The new 33XC & 37XC cartridges designed by David Tubb

[Geno C.]

I’m not the only one that’s ran them that fast and had them hold together. Get ahold of Chase Shroud from AB. He’s run them at similar velocities from his enabler. Over about 3200 they have a slump from nose deformation so they are erratic. I only ran them as bullets while forming because their bc is garbage compared to the 285 badlands solids that I run in a match.

 

[JB.IC]

Anyone have any data on RL50 and 300gn class jacketed bullets? (300 Atips)

tried 8133 and I pressured out early. I’ll try that again when I get some 275 Lazers as I’ve seen good data from Paul Phillips.

 

[47chevycoe]

Anyone have any data on RL50 and 300gn class jacketed bullets? (300 Atips)

tried 8133 and I pressured out early. I’ll try that again when I get some 275 Lazers as I’ve seen good data from Paul Phillips.

I’m shooting 300 hybrids with RL50. I got up to 122.4 gr but bolt lift was pretty stiff. Backed it off to 121.0. I’m getting 3150mv with that load currently.

 

[jetmd]

Not the best option but it will work. Will show signs of pressure early. Even more so then the .700 bolt body from defiance. better off going with a larger a tion with a larger action body and larger. Tennon 1.125 minmum

My thought was to build a 33xc on my Badger 2013 Lapua but the tenon is only 1.0625 so is this a NO GO?

 

[jetmd]

If it won't work I guess a 338AI would be my next best choice.

 

[JB.IC]

I’m shooting 300 hybrids with RL50. I got up to 122.4 gr but bolt lift was pretty stiff. Backed it off to 121.0 getting 3150mv with that load currently.

sweet. I’ll start a pressure test at 110gn and work up to 122 at 2gn increments.

 

[Steel head]

My thought was to build a 33xc on my Badger 2013 Lapua but the tenon is only 1.0625 so is this a NO GO?

You’ll possibly just see pressure signs early.
If it was me I’d totally build one on that sexy M2013.

 

[jetmd]

My plan was to run a 29" barrel, 265gr Badlands and be able to use my 338Ultra.

I would like to be able to try some ELR.

 

[Steel head]

My plan was to run a 29" barrel, 265gr Badlands and be able to use my 338Ultra.

I would like to be able to try some ELR.

I have 265 and 285’s and 338 edge brass and a long fast twist bartlein on order.
I plan on possibly running it single feed in a SA nucleus for now till I get a nice long action.
My lil mighty mouse 7mm is hard to spot for past 2800-3000.

 

[Chickentoast]

I have 265 and 285’s and 338 edge brass and a long fast twist bartlein on order.
I plan on possibly running it single feed in a SA nucleus for now till I get a nice long action.
My lil mighty mouse 7mm is hard to spot for past 2800-3000.

Feral kitten make sure the COAL will work without pulling the bolt in your SA. Remington custom shop built their RUM's on SA, so I thought I was good... but I would've had to pull the bolt to insert each round - and that was only with a 300RUM and 225 eld-m's - so I bought a LA.

 

[Steel head]

Feral kitten make sure the COAL will work without pulling the bolt in your SA. Remington custom shop built their RUM's on SA, so I thought I was good... but I would've had to pull the bolt to insert each round - and that was only with a 300RUM and 225 eld-m's - so I bought a LA.

Already checked
Even with a 285 loaded LONG it drops right on in with a barrel in it.

was actually kinda surprised!

 

[Chickentoast]

Already checked
Even with a 285 loaded LONG it drops right on in with a barrel in it.

was actually kinda surprised!

Damn that is sweet! The Nuke must have a larger opening than the 700. Enjoy!

 

[badassgunworks]

1.063 will work but is not optimum lapua and lapua cylinder cases like the xc raptor case need a 1.120-1.125 size tennon and a shank that is at least 1.250 minimum if not pressures will show up earley and you will never see optamum performance levels.

