.30 XCB wildcat, from scratch.

[lar45]

Larry, a couple of questions if you don't mind.
With running the slow powders at high velocity, have you ever run into problems with a higher secondary pressure spike? Or does this only happen with higher pressures, or powder selection?
Here is a link to Mountain molds experiments with high velocity in the 30-06.
http://www.mountainmolds.com/phpBB3/...c.php?f=8&t=37
Here is pic of his pressures.




Next question:
If you ever to decide to write a book on "Cast Bullets the Witchcraft and Science of it all" I would definately buy a copy.
Glenn.

[Larry Gibson]

Glenn

Yes I have run into "secondary pressure spikes" and actually they are fairly common with numerous powders. They also are indicative of an improper set up with the "box" (Pressure Trace in above example) to close to the muzzle blast or being jarred on the bench. Additionally you see what appear to be pressure spikes after bullet exit from the muzzle You see that in the pressure traces on the Oehler M43 printout in my last test report).

There are several problems with the Pressure Trace System pressure curve which you've posted. 1st of all 47.2 gr of 748 under a 180 gr jacketed bullet should not produce the psi's shown let alone a 180 gr cast bullet in the 30-06. Also the trace should have tick marks on it for muzzle exit and it does not. The wildly high "secondary pressure spikes" are indeed "off the chart". All three of those indicate to me an improper set up, improper input of sufficient data or an improperly affixed strain gauge (or a combination of the three). I know the Pressure Trace sight used to say (or still does) the bluing did not have to be removed to glue the gauge on and that it could be readily removed. I can tell you from practical experience and conversations with Dr. Oehler that that is not true. The bluing must be removed and the metal cleaned very well with a certain procedure followed and the gauge is permanently affixed to bare metal. If not you get wild readings. I suspect the graph you posted is the result of an improperly affixed gauge along with insufficient test data. Had I seen those traces during the testing I would have stopped the test and determined what was causing the erratic traces. To draw the conclusion that is drawn on that site from that trace with the insufficient test sample and obvious erratic measurements is, to say the least, not reliable.

Larry Gibson

[Doc Highwall]

This is what is posted on the RSI pressure trace web site about spikes like what is shown in post 600.

INSIDE the end of a long barrel. (See tech article.)

We believe this to be a gross example of "deflagration" or unburned powder burning AFTER the bullet exits. The scary bit is more than 81,000 PSI is read by the strain gage located over the chamber! It is impossible to know if the entire length of the barrel was exposed to this pressure. But if it was, then the load is approaching the yield strength of thinner parts of the barrel and "could" expand the bore.Ironically the exit timing, velocity S.D. and accuracy was great for factory ammo... but it does light up half the county when fired at night.

[Larry Gibson]

Doc

I've read that I don't know how many times and all I will say is it regurgitates numerous unproven theories. Where I really have a problem with that site is with statements like; "It is the club's "reference" ammo tested in a commercial lab to around 63,000 PSI but actually produced nearly 120,000 PSI in his old competition AR!"

Now if one knows anything about pressure testing with a strain gauge one knows the gauge must be placed directly over the center of the cartridge case, preferably on a cylindrical surface. Now, if anyone knows anything about how a barrel is secured in an AR upper receiver we have to ask how the area of the barrel inside the extension, the upper receiver with the barrel nut and handguard retainer was accessed to put the strain gauge over the chamber to get such an outlandish reading? Especially "in his old competition AR"? If they put the gauge forward of the barrel nut the measured psi would have been considerably less. If I was a betting man my money would be put on the commercial lab's 63,000 psi because the claim is BS.

Next time I pressure test I think I will just test that 47.2 gr Win 748 under a 180 gr cast in the '06 and see what the Oehler M43 tells us about it. If you have any real particulars on the load other than that in the article I would appreciate knowing them for the test? As I recall that was close to the max load under a 180 gr SPBT jacketed bullet listed in an older Hornady manual. As my old '06 notes show I worked up to that load w/o any excessive pressure signs.

Don't take my criticism as meaning the Pressure Trace equipment is bad. What I find difficult to accept is the claims made and assumptions on limited tests, especially when there is obvious problems with the set up or installation of the gauges. I base that on my experience with measuring pressures using strain gauges on 31 different firearms and a lot of different cartridges over the last 5 - 6 years.

Larry Gibson

Conducted the test on 9/22/14. Results posted in post 712 on page 36 this thread.

[Larry Gibson]

NOE 310-165-FN with RL 22, H44831SC and retest of AA4350

Forgot to mention on the last test report what the 1^stfive shots with the NOE 310-165-FN bullet did. When I have the down range screens up for a test in front of the 100 yard target I have learned the hard way to always double check the zero on another target before shooting through the screens. Thus the 1^st five shots with the NOE 31-165-FN bullet were shot on a zero check target. The load was the “start” load of 45 grAA4350. As you se the 1^st 5 shots went into 1.1” which was shortly found out to be 2480 fps. Not a bad start……not bad at all!

