Twist rate on a 223 (mold availability)

[randyrat]

I'm thinking about a 223 remington 700 heavy barrel about a 20- 24" barrel. The big question is what kind of twist rate is GOOD/BEST for cast boolits. Will a 1 in 12 stabalize a available cast boolit molds or should i persue a different twist rate.
I'm trying to buy smart by asking these questions before the investment in a rifle. My interest is 50 grain or larger possibly 70 grain cast, but that of course depends on molds that i can find.

I ask about the 1 in 12 because i seen 2 of them for sale today with that twist rate.
Give me an education Please.

[Shiloh]

Probably 1:9 for that application. I am no expert though. Others will definately know.
Barrels are available for 1:7 up to 1:14.

Seems like I've heard of 1:6.5.

Shiloh

[Shiloh]

Probably 1:9 for that application. I am no expert though. Others will definately know.
Barrels are available for 1:7 up to 1:14.

Seems like I've heard of 1:6.5.

Shiloh

[JeffinNZ]

If you want really good results from your .223 with cast go for a faste twist and get a 70gr + mould. LBT does a beautiful heavy .22 bullet.

Most 'standard' .22 cast bullet suffer from a low sectional density that does not lend itself to the best accuracy. That said my 1 - 12 Rem 700 does rather well with the Lyman 225415 and 225462.

[JIMinPHX]

I have a 1:12 & wish I had something a little faster. My gun does well with most boolits up to 50-grains, or maybe 55 depending on nose design. Above that, I get boolits that go through the paper sideways at 25 yards.

I have had much better results from blunt designs like the Bator, than with longer-nose designs like the Lyman 225415.

1:10 is probably the optimum twist for all around general purpose use with that caliber, in my opinion. Some others will probably disagree with me.

Faster twists will limit the velocity that you can use. Some people say that this is because the boolit will not be tough enough to take the high RPMs that the faster twist generates at high velocities. I can't confirm or deny that reasoning personally.

Some long range shooters go with heavy boolits & even slower twists, like 1:14. I am told that, this has some way of generating a complex spiral of reducing diameter as range extends. Apparently, if you shoot at the exact same range each time, this can be repeated regularly & accuracy can be good. It's never worked for me though. Also, if you shoot at varying distances (like in hunting), then this is a non-starter.

I have seen 1:14, 1:12, 1:10, 1:9, & 1:7 twists in that caliber. I have been told rumors of others as well, but never actually seen them myself. The fast ones like 1:9, are usually found on military rifles & are there because the newer green tip SS-109 penetrator ammo needs it for stabilization. The 1:7 twist is seldom found anywhere but on military style guns. It is needed for certain late ignition tracer rounds & little else. The really fast twists have a reputation for wearing out more quickly, but that's not the predominant problem when shooting cast boolits.

Several other folks here on the board have quite a bit of experience with this issue & have written about it extensively. If you search the archives, you will probably find a lot of information already posted. I believe that Beagle has a 3-part series written up on that caliber over on the cast pics section of the board. It's a very worthwhile read. Several others have debated the topic of twist ad-nausium. If you have the time to do some reading, there is plenty out there to be found.

[35remington]

Call me retro or whatever, but given accuracy limitations, useful range at which I personally use such loads (200 yards and under) and other considerations I would be more on board with a 1-12 or 1-14 twist than anything faster.

At best, due to expansion issues, I really don't see any .22 as a 300 yard gun with cast on any animate target, so my thinking tends to make a .22 hornet out of it. Those that are "into" other things may feel differently, but I'm pleased with the killing power and utility of my cast .22 loads that run in the vicinity of 2200-2700 fps out of these twist barrels. Such loads are repeatable, don't require a whole lot of voodoo to assemble, and kill well on the small varmints I use them on at the most common ranges likely to be used.

Trajectory is usefully flat as well. I find such twist rates with common bullets like the 225438, 225415, the RCBS 55 FN, and the Bator are very accurate in the 2200 fps range and still quite usefully accurate at somewhat higher velocities (I've had good luck with a 22-250 1-14 at 2800+ fps speeds). Further, I can load down to squirrel velocity loads of around 15 to 1600 fps and retain good accuracy without so much destruction.

Retaining small game hunting "bottom end" while also having varmint hunting capability is something I find handy.