 

[JB.IC]

1.063 will work but is not optimum lapua and lapua cylinder cases like the xc raptor case need a 1.120-1.125 size tennon and a shank that is at least 1.250 minimum if not pressures will show up earley and you will never see optamum performance levels.

what’s the reasons why it pressures out early like that for those smaller dimensions?

mine is 1.181” tenon and shank of OD of 1.33”

 

[Steel head]

My guess is material around chamber and action stretches a bit under load, case yields filling extra space because of pressure, action and barrel spring back but brass doesn’t.
Boom!
Sticky/stuck case plus any other artifacts that were caused.

 

[JB.IC]

Started to get pressure at 122gn of RL50 at 3024fps. 300 ATIPS 27” AI barrel. Could have kept going since the bolt lift was fairly light but the scrapes on the back of the brass were starting to really shine.

Somewhere around 2900fps is what I’ll end up testing again.

 

[BCX]

Started to get pressure at 122gn of RL50 at 3024fps. 27” AI barrel. Could have kept going since the bolt lift was fairly light but the scrapes on the back of the brass were starting to really shine.

Somewhere around 2900fps is what I’ll end up testing again.

33xc w 300?

 

[JB.IC]

33xc w 300?

300 ATIPS

 

[BCX]

Man you must have a tight bore. I push 300 A-tips w RL-33 from a 338 LM AI mag fed just over 3000 FPS w no pressure. Shoots good never bothered maxing out pressure.

 

[JB.IC]

Man you must have a tight bore. I push 300 A-tips w RL-33 from a 338 LM AI mag fed just over 3000 FPS w no pressure. Shoots good never bothered maxing out pressure.

Yea I’m not sure why it’s so damn slow. I expected closer to 3200fps. Some have speculated that the AXSR action isn’t beefy enough for more pressure. Idk

 

[BCX]

I can’t comment on the AISR. I’m running a Surgeon XL action

 

[badassgunworks]

When your tennon is too small in relation to the cartridge diameter that means your Chamber wall is too thin and sence on the xc case is long 3/4 of the cartridge is in the shank of your barrel which means you will run into signs of pressure earlier like for example hard bolt lift and extraction issues from expansion. Its best to try to keep at least .245 wall thickness in tennon area or thicker

 

[Swatdude1]

When your tennon is too small in relation to the cartridge diameter that means your Chamber wall is too thin and sence on the xc case is long 3/4 of the cartridge is in the shank of your barrel which means you will run into signs of pressure earlier like for example hard bolt lift and extraction issues from expansion. Its best to try to keep at least .245 wall thickness in tennon area or thicker

I just ordered a 30" Bartlein 33XC barrel with the modBB in the Heavy Varmint. The barrel diameter is 1.25" and going into a Barret MRAD maker's kit, which requires a tenon diam. of 1.1" with a threaded portion diam. of 1.1875" starting at approx. 2 inches from the bolt face. Basically an inch of the 33XC case would be in the 1-3/16" threaded area. At 3.75", the full 1.25" diameter continues to 5" before tapering to .9" at the finished length of 30". This is the same MRAD configuration for the 338LM and 338NM except this barrel will be longer than their standard 26" and NOT fluted. Are you saying there is a chance of pressure signs earlier in this config? The chamber wall thickness is 0.3825". Hoping to push a 285gr Warner Flatline close to 3200fps in this configuration.

 

[martyj]

I’m shooting 300 hybrids with RL50. I got up to 122.4 gr but bolt lift was pretty stiff. Backed it off to 121.0. I’m getting 3150mv with that load currently.

That is where I stopped with Rl 50 and hybrids also.
They were shooting about 2.5 group @600 yards 3150 fps

 

[Steel head]

 

[Chickentoast]

^What action you gonna run? Mag feedin'? I'm thinking about 2 338's - a short fat and a big case... Might try the Sherman Mega (WSM improved) for the short one.

 

[Steel head]

^What action you gonna run? Mag feedin'? I'm thinking about 2 338's - a short fat and a big case... Might try the Sherman Mega (WSM improved) for the short one.

