Bore erosion, pitting and tool marks

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   Dario, I doubt either of my DCRA 7.62 barrels or the 1958 Long Branch CMk 4 barrel on my No. 4 T has seen a corrosive primer. Not the case for the majority of No. 4 rifles that saw service in WWII. I believe most of the British .303 Mk 7 cartridges used corrosive primers, while most of the Canadian Boxer primed .303 was non-corrosive. 
Long story behind this, but I spun the BSA Barrel back onto my Fulton No. 4 Mk 1/3 (removing the new Criterion barrel) and shot it today. I had cleaned it well before I had put the BSA barrel away. After 40 rounds it was heavily fouled. This barrel has upwards of 10,000 rounds thru it, fired by me.  I cleaned it with Bore Tech Eliminator, and it was loaded with copper (evidenced by the blue on these patches). 

Here is what the bore looked like AFTER cleaning with Eliminator:

About 1 inch forward of the chamber. Note the significant firecracking. Also heavy carbon in the grooves that Eliminator did not remove. 

10 inches down the bore. The rest of the bore looks like this, no corrosion pitting.  

When barrels get this rough, fouling builds very quickly. Interesting enough, the first five shots I fired today grouped within 1 MOA. 10 shot groups then opened up to 2 to 3 MOA (shot prone in sling with Mk 1 service issue back sight). 

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britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: February 16 2024 at 2:15pm
	Dario, I doubt either of my DCRA 7.62 barrels or the 1958 Long Branch CMk 4 barrel on my No. 4 T has seen a corrosive primer. Not the case for the majority of No. 4 rifles that saw service in WWII. I believe most of the British .303 Mk 7 cartridges used corrosive primers, while most of the Canadian Boxer primed .303 was non-corrosive. Long story behind this, but I spun the BSA Barrel back onto my Fulton No. 4 Mk 1/3 (removing the new Criterion barrel) and shot it today. I had cleaned it well before I had put the BSA barrel away. After 40 rounds it was heavily fouled. This barrel has upwards of 10,000 rounds thru it, fired by me. I cleaned it with Bore Tech Eliminator, and it was loaded with copper (evidenced by the blue on these patches). Here is what the bore looked like AFTER cleaning with Eliminator: About 1 inch forward of the chamber. Note the significant firecracking. Also heavy carbon in the grooves that Eliminator did not remove. 10 inches down the bore. The rest of the bore looks like this, no corrosion pitting. When barrels get this rough, fouling builds very quickly. Interesting enough, the first five shots I fired today grouped within 1 MOA. 10 shot groups then opened up to 2 to 3 MOA (shot prone in sling with Mk 1 service issue back sight).

DarioPirovano Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May 20 2023 Location: Italy Status: Offline Points: 219	Post Options Post Reply Quote DarioPirovano Report Post Thanks(0) Quote Reply Posted: February 16 2024 at 2:44pm
	I tought all of the mk7 rounds were berdan primed, I need to come back study. Geoff, why the return to the bsa barrel? Did you want to finish completely the barrel life before using the new one? You did a good job with the criterion install! It was a nice shooter if I remember correctly

DarioPirovano Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May 20 2023 Location: Italy Status: Offline Points: 219	Post Options Post Reply Quote DarioPirovano Report Post Thanks(0) Quote Reply Posted: February 16 2024 at 2:46pm
	Firecracking apart, the ball burnishing job seems to have worked, this barrel is still very smooth

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: February 16 2024 at 3:06pm
	Most Canadian production Mk 7z in WWII was with Boxer non-corrosive primers. I have several thousand rounds of Defence Industries 1943 Mk 7z that is Boxer non-corrosive primed. It’s excellent brass for reloading. Note that Berdan primers are not necessarily corrosive, but I believe British Mk 7 and 7z was primed with corrosive Berdan primers during WWII. When I got the rifle, the BSA barrel was new as installed by Fultons. I did not understand the importance of barrel break in nor did I have a borescope. All I used to clean the bore was Hoppes 9 for the first several thousand rounds. I could see copper building up at the muzzle, so bought the Outers Foul Out system that removed the copper. Later I learned about Sweets copper solvent, and used that. My DCRA 7.62 was an entirely different story. It only had about 10 rounds fired when I got the rifle, but I understood the importance of barrel break in and copper removal. This barrel now has about 2200 rounds thru it and it remains quite clean and very little copper in the bore. Routine cleaning with Hoppes 9 is sufficient with occasional cleaning with JB.

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: February 16 2024 at 3:34pm
	Rule of thumb: If it British made MkVII its guaranteed corrosive primed & Errosive cordite. A "z"suffix" is nitro powder, but may still be corrosive primed. Canadian is a mix and match as mentioned. South African "303" is corrosive & errosive. South African "R1M3Z" is not.
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: February 17 2024 at 4:47am
	Cleaned the BSA barrel with Bore Tech C4. Three wet patches followed by nylon brush, 1 wet patch and let soak overnight. A bit of copper under the carbon, see it on the first wet patch on the second row after barrel soaked overnight. Then brushed with bronze brush followed by two wet patches and two dry patches. Doesn’t look like it took much carbon out by the looks of the patches, but it did when looking with the borescope. For about two inches forward of the chamber there is still a fair bit of carbon. First pic below is about an inch forward of the chamber. That will have to be removed with JB, but the rest of the bore is clean of all fouling (second pic below): I have the camera light turned about 2/3 the way up to show the contrast. If it’s turned up much more than that, the bore reflects too much light to see any detail making it look cleaner than it really is. Looking down the bore with your eye you would think this is a brand new barrel, like a mirror.

