Hollow Point long range stability?

[lar45]

Hello everyone.
I've got a question about HPs and long range stability. I seem to remember a long time ago someone saying that moving the center of mass rearwards helped with stability.
I have shot different nose shapes from a 454 out to 1000 yards, but never tried any hollow points.
So, anyone have any actual experience with the subject?
I started casting with a mold that's been on the shelf for a while. It's a NOE 480-375 gc, with the hp it drops at 355 from 50-50 WW-PB and is .480" and I sized them to .477" and lubed with Carnauba Blue. I shot them out of a Ruger Bisley, only at 25yds so far to get it on paper. I have 75yds at the house, but I wouldn't expect any problems to show up until at least a couple hundred yards.
My load was 20gn of 2400 for 1284fps.

[MT Gianni]

I know the 52 gr 22 cal and the 165 gr HP 30 cal are listed as target bullets not for use on game. I believe as you do this is to move the center of gravity to the rear and help stabilization. I also believe that the Quigley long range matches use standard lead bullets at 1000 yards. I would be interested in seeing what happens but believe that the stability is only one of a lot of factors.

[GregLaROCHE]

There are metal jacketed hollow point bullets designed with this principle in mind. They are strictly for competition and are not at all designed for expansion. They are quite popular and the basic logic makes sense. However, all the cast hollow points I know about are designed for expansion. Their shape is not meant for maximum aerodynamic efficiency. The same principles should apply, but will be overshadowed by the lack of aerodynamic shape. Maybe there is a mold that produces an aerodynamic hollow point boolit, but I just don’t know about it. Could be an interesting project for someone.

[onelight]

lar45 that is a great group

[fcvan]

I have 2 identical molds, a Lee 450 -200 RN and a 450-220 RN HP. Yes, both were the tapered base conical designed for the 1858 Rem Copy, and have been used as such. I have loaded them in a 45 ACP pistol, and 45 Colt carbine as cast, they measure fat enough to fire. I have also launched well with plain based gas checks, and just powder coated and sized to 452. I would not see a measurable difference in groups of 100 yards. Sure, greater distances might be a factor, I don't know. I just have not seen a difference for 950 fps or 1950 fps from a carbine, between HPRN or just a RN.

[Forrest r]

With my cramer rifle molds (1 cavity sp, 1 cavity hp) the hp is consistently more accurate. It has to do with nose slump when I push them over 2400fps.
[IMG][/IMG]

Just started playing with the MP hunter bullet tht has a wfn nose for the 30cal's, using it in a 308w.
[IMG][/IMG]

I'm doing head to head testing, today will be the 3rd outing. I'm doing 10-shot 100yd groups and do head to head testing typically testing 4 loads per outing. So far it doesn't matter if the bullet is a solid nose or a hp, same accuracy in the 2400fps/2500fps range.

Also just started testing the MP silhouette bullet for the 30cal's in a 308w. It has a strong nose like the lee 312-160-tl bullet and the xcb bullet. So far I've been testing the hp version of this bullet in the 2400fps to 2700fps range. The hp is supposed to improve accuracy. I have +/- another 200 hp versions of this bullet to use from my initial casting with this mold.
[IMG][/IMG]

I need to cast more bullets with this mold & plan on casting a couple runs in a #20 pot with both pins in this mold to do head to head testing:
hp version VS solid nosed
MP silh VS XCB
MP silh VS LEE 312-160tl
[IMG][/IMG]

So far the hp version of a sp bullet has out performed the sp solid nosed version with the bullets pictured below due to nose slump.
[IMG][/IMG]

So far in my limited testing with the MP hunter (only 12 different loads/10-shot groups) it doesn't seem to matter if the bullets a hp or solid nosed.

The MP sil hp still need head to head testing. This bullet should mirror the jacketed target hp results but you never know.

The last thing I was really interested in testing this year was the cramer #50. I have the mold that casts sp's in 1 cavity and a hp in the other.
[IMG][/IMG]

From testing it's big brother I know the nose will slump and the hp version will shoot better. My real interests lie in doing head to head testing with:
cramer #50 hp VS LEE soup can

The cramer is a 115gr hp fn, the lee soup can is a 113gr fn. Both of these bullets are a strong design, wouldn't surprise me if it takes 2600fps+ for 1 of these bullets to out perform the other.

Anyway that's my limited testing and what I have to work with for future testing.

[charlie b]

How do you know it is nose slump causing the issue? If it takes such high velocities to make something happen differently I would suspect the rotational forces have more to do with it.

[Forrest r]

How do you know it is nose slump causing the issue? If it takes such high velocities to make something happen differently I would suspect the rotational forces have more to do with it.

I really don't, just guessing. I will tell you what I do know and perhaps you'll see something that I'm missing.

All this started out at a gunshow, saw a canadian shooting team rifle, the cil 950t. Thought what a good platform for playing with cast bullets so I bought it. 1st thing I did was put cheap 1 in 10 twist ebco bbl on it and did a bunch of testing. Bought a apache 1 in 11 twist that had a chamber cut for the 175smk's just for the heck of it and had it on the rifle for awhile testing the same bullets i already tested in the ebco. I wanted a bbl for the 155gr smk's so I orders a 30" bbl from shilen with a chamber cut for that bullet and a 1 in 14 twist.

