Going from J bullets to cast and back, questions

[abosely]

Hopefully this is the right place to post this question.

I am having a rifle built in .375 H&H with a Lother Walther barrel.

Assuming a good cast bullet load. One with a bullet that fits the throat & bore, is the correct hardness, good lube, not shot to fast ect.

Thinking of using Beartooth Bullets' .375 cal. 255 grain GC SP bullet at between 1800 to 2200 fps.
I am guessing this load wouldn't lead the barrel when shot from a clean barrel, correct?


So the big questions:

If I have shot some J bullets and then switch to some of cast bullet load, without cleaning the barrel. What will happen? Will I get terrible leading and no accuracy?

It would be as in, I have been hunting with J bullets and then while still in the field I want to shoot some cast bullet loaded rounds (lighter loads) for small game.

Then to make matters worse, what if I needed to shoot a few J bullets after the cast bullets before I can clean the gun?

What will happen?
Will the accuracy go totally out the window, get a lead mine in the barrel or ?

Are there any loading "tricks" to make this doable or can this just not be done? Or at least not if I want to hit anything?

Allen

[Lead pot]

I bought a .45-70 Browning BPCR from a fellow that shot only factory jacket SN bullets in it.
When I shot some of my cast the things would key hole at 200 yards.
I spent a considerable amount of time cleaning the bore and never got the copper out till I borrowed one of those electronic bore cleaners from a friend and that got all traces of copper our and the rifle turned into a very fine shooter.
If you want to shoot cast stay with cast. I would not cover up the lead smears with copper or the other way around.
Not a good thing in my opinion,

[docone31]

Ok,
First, a brand new barrel has to be broken in. Mostly, just shoot it untill it groups well.
I routinely fire jacketeds, and lead, and then fire a few jacketeds to clean up the lead. I paper patch now, so I have not done that sequence in a while.
I was not happy with peashooter loads, and power loads in lead is a waste of time in my experience, 20ft groups, keyholes, etc.
Obviously accuracy is the main key period.
Back to your question.
If the barrel is broken in and fires jacketed loads well, lighter loads in cast will probably do ok.
If you are target shooting, you will probably swab the barrel at the range. If it is for plinking, or small game hunting, you will have slugged the barrel, and found the diameter that works. By the time that has been done, you will definately know more. Each rifle talks differently. I am fortunate, my patching efforts are well recieved by my rifles. A lot of folks on this forum have really helped me break through.
My suggestion.
Once you have the rifle, slug the barrel. I skipped that step first, and spent lots of time, cash, and castings without return. Once I slugged the barrel, I dialed it in.
After firing small 30-06 castings, and turning my barrel into a lead mine, I did fire a few milsurp loads and really cleaned it out. The cleaning shots were not that bad either.
I really liked my .375 H&H. I wish I still had it. A nice Ruger #1. It is a stout cartridge! I never fired castings in it. There are some folks here who have used the cartridge with good results.
You might consider paper patching also. I am definately sold on doing it. I am pushing a casting at jacketed speeds, and getting small groups at 100yds! For that, I use water quenched wheel weight castings.
Paper makes a bore real shiney after shooting. I like it.
Great luck with your rifle. It sounds good so far.

[Buckshot]

.................The concensus is that for best accuracy, firing cast after jacketed without cleaning any jacket fouling will cause accuracy issues with the cast ammo. I have not made a study of it by any means, but it would seem to me that accuracy effects on cast lead would be determined by the amount of jacket fouling present. Jacketed will also present the cast slug with at least a powder fouled and dry barrel. Firing jacketed after cast should present no problems.

.................Buckshot

[jonk]

I'll ususally let a foaming bore cleaner sit for a few hours then wipe it out. It won't get all the copper fouling but will get most of it, and I find it helps.

That said I've gone back and forth with no real issues with LIGHT loads- Red Dot and the like- but have had more problems with 2000fps+ attempts.

[Ricochet]

A simple wipe with an oily patch after shooting jacketed bullets before shooting cast makes a lot of difference. As noted, the dry sooty bore isn't a great path for cast boolits. Takes a few shots to lay down a good track of boolit lube.

[Larry Gibson]

Buck shot and Ricochet are pretty close to correct. I've done quite a bit of testing on this subject (including with my .375 H&H M70). What I've found is that for absolute best accuracy it is necessary to remove all J bullet fouling. This is because the J bullet foulding strips lead off the bullet or at least displaces it as the bullet travels over it. This creates more imbalance in the bullet which decreases accuracy. It also can lead to leading of the barrel if the J bullet fouling is substabtial.

However, it is my experience from testing that switching back and forth from cast to J bullets causes little concern with regular cast bullet loads out of sporting rifles. The first shot of J bullet out of the cast bullet fouled bore may not go in the group, essentially a flyer. How much can only be determined by testing. It also seems to be a 50-50 occurance with my rifles. Conversely when I shoot a cast bullet from a fouled J bullet bore it takes 3-5 shots before the previous fouling and "to lay down a good track of boolit lube" before accuracy settles down.

As Jonk mentions the higher end the load the more the problem surfaces. The patch through the bore is a quick fix if you've the equipment and time in the field. I've shot a lot of reduced loads with soft cast bullets over small charges of fast powders (primarily Bullseye) for small game while big game hunting with J bullets. They've worked fine out to 50 yards without any cleaning either way. Using the 375 H&H for example; 4 gr of Bullseye (no wad or filler) under a LLA lightly lubed .375 RB gets me 800+ fps and is a killer on hares, grouse and ptarmigan out to 75 yards even out of the J bullet fouled bore of my M70. Same with my .30/.31 cal rifles using the TL314-90-SWC over 2.7-3.2 gr bullseye.

Larry Gibson

[smlekid]

sorry to hijack this thread but what about gaschecks? wouldn't they cause a slight amount of barrel fouling? it is something I have been wondering for some time

[docone31]

I suspect they act more as a scraper, rather than adding to the fouling.