In 1-12 and 1-14 twists I've never had much difficulty getting such as the .223 and 22-250 to shoot well with minimal load development.

[Larry Gibson]

I've been shooting .223 since '67 (5.56 since '65) and know that a 14" twist handles 60-62 gr cast bullets very well. My 12" twist m700V (bought in '72) shoots everything from 40 gr 225107s up through the 225462 (62 gr with one single cavity mould I had) which gave the best accuracy. I also had some 228035s (70 gr) that i shot in the 12" twist. They shot very well also. With the 12" twist and carefully selected bullets you can get very good accuracy up through 2200 fps. With the 9" twist you are back down to 1800-1900 fps for the same accuracy. All has to do with the twist/RPM.

Concur with 35Remington; cast in the .223 and 22-250 is synonimous with a 22 Hornet.

Larry Gibson

[randyrat]

I would be tickled to get 2000+ ft/sec with a 60 gr cast bullet and shoot 200 yds. I just was not sure of the possiblities.
I will check out the cast pic section and do some more reading. Thanks for the great info so far.

[JIMinPHX]

Larry, how fast were you pushing that 70-grain boolit in the 1:12?

[c3d4b2]

The best groups I have shot were with 53 grain bullets (jacketed) in a 1 in 8 twist barrel.

[Larry Gibson]

Larry, how fast were you pushing that 70-grain boolit in the 1:12?

When I got my first chronograph (Oehler M10) in '75 I chronographed the last 3 shots with 228035 I had. They were loaded with 20 gr(?) of milsurp 4895 and did 2020 fps. It probably also had a dacron wad as I was using dacron as a wad back then. It may also have been close to a case full of original 4831 as I was also using it back then. The "?" mark is there as that's what's in my old loading notes. I'd had those 3 rounds left around for a couple years. I did not mark on the box what the load was. Back then, like most of us, I thought I'd remember. I didn't and shortly learned to mark every box of ammo loaded. The chronograph also "forced" me into much better record keeping. Good record keeping is something I heartily recomend to all reloaders.

Larry Gibson

[JIMinPHX]

Thanks Larry,
I'm pushing mine a little faster, like 2400fps. Maybe at slower speeds I might be able to get heavier boolits to play ball with me in my 1:12. Better stabilization with lower velocities is contrary to what Greenhill taught, but hey, it's worth testing. The reloading manuals all said that velocity had to be kept under 1,000fps to prevent leading, & that has been proved to be total bull.

I agree about the need for good record keeping. I print up targets like in the picture below & when I'm done shooting at them, I punch 3 holes & stick them in a loose leaf binder that is sorted by caliber & date. After that, I condense the results into a spreadsheet when I get time.

[NHlever]

I did have some problems with the new 225415 (50 gr) tipping in my 1-14" twist .22 hornet. It shot better at higher velocity , 2200 fps in my .223 1-12" twist barrel however. I have been toying with the idea of a 1-9" twist Ruger MKII, but haven't taken that leap yet.

[Larry Gibson]

JIMnPNX

Really has nothing to do with the Greenhill formula, Has to do with the RPM threshold. I know there are many disbelievers but you just chalked up another experience to the RPM threshold. For a 12" twist the the RPM threshold, if you cast and do every thing else correctly, is 2300-2400 fps. Most who shoot 12" twist .30 and below calibers find it is lower at around 2200 fps. Saving the targets is an excellent method, I've numerous 3" binders full of them and constantly refer back to them.

NHlever's findings also match mine with 225415 in 14 annd particularly 16" twist Hornets; it must be shot fast to hold stability past 50 yards. I run about the same velocities as he's found though with the 225428 I've been able to push the velocity higher with accuracy in the 14" twist. I think he wil find accuracy with the 9" twist to go south between 1850 and 1900 fps with either cast bullet.

Larry Gibson

[JIMinPHX]

Larry,
So then, how exactly do you calculate RPM threshold? is it dependent on boolit hardness, weight, length, caliber, velocity?

[NHlever]

JIMnPNX

Really has nothing to do with the Greenhill formula, Has to do with the RPM threshold. I know there are many disbelievers but you just chalked up another experience to the RPM threshold. For a 12" twist the the RPM threshold, if you cast and do every thing else correctly, is 2300-2400 fps. Most who shoot 12" twist .30 and below calibers find it is lower at around 2200 fps. Saving the targets is an excellent method, I've numerous 3" binders full of them and constantly refer back to them.

