Anyone had a problem with these bullets in the big bore calibers being too long to stabilize and as a result keyholing? Some of these bullets in the 400 grain weight are damn near an inch and a half long.

Not if you drive them fast enough. It's like using the WFN's in revolvers in that if it's going a bit too slow, they won't stabilize. I believe that top velocities or close to it is called for.

I was shooting a .404 Jeffery at between 2150 and 2200 and virtually every bullet was keyholing. I wasn't thrilled to order the Barnes in the first place because they are so darn long, but I was having a hard time locating Woodleighs. Should have just kept looking for the Woodleighs.

i was there..

under ~2170, it shot very nice groups..

over that, keyholing... requirement for twist gets faster the faster the bullets go.

it was shooting very nice, then in the 2200s, shooting keyhole patterns..

jeffe

quote:

Originally posted by jeffeosso:
i was there..

under ~2170, it shot very nice groups..

over that, keyholing... requirement for twist gets faster the faster the bullets go.

it was shooting very nice, then in the 2200s, shooting keyhole patterns..

jeffe

Revolutions per second go up as velocity goes up. Even Greenhill formula fudge factors use a constant of 180 for velocities over 1800 fps, 150 for velocities at or below 1800 fps.

Use a faster velocity and you get by with a slower twist.

Gyro stability factor increases with increased velocity hence increased spin rate from the same twist barrel.

Use a 10" twist barrel and you can use any bullet or velocity. 14" twist let him down with that long brass bullet ... or there is something else out of spec with the bullet or the barrel.

The 387-grain copper FN and 380-grain copper FP from GSC and NF respectively are much better solids, that's for sure, especially if at 2500 fps from a 10" twist.

The only time I ever saw a "landed" bullet stable at low velocity and not at high velocity, it was stripping.

quote:

Originally posted by NFMike:
The only time I ever saw a "landed" bullet stable at low velocity and not at high velocity, it was stripping.

Meaning an undersize bullet or an oversize barrel, regardless of twist.

A barrel can't twist what it can't grab.

Actually, it isn't regardless of twist. Given the same dimensional differences that created the problem in the first place, a faster twist is more liable to strip.

quote:

Given the same dimensional differences that created the problem in the first place, a faster twist is more liable to strip.

Makes sense to me.

Cheers,
Canuck

quote:

Originally posted by NFMike:
Actually, it isn't regardless of twist. Given the same dimensional differences that created the problem in the first place, a faster twist is more liable to strip.

O.K., I see that is possible, but the problem would not occur with a faster twist if the bullet matched the barrel properly.

And in some cases the faster twist might actually catch enough bullet bearing to get it spinning enough to stabilize when the slower twist would not.

And in some cases just switching to a full bearing surface bullet shank (with no grooves or minimalized driving bands) would prevent the stripping, regardless of whether 10" or 14" twist. I have seen that for a fact, using North Fork banded FP solid bullets that keyholed in my buddy's 10" twist (Winchester Custom Shop) .470 Capstick, though it handled the XLC and monolithic brass solids without keyholing. His barrel was oversized in the land and groove diameters. My 10" twist McGowen .470 Capstick shot the North Fork banded FP solids into tiny groups (round holes only) at almost 2400 fps. No keyholing. It had proper land and groove diameters to match your bullet, obviously.

This can be complicated.

the gun in a cz custom, 1x10, iirc, from mcgowen?

shot great sub 2150
shot keyholes past that
I was there, saw the chrono results and the bullet holes.

stripping? aint never heard of that, in relation to bullets

jeffe

quote:

stripping? aint never heard of that, in relation to bullets

jeffe

Me either. Would someone tell me what this is.

When the bands on a banded bullet (ie. any bullet with lands, where the majority of the bullet shank is nominal bore diameter) get sheared off/stripped away, usually (I think) because the rifling didn't engrave deeply enough to get a real good purchase on the bands. Presumably the shear strength of the lands was less than the force required to make the bullet follow the twist of the bore.

End result is that the bullet gets pushed down the bore without benefit of twist (or partial twist). I believe NFMike mentioned to me that sometimes the bullet might start stripping intially, but then grab on to the rifling and start rotating properly further down the bore.