Attachment 115432

Anyway this morning I slipped out to the range at oh dark thirty and set up for testing RL 22, H4831SC and a retest of the 47 gr AA4350 load that looked good in the 1^st test under the NOE 310-165 bullet. These were the same lot of selected bullets as the 1^st test.

I shot the retest of the 47 gr AA4350 load on a zero target w/o velocity and psi testing as that had already been done in the 1^sttest a couple days ago. I also decidedto include a “cold clean bore” test with it. Looking at the target you can see the 1^st, 2^nd and3^rd shots and then on the 4^th shot the group settled down. Shots 4 through 10 (7 shots) went into .62”! What else is there to say for a cast bullet at 2600 fps except WOW………

Attachment 115433


With RL 22 I tested 47, 48 and 49 gr. While None of the loads really gave me anything to write home to momma about the groups ranged from 1.9” to 2.7” for each 10 shot string. Internal ballistics were good but the RL 22 just didn’t shoot that well. Also the 49 gr load at 100% load density just broke 2500 fps. Nothing great in the.308W but with the increased case capacity of the 30x57 (30 XCB) it deserves a test there, especially since the psi was held down to 38,400 psi with the 49 gr load.



Next I ran 10 shot test loads of 46, 47, 48 and 49 gr H4831`SC with 49 gr also being 100% load density. The 46 gr load went into 2.25” at 2351 fps with 33,300 psi. Great the psi was down but so was the velocity and the groups size just made me yawn.



With the 47 gr load things began to look better. I called 2 shots out; one down and away and one high and inside. The other 8 shots went into 1.5” at 2411 fps with 34,900 psi……things were looking up!



Then I shot the 48 gr load of H4831SC under the NOE bullet……holy smokes! It is very hard not to blow a group shooting through all those screens but when you can see the group in the scope (16X T-16) it is hard to hold steady!.. Group for the 10shots was .78”! Velocity was still a bit low at 2467 but the psi was still down at 36,800 psi. The internal ballistics were extremely good. Just look at how smooth and evenly matched all those pressure traces are!
Attachment 115434


So was that small group an anomaly? The test of 49 gr H4831SC showed it probably wasn’t. The 49 gr load went into a 1.08”group….MOA! Can’t complain about the accuracy but the velocity was only 2490 fps at 37,400 psi. Again the internal ballistics were excellent. While maybe not the best load in the .308W H4831SC is looking pretty good for the 30x57 (30 XCB) with its larger case capacity.
Attachment 115435


Next test will be to load up 50 of the 47 gr AA4350 load and test at 100, 200 and 300 yards.

Larry Gibson

[Ford SD]

Very Interesting and Thanks for spending / sharing so much information with us
I always read your posts

[Doc Highwall]

Larry, I agree about the placement of the strain gage over the center of the case which is where I have my strain gage placed in my Remington 40X in 7.62 NATO. Shooting AA5744 powder with the SAECO #315 bullet I have seen pressure spikes near the muzzle that were approximately 10,000 psi higher then half way down the barrel.

I will have to get out my other lap top that I use for the strain gage that has all the data to see what the actual pressure was. I think it was around 20,000 half way down the barrel and around 30,000 about 3-4" from the muzzle.

[Doc Highwall]

Larry, nice shooting and report in your test. How did you shoot these off the bench with a rest or prone with a sling?

[Larry Gibson]

Doc

Don't get me wrong, I'm not saying pressure spikes don't occur because they do. I was just pointing out the problems with the pressure traces used on that site. I have lots of examples of such. Recently when doing the 7.62x39 with LeveRevolution tests for Junior1942 I used 3 different factory loads (Wolf FMJ and HP and Herter's FMJ) and my own favorite load with jacketed bullets as "reference" since I had just installed a new strain gauge on the test rifle. All 3 of the factory loads exhibited post pressure peak spikes. So was there a problem with my set up? With the attachment of the gauge? or with data input? No there wasn't as the test of my own proven load showed. The picture of the traces shows The Wolf factory HP on the left. Note the typical post peak pressure spikes. The trace on the right is with my own load (125 gr Speer over 22.5 gr H4227). Note the smooth pressure traces. The tests were conducted about 40 minutes apart with condition be basically the same. The test rifle (Mini Mk X) had remained on the bench and connected to the M43 so there was nothing different except the ammunition itself. The black tick marks on the pressure traces denote muzzle exit.

The other picture is of the Palma rifle on the bench for the testing of the NOE bullet.

