Build one of each and see which one handles pressure better.
I’ve build cheytac diameter stuff in a savage shanked barrel. It won’t run the pressure a big shanked action will. Very noticeable
-
Having trouble using the site?
Contact support
The new 33XC & 37XC cartridges designed by David Tubb
- Thread starter Butler12
- Start date
I’ve build cheytac diameter stuff in a savage shanked barrel. It won’t run the pressure a big shanked action will. Very noticeable
I think the AXMC has a 1.3" barrel shank diameter
I wonder if that would be good enough to use that platform assuming you were okay with single feed?
I wonder if that would be good enough to use that platform assuming you were okay with single feed?
I’d think it absolutely would be ok.
The tenon on the big AI is 30mm, that’s over an inch and an eighth I think.
I have a buddy right now having sad boy issues with 338 Norma with a standard rem 700 tenon.
He just can’t push it at all.
That was one of the reasons I went with a rum based 338.
It can be done but it has limitations.
I found the tubb ATR has a 1 1/8 x 18 tenon and a pretty chunky barrel extension.
Makes sense.
Yeah, that tiny bit of extra steel doesn’t seem like much but when you look at hoop strength numbers, it sure adds up quick
I would expect this since the cheytac stuff has a bolt face of .640. Now you're thinning the chamber wall too much. Not so with the .585 bolt face of the XC cartridge and extended length. To paraphrase my post above, if you are safe running 338LM in said action, you should be safe running the same action in 37XC as long as the chamber wall thickness remains the same the full length of the case and then some. Just an opinion but 41XC is getting the point it's thinning the wall too much and generating some pretty good ft-lbs. Read Tubb's article on XC. The point was the smaller bolt face.
Don't forget, the case diameter isn't changing with 37XC, just the bullet diameter. The chamber surface area ratio to case volume isn't changing from the shorter 338LM case much either.
Last edited:
I’m not referring to safety. I know they’re not blowing up. I’m referring to running them to their potential. Sure you can run a LM in a 700 and it works just fine. Remington made a 338LM in a factory 700. They wouldn’t do that if their testing and lawyers thought it wasn’t safe.
You know the 37 and 41 are the same diameter case right? How do you say the 37 is all good but the 41 is thinning the wall too much?
There’s a good reason lapua boltface actions like the surgeon 1581XL and stiller Tac338 beefed up their tenons and shank requirements.
In my experience with similar shank and tenon sizes having a stout custom action had always shown to handle pressure better than a production action like savage and Remington but that doesn’t allow you to fudge needed wall thicknesses.
In my experience with similar shank and tenon sizes having a stout custom action had always shown to handle pressure better than a production action like savage and Remington but that doesn’t allow you to fudge needed wall thicknesses.
Yes. See my post directly above yours. I'm open to info. What is the minimum diameter tenon you would run with 37XC?
Also, I posted on Dec. 19th about my MRAD 33XC barrel being built and the tenon diameter. Since then I read about the additional chamber surface area to volume but can't remember where now.
Last edited:
If anything, wouldn’t the 41XC have less peak pressure under higher powder charges because it has a higher volume for pressure to escape?
I’m sure the nuances of powder type being used has an impact on this but one should be able to cram more faster burning powder in the 41XC as opposed to the 33XC. In my mind it would seem that the 33XC would need more material to get to a safe potential peak pressure than the 41XC.
I’m sure the nuances of powder type being used has an impact on this but one should be able to cram more faster burning powder in the 41XC as opposed to the 33XC. In my mind it would seem that the 33XC would need more material to get to a safe potential peak pressure than the 41XC.
If peak pressure was directly in front of the chamber, wouldn’t an argument be made that more material would be require to reach its max potential than say a peak pressure occur some distance past the front of the chamber? I’m assuming that because the pressure is over more volume that it would require less material to reach max potential.
I did. I was thinking due to the energy pushing 9,000 ft lbs. a thicker chamber would be warranted. But that is just gut feel. I've been wrong plenty of times in my life and definitely not claiming to be the expert here. The gentlemen above spoke of the Surgeon 1581XL as being beefed up. But it still has a 1.125 threaded tenon vs. Deviant Tactical 1.06", which is chamber wall difference of 1/32". Someone else said going below .240 is a bad idea, which the Deviant is just below. A poster on the LRH forum talking about .338LM Deviant actions with chamber setback but again, it had probably been pushed to the limit. Still think since XC is longer case, bolt thrust would be same or less.
The MRAD is 1.1" for the first 2" from the bolt face (0.258 wall), leaving only about an additional 3/8" of the XC case in the 1.188" threaded portion for the MRAD interface. I'm still about 3-4 months for it being complete, so I will report back with results then.
I actually have a TacDriver 1.6” build going on right now in 37XC and I have two other MODBB barrels for the 33XC (might be selling the barrels). The A6 Supermag stock and Cadex Dual Strike Chassis are two I’ve seen personally. The Beast stock can work as well.
What I went with and what I wanted are two different things so keep that in mind. I went with a Krieger MTU that is 1.45” diameter at the shank. 36” with a 35” finish length. That is what was available locally so it was a constrained decision.
When I think about heavy class ELR rifles:
I personally want the shank length to be longer say 5” to 8” but I also like the extra weight. For the TacDriver action I want a shank diameter no smaller than 1.35”. 1.35” diameter can be found in stock some times but with the economy the way it is I wouldn’t count on that anymore.
