out black. Cleaned out the Fllitz with some more patches soaked in Butch's.

The Gouges/Voids in pictures above looked distinctly different then my first attempt with Schmootz in the barrel.

All of this Schmootz talk is making me hungry. Maybe a Pastrami Sandwich from Kenny & Ziggy's or fresh Pumpernickel Bagel double toasted with Irish Butter. Looks like a bagel run in the morning!!!

 

[mgunderson]

Hit it with the bore paste. It isn't the worst factory barrel.

 

[L.Sherm]

Looks alot some some savage barrels ive seen.

 

[ronemus]

It shows that it's a production barrel, not a high-grade custom. The defects you posted are minor and wouldn't lead to the large groups you're getting. The problem is likely to be the crown or a tight spot in the bore. It's easy to check the crown with the borescope. Tight spots (diameter variations) are best found by slugging, but paying attention to a tight patch as it progresses through the bore works fairly well; the bullet is not well supported after passing through a constriction and will produce shotgun patterns.

 

[quest450]

I think it is OK to be anal when you get a new competition barrel from your gunsmith, I do all the crazy woodoo break in process with every barrel my gunsmith chambers, I always inspect my new barrel with a borescope and I've never had a questionable barrel but there's a pattern when you break them in,
some copper a lot in the first five shots some do not, that's why I think checking for copper fouling after every shot when you breaking the new barrel in is important, I just wanna see the progress of less copper after every shot, it usually takes 3-7 shots to break my barrel in using GreTan method.

 

[snert]

If I showed images of all but the last 7 inches of my 1950's 220 Swift barrel you would say the stupid thing wouldn't hit a basketball at 50 yards. But I had confirmed kills on groundhogs to 700 yards and regularly shot the usual water bottles at 500. When it finally stopped shooting under 3/4 inch regularly, and 1/4 inch when properly (not fully) cleaned, I pulled it and scoped it. It looks like a very bad western PA gravel road in the spring time...pot holes, missing lands and grooves, smeared bullet jackets. But the last groups it shot were 3/4 inch and some less. It just wouldn't stay at 1/4 inch like it used to for 15 rounds.

Don't give up. It might be a load issue or even a matter of "bedding". All you have to lose is componants.

 

[bozo699]

Examples of Lines & Grooves:

These are just chatter marks, very typical in factory barrels. If you think your Remington is bad look at a Savage sometime. The pits in the next picture aren’t a good thing to have but unless you have have one on your crown I don’t think that’s your accuracy issue. try a different bullet and see.
Wayne

 

[searcher]

That the rifle doesn't like your standby load isn't surprising - and I'd not be inclined to blame the performance on those marks - yet. if I judged the accuracy potential of some of my barrels by bore-scoping them, they should shoot like a shotgun, yet once fed the powder they liked, all was well. Unless your barrel nut is loose, excessive slop between the upper/lower or something else is really loose or something else going on, even the worst barrels can usually be coaxed to shoot sub-MOA, given what it likes. I'd switch powders and do some experimentation. I assume your handguard is free-floating. Patience...

That said, it is "possible" that the rifle was shot a lot more than you think. Because there was little wear on the bolt doesn't really mean anything unless you know that is the original bolt. I change the bolts in my A/R's about every 3,500-5,000 rounds, which is how long it takes me to wear out the batch of brass I fireform to each new bolt. I'd look closely at the throat and the finish on the inside of the receiver where the bolt carrier runs. I think it would take a lot of shooting to wear out that Blackout - and I doubt it was worn out - but a new bolt can make a gun look like it was never abused. Hopefully - that was not the case. Fortunately, if it comes to that, there are some pretty decent barrels out there for not a lot of dough. Not match-grade stuff - but plenty good to get you under 1 MOA.

 

[Paul's Black Rifles]

I bet the previous owner was shooting subs and got some of them stuck in the barrel. The damage probably was from ham fisted attempts at removal of the stuck slugs.

Paul

 

[Benchrest Braxton]

If I showed images of all but the last 7 inches of my 1950's 220 Swift barrel you would say the stupid thing wouldn't hit a basketball at 50 yards. But I had confirmed kills on groundhogs to 700 yards and regularly shot the usual water bottles at 500. When it finally stopped shooting under 3/4 inch regularly, and 1/4 inch when properly (not fully) cleaned, I pulled it and scoped it. It looks like a very bad western PA gravel road in the spring time...pot holes, missing lands and grooves, smeared bullet jackets. But the last groups it shot were 3/4 inch and some less. It just wouldn't stay at 1/4 inch like it used to for 15 rounds.

Don't give up. It might be a load issue or even a matter of "bedding". All you have to lose is componants.

agreed, i have a 20 year old factory remington barrel that looks just as bad and i've shot a few 5 1" groups at 550 yards with it.

makes you really wonder about what actually matters for precision

 

[Oso]

There are 1-2 dozen of these pits/tear-outs/voids all dispersed throughout the barrel. If the rifle shot well then I could easily ignore the rough finish of the bore... but that is a big "IF".

Immediately after ensuring that everything was properly torqued down tight, I checked the crown. It is flat and the edge of the bore is crisp without any apparent irregularities.

Tomorrow, I will run a tight patch to see if there is a constriction in the bore.

 

[Oso]

This gun was "like-new" with minimal round count. The "barely there" Remington factory finish had no wear marks from cycling the action or handling marks on the exterior of the rifle. The Yankee Hill Phantom QD mount (circa 2010-2015) didn't even have any carbon buildup from use with a suppressor.

The only mark on the bolt is result of the rear action screw being proud by 1/32". When inserting the bolt back into the receiver the front edge of the bolt face can make light contact with the top of the screw if the bolt rides up the the receiver tang before it is inserted into the action. Tomorrow, I plan to lightly touch/kiss the rear action screw against a diamond wheel.

The Speer 125gr TNT bullet is one of most accurate and reliable performers out of the 300BO. It is extremely easy and forgiving.... similar to 69gr SMK for 223. I will load up some 125gr SMK and see if this rifle likes them better.

 

[SeabeeKen]

I had a savage 223 barrel that looked like a washboard from end to end and completely copper fouled in 2-3 shots. I replace it quickly

 

[Larry Koch]

Looks like a factory barrel, they have missing pieces of barrel. how do you think they can sell a complete rifle for 400 bucks.

 

[Darkside]

What ever Load you have made up for one gun usually Doesn't work as well in another gun. Try some factory ammo, or do load development for this gun. There is Nothing Wrong with that barrel, it's a factory barrel.