Larry Gibson

Attachment 115511Attachment 115512

[MBTcustom]

In case either of you two fine gents decide that your pressure trace equipment is just not performing properly, I would just like to offer my disposal services. Just saying.......

If I ever see one of those Ohler shooting labs for sale, I think I'll go take out a loan. I missed one several years ago before I ever heard of castboolits.com. By the time I found it, it had sold mere days before I saw it.
Yep. That's the one that got away. It was cheap too. I guess the guy didn't know what he had.

[Love Life]

So...not to be a bother, but when do the 30 XCB groups and info start rolling in?

[MBTcustom]

So...not to be a bother, but when do the 30 XCB groups and info start rolling in?

LL, the XCB boolit is part of the project as well.
I am only one guy, and this is the busiest time of the year for me (lots of people want to hunt with their brand new custom rifle instead of waiting for a whole nother year to show it to the buds at deer camp LOL!)
I don't know if Ian has done anything.
I don't know if Brad has done anything.
Bjornb is working up his cast loads and has done some impressive shooting with jacketed, but he just picked up his rifle a couple weeks ago.
run5runs rifle is finished (I hope) and I will be test firing it this weekend if the weather holds. As soon as I see a load give me 1/2 MOA, it's going in the mail. I was hoovering right around 1.25MOA last time out, and I concluded that it must either be the scope, or the bedding, so I stripped out all the bedding and redid it (better safe than sorry), and changed scopes, and I expect great things this time.
There are three more XCB rifles in cue (just got done reaming one 5 minutes ago) but the results are still in the hands of the shooters and owners of these rifles, and they are each at different levels of experience in this sport.
I am dying to get out with mine and do some testing, but to be honest, when I finally clear myself enough room to have a few hours piece, I really just want to sleep.
Oh well, the journey continues......

[Bjornb]

So...not to be a bother, but when do the 30 XCB groups and info start rolling in?

Well LL, since you just moved to Georgia you're always welcome to slide on down to Fort Lauderdale and shoot my XCB rifle. Really, I mean it. I'd enjoy that very much. I've got a decent loading room set up and a reasonable amount of supplies. I'm shooting mine again Sunday, got a lot of advice from Larry plus a bunch of the new NOE bullets cast up, so hopefully she will perform with cast.
BTW a box of 303 bullets went out to you this morning.

[Love Life]

Thank you Sir, and I'd love to meet up some time!! Are you using the copper enriched alloy or just good ol' Lyman number 2 alloy?

[Bjornb]

Good ol' Lyman number 2 for now, to stay within the scope of the XCB testing as originally laid out. I've got several pounds of Babbit and wouldn't mind cooking up some alloy using some of it. My issue with the Babbit is that there doesn't seem to be a standard for the alloy; it varies as to what it was intended for. I'll probably end up melting down some samples and see if Goodsteel can get them checked with his magic XRF gun.

[Love Life]

Dick,
How close to Clarks Hill reservoir did you get stationed?

About 4 hours away, but the majority of my family lives in Washington, GA.

[btroj]

Rest assured, Brad is doing plenty. If it stops raining he will be shooting today.

I have some ideas on where I want to go. Have had some initial success with higher velocity but have lots of room for more speed and better groups.

Just because it isn't posted doesn't mean it isn't happening. I just prefer to avoid the noise and distractions and do my own thing.

[Doc Highwall]

Larry, I know what you mean about pressure spikes as I have experience with them also. I believe they are caused from using too slow of a powder with a lite load and that the powder does not ignite till it is almost all the way down the barrel. I experienced this when not using a case filler, and I believe this is where using some would help.

First I am going to try a faster burning powder and if that does not work I will redo the tests using some polyester fiber fill in the case.

[runfiverun]

the filler quite often just takes place of more powder.
in the case of the slower powders like Larry showed in his earlier testing it's basically a "wash" when adding it or more powder as far as increases in velocity/pressure.
when working with an unkown powder/case combo i will quite often do a batch with and without and watch the results.
if the one with shows accuracy then i will replace the filler with powder as the next step and add filler again to the next batch.
if not then i slow down bumping the load and start working in 1/2 gr increments as i know i'm getting close.

[Larry Gibson]

Those with the faster twist barrels (10 and 12") are probably not going to load to case capacity and maintain accuracy with the 30x57 (30XCB) even with slow burning powders such as 4350, 4831 or RL19 under the 165 gr NOE bullet. Case capacity at 100% load density with those is going to be 52 - 53 gr which should be pushing the NOE bullet 2700+/- fps....which is probably a tudge fast for those twists. Might get close t 100% load density with regular 4831 though but it is going to be pushing that bullet hard in those twists also. With the others if load density gets at or below 85% then I suggest a filler of Dacron, Puf-lon, Grex #47 or the "Original" buffer.

Larry Gibson