Testing the 30XCB

[Bjornb]

your primers WILL definitely affect the powders you use.
with rl-19 I have found that the federal large rifle [210] or the rem 9-1/2 to be the primer of choice in almost all of my rifles I use it in. [with one exception the mag-tech 9-1/2 in my 257 bob]
the 25-06's both like the fed, my 7x57 Ackley likes the 9-1/2, the 7x57 likes the fed, but all the rifles shrunk groups by about 25% just through this one change.
H-414 might be worth looking at too, we have to balance out the pressure rise with the boolits
mush-ability.
backing the boolit out of the rifling is also something that may help too. [especially when switching to a faster powder]
jamming the boolit in the throat can cause the slower powder to increase it's burn rate, something I learned the hard way [using 7828 in the 0-6 with an oversized 314299]

I'll be doing a lot of testing with CCI 200, there's no Federal 210s available around here, been looking everywhere. I shot CCI exclusively before the shortage, and never had any issues.
Since I got me a Hornady OAL gauge and Tim made a modified XCB case for it, I have been able to seat bullets much more accurately. Right now I'm seating the NOE about 15-20/1000s off the rifling.

Today I discovered a stash of about 250 Norma cases in 7x57 that I had forgotten about, and I've spent most of the day converting them to XCB. These cases, being unfired and chamfered, measure 56.4 mm after being necked up. That's slightly shorter than the XCB cases I've been shooting (made from W-W 30-06 brass), and the Norma brass feels softer (cutting necks now), so It'll be interesting to see if that has any effect.

[runfiverun]

a little voice inside my head went yeahhh then NNNNnnnoooOOOOO!!
when hearing bout that norma brass.
no cut necks unless they won't release the boolit, you want the thickness to help center the boolits center with the center of the barrel.

[Bjornb]

OK thanks, still setting up, none cut yet, will try to load some before cutting. No damage done.

BTW just miked the Norma case necks. I turned the Winchester brass down to .0125 thickness; the Norma necks seem to all measure between .0125-.0135 uncut. So I'll definitely leave them alone for now.

There are 2 different Norma head stamps; one says Norma Re, the other just norma (small n). Not sure if that makes any difference.

[taco650]

Larry & other testers,

Reading the powder choices you are trying, what about my old favorite IMR 4831? Since I'm not going to have one these rifles built & am just sitting on the sidelines as it were, please forgive me if my suggestion is bad.

[Bjornb]

Larry & other testers,

Reading the powder choices you are trying, what about my old favorite IMR 4831? Since I'm not going to have one these rifles built & am just sitting on the sidelines as it were, please forgive me if my suggestion is bad.

Your suggestion is absolutely not bad; I'll be testing IMR 4831 in my XCB rifle very soon. I'm a little behind in bullet casting (hate casting in 95 degrees), but I'll be posting the results when I have them.

[runfiverun]

45 grs of 4831 will get you some velocity. [bout 2400 fps]
if you go much below that the powder won't fully burn.
Dacron does help clean it up.

[taco650]

45 grs of 4831 will get you some velocity. [bout 2400 fps]
if you go much below that the powder won't fully burn.
Dacron does help clean it up.

I've used it a lot in my '06 and its worked well in my factory M-77 all these years but like you suggest, the loads have filled up the case.

[Bjornb]

I'm taking a slightly different tack in planning a range trip for tomorrow (weather permitting). Running low on bullets, I loaded a total of 70 rounds with 5 different powders: AA4350, H4831SC, W760, IMR4831 and H1000.
No single charge got more than 5 cartridges loaded. Not overly scientific, but it will allow me to cover more ground and try to single out good trends. I'll be shooting newly formed cases (Norma 7x57), necks not turned.
The bolt closed with just a little extra effort on a seated .310 bullet, and extraction of loaded rounds went OK with the bullets keeping their seating depth. I seated all bullets to about a 5/1000 jump, using the ogive attachment (bullet comparator) on my Stoney Point tool.
The only variable that has completely changed is primer choice, all rounds are primed with CCI 200, 2013 batch.
Since barrel heat may have been a factor in previous outings I'll be pausing 2 minutes+ between shots.
Bjorn

[runfiverun]

regular norma was the stuff you bought pre-loaded, the Re marked stuff is components.
I doubt there is any difference, but might be norma's way of assuring new brass to their customers.

[Bjornb]

Yeah that makes sense. I went back in my records and looked at when I bought that brass. I said it was unfired, but it's really once fired, just cleaned in a SS tumbler. That had me fooled for a bit. Some guys really know how to get their brass shiny....

