Gear's 190x

[RickinTN]

So.....In my elementary cast bullet mind if a taper matching or pre-slumped design with a perfect static fit is not the velocity answer what is? I enjoy very good accuracy with the RCBS 165 Silhouette bullet in mild velocity ranges and haven't tried to push it very much. I do understand from others this bullet is "velocity shy". I reached the conclusion in my mind anyway, and possibly in error, that the silhouette bullets' limitations were due to it's limited bearing surface. The 185R in my rifle should remedy this situation as to my thinking it certainly maximizes potential bearing surface. I have also worked with a NOE version of the Ranchdog 165 bullet with standard lube grooves and get good accuracy at mild velocities. I do understand from others this bullet is also velocity shy and in my mind attributed it's shortfalls to it's many lube grooves and sort of a weakening of the bullet shank itself as well as it's relatively long un-supported nose (at least compared to the other bullets I've used). My thinking certainly could be in error here as well as other areas.
Gear mentions that maybe our attention should be turned to good dynamic fit as opposed to good static fit. How would we accomplish a good or perfect dynamic fit without starting with a good or perfect static fit? Maybe you could expound here a little for me Gear as I'm certainly all ears (eyes in this case). I do know that I have already re-learned a life lesson here in playing with the assorted bullets. It seems, like many other things I've experienced, that the more I learn about cast bullets the more I realize I don't know. It seems like every answer raises more questions. I guess that is what keeps my attention in the quest for the perfect cast bullet.
Thanks guys,
Rick

[btroj]

For over 2200 fps the MP 30 SIL is the way to go.

One thing to think about is this- your bullet is very snug against the throat at ignition. The bullet based comes under pressure and wants to move but the nose can't engrave the rifle fast enough. What can happen is this, the bullet base moves forward and the bullet body rivets into any available space, like between the end of the case neck and the end of the chamber. Bullet is now damaged and sometimes a lead ring is left behind. I think Gear actually found little lead rings at times, I'm sure he will chime in.

My understanding of what you need is a bullet with enough nose contact to keep the nose centered but not some much that the bullet has a huge area to begin engraving. This lets the bullet easily start into the throat while staying centered. As pressure rises the bullet has room in the throat to slump into, if pressure is high enough, while being held centered by that light nose contact. This is dynamic fit.

Think I of it this way, a morse taper is great for static fit but the bullet can't move at all. The bullet will change shape under pressure and no matter how much we think it has no place to go it will find places we don't think about.

What at we need is dynamic fit- what happens after ignition. How do we keep the bullet centered. How do we make sure it doesn't get squished into places we don't want it and deformed. This is very different from static fit but is far more important.

This is how I understand this at the moment. I am still learning much.

[RickinTN]

I'm not familiar with the MP 30 silhouette bullet but a search here found what I think may be it. If I'm looking at the correct line drawing and digesting what I think I see properly it is sort of a combination of a traditional bore-ride and taper-fitting design. Depending on the seating depth the bullet could be loaded to snug the leade or could be left with some amount of jump before the tapered part engages the taper of the leade. In the latter scenario the bore-ride portion would keep the bullet centered while the tapered portion is jumping to the leade? Maybe the best of both worlds combination? I am curious if I am analyzing this correctly?
What are the everyone's thoughts on how far the bullet should be designed to jump before the taper of the leade is engaged? I know each rifle is a science unto itself with different alloys and powders and charges are all being important factors. Should it jump .020"? .050"? More? I can see that it could take thousands of rounds with a single bullet design to begin to get any real answers and then all the other questions the answers raise.
Rick

[btroj]

Rick, I think you have a basic understanding. The bullet is somewhat self centering. It was designed by a guy who has designed a bunch of excellent bullets for this site over the years.

Too much nose to throat contact at ignition seems to be problematic. Seems counterintuitive but results don't lie.

I bet your bullet will shoot great at 1900 or so, the 190X sure does.

[btroj]

Go start your own thread about accuracy standards, that is not what is being discussed here.
I have asked politely for you to stay on topic. Bring it up again and it will be reported as baiting/trolling.

