More 9.3 x 62 Work

[9.3X62AL]

I know you folks are probably way past tired of hearing about this caliber and the CZ rifle from me, but indulge me just one more time--yesterday's Burrito Shoot was a fine day indeed.

The CZ wasn't used for the Shoot, but did come along for recreation. I installed a Leupold 2x-7x atop the rifle last fall for the Alberta trip, and that scope remains in place. I had not yet fired any castings from the rifle so equipped, so I de-coppered the bore Monday night to give the Mountain Molds 270 grain flatpoints a test-drive. Earlier work with this boolit and 18.0 grains of 2400 gave good service with the open irons, but velocities were a little lacking for a hunting load--about 1525 FPS, so I boosted the charge to 22.0 x 2400, hoping for around 1700 FPS and continued accuracy.

Well, the accuracy continued.......and how!

I started at 50 yards, and the scope setting for the 286 NosParts was pretty close for the cast loads. I began with 5-shot groups, and noticed that the first two or three were right on top of one another, and the succeeding rounds seemed to cycle outward. Hmmmmm.........cut things down to three round groups, and got one at 50 yards that Buckshot called 3/8", the rest hovering between 3/4" and 1", and one round a little out from the other two. I would say bedding might be at fault, but the groups weren't drifting around from the sighting points taken, as will occur when bedding is at question and you fire 3-rounders to see where the group centers drift.

I was pretty happy with this work, and Buckshot made ungracious remarks about me not trying the rifle at 100 yards. Slapped around in this way, I moved the target board out to 100, and was I ever glad that I did! The grouping behavior held, 3-rounders staying at or under 1.5", and two of those shots were often VERY close. Again, no "center drift" from group to group. I set the rifle to shoot these 2" high at 100, and I believe my "close rifle" for deer season is SET.

Every time I shoot this rifle--jacketed or cast--it makes me happier and happier.

[Bass Ackward]

I started at 50 yards, and the scope setting for the 286 NosParts was pretty close for the cast loads. I began with 5-shot groups, and noticed that the first two or three were right on top of one another, and the succeeding rounds seemed to cycle outward. Hmmmmm.........cut things down to three round groups, and got one at 50 yards that Buckshot called 3/8", the rest hovering between 3/4" and 1", and one round a little out from the other two. I would say bedding might be at fault, but the groups weren't drifting around from the sighting points taken, as will occur when bedding is at question and you fire 3-rounders to see where the group centers drift.


Al,

I don't think that's bedding. Sounds more like lube. As the barrel heats up, your lube left in the barrel starts breaking down and groups begin to open.

To know for sure, try 5 rounds fired 60 seconds apart and monitor barrel temp. No need to over heat. Then fire 5 and wait until totally cool how ever long it takes. If groups are smaller waiting than warm, then your lube doesn't like the heat.

You could go harder on the bullet or change lube. Or .... do yourself a favor and go to a slower powder. That thing ought to just love close to a full case of H-4831 or RL22 or something in that class for about 2200 fps. Oh it will shoot dirty alright, but your bullet will look at it as lube.

[9.3X62AL]

Bass--thanks for the suggestion, sir! Once the heat leaves in a couple months, that will get a try for sure. Lube was Javelina Alox, FWIW.

[Bass Ackward]

Bass--thanks for the suggestion, sir! Once the heat leaves in a couple months, that will get a try for sure. Lube was Javelina Alox, FWIW.


Al,

I .... suspected. 50/50 is the best for putzing but there are two things it doesn't like. Pressure and .... heat.

Running some data looks like about 52 to 56 grains of one of those ignited with a magnum pistol primer .... assuming you get a lube for that velocity level. The better the grade of lube, the softer in metal you can go.

But you know this. You just have to get over being afraid of the ol'girl and step on her. :grin:

[NVcurmudgeon]

Al, excelent results! I would suggest that you test higher speed loads in hot weather. I have built some pretty good loads in cool weather, only to have them turn into sour apples when the weather heated up. I think it is a case of velocity outrunning the lube, alloy, or both.

[Buckshot]

.............Well Al's work at the bench and his rifle and load performance was certainly darn good. He failed to mention that his last 2 groups at 100 yards both dropped in at 3/4" (3 shots). So the couple wide 'spoilers' previously had disappeared. The temp at the range yeaterday was in the low 90's and it didn't take too many shots to warm up a barrel.

He definately has a good hunting load as it now stands, and some dinking with lube, possibly another primer and maybe even scaling the slugs would have a positive effect. Might even try sneaking up another couple grains of powder, or as suggested, going to a little slower powder. If nothing positive results, Al still has the 'original recipe' :-).

Still, consistant 3 round groups hovering around an inch at 100 yards with a 270gr slug @ 1700 fps, is still a dandy hunting combination.

..............Buckshot

[swheeler]

DA; sounds like it would make a fine buck buster witgh cast, I looked at a CZ 550 American-IIRC locally, nice fit and finish, priced pretty decent too!

[9.3X62AL]

I think the next few range trips will include "cold shot" targeting from a clean/cold barrel, since this is the condition it will fired in while afield. Same story with the Ruger 77R in 6.5 x 55. These two rifles will be my game battery this year.

SW, check the rifling twist rate in the newer CZ's......I heard rumors that the rate had changed from the 3 turns/meter (1-13.3") to 4 turn/meter (about 1-9.8"). This was done to enable use of Woodleigh and other makes of 320 grain bullets. Check with CZ-USA to confirm that, I haven't done so.

[swheeler]

Yep,web site list it in inches 1/9.5- cast shooters always sucking hind teet!

[9.3X62AL]

Kind of a shame, that--the caliber did stellar work for 90+ years with the old twist and 286 grain bullets, and a company finally starts importing rifles in some number to the USA........and they re-pitch the barrel to satisfy the "Bigger Is Better" clique. Had this been the situation at the time I bought the rifle (summer 2002), I would likely have opted for a 35 Whelen--or re-tubed a 30-06, although .366" barrels are a little scarce.

[Nrut]

Yep,web site list it in inches 1/9.5- cast shooters always sucking hind teet!

swheeler....I ordered a CZ550FS late last fall and after reading this thread about CZ going to a faster twist I got a little nervous so I pulled a cleaning brush thru the bore last weekend and came up with 1:15 close enough to the 1:13.3 Deputy Al is talking about....So there may be some slow twist CZ's still floating around out there.....I got a .368" push thru resize die from Buckshot this last Friday and resized a bunch of RCBS .375 bullets last night....The gas check is below the neck as 45-2.1 said they would be in another thread......Going to the range today to see how they shoot.....I'll do this until my NEI mold arrives if the cold weather does'nt get me first........You going to smack a Buffalo again this year?

[swheeler]

If I get a buffalo this year it won't be the one I want! FWP drew for permits, early I might add, and guess what, unSUCKessful- but I will keep applying for buffalo and moose until I draw- I may have to have someone carry the rifle for me until I get my walker within range tho.