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Discussion Starter #1
My boolits are Ranch Dog 350's (gas checked) in a Marlin 45-70 (22" barrel)...I shot a few at a time (5-10) for a while and didn't notice any problems but the other day I shot 50 and after about 15 rounds my accuracy went from one ragged hole at 50 yards to 6" groups...

The bullets are cast from Rotometals Hardball alloy (2% tin - 6% antimony - 92% lead), water quenched, 30 BHN...they are .460" diameter (the gun slugs .457").

The load is a warm one (2,050 fps) with 52 grains of H322.

After that session I noticed some mild leading, but nothing major...I suspect not enough lube (Alox) but I don't know for sure.

Any idea how accuracy can go from great to terrible that fast?
 

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Given that your first 15 were straight and true, I imagine that your size is good.

I'd also think that your lube works too, but I'd question barrel heat.

I use White Label BAC, but everybody has their favorites and alox is among them.

Keep your barrel cool for accuracy shooting at the bench.

Use a bore brush with some copper Chore Boy strands wrapped around it to remove the lead - real efficient.

I use straight wheel weights, air cooled and I move them fast with gas checks and under 1500fps w/o them. I shoot a cast 180g 30-06 load with a check at full jacketed speed and so far so good with accuracy and no leading.

Bullet size, check for all screws and mounts optics etc. being tight, loads measured for charge individually and if all is good, it's a hot barrel.
 

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Discussion Starter #3
I didn't think I got it that hot, but maybe...

All screws are tight, weighed every charge, every bullet, and every case....if that first group had not been 6 inches high, I would have sent it in for the postal match :) (its still sighted in for the BT 405's)
 

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Discussion Starter #5
August said:
If I shot dozens of rounds that hot, I'd probably be flinching like crazy, as well as exhausted.
Heck, these loads ain't nothing...you should try the ones with the 405's @ 1,900 fps, now those will get your attention! ( I still love them though ;D)
 

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Ridge –

To go from shooting 1- ragged hole groups “to” 6” groups in 15 shots.

That’s leading – easy to say, but harder to find the reason – Why??

Have you cleaned the barrel yet?
 

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Rotometals Hardball alloy is already at 16 BHN. I would cast and air cool the bullets at that hardness. I've seen more barrel leading from alloy that was to hard then being to soft. Doesn't take much barrel leading to cause accuracy to go out the window. I run my 357 max at up to 2200 fps with air cooled wheel weights which are at 12 BHN and I get zero leading. Some of my 45 Colt loads are at 1700 plus fps with the same alloy and same results. Just my opinion but I think your alloy hardness is the culprit.
 

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Gohon said:
Rotometals Hardball alloy is already at 16 BHN. I would cast and air cool the bullets at that hardness. I've seen more barrel leading from alloy that was to hard then being to soft. Doesn't take much barrel leading to cause accuracy to go out the window. I run my 357 max at up to 2200 fps with air cooled wheel weights which are at 12 BHN and I get zero leading. Some of my 45 Colt loads are at 1700 plus fps with the same alloy and same results. Just my opinion but I think your alloy hardness is the culprit.
+1 ;)
 

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Discussion Starter #9
I figured it was the leading...but didn't expect it to be because the boolits are too hard :-\

I don't really need them that hard, but I would like to keep them at 19-20 BHN.

I have not thoroughly cleaned the barrel in quite a while, there has been no reason to until now...I'll clean the barrel and try the boolits with the better lube coat...and if that don't fix it I'll look into hardness.

I remember reading about it somewhere, but don't remember exactly how it worked....can I re-heat bullets that are already cast and let them air cool? Will that soften them up?
 

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As you’re cleaning that bbl try to determine just where it is leaded. A good way to start is by running a wet patch on a jag… If it’s leaded badly, you might not get it thru…
Is the leading at the muzzle, just out of the chamber, or the whole length? ? That will be a clue as to what’s going on… Does the lead come out in smears or long strands??

Re; reheating the bullets – trying to save the GC’s :D
Yes – but the temp must be close to the melting point and held there for a while before AC…
 

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Discussion Starter #11
Its not leaded badly, at least not enough to be noticeable looking down the bore (the rifling is still clearly visible all the way down).

