This is a compilation of responses to my request for information regarding rifle break-in procedures of subscribers to rec.guns. There were a couple of others that were not serious replies. The final two responses were not submitted by rec.guns subscribers but were rather obtained by me from friends.
Sinclair International has a good booklet for $9 that covers this very well. Most of the books say to shoot a round, clean, shoot a round, clean, do this about 10 times. Shoot three, clean, shoot three, clean, for about 30 rounds. I will use a "bore conditioner" like tetra-bore. A good break-in results in a good shooter that doesn't get fouled as easy and is easier to clean. Never overheat the barrel.
I recently bought a new Remington M700VLS in .308 and asked the same question of C.E. Harris, a regular contributor to American Rifleman and the former QA Manager at Ruger. He suggested a thorough bore cleaning after every five shots, for the first 100 shots fired. The cleaning would consist of pushing out the loose fouling with a tight fitting, wet patch. Then allow the solvent to soak in the bore for approximately five minutes. Then using another wet patch push out any fouling the solvent has loosened. Then put a series of dry patches thru the bore until they come out clean. Repeat the solvent treatment if necessary.
The goal is to polish the bore in order to improve accuracy/consistency of shots. One will also benefit from ease of cleaning, less fouling and longer accuracy life before any cleaning is required.
I use RemClean to polish the bore, Remington rifles tend to have rough bores (about 2/3 do) and this is my solution to problem. I have since started to do this to all my match barrel and I have only seen improvements, if not in accuracy in ease of cleaning, less fouling per number of shots ...
Shake the RemClean well, use a tight fitting patch and a rod guide. Insert the soaked patch in the bore. The goal is to polish the bore and not to disturb (or create ramps as one enters and exits) the crown and the throat of the rifle. Place the rifle in such a manner that it is against a wall, I place a rag at the muzzle to dampen the blow of the rod, there you have your muzzle stopper. I place my leg in a position as to stop the rod from exiting the bore. This ensures that you will keep that patch in the bore and you will not exit and re-enter the bore 60-80 times. If you care for visual assistance use a magic marker and mark your rod at the end of each stroke, mark it about 1.5" before it actually exits the bore as to give yourself a time to react (on SS rods use electric or masking tape). One needs to inspect the bore before you decide how much polishing is required (experience will help here). The bore should be mirror like, if not you need polishing (I would do it even for a mirror like bore that fouls after 10 shots (you can see the copper streaks when looking at the bore at the muzzle end, look sideways). I push and pull 20 times, I change the patch to a newly soaked patch with couple of dry/clean patches to clean what you just did. For a rough bore I do this four times (about 80 push and pulls, the barrel will actually heat-up at little from this if you do it fast). I change the patch every 20 strokes with couple of clean ones in between. Once I am satisfied I pass few clean patches through. I then clean the chamber (use a pencil with Kleenix around it, nice and thick to a nipple..). Clean the guide rod too, inside and out before inserting it back into the action. You do not want it to give you a false reading on the patch (most people clean a clean bore because they see dirt on the patch which is coming from the guide and not the bore).
I then rap Kleenix (tissue paper) around the jag and I use it to finish my cleaning. Tissue paper is soft and it conforms to the land/grooves well and it removes the residue at the base of the rifling (which is missed by the patch). I roll the Kleenix on the jag like a cigarette and then I roll it the other way (use both sides of the same piece). I clean until there is no more thin, black streaks coming out. I then oil the rifle IF I AM NOT GOING TO SHOOT IT FOR MANY MONTHS, if not I leave it as it is.
A polished bore would not foul as fast, it will be very easy to clean and would not walk the shots as much as a non polished bore. I have shot my magnum in the provincial (4 days of shooting) and then I took it to our monthly sniper match without cleaning. I did not notice any accuracy degradation after 250 shots of HOT magnum loads with 220 gr match bullets. It then took me about 20 minutes to clean the rifle, fast and easy.
I then shoot one round and clean the barrel with Shooter's choice (or your favorite ammonia cleaner), I do that for 10 shots I then clean with RemClean again, I then shoot 3 shots and clean in between the shots (7 times) and then I shoot four 5 shot groups with cleaning between each group. hence the barrel is broken in with 10+21+20=51 shots.
I have found that polishing improves accuracy (consistency mainly, you do not get those nasty flyers anymore), the bore does not foul easily, it is really easy to clean and the accuracy of the rifle last lot longer before a cleaning is required.
On a new rifle, shoot 1 round, clean completely until patches come out clean. Shoot 1 round, clean completely until patches come out clean, repeat until the second patch comes out clean after the first wet patch.
Then shoot 3 rounds, clean completely until patches come out clean, repeat as with the 1 round session until second patch comes out clean.
Then shoot 5 rounds, clean completely until patches come out clean, repeat as with 1 round session until second patch comes out clean.
Lapping barrels is a good idea after this conditioning. the type of lapping is dependent on how rough the bore is. one way is to sandblast bullets, compounds that can be used are valve grind compound or jewelers polish.
Shoot 1 round, clean completely, shoot one round, clean completely, repeat until the cleaning process is very easy. in his experience this will take at least 25 rounds. He said the change in ease of cleaning will be very obvious.
In regards to fire lapping he said he has never done it but he knows that some people swear by it as a way to get better uniformity in the bore. He said that if I get bad reports from anybody on fire lapping I should question them very thoroughly, in all his years of benchrest he has never found out anything bad about fire lapping.
If I ever use sweets 7.62 be sure to oil the bore after cleaning or it will develop rust in the bore.