With that same rl-19 load and that cramer #43 bullet the sp bullet would start to fail as I approached 1900fps in the ebco. I didn't shoot that many in the apache bbl but I thought I was in the 2100fps range. The shilen bbl is running just under 2500fps.

EBCO:
1 in 10 twist 20" bbl ='s 1850fps 133,000rpm

Apache:
1 in 11 twist 25" bbl ='s 2100fps 137,000rpm

Shilen:
1 in 14 twist 30" bbl ='s 2475fps 128,000rpm

The 30" shilen has the lowest rpm's and the highest velocities.

The Shilen has the tightest bbl, 300/308
The Ebco was supposed to be 300/308
The Apache is 301/308

I'm still using the same brass jag to clean the bbl's with along with the same patches. The Shilen takes some force to push a dry patch down the bbl. The Ebco is easier then the Shilen and the Apache is easy compared to the other 2 bbl's.

[charlie b]

The only reason I asked is because I do notice opening up of groups above about 2100fps in my 10 twist Savage rifle. Solid nose bullets. I attribute it to the RPM issues at the higher velocities.

A hollow point design may react differently to the increased RPM.

[popper]

SP slump. Needs to compare fn vs hp.

[Forrest r]

The only reason I asked is because I do notice opening up of groups above about 2100fps in my 10 twist Savage rifle. Solid nose bullets. I attribute it to the RPM issues at the higher velocities.

A hollow point design may react differently to the increased RPM.

I thought you asked an excellent question!!!

Like I posted above, guessing it's nose slump. Very well could be a combination of things. Popper has done a lot of high velocity cast bullet shooting & myself, I try to pay attention to what he posts/says.

[lar45]

While testing the 30XCB bullet, in my 14 twist 30-06 XCB, we were looking at why gas checks were coming off at higher velocity.
Tim brought over a pickup load of saw dust that we filled cardboard boxes with and made a 8' stack of them to slow the bullets down gradually with minimal impact distortion.
Sorry if this isn't exactly clear, it's 12:45 AM...
Anyway, we were able to catch the boolits relatively unharmed to take measurements and pictures.
My take on it was that as the velocity went up, it appeared that lube was stacking up at the base in front of the gas check and hydraulically swagging the gc shank downso the gc would loose it's grip and come off after it left the barrel.
I think Tim/Goodsteel has the pics saved someplace. This was an experiment that Tim wanted to do, we just used my range and the test gun he built for me.

You might look at the holes in the targets to see if there's any indications of nose slump. Like a cleanly cut hole, and see if the size of the hole increases as you bump the velocity up in 100 fps steps...
Sorry if this is clear as mud, it's almost 1.

[Larry Gibson]

"My take on it was that as the velocity went up, it appeared that lube was stacking up at the base in front of the gas check and hydraulically swagging the gc shank downso the gc would loose it's grip and come off after it left the barrel."

I also was experimenting with the same at the same time. I think it's either the theory you and Tim came up with or the lube was hydraulically being force between the GC and the bullet GC shank. I found around 3000+ fps was where I started losing GCs off the 30 XCB out of the 16" twist. Not all GCs came off at that velocity level so whatever was happening was not consistent.

As to the #43 bullets nose "slumping" I do not think that is what is happening. Yes, I used think that unsupported bore riding noses could "slump, especially when pushed hard at higher velocity, but after recovering and inspecting many cast bullets I don't think so anymore. Evidence is showing the bullet tilt in the bore as many of the recover bore riders had rifling marks engrave more on one side of the nose than the opposite side. Those bullets had no indication of "slump" but of tilting in the bore. That is why I've come to believe bullets with a larger % of actual groove diameter bearing surface will shoot accurately to a higher RPM. I recommend a bullet for HV/RPM have at least 60% such bearing surface with minimal bore riding nose if any. That is what drove the minimal nose/maximum bearing surface design of the 30 XCB.

Thus I would conjecture the #43, with what appears to be less than 50% bearing surface, with the solid nose has more weight forward (at the tip no less) in the unsupported bore riding nose. That is probably causing slight tilting of the bullet compared to the HP #43 with it's weight rearward where it is better supported by the bearing surface of the bullet. It doesn't take very much such tilting to induce in a bullet at launch a bit of yaw which probably won't even be noticeable in bullet holes. Yet it would be sufficient with the more weight forward solid #43 to have a greater adverse affect at higher velocity/RPM.

[Thumbcocker]

lar45 that is a great group

And pretty boolits

[bluejay75]

@Lar45. Good shooting and good looking boolits.

@Forrest. Did you shoot the MP Molds Hunter boolits yet?

[Forrest r]

Yes, I actually was out yesterday & did testing with the MP hunter using rl-7.

I'm having lube issues with the hunter and the silhouette bullets. Easy enough to test, I have hunter bullets that are pc'd. Simply re-do the same loads I just tested and see what happens with the pc'd bullets.