DarioPirovano Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May 20 2023 Location: Italy Status: Offline Points: 219	Post Options Post Reply Quote DarioPirovano Report Post Thanks(0) Quote Reply Posted: February 18 2024 at 7:46am
	Went to the range today with the no4 mk1 Started at 200mt, group was low and left, after 15 rounds it started grouping well and went to the 300mt target, fired two 5 shots groups. First rounds at 200mts: 300mts target: I see a little improvement in group size after the deep cleaning.

Goosic Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: September 12 2017 Location: Phoenix Arizona Status: Offline Points: 8842	Post Options Post Reply Quote Goosic Report Post Thanks(0) Quote Reply Posted: February 18 2024 at 10:44am
	I will clean all my rifles as necessary after shooting, except for my target rifle. I leave that one partially fouled if I intend on shooting it within a week or two after its initial outing. While I am all for keeping your rifle clean and the bore unobstructed with unnecessary carbon and copper. I learned that a well worn rifle barrel is best left alone. In some instances, overcleaning the rifling on a well used and worn barrel can significantly reduce the accuracy...

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: February 18 2024 at 3:06pm
	One thing I do occasionally is switch to a different cleaner for a couple of cycles then switch back. I've found that cleaner (A) my be really my preference, but like anything its not perfect. temporarily switching to cleaner (B) frequently finds & cleans something that (A) wasn't that good at! You just have to check that (A) & (B) aren't the same thing, rebranded!
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: February 18 2024 at 6:19pm
	Agree. I’ll do the same between using Hoppes 9 as routine cleaning, when switch to Eliminator. Then back to Hoppes. Then every 300 - 400 rounds, clean to bare steel with JB. The problem with rough or neglected bores is that it begins to strip copper off in lumps. Then accuracy goes to crap. The best approach I believe is to keep a new barrel clean, don’t let it build up with carbon and copper. Proper break in really helps with easy cleaning. Different problem if you’re trying to get an old shot out barrel to shoot decent. Living in a very dry climate like Goosic does removes the environmental factors that can destroy a barrel that is not kept clean of fouling. Not cleaning barrels in humid environments (like southern Ontario or the UK where home air conditioning is not that common) is asking for trouble.

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: February 19 2024 at 2:50pm
	That's another thing I like about the M-Pro, you can leave the bore cleaner in permanently,like Hoppes #9. Its a long slow steady form of deep cleaning with no physical scrubbing.
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: February 19 2024 at 2:52pm
	Same for the Bore Tech products, also contains an oil that is a short term rust preventer.

DarioPirovano Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May 20 2023 Location: Italy Status: Offline Points: 219	Post Options Post Reply Quote DarioPirovano Report Post Thanks(0) Quote Reply Posted: February 19 2024 at 4:16pm
	Im trying to find a suitable cleaning routine that prevents major carbon buildup, i don’t want to clean to bare steel every time I go shoot, just every 300rds. This time I tried just 10 strokes from breech to muzzle with a very tight bronze brush, and 10 patches soaked in alcohol, 1 soaked patch and one dry, till clean, then dry out the bore and a couple of clp soaked patches.. Did it with the bore still quite warm, most of powder fouling was dissolved by alcohol. I have c4 carbon remover and eliminator solvents, but I don’t know if I want to use them after every session…

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: February 19 2024 at 4:37pm
	I’m trying one other product that was recommended by an F-Class shooter. It’s a penetrating oil called Free All. Get it at the auto parts store, inexpensive. Seems to work fairly well with bronze brushing to remove carbon. I agree, it here is no need to clean to bare steel every time, I think that is overdoing it unless your shooting bench rest. My regular routine with good barrels is to just clean with Hoppes 9 letting soak overnight. Badly pitted barrels that quickly build up fouling you have to figure out what works best. The slow soak method with Hoppes might be best as it will leave some amount of copper and carbon in the bore.

DarioPirovano Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May 20 2023 Location: Italy Status: Offline Points: 219	Post Options Post Reply Quote DarioPirovano Report Post Thanks(0) Quote Reply Posted: February 19 2024 at 4:46pm
	My bores works good when fouled, I still have to try the uf55 which have an almost new bore, last time, fouled it shot very good, next week I’m going with my two mk2’s and see how the pitted and the good barrel goes. I bought a set of roll pins, got one that fits just snug inside the mk1 aperture, hoping to get an improvement… reduced the hole from 2,5mm to a 1,6mm

Mayhem Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 06 2016 Location: Australia Status: Offline Points: 335	Post Options Post Reply Quote Mayhem Report Post Thanks(0) Quote Reply Posted: February 19 2024 at 5:32pm
	I'm not sure there is a 'one size fits all' approach any more. Now that I have a bore scope, I can use that to see what is in the bore and then target that.
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