[45 2.1]

My understanding of what you need is a bullet with enough nose contact to keep the nose centered but not some much that the bullet has a huge area to begin engraving. This lets the bullet easily start into the throat while staying centered. As pressure rises the bullet has room in the throat to slump into, if pressure is high enough, while being held centered by that light nose contact. This is dynamic fit.

Not so................. After recovering several hundred long range high velocity boolits out of bolt guns and semi-autos, you will find the current two dimensional boolits that are available will not work that way and give results that I want.

[btroj]

What current 2 dimensional bullets? Like a bore rider? Certainly not a Loverin.

I was speaking more of the 30 SIL, not a simple bore rider. Bore riders aren't gonna do squat at higher velocities, I know that.

[geargnasher]

45 2.1 has referred in conversation to the typical Lee bore-riding design as 'two dimensional', meaning that there is no taper, only a bore-riding cylinder and a bearing cylinder with an abrupt transition between. The only time I ever got one of those to shoot at any sort of high velocity was in my 7mm-08 using the 130-grain Lee design at just over 2600 fps. I was attempting to duplicate the results of someone else, and while I got three-inch round groups, I got nowhere near as good of results as he did. I think the only reason it worked at all was because the bullet was changing shape so much and the nose was pretty short.

I have fired three different bullet designs through my .30XCB using several different alloys and a variety of powders. My study largely involved the 190X, 185G, and 45 2.1's .30 Sil design produced by MP molds. I wanted to compare bullet design characteristics, so I chose 50/50 WW/pure plus 1% tin (I know, I know) water quenched and aged to 19-21 bhn and the one powder that I had worked up to the best potential I could achieve for each bullet near the limit of the alloy. They all seemed to shoot best right at 2400 fps with H-414, so I set about generating a lot of target data with the same load, lube, powder, powder charge, and the three different bullet styles. What I found out was the 190X was a consistent 1.5-2 MOA shooter at 100 yards, the 185G right at 1 MOA, and the .30 Sil averaging ten-shot groups at 5/8", some less, one or two in the 3/4" range. I cast those .30 Sil's from a defective mould that Miha cheerfully replaced but the check shank is still wrong so I sent the replacement down the road without casting with it. The stockpile of .30 Sil bullets I have are all of this alloy and a large percentage of them have nicks in the bands from having to beat them out of the mould with a club, so they aren't the best candidates for accuracy. They shot the best, by far, than the other two designed by me, regardless. I don't know why that is exactly, but I have an idea, and am aiming to fix that with the next Accurate mould I have drawn up

Also, keep in mind that this is just a single data point from a guy who is a long way from figuring this out, someone else might very likely take the 190X and load it so it shoots holes at 2600 fps from the same rifle. I do think it is interesting, though that the nose shape of the 185G and .30 Sil outshot the Morse Taper fit of the 190X handily at high velocity. I do believe the 185G would shoot much better if the nose tip wasn't a nominal .301" and didn't engage the lands hard. I had it custom-made for a different rifle with a .3015" bore ahead of the throat and it's way too tight in this one. The .30 Sil shot best when seated so it didn't touch anything when chambered and had about .005" jump.

Gear

[btroj]

The 30 SIL shot best while jumping a tiny bit? Interesting. I have been seating mine with just the slightest bit of nose contact but leaving the taper well off the throat.

Traditional 2 dimension bullets aren't even on my radar. I can't even tell you the last time I cast any.

I have not tried any powders in the 414 burn range but I ink maybe I should. I bet my powders have all been a bit slow and I'm not getting good obturation because the alloy I'm using is harder than yours.

Gear, I think we are both being laughed at here. There is a guy who keeps telling us about tin and I know he is just laughing his butt off because we are learning he was right. Man do I hate having to admit that.

I have a bit of RE 15 left and I need to give it a shot. The faster pressure rise may just help me out. Will let you know.