Last week I did ladder tests using the MP silhouette bullet & found it extremely odd that 3 loads in 1gr increment increases shot the same groups. I need to cast more of them and pc them to do a re-test with that bullet as well.

GC's coming off hydraulically is real & I believe this is what's happening with these MP bullets. I've done a little testing with gc thickness, materials used to make the gc's and the shape of the base of the bullet/gc.

[popper]

GC's coming off hydraulically is real I read larry's write up of GC problem. Lino bad/#2 good IIRC. Not sure if it is really hydraulic/friction/work soften base. Seems like the GC shank was longer and smaller which is indicative of weakened alloy at the base. GC does act as a scraper so could 'collect' lube/crud at the front edge, added force to pop the GC off. We assume base pressure shrinks the L.G. and pumps lube to the bore. Agree with larry on the #43 bore rider but same HP or SP should fit the bore the same. Test should be done with FP & HP (same mould) to verify any stability improvement/difference. We also don't know if our grease lubes vapor vs liquid at pressure.

[Forrest r]

Popper that's why I'm so interested in the MP hunter bullet, a fn vs hp fn. The hp is 147gr & the fn is 152gr. Same with the lee soup can vs the cramer #50. FN's vs FN HP's.

The MP hunter has a HUGE lube groove, I keep getting targets like these for 3 outings now.
[IMG][/IMG]

The bottom left target, 1 7/8" outside to outside
[IMG][/IMG]

That hunter bullet really locks into the throat of my 308w. Sized to .310" if fills the freebore & the nose is +/- 75% supported.
[IMG][/IMG]

I'm going to switch over to pc'd bullets and see if things improve with this hunter bullet. This bullet should do better than 2400fps, I'd like to get in the 2600fps+ range. The difference between the fn vs hp fn should show up when approaching 2700fps.

I know this rifle will push cast bullet 2600fps+, done several 1 1/2" 10-shot groups @ 100yds with the lee 312-160-tl bullet doing +/- 2680.

Another issue is the brass I'm using for these tests, it's mixed head stamp nato 308w brass. Have no idea how many times they've been shot. I did the primer pockets, flash holes and neck turned them, but I really should break out some good brass. I do have 2 separate lots of 1x brass from the same maker/same lots, just never did anything with them.

That #43 bullet is a 188gr sp that's 1.140" long. The unsupported nose is .505". That's a lot of unsupported nose hanging out there. At 1st I thought the same as larry, it's simply tilted in the bore. So I use a egan MX taper die on the nose, that die sets the nose square to the base. Loaded those up and checked them with a hornady concentric gauge & went out and re-tested. No love

Decided to make my own bump die so I made a 3/4* die for a herter's 9-ton swaging press, even tried a couple of different designs for the gc base on the push rod. Loaded those up and checked them with the concentric gauge and still no love.

Could it be the rifle??? Sure. But it does have a floating bolt face & I set the oal's of my loads so that the final oal is set with the bolt close with the bullets out into the lands. The bolt close pushing the bullet back into the case and locks the bullet into the lands. This can be seen on the hunter bullet pictured above. Could of shilen got the throat off center??? Perhaps
[IMG][/IMG]

A +/- 190gr cast bullet doing 2450fps+ in 308w is nothing to sneeze at. Just need to get a couple things sorted out along with more range time. It would be nice to be amble to push these different bullets to their limits to be able to find out if the hp truly does make difference.

Time to up my game and start doing bullet sorting, visual & weight. Right now I'm not doing any sorting & shooting everything I cast. I also need to use quality cases from the same lot that are match prepped and inspected. I also need to run every bullet that passes inspection thru a bump die to make sure the gc/bullet base is true to the body of the bullet/seated squarely.

[charlie b]

Be careful with the heavier bullets at higher velocities. You can exceed max pressures for the rifle without much problem. Many max 190gn loads are less than 2400fps. Jacketed max loads are in the 2600fps range.

If you want best accuracy at these kinds of velocities you do need to weight sort and be very mindful of the bearing surfaces. Remember that flaws at the surface are where most of the rotational speeds are highest so will induce more error than flaws along the centerline of the bullet.

I weight sort to 0.5gn 'batches'. I chose this number from measuring jacketed bullets. Sierra 168 Match Kings were 167.9 to 168.1gn. 0.3gn spread. Hornady 168AMax, which have been very accurate for me, have a 0.6gn spread. So I figured 0.5gn for my cast bullets would be ok. Sometimes I will get a bunch of cast bullets sorted down to 0.1gn to use for specific testing.

I shoot powder coated bullets exclusively now. I did quite a few tests with lubed and PC and found no difference in accuracy. BUT...some bullets will shoot better or worse with PC. Why? Size of the bullet. The PC adds ~0.002" to the dia of the bullet. Not much, but, it can make a difference. With tapered bullet designs it means the bullet has to be seated deeper in the case. For nose riders it means you may need to size the noses of your bullets. Not difficult, but, may introduce another source of error in the mix.

Also, if you size down your bullets very much, then you may need to size them before and after PC.