Thanks,
Gene

Holy cow! A 10" twist McGowen did that!

Sounds like an undersized batch of bullets to me. The multi-cannelure "banded" shanks still have considerable bearing surface, so that should not be an issue, if the are big enough in diameter.

Just hoping it is only a bad bullet. We know your twist is sufficient.

Not sure where the 1 in 10 twist notion got started. The .404 Jeffery is typically a 1 in 16 twist. I will talk to CZ on Monday. I think the twist is more like 1 in 14 or 1 in 16.

quote:

Originally posted by MJines:
Not sure where the 1 in 10 twist notion got started. The .404 Jeffery is typically a 1 in 16 twist. I will talk to CZ on Monday. I think the twist is more like 1 in 14 or 1 in 16.

My CZ .404 Jeffery has a 1:10" twist McGowen barrel. I am the one to inform the world of this.

Having become visually familiar with this rifling from a stainless version of it on my M70, I can recognize it at a glance.

I nearly fainted with joy when I peered into the muzzle of the CZ and it screamed "10-INCH-TWIST-MCGOWEN" back at me.

I called Harry, he confirmed it.

I measured it, I confirmed it.

You go measure your twist and report back, please. Unless CZ changed something since the original run, it is a 10" twist McGowen. Perfection.

Also put some calipers on those keyholing bullets, please.

The bullets measure .422 with the calipers.

I'm getting one hole groups with the 400gr Barnes Banded Solids at 50 yards from my 416 Rigby at 2450fps.

Pretty much all Barnes solids are at least .001" under, if not more. Some "458s" that I meassured were .4568. I'm not faulting them on that. If I made them out of that material and of that design, I'd make them way undersized also. CYOA

If the dimensional "problem" is puting you on the very edge of failing to grip sufficiently for rotational acceleration, a tighter twist can put you over that edge. Obviously MJ is there. Yes RIP, if there is no dimensional discrepancy, a fast or slow twist makes no difference as far as the bullet being spun up.

Stripping is the domain of landed bullets only. A smooth sided bullet is virtually immune to stripping unless there is a gross mistake (shooting a 411 down a 416 barrel) in loading.

Due to the fact that monos do not yield to the rifling as a cored bullet would, the point is to make sufficient surface contact with the barrel to spin the bullet up but no more. Anything beyond that is placing excess stress on the barrel. Not a big thing in bolt guns but can be of concern with some guns, especially doubles.

I wouldn't depend on the bullet being spun up later down the barrel. The bullet should be fully engaged and up to the rotation of the rifling before it has traveled much of the length of the contact area. Certainly before the end of the contact area. I would say no more than 1/2". Beyond that and you take the risk of fully stripping.

MJ RIP is correct. Even undersized, the Barnes has a bunch of contact area. There is more to what is going on than what meets the eye. I would get a slug of the barrel to check groove diameter. Also have the bullets checked with an accurate CAILBRATED mic. They could be smaller than what you indicate. Calipers are a great general shop tool for case length and such but for precision measurement, they aren't much better than a yard stick. If you have much in excess of .0015" difference between bullet and groove diameter, that coupled with the twist, is enough to do what you are seeing.

So what is the bottomline here? One needs a mono bullet made to a diameter that is compatible with the groove and land diameter of each barrel?

When do the benefits of a banded mono start to fade? I don't want to poo-poo mono bullets but are jacketed bullets that bad in the first place?

The only improvement in jacketed bullets that would be nice is for them to flatten the point some so that act more like NF FP bullets and others that apparently increase penetration.

The now out-of-production AGS solids in .416 have a rather flat end and they have not failed to penetrate, not yet anyway.

From the casual observer standpoint, it would seem that one must try different brands of bullets to see if they are stable in their own specific rifle, and at what distance?

I tried this firing from almost point blank out to about 25 yards with the 416 AGS after reading all this stability "stuff" and couldn't see any instability as far as observing the hole in the paper. I suppose one needs to try this with any bullet but is seems this is getting all too complicated, or difficult, when one might be better off concentrating on shooting some animal accurately than worrying about bullet stability, unless one wants to experiment to some undefined extent. And if that FP ever jams (albiet only a magazine rifle concern) all the penetration in the world isn't going to save you.