[cbrick]

Alloy strength and pressure curve must be matched pretty closely I think. Your heat treat could be all it takes.
I can water drop my range scrap and get 24 BHN. I do know it doesn't matter what temp I heat treat to, it all comes out the same. Yep, 375 or 440 degrees it gives the same BHN. I think it is the low tin that does this. I bet adding tin would give a variation in hardness based on heat temp but would also lower the hardness I achieve. Tin is a double edged sword.

Not necessarily, all of the heat treat testing I did was with 2% Sn & a little at 3% Sn and COWW, convection oven HT will/can reach 30 BHN. Your correct that Sn can limit the amount of HT that is achievable but not at the percentages were talking about here or the BHN range your looking for, after about 5% Sn is where it will start to effect final BHN.

Conventional wisdom has it that Sn will also increase age softening and a test I did with 2% Sn age softening in 10 years was 30 BHN down to 26 BHN so . . .

Your right also that experimenting with alloys and their BHN can take years. All of my testing was with a single alloy and a single load and all from the same lot numbers of components (powder, primers, brass and lead) and it took a year and a half. Not trying to discourage you from testing, really I'm not but that can be a whole new can of worms itself.

Given your "tested" alloy of 1.8% Sb and 0.25% Sn (very close to tested COWW BTW) I suggest adding 1.5% Sn and trying that. Metallurgical wisdom says not to use more Sn than Sb, I tested this with 3% Sn and 2% Sb for some time and the only real difference I noticed was that my Sn supply was disappearing faster. I could detect no advantage and no detriment except for having less Sn.

Having said all of that keep in mind that all of my such testing was with high end long range revolver loads and not pushing the velocity envelope in rifles as your doing.

This thread turned into a fascinating read once cleaned up and I hope I've added something to the conversation. Keep up the excellent work, I'm all ears.

Rick

[jmort]

For what it is worth, Beartooth Bullets uses 94/3/3 heat treated and get similar results as mentioned. Age softening not serious issue.

[btroj]

My testing was done at the request of another member here, he said it would help me understand how the alloy constituents interact. Boy was he right.

I was a bit shocked when I heat treated my alloy to both 440 and 375 for 30 minutes then quenched. I expected to see a variance in hardness based on heat treat temp but did not. What I need to do is see what happens if I boost the tin content and repeat the testing. Does the tin/antimony ratio alter heat treat hardness based on temp? Don't know, need to find out.

As for a whole can of worms, boy is it ever. Casting a bunch of bullets, air cooling some, water dropping others. Heat treating some to different temps then quenching. Testing hardness daily for a few weeks all while keeping good records. I always keep some from a batch as cast to have a way to see how the alloy is changed by whatever heat treating I do.

By the time I get done with the basics of the testing I am too tired to even go shoot em! Sadly, that is what I need to do. Cast some up, test daily for a week the. Shoot some each week while continuing the hardness testing to come up with some idea of how hardness, alloy content, and pressure affect the final outcome on the target. No simple task!

[cbrick]

As for age hardening your alloy whether air cooled or HT'ing the hardening/time curve is dependent on the Sb percentage, the lower the Sb the longer to reach final BHN. Higher Sn percentages will also effect the time curve but again, very little at the percentages were talking about here. A paper by "Key to Metals", a major supplier of lead alloy for the manufacture of wet cell battery plates refers to 6% Sb as sufficient for the strengthening/time curve for industry to use the plates almost immediately while 4% and under not so much. Thus our waiting for our bullets to age.

An interesting side note is that the metals industry refers to quenching Pb/Sb alloys as "strengthening" the alloy while bullet casters always refer to hardening. Perhaps strengthening would be a better term for what were trying to achieve.

Rick

[geargnasher]

How "strong" has anyone managed to make Lyman #2 alloy by heat treating? Not much stronger than straight clippy weights at 2.5%/.5% water-dropped straight from the mould I bet, probably not even that strong. Anyone?

Gear

[btroj]

What I want to see is how do alloys of the same hardness but vastly different compositions behave with the same load.