I’m thinking a Tac338 in a KRG whiskey 3
They just informed me I can run up to a 1.3 straight tube
It will probably be single action
I’ll probably order a 35” 1-7.5 or 1-8 barrel next week

 

[BCX]

Dam 35", Im still torn on the 33xc vs 338 LM AI. Some guys seem to run into pressure early. Actually sending a Surgeon XL 338 AI out monday for a fresh barrel. Bartlein GT 1-9-1-8. My smith does have a 33 XC reamer for solids.

 

[Steel head]

Dam 35", Im still torn on the 33xc vs 338 LM AI. Some guys seem to run into pressure early. Actually sending a Surgeon XL 338 AI out monday for a fresh barrel. Bartlein GT 1-9-1-8. My smith does have a 33 XC reamer for solids.

I’m going 37XC
I already have a sporty 338

 

[BCX]

Im heavy w 338 components and its time for a fresh tube.

Funny, i spoke w JJ Rock today about a 375 CT. Cadex or JJ Rock in 375 CT.... o the sleepless nights!

 

[Geno C.]

Make sure you look at stock/chassis options when considering a jjrock

 

[Steel head]

Make sure you look at stock/chassis options when considering a jjrock

That’s been a major consideration in my research for a 375 action.
Sadly XLR isn’t doing big action inlets anymore

 

[Bravo6niner]

Haven’t shot it much but my 1581xl and homemade AX chassis front end are working out well so far. 37xc, 33” k&p 1/8 twist.

 

[BCX]

Make sure you look at stock/chassis options when considering a jjrock

Yes, going to take a ride down to EO and ck out the Cadex chassis. With my luck i will be leaving w a Cadex Shadow in 375 CT.

 

[BCX]

That’s been a major consideration in my research for a 375 action.
Sadly XLR isn’t doing big action inlets anymore

You will just have to use a Surgeon XL w AIAX chassis.

 

[Swatdude1]

Anyone know what the OAL of a 41XC 505g Warner Flatline is? Wondering if it will fit in 5" box mag. From the pics I've seen I'm guessing not.

 

[Geno C.]

What is the 5” mag of which you speak?

 

[Swatdude1]

What is the 5” mag of which you speak?

Cadex if it can be made to work with .585 bolt face and action. This is what I hate about forums. I don't even have my 33XC Bartlein MRAD barrel in hand yet and I am already thinking of a dedicated 41XC build. It would be a ways down the road. My next purchase is an AREA 419 ZERO.

 

[Geno C.]

Is it for a 50bmg then?

 

[BCX]

Cadex shadow w a .590 BF would be badass.

 

[Swatdude1]

Is it for a 50bmg then?

TUBB 41XC Build.

 

[Geno C.]

I was referring to the mag. The Cheytac mags I have at in the 4.5” area. A far cry from 5”. 5” would fit the 375 Cheytac with solids better

 

[atepointer]

I was referring to the mag. The Cheytac mags I have at in the 4.5” area. A far cry from 5”. 5” would fit the 375 Cheytac with solids better

Geno we have some awfully nice weather I think it's time you pack up the wagon and head south. Pop a flare when you come this way

 

[Geno C.]

I’m going to try

 

[ReturnFire]

I’m looking for a little help from some of you fellas. I’ve got an Impact 787 w/Lapua bf that I had planned on using for a 30XC or 33XC but I just got the brass from Tubb and damn it’s bigger than I thought. I’ve ordered a Bartlein mod400 barrel 1.25x5” then finishes at 1” @ 32. Have I bit off more than I can chew for this setup?

 

[Steel head]

I’m looking for a little help from some of you fellas. I’ve got an Impact 787 w/Lapua bf that I had planned on using for a 30XC or 33XC but I just got the brass from Tubb and damn it’s bigger than I thought. I’ve ordered a Bartlein mod400 barrel 1.25x5” then finishes at 1” @ 32. Have I bit off more than I can chew for this setup?

Well most 700 clone action’s are limited in tenon diameter of 1.06 and I’m guessing the impacts is similar.
That and action strength will limit you on maximum pressure but I don’t think it’s enough to make it a non viable option.
I’m leaning towards a bit bigger action with a 1.125 tenon for my 37xc build.

