34xcb?

[Wolfer]

Have I unknowingly built a 34XCB

I realize the XCB line is to get bench rest quality rifles shooting cast at high velocity. That was not my goal. I just wanted a cast friendly hunting rifle that utilized excess parts I had laying around. Plus it's been a fun project.

Recap
I started with a shot out 7x57 military barrel with small ring threads that would fit one of my Turkish actions.
Jim Dubell bored it to .338 with a 14" twist
I ran a .338-06 reamer in until it cleaned up the 7x57 shoulder.
I cut .260 off of my 338-06 dies and adjusted the shoulder down to where they would chamber. First one was cut a little short so the neck wouldn't hang up.
After fire forming I did a pound cast using Goodsteel's method to see that my brass could not be longer than 2.248

I trim my brass to 2.230

Ive been calling this a 34-57 because a case holds 57 gr of FFFg. On an old thread in the gun smithing section I called it a 34x60 because of the similarities to the 35x60 which is an 8mm case with a long neck.

What I have is a short 338-06

Would the original designers of the XCB line have a problem with me calling this a 34XCB?

[Old Coot]

Wolfer,
That's a very interesting cartridge and rifle. Have you been able to chronograph any loads yet?
What bullets are you casting for it?
I will be very interested to follow this thread and the development of this cartridge.
Brodie

[Wolfer]

The only 338 mold I have is the Lee 220 gr.
I got my barrel back pretty recently and have just tried to get it ready for deer season. That starts next Saturday.

My go to rifle/cast powder is 2400. 22 grs is where it started coming together. My chronograph said it was running 2075 fps. I'm not sure this is right. It seems a little fast to me.
Groups are running in the 2" range at 100 yds.
Im confident I'll get the gun shooting better than this but for now I'll take it hunting.
My throat mics .342 but the boolits I had cast are .339 and my alloy is 1 WW-2 lead, quite soft.
Ive mixed up some 50-50+2% and beagled my mold. I suspect this will help.
Woody Roberts

[Bjornb]

It sure looks like a 34 XCB (or a 338 XCB) to me. Cast the bullets hard, lube with White Label 2500+ or 2700+ (Carnauba Red), start with 45 grains of any of the 4350s for about 2300 fps. Great choice of twist. Move onto Leverevolution or even 3031 for higher speed. Good job.

[Larry Gibson]

Okay by me. Be interesting to have an actual 34 XCB to marry with that case.

Larry Gibson

[Larry Gibson]

So how is it shooting?

Larry Gibson

[Blackwater]

Very nice rifle and great thinking. I bet the deer are in trouble!

[Wolfer]

Larry
As deer season opens on Saturday once I got an exceptable load I quit experimenting and just loaded up some to play with. Groups from the bench ( which is two boards layed across my pickup bed ) will hover around 2" at 100 yds. I haven't shot any 10 shot groups yet but I can tell they will open to 3 maybe 4"

At 21 gr of 2400 the groups were stringing vertically. IMO this means a load problem, usually needs more powder. While 100 yd groups were acceptable 200 yd groups ran closer to 12".
At 22 gr groups leveled out, tightened up somewhat. My ES was 21 SD 5. Velocity 2075. This tells me I'm getting into the pressure area 2400 likes.
I tried a few shots of LVR but at 2300 fps I felt the pressure was too low for good burn and my soft /undersized boolits were not up to it.

I only want around 2000 fps with accuracy staying linear. I haven't shot the 22 gr load at 200 yet but I don't think I'm there.

This is a fairly short/ light hunting rifle and recoil above 2000 is more than I really want. I'm not recoil sensitive but if I need more power I have a 338 win mag.

Blackwater
Where I deer hunt 60 yds is a long shot. A good many of my deer are killed with my 45 colt. However I can't wait to blood this thing. I've been out a couple times trying to call up a coyote but no luck yet. We have a horrendous crop of rabbits this year and I suspect coyote calling will be rough.

[Blackwater]

Wow! Wish we had your problem with the rabbits! We don't have that many any more now that farming practice has changed so drastically. I miss a good meal of rabbit now and then, but with the scarcity, I won't shoot one any more. They're having a hard enough time with the coyotes, etc. now without me adding to it all, and I don't really NEED a meal of rabbit, but I sure do miss it.

[Wolfer]

I haven't eat a rabbit in a long time. When I was a young man we hunted with beagles and 22 pistols. We didn't kill many but it sure was a lot of fun. In a full day of hunting we rarely killed less than two or more than five. Just enough for supper that night.

