Throat erosion - a word of warning

[ejg]

Another point that possibly has no effect on a long range shooters, is the barrel temperature. A hot barrel does not necessarily need to wear faster than a cold barrel. On just about every thread about barrel wear we hear that we should not shoot a barrel hot as the wear goes through the roof. We read it once and repeat it over and over.
I know I am repeating myself about the Heckler & Koch research into barrel life of cold or hot shot rifles. They were made aware that rifles that were used on the range in single fire 5 or 10 rounds for standard shooting training seemed to be shot out with lower round count than rifles shot on full auto. They could prove that it was the case. Maybe hot steel favours thermal shock behaviour which leads to less fire cracking.
edi

 

[NigelM]

Another point that possibly has no effect on a long range shooters, is the barrel temperature. A hot barrel does not necessarily need to wear faster than a cold barrel. On just about every thread about barrel wear we hear that we should not shoot a barrel hot as the wear goes through the roof. We read it once and repeat it over and over.
I know I am repeating myself about the Heckler & Koch research into barrel life of cold or hot shot rifles. They were made aware that rifles that were used on the range in single fire 5 or 10 rounds for standard shooting training seemed to be shot out with lower round count than rifles shot on full auto. They could prove that it was the case. Maybe hot steel favours thermal shock behaviour which leads to less fire cracking.
edi

Now there's a controversial theory Edi. Everything I have read suggests that long shot strings cause excessive wear due to heat build up. It's certainly not my issue as I am pretty anal about not over heating my barrel. Would be interested to read that research if you have a link to it.

 

[Sharpie]

Understood, but that Aussie paper, if you study it, does go into some very fine details about e.g. the mechanism of fire-cracking, the variation of steel types, how the steel becomes modified in use, the influence of temperature, discussion of the gaseous composition of the different powders and how they might affect things.

Nothing there that can be directly applied to a specific application, or guide you to this powder or the other, or this barrel vs. the other.

Nevertheless I found it to be an interesting read.

Now, discussing cleaning products: I have a big bottle of Butches Bore Shine, which is a traditional ammonia based copper solvent, which is what I have always used. It does a great job dissolving copper fouling, and loosening other stuff, however my researches suggest that impregnating a fire-cracked bore (they all are, to some extent) with such chemicals may not be ideal, the ammonia particularly, so I would like to learn about alternatives.

Perhaps just a diy mix of e.g acetone and ATF would be milder, keeping the ammoniacal stuff for the occasional deep clean.

As well as trying to understand why SS barrels are considered desirable, compared with "chromolly" plain steel.

 

[ejg]

Now there's a controversial theory Edi. Everything I have read suggests that long shot strings cause excessive wear due to heat build up. It's certainly not my issue as I am pretty anal about not over heating my barrel. Would be interested to read that research if you have a link to it.

I will try find it, was quite a few years back. I remember a picture of the H&K rifle being cooled in a barrel of water after each 20 round mag on full auto. Either way it won't help us other than to prove fire cracking / thermal shock behaviour might be the main culprit in barrel wear. Tune the barrel steel to have better thermal shock behaviour and you have longer barre life.
edi

 

[ChesterP]

Understood, but that Aussie paper, if you study it, does go into some very fine details about e.g. the mechanism of fire-cracking, the variation of steel types, how the steel becomes modified in use, the influence of temperature, discussion of the gaseous composition of the different powders and how they might affect things.

Nothing there that can be directly applied to a specific application, or guide you to this powder or the other, or this barrel vs. the other.

Nevertheless I found it to be an interesting read.

Now, discussing cleaning products: I have a big bottle of Butches Bore Shine, which is a traditional ammonia based copper solvent, which is what I have always used. It does a great job dissolving copper fouling, and loosening other stuff, however my researches suggest that impregnating a fire-cracked bore (they all are, to some extent) with such chemicals may not be ideal, the ammonia particularly, so I would like to learn about alternatives.

Perhaps just a diy mix of e.g acetone and ATF would be milder, keeping the ammoniacal stuff for the occasional deep clean.