Bullet availibility comes and goes, for various reasons. I suppose even Woodleighs will fade from the scene at some point.

And since the AGS's are now defunct, maybe I am now into the experimental stage of finding a replacement, magical Susan that we are seemingly always Desparately Seeking.

quote:

Originally posted by NFMike:
Actually, it isn't regardless of twist. Given the same dimensional differences that created the problem in the first place, a faster twist is more liable to strip.

Hey Mike
it's jeff.. I'll see you at DSC or HSC in a couple months!!

got any 450gr .475s ?

You aren't saying that it's possible for a twist to be so fast that it strips a banded bullet, where another twist wouldn't, are you?

oh my.

jeffe

Hello Bill,

I am sure many people feel like you. Even those that debate these more intricate issues do not always agree with each other as to the reasons behind it, and has to revert to what works in practise.

However, only through intelligent questioning can we find out the reasons why something is happening, or failing that, find the most plausible explanation. Not being scientists, does not make it any easier for us.

We have to strive for improvement, and that is the good thing about the debate, so we can create better designs, be it bullets, barrels, actions, sights, scopes or case design. Some of these things may still be the same as a 100 years ago (like a K98 action), but bullets and scopes have improved tremendously.

We talk about a bullet revolution that has taken place in the last decade. Just think about the first Nosler Partitions, then the TBBC's, then the Barnes-X being the first expanding mono metal, then the innovative design of Gerard, etc (I am not going to mention Rhino bullets)- how much they are better is debateable and we may not have concensus, but they are better. The argument that they all kill is conceded, but we need to recognise that the premium products are better, even though they come at a premium.

Rather spend and extra buck on a bullet, than a extra bullet on a buck.

Chris

Th

quote:

Originally posted by MJines:
The bullets measure .422 with the calipers.

which is exactly what they should from barnes.. .458 is about .457, .475 is about .474 or LESS

????

jeffe

Just shot some Northfork .423 flat pointed 380 grain solids in my 404 Jeffery with a Lothar-Walther barrel. No keyholes here.
Velocity around 2180
Target 100 yards

Rusty, Mike..
why don't you two meet up at carters, and shot a couple rounds through each otehr's loads/guns? you BOTH have very mild loads, and it will show us "stuff"

jeffe

I got a great idea. Why don't we make it a Saturday or Sunday morning down at my range Bayou Rifles. It won't cost you anything but time and gas. We can stop in Pearland and have lunch afterwards.

Mike,
I will be glad to send you some Northforks to try in your 404 Jeffery.

Rusty,

Name the date. I would love to. I know that you have ordered a Chapuis in 9.3x74R. I would be happy to tote mine to the range to play with.

Thanks for the offer on the Northforks. I am going to call CZ tomorrow. CZ sells some .404 Jeffery ammo (made by A-Square). I am going to get some of that just to see how it shoots. If it shoots the CZ ammo then I will understand that the Barnes are simply too long. If not, then CZ has some work to do on the rifle.

Mike

MJ, I plugged in the new banded solid into my original load using Barnes super solids. My load produces 2160fps & accuracy wasn't quite the same as the mono solid but still right at 1MOA. No signs of key holing. Maybe you just have a bad batch??? FWIW, my bbl. is a 23" 1-14 PacNor.

Chris,

It is not that I am anti-improvement but if the mono bullets are that sensitive to diameters as a result of varying groove diameters then it may be an uphill battle. When is it a case of diminishing returns?

And the improvements, good or bad, are always incremental anyway. Noslers are just improved H-mantle bullets that originated in Germany.

Maybe the mono's will generate a whole new reloading industry where you have to swage all your bullets to suit your rifle.

Jeffe

I won't be in Dallas this year. No, I am not saying that tighter twists are bad, just that the bullet/barrel fit needs to be good. In fact, if one wants the "traditional" heavy weights in a mono, a tighter twist comes close to being mandatory. It is a paradox though; the heavier (longer) the bullet, the tighter the twist, the greater the stress the twist puts on the bullet which, having greater mass, is trying greater to resist being accelerated to rotation. That's why I don't/won't make 411-400s or 458-500s. One, they are not needed and two, eliminate any twist concerns.

