I'm shooting a scoped Ruger 77/357 Rifle with an 18" barrel. I'm noticing that 158 gr. Hornady XTP bullets deliver more precision (better groups) than coated lead using same bullet weights and velocity. Is there some reason for this? The coated lead bullets are .001" larger (.358) than the FMJ (.357) Hornady. Velocity is about the same at 1500 fps. I haven't slugged the barrel but I've been told the bore is .357. Do the lead bullets need to be .002" larger than the bore? Is this a velocity thing, bore dia related or something else?

Thanks.

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That's just somebody talkin.

I like coated lead bullets because of economic reasons. 1 minute of angle makes little difference to a hog or deer out to 100-150 yards. That said, though, I can shoot lead with about as much accuracy as I can FMJ. What I'm saying is that the gun and whatever bullet I shoot is more accurate than am I. But, 50 years ago that was not the case!!! Casting and coating your own bullets is cheaper and a lot more fun than buying FMJ.

There are a number of reasons. But I found the most common to be, the soft lead is stripping out where the jacket is hard enough to "take" the rifling. Use a harder alloy. There can of course be other causes.

Ivan

Maybe. Lead bullets or coated lead bullets can be finicky. Size & alloy matter. Roughness of bore & depth of rifling matters. Try a larger dia bullet. I run 0.357" in anything 9mm.

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NRA Cert. Inst. IDPA CSO

I don't remember the particulars but as I remember, pushing lead over 1200 (I also read 1400) fps affects accuracy. I shoot a 32 Winchester Special that is very good with jacketed soft points but just terrible with lead, both the same weight. The technicals really don't matter, the results do.

Differences in rifling designs and twist rate can also make a difference. Lead bullets should be slightly larger than actual bore diameter by 0.001"-0.002" to prevent any gas blow-by to get the best grouping performance.

I could recite a long list of possible reasons, but they might all be wrong. The fact is, sometimes a gun just likes one bullet and doesn't like another one, and that's about as accurate an answer as you'll get.

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Pisgah

Your choice of Hornady's XTP as the jacketed bullet of choice is part of the reason. Hornady has spent years tweeking the design and just as important production requirements to ensure their jacketed bullet is the standard against which all others are measured, at least in terms of accuracy. They have been widely used by bullseye and silhouette competitors who wanted to get the best out of their guns. I used the 115 XTP in my 9mm bullseye gun and 1" to 1.5" groups at 50 yards from a machine rest were routine. XTPs are not the only game in town. Nosler makes jacketed hollow points of similar precision, but are routinely more expensive.

Lead bullets by comparison are a far more "iffy" proposition. From what I'm told by manufacturers of high quality lead bullets, it is almost impossible to equal the precision found in high quality jacketed bullets like the XTP. Most manufacturers don't even try.

Keith

Cast bullets will shoot at least as accurately as jacketed bullets, but bullet fit and alloy mix are very important. Lacking precision in these areas, bullets will produce secondary accuracy at best.

Powder coating is fine, but for top accuracy, check what the competitive cast bullet shooters use. I think you'll find few, if any, that use powder coated bullets. They generally use conventionally lubricated bullets.

Lead bullets are no less accurate than jacketed bullets. Most of the time, it's the user that doesn't produce accurate ammo. Reloading lead bullets is a bit more involved than jacketed bullet reloading (size, diameter/fit, lube, etc.)...

Total noob question hopefully on the OP's topic . . .

Is it possible that jacketed bullets have a more consistent, maybe concentric profile, because of the way they are made, than lead bullets?

Cast alloy bullets, made by a real pro using a good mould should be as just as concentric and uniform as jacketed. However, I would guess most cast bullets, including mine, don't measure up to such a standard.

Not in my experience. Compare like this; measure and weigh 50 jacketed bullets and weigh and measure 50 cast bullets of similar caliber. Is there any marked difference in variations between the two? I have measured some "premium" bullet and found .001" variation in diameter, and I've measured some of my cast and sized bullets and they measured .0005" variation....

True, that's the sort of imperfect cast bullets most of us make. Precision casters can do much better.

Jacketed bullets are more uniform . Weigh 100 XTP's or any other well made jacketed bullet . You'll see a very small difference in weight . Now weigh 100 cast bullets ( before sizing & lubing ) unless you're an experienced caster with good moulds & technique variation will be larger . Now weigh 100 swaged lead bullets you'll find that like jacketed , the variation is small because they're very uniform . I've done this . As a Outdoor Precision Pistol competitor I want the smallest groups I can get @ 50yds . Bullets & loading technique are the most important part of it . Only use swaged bullets for target loads as you'll get severe leading if you push them over 800fps . I've yet to see anyone use either coated or plated lead in competition when shooting @ 50yds . The action pistol crowd may use them as they shoot @ much shorter range & their targets are bigger . The only handgunners that shoot for score @ 50yds are Bullseye , PPC , Free Pistol & Bianchi Cup . At 25yds with a good gun one can shoot rocks & still clean a target .