As well as trying to understand why SS barrels are considered desirable, compared with "chromolly" plain steel.

There are a number of effective and very good bore cleaners on the market for copper removal now widely available, that are Ammonia-free. These include, in no particualr order of merit:

• M-Pro7;
• Wipeout Patchout and Tactical Advantage;
• KG products KG-12 Big Bore Cleaner.

There are more, but I have found the products above to be the best one's I've used.

 

[dlz90]

Great thread to the OP I have a 17 Remington a renowned barrel burner IMHO unjustified I used exclusively RL15 the original barrel lasted some 4/5000 rounds before accuracy suffered even then it would shoot the first 3 or four rounds around an inch on a clean barrel before it really started to open up, I never once measured throat erosion and cared little about it in fact I just shot it and enjoyed its deadly performanceI got it rebarreled eventually though, Steve Kershaw fitted a LW50 it has shot maybe 200 rnds I will not measure throat erosion I will not clean it to much maybe every hundred if I can be bothered I also do not shoot max loads for me its the hunting if your rifle is shooting 1/2" jeeze be happy that's excellent accuracy many a shooter would love that so as already mentioned shoot hunt enjoy.

D

 

[Sharpie]

There are a number of effective and very good bore cleaners on the market for copper removal now widely available, that are Ammonia-free. These include, in no particualr order of merit:

• M-Pro7;
• Wipeout Patchout and Tactical Advantage;
• KG products KG-12 Big Bore Cleaner.

There are more, but I have found the products above to be the best one's I've used.

I think that these products are aqueous chelating agents, rather than the stinky traditional chemical direct solvent stuff that I still use, since I have a big bottle of it, and it works, laboriously, with rods, brushes, jags, patches, a bore guide etc.

I do appreciate that ammonia may not be great for barrel steel, particularly if left in for more than a few minutes, and should be neutralised afterwards with at least some oil afterwards, which then has to be cleaned out again before use.

Interested to learn about alternatives, how they compare, even with just a squirt of magic foam down the bore, then a pull-through with a boresnake. I'm all for labour saving, if it works.

 

[20-250]

I never use products containing ammonia. Haven’t done for years.
Forrest Bore Foam, if left to work for longer than the 15 minutes (if I remember correctly) recommended on the can is a superb remover of carbon and copper fouling. I use repeated applications of that followed by a run through with Hoppes benchrest copper solvent. No scrubbing, just patch out after each product has done its job.

 

[Tikka CTR yummie]

It appears to me that Laurie is advising that some of the latest wonder powders are not particularly good for your barrel. Their manufacturers have gone all-out for performance, for which some do have a genuine use. He should know.

As for the durability of the barrels themselves, their steel, whether they are hammer-forged, buttoned, even cut-rifled, that's not something that most of us here are likely to have to worry about, in our lifetime.

Particularly those whose idea of maintenance is to maybe run a brush and a patch through once/year, whether they think it needs it or not, or just pull a boresnake through periodically.

BTW, 0.5MOA performance doesn't mean being just being able to shoot a 3-shot group into a cloverleaf at 100 yards, once, whilst ignoring the times that it doesn't work, and ignoring the fliers, and assuming that it is just a matter of later twiddling a hunting 'scope to actually align the point of impact with where you are aiming. And that that will apply over all ranges.

Long range shooting, several 100s of metres, trying to get close to the V-bull, and putting many many rounds through the barrel, is a quite different discipline. Which does develop some skills applicable to hunting, but not vice-versa.

Shooting off-hand, from field positions, is one thing. Improvised rest, fencepost, tree, rucksack etc. better. Use a pair of sticks, better. Quad sticks, possibly better still. Bipod also good, if it it is actually practical to use one in the field.

Good luck to those who claim that they can do that, every time, sub-MOA.

I am very suspicious of these wonderful shooters who can shoot sub MOA at all distances, very unlikely, more of a boast. A lot like, you should've seen the massive fish I caught, it was thiiiiiiiiiiiiiisssssssssssssssssssssssssssssssss long.