Rick, what I am after is seeing how does the amount of free antimony affect hardness. The amount not bound in an intermetallic with tin. In short, how does my 1.8/.25 alloy behave if compared to 1.8/1.0? Does the extra tin alter final hardness? Does it alter heat treat hardness based on heat treat temps?

So much we think we know but sometimes we need to see them for ourselves.

Rick, this article and some pressure from another member here are the things that spurred my interest in alloys and heat treating. I want to expand on what you did, not duplicate it. You gave an excellent start point for me, I just want to see how other alloys behave in similar situations.

http://www.lasc.us/HeatTreat.htm

I am sure you are quite familiar with this?

[runfiverun]

4/6/90 my go to right after ww's and soft lead [water dropped] starts failing.
I use it in the 223 at 2800, and some other target type uses because I generally get increased accuracy from it.
I wrote of it's use in the AR dissertation.
it has out grouped both ww and lino-type alloys and has shot faster and casts like a dream at lower alloy temps letting me keep lower [more consistent] mold temps over a longer period of time.

[btroj]

Ok Guys, here is a blast from the past.

http://castboolits.gunloads.com/arch...p/t-40767.html

How do ductility and "hardness" interact in the bore? This testing showed that adding tin increased ductility of the alloy. Is that good or bad for high velocity? I don't know. This would explain, to a certain extent, why someone keeps telling us to stop adding tin, wouldn't it Gear?

I will let you naw on that for a while.

[btroj]

4/6/90 my go to right after ww's and soft lead [water dropped] starts failing.
I use it in the 223 at 2800, and some other target type uses because I generally get increased accuracy from it.
I wrote of it's use in the AR dissertation.
it has out grouped both ww and lino-type alloys and has shot faster and casts like a dream at lower alloy temps letting me keep lower [more consistent] mold temps over a longer period of time.

Pretty much hardball plus tin? Yikes.

Have you you compared it head to head with 2/3/95? Just curious.

[popper]

heat treatability an alloy just having lead, antimony, and trace arsenic has vs. one that has some tin in it

My normal 3% Sb/~1% Cu alloy H.T. 400F/1 hr is softer/weaker than Isocore/Pb 3/1 with ~0.3% Cu replacing Sn when H.T same way. I'm assuming the large core is 4/2 Sb/Sn. If the calculator is correct, 97/2/0.7/0.2, shot added to both. But the 3% alloy shoots better @ 2400 168 gr GC in the 308. Kinda reverses with the BO PB. funny. Results ~ a month after H.T. for both. 308 ammo I loaded last fall still shoots the same. Hope this helps.
edit: my BO PB testing (until interrupted by scope failure) indicated alloy strength needs to be matched to pressure/velocity (curve); too hard OR soft @ fps is bad. More testing after I get the good scope back. Bottom line - alloy, powder & charge, boolit design all are part of the equation. Got to review my math on solving 4 unknown in the equation.

[cbrick]

How "strong" has anyone managed to make Lyman #2 alloy by heat treating? Not much stronger than straight clippy weights at 2.5%/.5% water-dropped straight from the mould I bet, probably not even that strong. Anyone? Gear

I can't answer that, I've never used Lyman #2 for the same reason I've used very little lino. Higher Sb percentages increase the bullet shattering on steel targets and steel is the only targets I was shooting. The 5% Sn could well be enough to effect the final BHN, the 5% Sb should shorten the strengthening/time curve. I never did test either 5% Sb or 5% Sn heat treating.

With all of the testing that's been done for high velocity rifle has anyone tested the effect of higher BHN on group size? All of my testing concluded that as the BHN went up (to 30 BHN) the groups opened up. Again, this was with high end revolver at 200 meters, not rifles. I settled on 18 BHN after that 1 1/2 year test for the 357, 190 gr bullet at 1550 fps. Your pressures will be well over what I was running (40,000+) so such testing in the rifles would be, at least to me, extremely interesting.

Lyman #2 heat treated, more testing only means more range time right? That can't be bad thing.

Rick