The best twist rate for my 243 Win project?

[Otakar]

Hi folks;
I want to build a 243 win on a small ring Spanish Mauser action. I want to shoot bullets in the 95-107gr category and a barrel length of 24". I plan on using an E.R.Shaw barrel. The choices are, 1:12, 1:10, and 1:8 twist rates. I will discount the 1:12 off hand automatically, but which of the other two twist rates would be better for the modern polymer tip bullets in the 95-107gr category. This rifle will see little hunting and mostly plinking at 200 yards. My other two 6mms are magnums with 1:12 twists for the light hi-velocity stuff (85gr-), I just want something else in the .243 caliber for common off the shelf shooting, and the .243Win is my choice. my other two are the 6mm-284 and 6mm-6.5 Rem Mag.
Thanks for any help you can give me.

 

[SJB358]

No good reason not to use an 8 twist. It'll work with light bullets and hammer the longer 105-107's as well. A fast twisted 243 is a great thing to watch with sleek bullets.

 

[Ridgerunner665]

Yep...8 twist

 

[Guy Miner]

Agree, with 107's in the plan, go with the fast 1/8 twist.

Guy

 

[Otakar]

WOW, so far unanimous. That is what I love to see. I was leaning in that direction also but just was not sure. I will wait till the end of day today to see if anyone else chimes in with their thoughts and order the barrel tomorrow. Do you guys think that the 24" barrel is the better choice for that cartridge/twist rate combination? I think that 22" is much too short (just an opinion) and the 26" might be a waste. But, you guys might think that a 22" might be more than enough, (or not). I have not used the Spanish Mauser Action for anything this substantial but know that the rifles were chambered in 308 NATO and figure that the 243 should be no problem. I have four of these actions and want to start using them up.

 

[DrMike]

Your Spanish Mauser action will work well with a .243. I hate to break a streak such as witnessed above, so I won't. An eight twist would be excellent for your build. I don't believe a 22 inch barrel is too little, but I enjoy the balance with a 24 inch barrel on those rifles that are so built. Sounds like a fascinating build.

 

[SJB358]

I'd be fine with a 22" barrel on a 243. Son has a 20" barreled 243 and it does just fine as well. Can't go wrong if you like it.

 

[Otakar]

At this time I have a 243 Win built on a Yugo 98 short action with a 22" barrel. I'm not sure what the twist rate is at this moment. It is a good shooter with lighter bullets but not the heavy ones. So I imagine it is not a very tight twist. Because it was one of these early 90s builds by one of the companies that were doing that at the time (don't remember who) It has one of these UGLY stained (most likely Birch-wood) that is stained this ugly brown color. I want to take it apart use the action to build another rifle in 8x57, sell the barrel and stock on eBay and than build this new rifle on one of the Spanish 93 actions I have. Here is the last project I finished for my son in 8x57 Mauser. It is built on a large ring Turk-98

 

[6mm Remington]

Otakar you goofed up. It should be a 6mm Remington, not it's ugly little brother! I go with the other guys and a 1-8 twist should work well with the heavier bullets.

I think a 22" barrel would work fine. I had and now belongs to my son a Remington Model 600 with an 18 1/2" barrel. If I remember correctly my handload using IMR4350 and a 100 gr. Partition chronographs at 2850 fps. Just me but I think I would lean towards a 24" barrel but the shorter barrel should work fine.

The same powder and almost the same load, only .4 grains higher in my 26" Ruger #1B chronographs at right at 3150 fps.

 

[Otakar]

Well, If I buy the 24" barrel, All I need is a hacksaw to make it 22", Right? . 1:8 it is than. here is a stock I am working on for my 7.62x45 Czech, using a M-93 small ring Turk. The blue at the end of the stock is just Painters masking tape over the recoil pad. As I mentioned in a previous post, I have a 6mm-284 and a 6mm-6.5mm Rem Mag, so my big stuff is covered. On the 6mm-6.5 Rem Mag, That is only one of the reasons I chose the .243 Win. I mannaged to push a few 75gr bullets at 4100FPS. But normally I keep it at 3900FPS

 

[Otakar]

I just ordered the barrel. 24" 1:8 4140 Chrome-Molly 1 1/2 Contour. Also ordered a stock rough from Richard's. Same stile as the one in the previous post but not a AAA like that one just a "Semi-Fancy".