Given the time, best of equipment, and skill, there is no reason a cast bullet's accuracy can't equal the uniformity and the ultimate accuracy of a jacketed counterpart. However, looking at it from a practical perspective, it's a lot easier to just use jacketed bullets. Not many competitors, particularly those who shoot handguns and use lots of bullets have the time and incentive to cast precision bullets. Few would be satisfied using a single-cavity mould, pretty much a necessity for doing the best job possible.

From my experience coated bullets do not group as tight as a good well made cast bullets. Me and my shooting buddy have benchrest tested them many times at 25 and 50 yards. The difference is quite noticeable.

I cannot say that I've seen any appreciable difference between MBC coated bullets and Hornady FMJ bullets at 50 yards in my Henry 357 magnum with a 20" barrel. And, as I said earlier, either would kill a hog at 100 yards. I've shot a lot of different coated lead loads in the Henry, but only 158 grain Hornady FMJ XTP that I loaded.

Easy answer micro groove barrels not made for lead bullets

Micro-Groove bullets will shoot lead and shoot lead well, but it takes an oversized bullet to get good accuracy. I've gotten good results using wheelweight alloy in a Marlin .45-70.

Ed Harris, a well-known cast bullet expert and former AMERICAN RIFLEMAN technical staff writer, suggested oversized bullets harder than wheelweights in Micro-Groove barrels for best results. Harris has had far more experience than I have in this area, so believe Harris.

AS A SHOOTER, AND COLLECTOR OF MARLIN LEVER GUNS FOR DECADES, I READ EVERY ARTICLE THAT I EVER RAN INTO, PARTICULARLY ABOUT THEIR UNIQUE MICRO GROOVE BARRELS......

I NEVER READ SUCH AN ADVISORY......

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'Nam 1968-69.DAV,VFW,NRA Inst.

one eye joe-
I have read such reports, though not recently. This was a common-held belief by some who, I suspect, had little or no real cast bullet experience with Micro Groove barrels. Perhaps we are now beyond this bit of flawed "conventional wisdom".

Want the graduate course on cast bullets . Browse the Cast Boolits Forum . Virtual treasure trove of information from some extremely talented & dedicated folks . Keep an open mind & you'll find what will work & what won't .Tons & tons of research from shooters who live & breathe cast bullets .

re: "Micro-Groove bullets will shoot lead and shoot lead well, but it takes an oversized bullet to get good accuracy. I've gotten good results using wheelweight alloy in a Marlin .45-70."

not to assert any particular argument here, as I am not really a 'rifle guy'....yet I did spend the better part of one summer striving to make a particular Marlin 45-70 1895 model lever gun built in the late 1970s, shoot with some semblance of 'accuracy', ANY of the variety of cast lead I had on hand, in 4 different weights (300-350-405-500) and 2 different bore sizes, along with about a dozen powder recipes.

Some of them at 50 YARDS(!) would keyhole. And 'group' was not in question, as even 3-shot targets weren't believable.

However, put in factory FMJ 'lever-rolution' whatever with the ballistic tips, and it would produce palm size 5-shot groups.

Previous owner seemed happy to regain possession.

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Dum vivimus Vivamas

Just curious... what was the diameter of the bullets? I ran mine through a .461" die, but don't recall if the bullets were actually that large; may have been about .460".

"Just curious... what was the diameter of the bullets"
most were .458, one was .459
My working conclusion was 'that rifle didn't like lead anything' but was fine with FMJ.

I had loaded a raft of single shot 45-70 cast loads over a few years for a Browning Traditional Hunter that was satisfied with what I was feeding it.

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Dum vivimus Vivamas

I was wrong; my bullets are about .4595". With cast bullets, I've found that a cartridge loaded with the largest diameter bullet that will chamber without difficulty will shoot best, provided the alloy is right for the load. But, there are exceptions to everything.

When I first started loading for this rifle I remember some pretty nice groups using Hornady XTP bullets. I went back and tried those again today using a mid-range load around 1400 fps. The good groups I remember were still there so now I have a theory that I was pushing the coated bullets too fast. Some were in the neighborhood of 1700 fps. Back to the drawing board with the coated bullets. I want to use coated if I can as XTP bullets are twice as expensive. If this doesn't work out I'll just go back to using XTP. I really like those bullets.

Thanks for the help. I got some good ideas from these posts.

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