I'm not home right now, may be there this weekend...I'm not far from Larry's house though.

I only have about 30 more with the GC's already installed now that I think about it (the ones I re-lubed), I guess it would be simpler to just dump the others back in the pot.
 

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Discussion Starter #13
Rowdy said:
Did ya do a “drive-by” on Larry’s mailbox.? ;D ;D ;D
LOL....no, got sent the other direction...to CT, I always refuse these loads but I took it this time because we have a lot of guys trying to get back to whats left of their homes in AL and MS. I won't be getting home this weekend...

I was still a ways from his house, but figured I'd go that direction...I was in Montoursville, PA, delivered a load of 7/16" OSB to the Lowes there this morning.
 

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Discussion Starter #14
Rowdy said:
As you’re cleaning that bbl try to determine just where it is leaded. A good way to start is by running a wet patch on a jag… If it’s leaded badly, you might not get it thru…
Is the leading at the muzzle, just out of the chamber, or the whole length? ? That will be a clue as to what’s going on… Does the lead come out in smears or long strands??

Re; reheating the bullets – trying to save the GC’s :D
Yes – but the temp must be close to the melting point and held there for a while before AC…
I just got finished cleaning it...and that may have been all it needed, I hadn't cleaned it "good" in quite some time. The leading wasn't all that bad but I guess it was enough to wreck the accuracy, it was at the muzzle (ran out of lube).

I may try for another group tomorrow.
 

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Are you using Ranch Dogs lube dipping method? I think with faster rifle loads you really need more than just tumble lubing. I do a very light tumble before seating the gas check with a Lee push through sizing die. I then dip my boolits in alox and stand them upright on wax paper. A ring of lube forms around the base of the boolit as it hardens. I then take the boolits which have this ring of hard lube around the base and carefully push them through the sizing die base first. Since they're already sized this step just takes all of that extra lube and packs the lube grooves full.

I had the same thing happen that you described when I was tumble lubing the conventional way. The last 4 inches of barrel would lead so bad that one minute I'd be shooting good groups, then they would start flying all over the place.
 

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Discussion Starter #16
Centaur 1 said:
Are you using Ranch Dogs lube dipping method? I think with faster rifle loads you really need more than just tumble lubing. I do a very light tumble before seating the gas check with a Lee push through sizing die. I then dip my boolits in alox and stand them upright on wax paper. A ring of lube forms around the base of the boolit as it hardens. I then take the boolits which have this ring of hard lube around the base and carefully push them through the sizing die base first. Since they're already sized this step just takes all of that extra lube and packs the lube grooves full.

I had the same thing happen that you described when I was tumble lubing the conventional way. The last 4 inches of barrel would lead so bad that one minute I'd be shooting good groups, then they would start flying all over the place.
Yes...I dipped them, but only once. (these were the first ones I've ever lubed, so there was a slight learning curve ;) and I goofed it up a tad)

I lubed some more and did things a bit different this time...no tumbling (used WD40), installed gas checks, dipped once and let sit for 24 hours, ran through the sizer, dipped again, let sit for 2 weeks (thats MUCH longer than needed, but it took me that long to get back home), ran through the sizer again to remove the excess lube...the finished product looks much better than before, the grooves are full.
 

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I bet they will work a lot better next time out.
 

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Discussion Starter #18
OK...I blasted a few rounds today 8)

The bullets did MUCH better today, but the barrel is still leading under the front sight (just one land, in the last 2 inches or so)...I give up, I'm gonna order a fire lapping kit from Beartooth.

I wasn't having any trouble with the 405's at 1,900 fps...but as I creep up on 2,100-2,150 fps I think the rifle is trying to tell me everything is gonna have to be smoothed up a little. :)

I may start a thread on barrel lapping, I'm gonna search first...
 

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Ridgerunner665 said:
My boolits are Ranch Dog 350's (gas checked) in a Marlin 45-70 (22" barrel)...I shot a few at a time (5-10) for a while and didn't notice any problems but the other day I shot 50 and after about 15 rounds my accuracy went from one ragged hole at 50 yards to 6" groups...