My 33XC barrels are 1.35” diameter for 8” then taper to 1.25” at the muzzle for a finish length of 30”. So, not quite a straight taper but close. I do not plan to use these in a light class. These are for fun. I feel like these are beefy enough with the TacDriver action to get all the potential out of the 33XC cartridge.
When I think about light class ELR rifles:
If I was wanting a lighter configuration then I think the 1.35 or 1.45” MTU is a good compromise. Although I’d rather the shank length to be around 5” for something as long as the XC cartridges.
I am thinking of building a 33XC on a long action impact. I can save a ton of money being able to buy stuff off the shelf instead of having to custom order and wait.
I see the debate on the tenon thickness, is it really that much of an issue or overblown?
I see the debate on the tenon thickness, is it really that much of an issue or overblown?
I think it depends on the barrel, powder, and bullet combo but I think it could be the difference between an action getting pressure at 2900fps and 3300fps with a 300gn class bullet. We lose accuracy when we say general statements so consider that when I give you those velocity ranges. I experience it first hand.
Probally going to go for a strait taper 1.25 out to 30" shooting 300gr on the milder side to preserve barrel life.
2900 is 338 edge territory, I’d be pissed if I was burning 120 grains of powder for that speed or anything close.
If I could do it over again I would have did a 338LM IMP. I don’t see much reason to shoot a 300gn bullet over 3000fps. I thought it was cool initially but eh not so much anymore.
What about the 338 norma? All i know is i want a big bore i can run on a normal long action with lapua BF
Because of my budget and the Canadian law, I’m stuck at 300PRC in a factory barrel for now. If your budget doesn’t constrain you, spend the $$ upfront or practice offhand unsupported. Half ass is dumb ass. If you can’t afford to shoot it enough to burn out a barrel, be realistic and step down in performance before you put your build together. It sucks being a poor, but a honest man has few detractors.
Fantastic cartridge but not a powerhouse unless you run the improved version.
Mag feed 250’s and 300’s easily and it’s super easy to get a good load.
It’s about 150 fps behind my 338 edge with 300 OTM’s or 285 solids.
I started doing some speed and Pressure plots from data tubb posted.
Some interesting pressure plots that I need to work back from loads from others with speeds.
I have a 30” 33xc barrel for my AXMC, I got really early pressure at 3125fps / 125gr 50bmg with 300gr Berger. For my 338nm barrel , I got excellent result ,2950fps 88.2 RL26 5fps ES with badland 250gr solid. Those badland bullet is no joke.
if you work that out it’s easy to see why you had pressure.I loves me some badlands!
I’m having real good luck w Warner Flatline 256 in a 338 LM AI. Pushing them at 3350 fps w N570
Pressure Testing the 33XC
Load Developing for ELR cartridges comes with special considerations, both for accuracy, but especially for cost. Every time you pull the trigger a lot of money is heading down range. The projectiles are significantly more expensive, the powder charges are large enough that powder costs...
www.coastalprecisionconsulting.com
Don’t overlook the time tested 338 LM. Plenty of brass and factory ammo available!
Long live the 338 LM
Even at 2700-2800 of standard lapua and Norma with 300 OTM’s I’ve seen some good results out at 2500-3000.Don’t overlook the time tested 338 LM. Plenty of brass and factory ammo available!
Long live the 338 LM
Definitely better splash than my 7mm.
Or you could set them up for 250-265 solids
Last edited:
I ordered (200) 338 285gr Warner Flatlines but at shotshow, a person with massive experience in this area told me I would most likely have better luck with the Badlands 275gr Super Bulldozer 2. I am hoping I can use that bullet for my MRAD 338NM barrel and my 33XC MRAD Barrel. With the Badlands high G7BC, I do think there is a benefit to pushing it over 3100 fps. TUBB was getting 3200 with the Warner bullet. Barrels are relatively cheap but finishing them and load development is not. Turning the ModBB for the MRAD interface is going to be around $1900 all in. This same person told me the Bartlein ModBB was showing much promise in extending barrel life at least 30 to 40% depending on how hard you are pushing it. I will be disappointed if I can't get into the 3100's with the Bartlein/Badlands combo. Will probably sell my 200 WF 285s with TUBB ring mod.
I have the Warner 285 with tubb nose ring. I used 50 bullets for 33xc load development, still haven’t got my ideal load. Kinda frustrating . Meanwhile I have 2 338nm barrels and I ordered some badland 255gr. 15 rounds later I got my perfect load , under 10 ES , .4 moa (5rds) at 110 yards.
8 , I used H50bmg which tubb recommended but I haven’t found the node From 120~128gr. @128 I experienced pressure with heavy bolt lift. I got some RL50, which I will give it a try later. So far my 33xc barrel don’t like 300gr Berger and 285 Warner. Normally I can identify the node w/ seating depth within 50 rds, but not the 33xc.
Last edited:
I ordered 8 as well since Tubb said that would work with solids and standard bullets.
I have 2 getting spun up this year a GT 1-9 to 1-8 and a 1-7.5. Seems like the 33XC can be finicky? Possibly the powder to fill rate? Looking like I'm sticking w the 338 LM AI. Hearing to many horror stories w the XC.
If I can start all over again, I would get 375cheytec size action instead using 338lm. Few people experiencing early pressure with 338lm action size.
I believe this to be true based off my experience and non-scientific testing. I can’t spend a lot of money to run a controlled experiment. But I found it extremely hard to find a node with seating depth within the limitation of the pressure I was getting. So that left a lot of case capacity that wasn’t being used.
I think, personally, the 338LM AI or IMP is the way to go.
The 37XC is being built right now an I like the idea of that based off the data I’ve seen form others.
