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Larry Gibson
Coming up on a years worth of experimenting with the 30 XCB (310-165-FN) in the 30×60 XCB cartridge. I have put over 1400 test rounds through the rifle (a VZ24 M98 with a Broughton 31″ barrel put on and chambered by Tim Malcom) so far. I have ran numerous tests with different alloys, lubes, powders and bullet sizes. The tests have mostly been with 10 shot groups at 100 yards but numerous 200 and 300 yard tests for linear group dispersion and accuracy have been done. I have pushed the velocity up to 3100 fps which is close to the top end of the RPM Threshold.
The testing results have clearly demonstrated that a properly designed bullet cast of a ternary alloy can indeed be shot at jacketed bullet velocities with excellent accuracy consistently with repeatable results. I have found that around 2950 – 3000+ fps some strange things begin to happen though. The problem is one of GCs being lost. It appears there’s some heat transfer from the hot gas but probably mostly friction to the GC which then melts the alloy and the GC is lost. The bullet may very well be “plasticizing” (getting soft and putty like) in spots on/in the bullet or it’s entirety. The velocity, pressures, BCs and other data were mostly measured with the Oehler M43. Some velocities were measured with the Oehler M35P and some of the testing was simply for accuracy/score at 100, 200 and 300 yards. The load posted today is such.
The load used in the photo has become my favorite load. In the beginning of the XCB project I prophesized that 2800 – 2900+ fps with excellent accuracy should be possible with a 16″ twist. Turns out that is exactly what is possible. You can also sneak up on those velocities with a 14″ twist if everything is done right as Bjorn is doing with his 30×57. What I have found for a “standard load” in the 30×60 XCB is the XCB bullet cast of #2 alloy and WQ’d or HT’d. I do a visual examination eliminating any bullet with even the slightest visual defect. The bullets are then weight sorted and segregated by .1 of a grain. The bullets used in the 20 shot group shown weighed, naked, 158 – 158.5 gr. The bullets drop at .3105. The bullets were seated into uniformed Hornady GCs using a .311 H&I die in a Lyman 450 with the Lyman GC seating tool. The GC seating tool is then removed from the 450 and the bullets are lubed with Lar’s White Label 2500+ and the GC crimped on in the .311 H&I die. The bullets are then push sized through a hone Lee sizer to size them .310. The cases are formed and fire formed Winchester 30-06 cases. The necks are turned to allow .0005 clearance around the neck in the 30×60 XCB chamber. The cases are NS’d in a shortened ’06 Redding Bushing die or in a shortened Lee Target loader. With either the inside neck diameter is just enough so the Lyman 31 M die just uniforms the inside for consistent neck tension. I use WLR primers. The standard load is 53 gr of AA4350 which gives right at 99% load density. The 30 XCB bullets are seated so they just touch the leade when chambered.
The standard load muzzle velocity runs 2890 – 2910 fps with the average, depending on temperature running right around 2900 fps. The measured pressure (M43 Oehler) runs right at 49 – 50,000 psi. The measured (M43 Oehler) BC of the 30 XCB bullet at 2900 fps is .250.
The group shown is 20 shots at 100 yards from a cold clean barrel. The high shot at 11:30 is the 1st shot (fouler) but is still kept with the group. The shot out at 2:30 is the 18th or 19th shot. Though the temperature was only 53 the barrel still heats with a long test string and mirage became a factor after 14 or so shots. The over all group size of the 20 shots is 1.607″. The groups size of the 19 shots excluding the fouler is 1.250″ The core group of probably 14 shots is right at .75″ all of which were shot before the mirage became a factor.
I have a large box of newsprint which will be thoroughly water soaked and placed at 300 yards. My intent with that is to catch some bullets relatively undamaged to measure and inspect. Perhaps that will tell us what is happening to the bullet inside the barrel during acceleration? Might get out today to make that test.
Larry Gibson
Larry Gibson
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LongPoint
My XCB should be the same as yours except I specified #2 alloy and for the bullet to drop at .310 – .3105. Swede did an awesome job as that’s exactly what my mould drops them at
. Yes, 2900 fps is “screaming fast” especially for a cast bullet that holds that kind of accuracy. You must understand there is more to accomplishing that than just the bullet. A bullet of proper design is necessary but so are several other things. For example your M1 Garand 30-06 isn’t going to do that. Actually the 30 XCB bullet you have is probably the best bullet design for getting higher than 1900 fps and achieving useable accuracy. The problem with a 185 gr cast bullet is you’ll end up with a bore riding nose which works against achieving as high a velocity as is probable with the 30 XCB.So in the 30 XCB you have an excellent bullet which is proving to be the best high velocity cast bullet. It is also proving to be very accurate at “normal” cast bullet velocities. I’m posting 3 groups I shot a couple days ago. I shot 12 shots at 100 yards (2 fouler/sighters) and then 10 for group), 10 shots at 200 yards and 10 shots at 300 yards. As mentioned in previous threads non-linear group expansion at 200 and 300 yards is a dead give away the bullet is above it’s RPM Threshold and is being pushed too hard for useable long range accuracy. If the load is accurate at 100 yards then linear group expansion can be expected out to 300 yards. Of course the wind can have an effect at that range but it and it’s effects are measureable. Keep in mind linear group expansion is not expected that the groups will be exactly 2 times the 100 yard group size at 200 yards nor exactly 3 times the 100 yard group size at 300 yards. What we can expect with normal linear group expansion is if the rifle/load normally shoots between 1 – 2 moa at 100 yards we can expect a 200 yard group of 2 – 4 moa and a 300 yard group of 3 – 6 moa. And yes at longer ranges bullet drift does come into play but we are talking cast bullets and only 300 yards here.