Lots of Tubb guns on the XC cartridge and they do ok without ginormous actions, tenon and barrel diameters
Tubb’s data is probably just fine in your impact or at least close.
At worst you tone it down 100 fps but a 1.00ish G1 375 at 2930 is quite impressive in my experience at a mile or two.

The 37XC is to the 338 lapua what the edge/RUM is to 300 win mag.

 

[rancher5]

That’s good new to me!

300 Bergers work great, I keep it around 3150, plenty of shooters run 3200 plus, with no problems that I know.

 

[Swatdude1]

Well most 700 clone action’s are limited in tenon diameter of 1.06 and I’m guessing the impacts is similar.
That and action strength will limit you on maximum pressure but I don’t think it’s enough to make it a non viable option.
I’m leaning towards a bit bigger action with a 1.125 tenon for my 37xc build.

Lots of Tubb guns on the XC cartridge and they do ok without ginormous actions, tenon and barrel diameters
Tubb’s data is probably just fine in your impact or at least close.
At worst you tone it down 100 fps but a 1.00ish G1 375 at 2930 is quite impressive in my experience at a mile or two.
View attachment 7791363
The 37XC is to the 338 lapua what the edge/RUM is to 300 win mag.

I read David or someone state why the normal tenon diameter will be just fine. The XC case is the same diameter but about .45" longer than the 338LM. More pressure is applied over a larger chamber area, which is approximately proportional to the additional powder capacity. Volume of cylinder=approx. extra case volume=.293 x .293 x 3.1416 x 0.5L=0.135 cubic inch. Additional case surface area=0.585 x 3.1416 x 0.5L=0.919 sq.in. This is a simplified equation since the taper and shoulder angle comes into play but what you will find is the surface to volume ratio for the extra cartridge length is roughly the same as the ratio for the case itself before adding length.

I think there was more worry with using existing 338LM barrels which when reamed, extended past where the taper began. I ordered a 33XC Bartlein ModBB in Heavy Varmint with the full diameter 5-inch section prior to taper. I wouldn't expect any issues with that even with 37XC. Do the math: .375-.338/2=0.0185 chamber wall difference at the neck only. I can't imagine slightly more than 1/64th difference in thickness would matter, again, factoring the additional pressure spread out over a larger area of the .585 diameter of the case.

Guys on the long range hunting forum are running Deviant Tactical Actions (1.0625” X 16 T.P.I.) with 37XC and having no issues. Chamber wall of .344 vs .362 for .338. Basically a hair more than a 64th.

 

[ReturnFire]

I really appreciate the insight fellas. I feel a lot better now. I just gotta find some 245 and 300 Berger’s

 

[Steel head]

I read David or someone state why the normal tenon diameter will be just fine. The XC case is the same diameter but about .45" longer than the 338LM. More pressure is applied over a larger chamber area, which is approximately proportional to the additional powder capacity. Volume of cylinder=approx. extra case volume=.293 x .293 x 3.1416 x 0.5L=0.135 cubic inch. Additional case surface area=0.585 x 3.1416 x 0.5L=0.919 sq.in. This is a simplified equation since the taper and shoulder angle comes into play but what you will find is the surface to volume ratio for the extra cartridge length is roughly the same as the ratio for the case itself before adding length.

I think there was more worry with using existing 338LM barrels which when reamed, extended past where the taper began. I ordered a 33XC Bartlein ModBB in Heavy Varmint with the full diameter 5-inch section prior to taper. I wouldn't expect any issues with that even with 37XC. Do the math: .375-.338/2=0.0185 chamber wall difference. I can't imagine slightly more than 1/64th difference in thickness would matter, again, factoring the additional pressure spread out over a larger area.

Guys on the long range hunting forum are running Deviant Tactical Actions (1.0625” X 16 T.P.I.) with 37XC and having no issues. Chamber wall of .344 vs .362 for .338. Basically a hair more than a 64th.

Oh I think it will be fine but you won’t be able to step on it like a lot of ELR types do or have as much resistance to sticky bolt lift.
A pretty well known Local ELR builder here advocates a .240 minimum wall thickness.

If I had the parts in question I’d still build it