 

[User00033]

I am very suspicious of these wonderful shooters who can shoot sub MOA at all distances, very unlikely, more of a boast. A lot like, you should've seen the massive fish I caught, it was thiiiiiiiiiiiiiisssssssssssssssssssssssssssssssss long.

You'd be surprised by what can be achieved in calm and clear conditions by quite a few of today's mass produced rifles, high BC bullets and half decent reloading.

I know I am.

In recent times, say the last 4-5 years, I've seen a significant, measurable improvement to my field accuracy. I've certainly concentrated on my technique - Nathan Foster's book has helped a lot with that. The more I practice, the better I get. Sound's obvious enough eh. But the simple fact is, the precision and accuracy of my shots at longer ranges (assuming consistent wind) is good enough for me to be confident that I can and will shoot a goat in the shoulder pretty much every time at whatever range I choose out to about 700m, which is roughly the limit of what my rifle will do power wise. I shoot prone, or sitting with a tripod.

Something that me and my mates do a lot is MOA gong shooting. Setup the correct diameter gong up at the correct range - three gongs is a good number split by say 200yds - and give them three shots each. It has to be blowing 40 barstards for us to consistently miss, and oftentimes we'll all hit with every shot. It's extremely gratifying and confidence boosting to be able to do that.

Drop testing, gong shooting, long range rabbit shooting (very very good practice) and blowing up water filled milk bottles - lots of ways to improve skills and confidence. It is extremely helpful to be able to do this freely within a short walk of where you live, like over the road in my case. Rural living and a less restrictive culture goes a very long way to getting sufficient practice.

No I'm not claiming to be a sub MOA shooter at all distances, all of the time. But I'd put a keg of ale on being able to deliver the goods most of the time within the limits of what I regularly shoot for pest control and general hunting. And a final comment is that I use smaller calibre, heavier rifles for a reason - they are considerably easier to shoot accurately than lightweight heavy recoilers.

 

[Tikka CTR yummie]

I wasn't critising you, more a general comment. I am sure you are a fantastic shot.

 

[User00033]

I wasn't critising you, more a general comment. I am sure you are a fantastic shot.

That's an interesting response. Why the sarcasm?

 

[Tikka CTR yummie]

That's an interesting response. Why the sarcasm?

There was no sarcasm at all. It was genuine, aimed at the Americans not you. Let's forget it. Crossed wires.

 

[ejg]

On forums it is often difficult to judge who is who. At first glance one would think someone is just shooting their mouth off however there are quite a few people on this forum that work more like research scientists at their sport than just taking a shot every now and then. Many work professionally in rifle building rifle design as well as the bits that surround a rifle.
edi

 

[royr]

Morning Gents,
Have found these two sites below, helpful in giving predictions on barrel life with different burn-rate, heat potential powders.

Pierre Vanderwalt.

Barrel Life Calculator - Pierre van der Walt

pierrevanderwalt.com

The EXCEL formula from Accurate Shooter:-

You are being redirected...

Bullet stability (Chrono'd bullet speed is required)
Calculating J.B. Miller gyroscopic stability of bullets:-

JBM - Calculations - Stability

www.jbmballistics.com

Regards
RoyR

 

[Tikka CTR yummie]

Morning Gents,
Have found these two sites below, helpful in giving predictions on barrel life with different burn-rate, heat potential powders.

Pierre Vanderwalt.

Barrel Life Calculator - Pierre van der Walt

pierrevanderwalt.com

The EXCEL formula from Accurate Shooter:-

You are being redirected...

Bullet stability (Chrono'd bullet speed is required)
Calculating J.B. Miller gyroscopic stability of bullets:-

JBM - Calculations - Stability

www.jbmballistics.com

Regards
RoyR

Eye opening to say the least, especially the calculator concerning powders and bullet count

 

[Odders]

I remember the Border boys telling me that as a rule of thumb it’s roughly 10 thou per 100 rounds.

If that were truly the case, the L1A1 I use "over the Pond" should be a smoothbore by now.