Checking the match results for last years CBA”Nationals” proved interesting. Now Dawn, my rifle, would fall into their “Heavy Rifle” class. So that’s the scores I looked at. The Heavy Rifle competitors averaged 1.373 moa for a 100 yard 10 shot group and a 200 yard 10 shot group. The Heavy Rifle match winner averaged 1.171 moa for his 100 and 200 yard groups. I had just shot an moa average of 1.10 with a cast bullet (the 30 XCB) at 2900 fps with three different 10 shot groups at 100, 200 AND 300 yards. Hardley what some have called “okay for hunting accuracy”………. 😮
So the point here is; there are doubters and naysayers who don’t think cast bullets can be shot at such high velocity and maintain such accuracy. I am not the only one who is actually shooting cast bullets this fast with this accuracy, others doing it also now. There are several others now with 14″ twist rifles of .308W or 30×57 XCB cartridges that are happily shooting 2600+ fps. The rifle I use is a 30×60 XCB with a 16″ twist and can reach 2900+ fps with such accuracy. Bjorn has a 17″ twist 30-06 XCB and is doing the same. All are using the NOE 30 XCB bullet. If you don’t want to go with a rebarrel then some 14″ twist factory Palma rifles in .308W are still out there. However, most these days are with 13″ twists. Or you could use a 10 or 12″ twist .308W or 30-06. Check out my thread on HV in 10 and 12″ twists here on the NOE forum. You’ll see there that 2300 – 2500 fps with very useable accuracy is possible.
You have taken the first step by buying your NOE 30 XCB mould. It is probably the best designed cast bullet in .30 caliber for higher velocity. So is true high velocity with cast bullets hard to do? Yes it is but it is not as hard to do as some would have you believe. There is not witchcraft or voodoo involved, just science. The first step is to learn how to cast really excellent top notch bullets. I used to think I could cast really good bullets when I started pushing velocities up. I had another think coming! Learning to cast really exceptional bullets is also not hard but it takes diligence and the correct alloy. Let me say right up front if you want to go cheap with scrounged range lead or WWs then you won’t get there from here. Let me use an analogy; if you had a Ferrari would you put regular gas in it and ride on retread tires and expect to successfully drive 150 – 200 mph? Some just might but they’re not going to take that Ferrari to top end with those. Same if you want to shoot 2600 – 2900+fps with a cast bullet like these groups show you it can be done. So let’s leave it there at that and look at the groups. If you decide you’re in for the ride let us know. There are several of us who will gladly help you or anyone else get where we are at. No secret squirrels codes with us.
The 100 and 200 yard aiming diamonds are .75 on a side. Four of them make up the 300 yard aiming diamond for about 1.5″ on a side.
Larry Gibson
LongPoint
My bad, you did read that. I must have had a dyslectic moment; should have read 158 – 158.5. My 30 XCBs cast of #2 alloy with Hornady GCs and 2500+ lube run 164 +/- fully dressed. Bjorn caught the error and I corrected it in the post. A very good reason why we must double check figures, especially load data, taken from internet posts. My apologies.
Larry Gibson
steveleonard
Larry, In your first post, you write that bullets were segregated by .1, then the 20 shot group specifies bullets of 158-158.5. Is this a misprint and can you clear this up? Wondering if I need to be more passionate about weight segregating my own bullets.
I’m a believer! Thank you for the write up, I hope to learn more from your experiences.
yodgsandman
Yes you do need to be passionate about weight sorting your bullets. I do weight “segregate” into .1 gr groups but then put those weights into a +/- “lot” that have proven to shoot accurately as in a group and which hit to the same point of impact out to 300 yards. That “lot” in the use of #2 alloy in the NOE 310-165-FN 30 XCB mould I have has consistently been from 158.0 – 158.5 gr. In the test the 30 XCB bullet in my .308W Palma rifle, my 30×60 XCB rifle, my 24” barreled with 10” twist .308W pressure test rifle, my M70 target rifle with 12” twist 26” barrel, an M1A with issue 12” twist M14 barrel and 3 different 30-06 rifles with 10” twist barrels I have fired over 5,000 30 XCB bullet of various ternary alloys.