The bullets are cast from Rotometals Hardball alloy (2% tin - 6% antimony - 92% lead), water quenched, 30 BHN...they are .460" diameter (the gun slugs .457").

The load is a warm one (2,050 fps) with 52 grains of H322.

After that session I noticed some mild leading, but nothing major...I suspect not enough lube (Alox) but I don't know for sure.

Any idea how accuracy can go from great to terrible that fast?
Your getting blow by because your alloy is too hard, brittle, and your bullet is probably too small. Change your alloy by cutting it with 50% pure lead and water dropping the bullets you will be around 20 BHN. You need to fit the bullet to the leade, step, and throat so that it has minimal jump. You need to take a chamber cast and figure out those measurements. Your bore might have some tight spots, what are you feeling when you slug it? Your powder and load is waaay too hot, causing too much initial pressure and causing the bullet to hits the lands too quickly and causing skidding.

I know what you are thinking. Harder is better. The harder the bullet is when it hits the rifling the less chance it has to deform. This is true, but you are getting to much of a good thing. That bullet, even if it was sized properly is ramming into the rifling which causes it to start spinning at 100,000 r's and that hard alloy is stripping because it does not have enough plastic qualities.

If you don't want to take a chamber cast, load a dummy and get a good engraving, size the bullet .002" larger than you are doing now, change your alloy to what I said, and use a lower pressure powder AND load. There is no reason whatsoever to drive it to those velocities. You should be around 1,600-1,800 range. What you are gaining in testosterone, you are losing in all the other qualities that make shooting cast bullets relevant.

When you get it figured out, you will rarely if ever have to clean your barrel.

Respectfully, Rif
 

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Discussion Starter #20
RIF said:
Your getting blow by because your alloy is too hard, brittle, and your bullet is probably too small. Change your alloy by cutting it with 50% pure lead and water dropping the bullets you will be around 20 BHN. You need to fit the bullet to the leade, step, and throat so that it has minimal jump. You need to take a chamber cast and figure out those measurements. Your bore might have some tight spots, what are you feeling when you slug it? Your powder and load is waaay too hot, causing too much initial pressure and causing the bullet to hits the lands too quickly and causing skidding.

I know what you are thinking. Harder is better. The harder the bullet is when it hits the rifling the less chance it has to deform. This is true, but you are getting to much of a good thing. That bullet, even if it was sized properly is ramming into the rifling which causes it to start spinning at 100,000 r's and that hard alloy is stripping because it does not have enough plastic qualities.

If you don't want to take a chamber cast, load a dummy and get a good engraving, size the bullet .002" larger than you are doing now, change your alloy to what I said, and use a lower pressure powder AND load. There is no reason whatsoever to drive it to those velocities. You should be around 1,600-1,800 range. What you are gaining in testosterone, you are losing in all the other qualities that make shooting cast bullets relevant.

When you get it figured out, you will rarely if ever have to clean your barrel.

Respectfully, Rif
With all due respect, I want those velocities (its a trajectory thing)...I don't think hardness is the issue, I just shot this with a load that is 24,000 cup (at best)...no leading either. My bullets are sized at .460" (and meticulously measured and sorted)...I dug 3 of the bullets that made this group out of the berm, they could almost be fired again :)...and the bullet spin, in a 1 in 20" twist, even at 2,050 fps, the bullet isn't spinning anywhere near 100,000 rpms (see below)...the alloy I'm using is not brittle, the pics of the recovered bullets prove that...fired into hard packed shale, they stayed in 1 piece, didn't even expand with the reduced loads...with the hot loads some of the nose was chewed off, retained weight was around 230 grains IIRC.



Spinning...Bullet RPM = MV X 720/Twist Rate (in inches)

My 45-70 boolits, hot load (1 in 20" twist)
2,050 fps x 720 = 1,476,000/20 inches = 73,800 rpms

My 308 target load (1 in 12" twist)
2550 fps x 720 = 1,836,000/12 inches = 153,000 rpms
 
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