Here they cycle every few years. I plan on eating a few this year. This summer it was very common to have nine in the yard at one time.

[GabbyM]

Very cool project Wolfer.


From the numbers you published it looks to be an ideal length for a Mauser action.


Looks like you’ll easily be able to exceed the cast bullet velocity limits of a 220 grain in 30-06.

[Wolfer]

A few years ago I built a 270 on a VZ 24 action. I had to do considerable work on the feed rails to get it to feed right.
For whatever the reason this one feeds like scum off a Louisiana swamp. All five go straight in.
Perhaps the shortening?

Im sure I can pass 30-06 220 gr velocity. However I've never been fond of 30-06 220 gr recoil in full power loads.

[GabbyM]

Hear that about the recoil.
I am a 30-06 shooter. Have a nice 220 grain flat nose from accurate Molds. Need to do more testing before posting a bragging thread. However so far it shows great potential. Power wise a ten twist 30-06 is obviously served with cast 220 grain bullets it's predecessor was designed for. For paper punching I like my Lyman 311672 in 160 grain. WE have a gong plate at the back side of our forty acre from the lot which is about 335 yards. Lyman 311299 at 200 grains is great for that but it does work you numb after about fifty rounds. 160 grain bullet still hits the gong and punches my shoulder about like an M-16. But we generally can't hear the gong ring. Need a spotter looking through a scope to see the little bit of swing upon the gong. It's a very heavy gong. With the 220 grain bullets. I can hit it, chamber a round then still see the plate swinging. But yes it kicks on both ends.

[JHeath]

Cool. It bridges the performance gap between the 33xcb and the 35xcb. Only a matter of time before we wake up to the 34xcb wssm ai, for that something extra.

Just teasing a bit. Neat project.

[Doughty]

Wolfer,

I shoot a similar cartridge. I call it a .33 Krag. As the name suggest it is a .30-40 Krag case blown out to .338. I believe this would be very close in case capacity to your case. My full power load uses a 225 gr., gas checked cast bullet. Loaded with AA 2520 at around 44 grains it gives 2400 fps. I fire this in a custom Ruger #1 with a 1-12 twist Lilja barrel. Recoil is stout, but I have killed a lot of big game with this load.
Another load is a plain base 247 grain cast bullet using around 16.5 grains of AA #9 which gives around 1400 fps. This is a very pleasant load to shoot. It is very accurate but is on the verge of stability problems at 200 yards.
I think you will come to really like your new rifle, even if it is constrained by the limitations of a bolt action and a rimless case ;>)

[Wolfer]

Capacity would be very close to a 33 Krag. I'm not sure how long a boolit/bullet I can stabilize in this 14" twist. I suspect the Sierra 215 gr would have to be pushed pretty fast.
The online twist calculator I used said this Lee boolit would stabilize in a 17" but it had to be going faster than I wanted.

As I recall the Barnes 210 TSX required a 12" but if I need to shoot them I'll use my 338 mag.
NOE has 201 gr listed that I like the looks of but showing 0 in stock.
I would really like to have a scaled down version of the RCBS 35-200 with a small HP. I don't know what that would weigh, 190 maybe? We've shot one coyote with this Lee boolit in my 338 mag. One kill does not a story make but let's just say performance was superb. The HP is probably not necessary. Especially when velocity passes 2000 fps.

Ps
I've always been fond of single shot rifles but have never owned one.

[frnkeore]

I shoot a 242 gr, PB, 1.19" long bullet at 1470 fps, in a 14 twist barrel. I also shoot the NOE 340 224, that that is 1.13" long and weighs 232 gr, in my alloy. The 242 gr is a custom bullet but, the NOE is available in PB and GC. I can shoot, at that same velocity another custom bullet that is 1.25" long plus, the NOE 340 365 that is 1.32 long.

Frank
153112153113153114
---------Custom 1.19 -------------- NOE 340 224 ------------------------ NOE 340 224
153115
NOE 340 365

Lines and dots on last 3 targets are 3/4". All targets shot at 200 yards

[Wolfer]

The Lee is 1.030. I fire formed my brass with 11 gr of unique. Didn't chrono them but they were very mild and seemed quite accurate.

[frnkeore]

I have that same bullet mold but, I bought mine 20 years ago. I never tried mine in this rifle because the bore riding nose is undersize. I hope the later ones have corrected that.

One other thing about the NOE 340 224, it is designed to fit the neck and throat of the 338/06.