I’ve found that #2 alloy consistently gives the best accuracy from regular velocities in the teens to the high velocities shown. Consistency in casting along with using a quality alloy and learning how to cast quality bullets for HV is a key as previously mentioned. Even then the visual inspection must be scrupulous in eliminating any visual defect what so ever, no matter how small or inconsequential you think it may be. If there is any visual defect at all the bullet is rejected for HV use. I generally cast 400- 500 30 XCBs at a time. Visual inspection eliminates about 30% of them. Understand that most of those bullets I eliminate with visual defects I used to blissfully shoot similar “defective” cast bullets at 1800 – 1950 fps all the time with great satisfaction. But for HV use I have found those bullets with any visual defect, no matter how small, will invariable increase inaccuracy (that simply means the groups get larger), especially at 200 and 300 yards. Such defects may not appreciably increase inaccuracy at 100 yards where it will be noticed. Only thorough testing at 200 yards, and even more so at 300 yards, will show the adverse affect on accuracy those small defects have.
I then weight sort the remaining 70% +/- bullets that have passed the visual inspection. I weight the bullets and sort them into 0.1 gr increments. I do that because it gives me a “quality assurance” that that casting “lot” is producing quality bullets equal to other proven “lots” of the same bullet from the same mould of the same alloy. In the case of the 30 XCB cast of #2 alloy I find that most of the bullets will fall into the 158.0 – 158.5 gr range. Out of the 70% +/- that passed the visual inspection another 10 – 15% will be rejected because they mostly weigh less than 158.0 gr. A few (usually less than 10) will weigh more than 158.5 gr but those usually have a sprue that did not cut clean.
Speaking of sprues that don’t cut clean; as I weight sort before weighing if the sprue cut is not clean I lay the bullet on a lead block and cut the small sprue remnant off with a sharp knife.
Thus out of each casting of 400 – 500 bullets I will end up with 250 – 300 that are suitable for HV loads.
I have tested numerous times at 200 and 300 yards for accuracy and linear expansion as previously mentioned but I though a couple weeks ago a thorough test at 300 yards was needed. Thus I loaded up a series of 8 ten shot test strings of the same load for testing in the 30×60 rifle. The load was the “standard” 30×60 load as demonstrated in this thread. The only difference between each test string was the weight of the bullet. Each string increased the bullet weight by 0.1 gr from 157.8 to 158.5 gr (naked bullet weight). On the light weight end of the bullet weight bell curve there are invariably 50 – 80 bullets that weigh 157.8 and 157.9 grs. Those look awfully good and shoot just fine at 100 yards and seem to shoot well at 200 yards but I had real concerns about 300 yards based on singular limited tests previously. The question was; is it really necessary to reject those two weights from the “lot”? Thus those two weights were included in the testing.
I conducted the test on 14 January 2016. The weather was fine with a temp in the low 50s and little wind. The 300 yard range at Sara Park here in Lake Havasu City is well bermed on the sides so the wind was not a factor. The rifle barrel was cleaned between each test string and 3 foulers fired prior to the test. When completed I plotted the group sizes on a graph by weight. It is very plain to see, as the results show, that visual and weight sorting is very beneficial if you are shooting HV at longer ranges. It also demonstrates that thorough test at longer ranges is also necessary for consistent results.
The 157.8 group had 2 fliers low out of the core eight shot group that was 3.2” with the overall group size at 4.1”. The 157.9 gr test had 3 shots out of the core group of 3.3” for an overall group size of 4.3”. Then as you can see the remaining six groups of 158.0 to 158.5 grs gave consistent 3.1” to 3.37” groups for an average group size of 3.2” for 60 shots at 300 yards (red line). The center of the group point of impact was also essentially the same at 300 yards.
We should note that after the completion of this test was when I conducted the 100, 200 and 300 yard test posted previously. That 300 yard group validates the “lot” acceptance spread of 158.0 – 158.5 gr. It is also noteworthy that the “standard” load in the 30×60 rifle, Dawn, will shoot 1 – 1¼ moa at 100 yards on demand. This test plus the linear expansion test all were conducted on the same day. It demonstrated with 8 ten shot groups at 300 yards (80 record round) that linear expansion with cast bullets is quite possible to 300 yards regardless of what match stats may indicate.
So bottom line is I recommend if you are going to shoot HV in any twist rifle beyond 100 yards then visual and weight sorting is essential, even if you think you have just cast the most perfect bullets known to man…..visual and weight sort.
Larry Gibson
SwedeNelson
stephenquick
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