[FrankG]

Ive been following along and have a question on the round , I checked manuals and find the 7.7 x 58 jap close to being a twin , not identical but very close .

That being said , 4320 and 4064 worked very well in a Jap sporter I had many years ago . It had a very good bore and tighter than usual chamber for a war time rifle . I used 30-06 G I cases reformed in Herters dies .

[runfiverun]

the 7.7, 303, 7.65 argie, and x54r are all close in case capacity.
their loads can be slightly modified to make loads for this round.
the only one really close in pressure is the x54 round.

the two loads I posted earlier [with the jacketed bullets] were both done this way.

[taco650]

Larry,

Thanks for the explanation about grain size, etc. I was only looking at burn rate & that's why I suggested it. Now I will shut up and "watch the show"

[geargnasher]

10-shot, 2 MOA, at 2600 fps? I'm getting that now with a ~182 grain bullet, 12-twist, and H-414. Haven't checked the dispersion at longer ranges yet. It appears we all have different standards, different approaches to loading/building them, and different goals, which is fine and will show the versatility of the cartridge (like all cartridges similar to it), but mine is a bench rifle and if I can't make it shoot 3/4 MOA at least at near the top of it's velocity potential I feel that my work isn't done.

Gear

[MBTcustom]

That's Awesome Gear.

[geargnasher]

For a rifle that put five 150 gr. Berger Match bullets into .084" at a hundred yards after two sighters/adjustments with the first (and last) load tried w/jacketed, I think my 2MOA load sucks rocks and I have a lot left to work out. If anyone wants to duplicate that, they can go with fireformed brass, un-annealed, necks at .0133", Miha/45 2.1 "30 Silhouette" from water-quenched 50/50 @ 19bhn, seated .005" off the throat, Federal LR primers, SL-68 or Felix lube, and work up from 43 grains H-414 in half-grain increments until you get to 2600 fps. I'm not giving my load because it's pretty hot, USE YOUR OWN JUDGEMENT ABOUT WHEN TO STOP INCREASING THE POWDER CHARGE. Same powder gets under 3/4 MOA at 2400 fps, right where the alloy gives up in every .30 caliber I've shot it in including two ten-twists factory .308's. This is a 12-twist, 23.5" barrel.

Maybe some of you fellows who ponied up the bucks for Quickload could help us out here with some pressure estimates? My barrel is six groove, narrow lands, I'd have to look up my case volume, but I'm using military brass and it's a bit smaller than some of the numbers I've seen here. IIRC they hold about 48 grains of H-4350 to the BASE of the neck.

Gear

[MBTcustom]

I have Quickload. If you PM me your h2o weight, and two powders you have tried with average speeds at a certain charge weight, I can get close to good estimate.
Of course, that's assuming Quickload is accurate on its pressure estimates.

[geargnasher]

Cool, Tim, will do what I can. Honestly, I only chronographed the H414 loads because of the several other powders tried it shot the best by far with three bullet designs all close to the same weight. No sense in dragging out the chrono if only half the shots hit the paper. Yeah, load development hasn't all been roses.

Gear

[MBTcustom]

Understandable. Just give me two loads with that powder (preferably loads where the spread settled down to a low SD)
That way, I can attempt to marry the program to your particular situation.
At least that's what I do. It's the only way I can call my shot with a new load and get close to the speed QL advertises, and I assume the pressure would be no different.

[Bjornb]

Some more lead was flung downrange this morning by Big Bertha, my XCB rifle.


As mentioned in a previous post I was running low on NOE XCB bullets, so a number of 5-shot strings were loaded.
For this outing I used newly formed, once fired Norma 7x57 Mauser brass, run once through the XCB FL sizing die and the case mouths chamfered. On advice from Runfiverun none of the case necks were turned. Of almost 70 rounds shot, maybe 5 required some effort to close the bolt (bullets sized .310). Good call.

The powders shot were: AA4350 (to establish baseline and repeatability), H4831SC, WW760, IMR4831 and Hodgdon H1000.
The only MAJOR changed variable was that CCI 200 primers were used instead of WLR primers. The cases were obviously also a changed variable, but I'm not really qualified to judge how much that changed the outcome today.
Lars 2500+ lube and Hornady gas checks were used as before.
I'll let the photos speak for themselves:


Velocity in the first picture was 2325 fps, not 2375 as written.