Frank

[runfiverun]

well your super close to the xcb V-2 I have been after Tim to build for quite some time now.
I wanted a slightly longer case length, but you have the idea.

[taco650]

This is an interesting twist on the XCB theme. Why did you choose the 1/14 twist? A lot of 338 bullets are long and since you're not going for max speed like Larry & Bjorn are with the 30 & 35 XCB's, I would think a little faster would be more stable.

[Wolfer]

I didn't really plan on shooting anything longer than the 220 Lee. From what I could tell from online twist calculator that boolit could be stabilized in a 1/17 but I was afraid I would have to push it faster than I wanted to.
I wanted to be able to shoot some mid power loads in the 1500 fps range. I feel like this will let me do it.
Eventually I plan on getting a 200 gr flat nose mold but not sure when or where.
The round nose Lee cast soft has been doing an excellent job on game so far.
Ive cut the stock to fit me. It wears a 2-7x33 Leupold and Timney trigger. So far it is everthing I hoped it would be. It's short, light and handles like a grouse gun. Has the ability to shoot any old range scrap with plenty of power for deer.

[Wolfer]

well your super close to the xcb V-2 I have been after Tim to build for quite some time now.
I wanted a slightly longer case length, but you have the idea.

R5R
Were you wanting to stop your shoulder where the 8mm Mauser does? Then add a longer neck?

[frnkeore]

I didn't really plan on shooting anything longer than the 220 Lee. From what I could tell from online twist calculator that boolit could be stabilized in a 1/17 but I was afraid I would have to push it faster than I wanted to.

The Lee bullet will actually be stable at 1400 fps in a 19 twist barrel, 14 twist handles 1.32", 12 twist, 1.5" and 10 twist will handle a bullet 1.8" long, all of them at 1400 fps.

If you build a rifle with a new barrel and don't do your home work on the actual twist needed, you give up one of the perimeters to accuracy.

The twist rate calulators are real and accurate. The twist rate calulator, gives a stability factor of just over 1.5 (near perfect for balance) for my 1.32 long bullet @1470 fps, in a 14 twist and you can see from the target, that even at 200 yards, it shows no sign of instabity (tipping).

For accurate opinion to be formed, the data that creates it needs to also be accurate.

Frank

[Bjornb]

This is an interesting twist on the XCB theme. Why did you choose the 1/14 twist? A lot of 338 bullets are long and since you're not going for max speed like Larry & Bjorn are with the 30 & 35 XCB's, I would think a little faster would be more stable.


When I first read Wolfer's OP I was mostly intrigued by his cartridge dimensions; he has truly created an "XCB" type cartridge, as far as the case dimensions are concerned. The fact that the first rifle chambered has already drawn blood makes the project even more impressive.

That being said, the rifles and cartridges are just part of the XCB project; shooting cast bullets at high velocity is the other half. That's one reason why Goodsteel designed the chambers of both the 30 and 35 XCB with very tight neck clearance; neck turning is required.

The reason I gave specific loading advice in post #4 is that I'm truly curious about what kind of velocity you'll get if you try to push that Lee bullet, cast from a harder alloy, into the 40K psi range.

I have read and re-read Frank's posts; did you join the XCB fraternity Frank? Those speeds you describe are a little pedestrian don't you think?

Good job Wolfer!

[Larry Gibson]

frnknore

So why are all you accuracy only shooters using the slower twists at those pedestrian velocities?

Wouldn't a faster 8 - 10" twist do just as well?

Larry Gibson

[Wolfer]

Thanks Bjornb
After deer season I plan on putting it thru its paces. Just for curiosity sake. Since I'm primarily a hunter and rarely shoot off a bench my accuracy demands may not be as high as many folks are.
For instance at the longest distance I might shoot if a gun will land EVERY shot within 2" of my crosshairs I consider it good enough to go hunting with. Most of my guns will do considerably better.
Elk hunting rifles have different requirements than whitetail rifles.
Ill keep you posted.

[frnkeore]

Velocity really doesn't mean anything to me, unless it comes with accuracy. Show me how you can get the same accuracy as I posted, with PB bullets at 200 yards and 3000 fps and I'll be all over it.

My input here was only on bullet stability. Velocity doesn't have a lot of effect on stabilty but, if a bullet is stable at <1400, it will slighty increase as velocitys go higher. Shooting is still very subjective (meaning everyone has there own ideas) and that is very hard to change. My only concern here is accuracy, wether it be in word or on the target.