 

[Tikka CTR yummie]

If that were truly the case, the L1A1 I use "over the Pond" should be a smoothbore by now.

I know what you mean. My military rifles are all smooth bores, especially the mint deep landed 1889 Schmidt Rubin, K31 and Mosin Nagant, I have been shooting for years. I think the point is that high velocity rifles with modern powders do have a lot of friction and heat at the throat due to the smaller bores. Or maybe the metal isn't as good as it was decades ago. I think he has misunderstood the wear. 10 thou per 100 rounds is not conceivable. Unless he means 10 thou of a mm.

 

[hammo]

As I understand it, a straight walled case GENERALLY causes less erosion.
The more overbore a case is, GENERALLY greater erosion.
What about a bottleneck case with a very long neck - 1 inch or more, could that sacrifice the inside of the case neck instead of bore ?
I think an area just in front of the case shoulder is getting the biggest pounding, as the case shoulders vector the hot gases into a cone.
Thoughts on this anyone?

 

[Laurie]

Straight-wall designs generally cause less erosion because they generally have a lower capacity / charge weight to bore area ratio, and most (not all) use lower pressures than modern bottlenecked types. Those that do use higher pressures such as .458 Win Magnum tend to see fewer shots fired in a year, and very few if any 20-round strings in competition. If you built a say .224 cal straight-wall running at 65,000 psi it would produce greater erosion than a same performance, same pressure well-designed bottlenecked design if you accept the TP (turbulence point) hypothesis.

TP theory says that the case shoulders direct the flow of partially burned powder kernels infused with superheated gas that forms at the case mouth and allied to neck length either retains this highly erosive mass inside the case-neck or pushes it outside into the leade where it wears the barrel out quicker. The simple test is to take a scale drawing of the case and extend the shoulder lines forward until they intersect - that's where the TP will form. If outside of the case-neck, bad; if inside, good.

A real-life example is to be found in the sixes - the early 50s design 243 Win with 20-degree shoulders and a short neck; the slightly later 6mm Rem with 26-deg shoulder angle and much longer neck with its TP inside the neck; the still later smaller capacity 6mm Tubb XC with 30-degrees shoulder and longer neck. All other things being equal (bullet weight, pressures, propellant flame temp / heat values, rate of fire / barrel heating) the XC and 6mm Rem should give longer barrel lives than the 243 Win, but they're not equal here as there are capacity / charge weight variations across the three.

There are however reformed, enhanced variants of the 243 that simply involve running a 243 case through the new version's die and/or a small amount of fireforming. The 6mm SLR (Super LR) simply grafts the XC's 30-degrees shoulders and long neck onto the front end of the 243 case, no other change, by pushing the shoulders back and reforming them. Ballistically you still have a 243 Win (6mm-08) with maybe 1gn less water capacity due to the reforming, but with a 'more efficient' front-end that moves the TP back inside the case.

Super LR

The 6mm Competition-Match is a similar modification with a 31-degree shoulder designed by Joe Hendricks and used now by his son Joe Hendricks Jr very successfully in US Hi-Power XTC.

Both cartridges claim to enhance barrel life over alternatives in the competition role, in some cases provide a doubling of barrel life. However, it turns out there is a degree of sleight of hand here. Yes, the front-end is far better than that of the 243, but few use that cartridge in serious competition and none in disciplines like PRS and XTC with high round-counts and rapid fire-strings, where the smaller 6XC is the obvious choice. Such users burn through two XC barrels in a season despite the efficient case-design. The SLR and C-M give enhanced life because having the larger 243 Win case capacity lets them use cooler burning propellants - Hodgdon H1000, and even more so Viht N165. So despite being more over bore-capacity, they reduce barrel life compared to the very well designed XC. (N165 has proven itself in this respect in several cartridges and this isn't a shooting / urban myth) So, there is nothing to stop you loading your 243 Win with this propellant and treating your barrel more gently. (Because of its burning rate, it's only really applicable for use with heavier bullets though, 100gn and above.)