 

[Dwh7271]

I believe you're going to be happy with that.
I am also a Mauser fan. Currently have a couple more to barrel, both VZ24s.

 

[Otakar]

I have two built on Vz.24s at the moment and have three more waiting. One will be a 450 Ackley. one a 338-8mm Rem Mag. Plus I still have for more complete VZ-24 rifles.

 

[Otakar]

I just looked at my eXcel spreadsheet of my firearm inventory, which I keep all of my parameters on all of my firearms. The 6mm-284 and the 6mm-6.5mm Rem Mag are both 1:10 twist and my Yugo Mauser 243 Win is 1:11. Now I am glad that I ordered the barrel in 1:8.

 

[taylorce1]

I wouldn't ever use a M93 Mauser action for a .243, just not a good idea in my opinion to run them at those kind of pressures. I know a lot are sold as .308 Win rifles but they were actually supposed to shoot the 7.62 CETME cartridge and not the .308 or 7.62x51 NATO. The action only has two locking lugs and was designed for pressures of the 7X57 cartridge, plus it has no protection for your face in case of a pierced primer or case rupture. These rifles often suffer extreme locking lug set back with modern high pressure cartridges.

I know you already bought the barrel but that action would have been a great candidate for a 6.5X55 with 1:8 twist.

 

[Otakar]

Too late, already ordered the barrel and stock. A 6.5mm is not a caliber I am even contemplating, or would even be interested in. The Spanish army had their inventory redone in 7.62 Nato so I am not worried about it. I have been shooting a Mk.X MiniMauser in 7.62x45 Czech at max pressure+ for many years with no problem. The Minimauser is tiny and not even close to being as strong as a M-93. At this moment I am finishing up a M-93 Turk in the caliber and am half finished with a second one. One with a scope and one with a peep sight. I also shoot a Thompson Contender pistol with a 307 Win which is nothing more or less, than a 308 Win with a rim. I have shot a couple of 308s in it just to see if they will extract (they don't) and that is MUCH less strong than the M-93. If I'm worried about the pressure, I will just not load at full load capacity. Since I am going to use a 24" barrel with a tight twist, I can use slower powders and keep the pressure down. In my Thompson pistol (14" barrel) I shoot exclusively AA2200 35.6gr with 165HPBT bullets and that is an extremely fast powder with no issues. My groups are a consistent 1-"@100 yards with a 6x scope. I have 0 issues with extraction. I have actually gone down from 36.2 gr of powder because the cases sometimes got stuck on hot days. The chamber wall thickness on the Thompson is 1/3 that of what it is on the M-93 and the locking mechanism is also not as strong. I am not worried about the 243 Win in this action. I just have to make sure that everything is headspaced properly. This is what causes major problems. If headspace is too great, that can sheer the locking lugs off. This is the issue on some of the military rifles with mismatched bolts.

 

[taylorce1]

I'm just a guy on the internet, I can tell you it's not safe and you can find another 100 who says it is. I'm just saying I wouldn't use a 93 action for anything .308 based and run it to 60K psi. Keep an eye on the headspace, more than likely you'll have lug setback and not a catastrophic failure. It's also a free country so you're free to do things I wouldn't.

The Mini Mauser while not a true Mauser action was designed to handle 65K PSI loads from the .22-250, I doubt your 6.72X45 Czech runs any hotter. So again it's just my opinion that you're pushing the envelope using an action that was designed for a cartridge that shot with a max pressure of around 51K, and uses 100+ year old metallurgy and heat treating processes. You don't have to take my word for it, go ask a few gunsmiths if they'd build and risk there reputation a .243 on a Mauser 93.

 

[Otakar]

I do agree about not pushing the high pressures. I do not plan on doing loads to 100%. I don't need to. I have other 6MMs that can do that and approach the 4K-fps. I am looking for something to shoot at under 3K with the 95+-gr bullets. Looking to push a 95gr+- bullet at around 2750-2800fps with a slow powder. This should keep the pressures well below the max. I do realize that I can't be stupid with this thing. Here is one fact, If these actions were so dangerous, they would not be allowed in the US. Here is a very nice article. http://www.chuckhawks.com/small_ring_mausers.htm