Frank

[Larry Gibson]

No need to get defensive Frank. I wasn't criticizing your concern for just accuracy or the sport you engage in. I just wanted your input on two questions relating to your post #24 regarding your statement of " If you build a rifle with a new barrel and don't do your home work on the actual twist needed, you give up one of the perimeters to accuracy."

I happen to agree with that statement and just wanted a bit of further input from you. No need to justify what you do, just asking the reasons why the slow twists and wouldn't a faster twist do as well(?). An answer to the questions would be appreciated. If not then that's okay by me.

Larry Gibson

[taco650]

I didn't really plan on shooting anything longer than the 220 Lee. From what I could tell from online twist calculator that boolit could be stabilized in a 1/17 but I was afraid I would have to push it faster than I wanted to.
I wanted to be able to shoot some mid power loads in the 1500 fps range. I feel like this will let me do it.
Eventually I plan on getting a 200 gr flat nose mold but not sure when or where.
The round nose Lee cast soft has been doing an excellent job on game so far.
Ive cut the stock to fit me. It wears a 2-7x33 Leupold and Timney trigger. So far it is everthing I hoped it would be. It's short, light and handles like a grouse gun. Has the ability to shoot any old range scrap with plenty of power for deer.

Sounds like a great combination for a "home-grown" hunting rifle! Enjoy!

[Larry Gibson]

Wolfer

If you ever get interested in the HV end for that rifle then Accurate may be able to make a bullet of appropriate design. Basically a fatter 30 XCB (or skinnier 35 XCB) would be ideal. Maximizing bearing surface (60+ % of bullet length is best) with minimal lube groove depth and a short nose that begins it's ogive at the lead with no bore riding length would be best. Accurate's FN 30 XCB could perhaps be enlarged to fit the .338? That Accurate FN XCB has held up quite well in 14" twist .308Ws and 30x57 XCBs. The only change I would suggest would be to make the lube grooves only .008" deep. That should be a very good cast bullet for HV use in hunting.

Larry Gibson

[Wolfer]

Larry
I can't find any info on those molds on the accurate website.

[Larry Gibson]

Should be the 31-160G. Accurate may not have it on their web site. Enlarged to .340 it may weigh close to 200 gr.

Larry Gibson

[oldblinddog]

31-160g
153837

30 XCB
______________________________
31-180Q
153838

Ranch Dog with XCB lube grooves.

[Wolfer]

Is there any reason those boolits wouldn't work as well at a lower velocity. Say 1600/2000 fps?

[Larry Gibson]

No reason at all. Should be fully stabilized at 1600 fps if the bullet is not over 1.25 in length.

How long is the bullet you are using?

Larry Gibson

[Wolfer]

The Lee is 1.030

This boolit/ gun has taken 3 deer so far and I have to say performance has been excellent. After deer season I'll get it shooting better I'm sure. It's plenty accurate to deer hunt with but I'm sure it will do better.

[Larry Gibson]

As frnkeore mentions in his post above you shouldn't have any trouble with stability with the Lee bullet. The Applied Ballistics program shows it to stabilize at 300 fps in a 14" twist. Appears it's meeting your needs quite well. Be fun to see if the Lee holds to HV though. Just depends on what you want it for and what you want it to do.

Larry Gibson

[Wolfer]

I have mixed up some 50-50+2% I'll water drop some of them and see what they do.
Ive only used LLA in my rifles. I had to put on 3 coats to get past 1700
I lubed a few with my home made lube I use in my pistols but didn't shoot very many. They shot the same as the LLA at the time. I'll try it again with the harder alloy.

My lube is about 60% beeswax and 40% Corona wound salve. The salve is a beeswax/lanolin mixture. I add beeswax until it's about the consistency of NRA 50/50.

It goes against my grain but I may have to buy a suitable lube.

[Larry Gibson]

If you do check out Lar's NRA 50/50 or 2500+ lubes.

Larry Gibson

[Wolfer]

In speaking with Tim this morning I found out the XCB name is copyrighted. Hereafter I will refer to this cartridge as the 34-57
Woody Roberts

[taco650]

In speaking with Tim this morning I found out the XCB name is copyrighted. Hereafter I will refer to this cartridge as the 34-57
Woody Roberts

Works for me. I'm sure you don't want Tim, Larry, Bjorn and the other XCB originators sending their attorney after you for copyright infringements LOL!

For what its worth, I think you've come up with a great medium range big game caliber! The basic components are quite common and easy to find. BRAVO!