Will

That is a decision that is for each individual to make on their own, whether there are any benefits, or lack of, in using a mono. Ya, ain't dead yet. If it ain't broke, don't fix it.

Rusty

My 404 test barrel is also a LW. It measures .4226" groove diameter, so it is snug to begin with. If MJ's is just as much over (still in specs) as yours is under, I'd expect that mine won't shoot as well in MJ's and his loads will work fine in yours. If MJ's rifle shoots mine OK, those Barnes must be WAY under.

NFMike,

I am not opposed to trying my best to use your monos. As soon as the 470 gets back from some factory tweeking, I hope to use the few 500 gr. FP's I have to regulate it. I'll take the increased penetration everyone claims.

I hope to get the velocity up to 2200 fps. The only one I have shot was at 2162 fps and dead on at 25 yards. So I am hopeful, assuming you get these back into production soon.

MJines, the 400 grain Barnes Banded Solids shoot very well in my 404J, at the two velocites I have tried (2150 fps and 2250 fps) very accurate, no keyholing. In fact they leave a nice semi-wadcutter type hole. Barrel is a Kreiger, haven't measured the twist.

Mike (nf)

i agree... and feel that a mono bullet COULD perform as well, if it was the same length as the "classic" load, as long as the now 435(just making it up) was the same length as the 500gr...

yes, there is a window that making monometal bullets needs "A" twist... and if that twist happens to be, ohh... 19, and the gun normally has,,, oh... 20, then an 18 works out nice!!

jeffe

Mike,
Thanks for the heads up!

Here is the pic, again, showing 10" twist McGowen rifling engraving on a North Fork .423/380-grain SP. No stripping or smearing here. MV was 2526 fps and a single shot killed a bison bull right now.



This barrel was slugged at .423", I have no measure to the 4th decimal.

However, look how narrow the McGowen lands are, 6-groove, 6-land. This may explain why that barrel needs a full diameter bullet. Think about it.

Some of my attempts at interpolating between the .001" graduations, on a few .404 Jeffery bullet shank diameters:

Barnes TSX 400 grainer: .4220" (multi-cannelured like the solid)

North Fork SP (grooved), FP (banded) 380 grainers: .4233"

GSC HV (banded) 320 grainer: .4240"

Grooved and banded bullets should be full diameter.

Going sub-caliber with a multi-cannelured bullet like the Barnes bullets, which are neither banded nor grooved, is a very interesting thing ...

Correcting my eye-balling between thous' by assuming Mike Brady's bullet is actually the correct one:


NF = .4230"
Barnes = .4217"
GSC = .4237"

Damn, those ARE some narrow lands you've got there! Not really apples and oranges comparing the softs to solids. The softs will bump up to compensate for an oversize barrel. Solids don't bump.

Not bad eye balling; at the base the 423 softs are .4231

Mike,
Whatever you say , O.K., about "your" soft, but it has a solid copper shank that I would think would have no better obturation or bump-up than a solid copper shanked banded FP except for the greater bearing surface due to the grooving instead of banding.

Anywho, both your solids (CP and FP) and GSC solids (FN) and HV's all shoot well in my skinny landed 10" twist barrels of 0.423", .475 and .510 groove diameters.

FP's and FN's stayed nose first and did not keyhole until the tenth compartment.

I have not shot the TSX or "banded" solids even at paper yet, but I am now on notice to watch out for keyholing with my skinny-landed fast twists.

BTW,
Are there some variable diameters of either the North Fork or GSC band diameters going from nose to base of the bullet?

Are these things complicated or what? They shoot great.

You patent holders need not reply.

Ron,

Those are some narrow lands on your 423 NF pic. Not too aweful large in expanded diameter either. I am sure the NF bullets are excellent but I will stay with my Woodleighs (although if North Fork ever makes a .510 bullet I'll give it a try).

My vote is typical undersized Barnes bullets and more than likely a large sized barrel.