NHlever's findings also match mine with 225415 in 14 annd particularly 16" twist Hornets; it must be shot fast to hold stability past 50 yards. I run about the same velocities as he's found though with the 225428 I've been able to push the velocity higher with accuracy in the 14" twist. I think he wil find accuracy with the 9" twist to go south between 1850 and 1900 fps with either cast bullet.

Larry Gibson

Larry, I did try some commercially cast 225438's in my hornet. They had really disfigured gas checks, but did shoot much better than my new 225425 boolits. I had shot some commercially cast 225425's before I bought the new mold, and they actually shot better than my most used 22596 one holer. When I got the new mold I was a bit disappointed to see how much Lyman had changed the mold from the commercial ones I had which were cast from an older mold. The new one has a longer nose, and casts almost 5 grains heavier with the same alloy. It actually looks more like my 22596 than the old 225415. I may get one of the 225438 molds while they are still available though I do have quite a few .22 cast boolits laying around.

[watkibe]

I have never investigated twist rate much, but I did have some experience contrary to the popular wisdom. I had a Remington 788 in 223, which had the then-standard 1:12 twist. According to the "experts" the twist was too slow for heavy bullets, but it was really accurate with 70 gr bullets. I figured that evidence outweighs theory every time.

[Larry Gibson]

Larry,
So then, how exactly do you calculate RPM threshold? is it dependent on boolit hardness, weight, length, caliber, velocity?

The RPm threshold is indeed "is it dependent on boolit hardness, weight, length, caliber, velocity" and rate of accelleration. It also is very dependant on bullets design and fit to the throat.

Your load crosses the RPM threshold when accuracy will really start going south in a non-linear fashion. With normal dispersion as range increases you can generally figure twice the group size (accuracy) with double the range, i.e. 1" at 50 yards is 2" group at 100 yards and a 4" group at 200 yards. With regular type cast bullets and alloys The RPM threshold is going to be between 120,000 RPM and 140,000 RPM given a loads ability to withstand accelleration without becoming too much imbalanced. A load that is over the RPM threshold will give , i.e. 2" group at 50 yards. a 5" group at 100 yards and a 10-15" group at 200 yards.

Most here use the machinist calculation for RPM which is close enough. Ballisticians use RPM= velocity/(twist in inches/12) x 60, sometimes written as R (in seconds) = (12/T)*V. In other words a velocity of 1950 fps from a 10" twist gives 140,456 RPM. Most of us simply round up or down (140,500 RPM) which is close enough for either method and close enough for our use.

You can push the RPM threshold using specially designed cast bullets or using the older Levern style if your rifles throat will support the bullet length. Alloys must be more specific, medium and slow burning powders used and attention to the details of casting, bullet sorting, consistency of the load, etc. ad nauseum must be all taken into consideration and used. Smaller calibers have a lessor RPM threshold than do larger calibers.

Larry Gibson

[Larry Gibson]

NHlever

You have me at a disadvantage, I am not familiar with 225425 or 22596.

Larry Gibson

[NHlever]

[QUOTE=Larry Gibson;574279]NHlever

You have me at a disadvantage, I am not familiar with 225425 or 22596.



Sorry Larry, clumsy fingers. I meant the older 225415. The 22596 is an old, perhaps Ideal single cavity mold that casts very well. It has a longer nose, and slightly smaller meplat than the old 225415, and weighs 48-50 grains. I think there is some detailed work with it in the cast .223 information on the Castpics site. I had some difficulty with it too, but I have also gotten some pretty good groups with it in both the Hornet, and my .223. I do think the shorter, and better balanced 225438 is better for the Hornet, as was the old 225415.

[georgewxxx]

Larry you mentioned using 228035. Isn't that a plain based boolit? At least the 22835 is and I'm assuming your was just an updated number version.

These are what .22 moulds I had on hand when doing a 218 Bee write up for Casting Fellows and Beagles articles on Castpics if you want to identify some different .22 mould designs. The 22596 you asked about has never been a favorite. In the 5 different .22 calibers I worked with it's been a pain to get anything but mediocre results with. ...Geo

L/R: Hensley & Gibbs #62 Sized with round nose punch, sized nose first, as cast 65gr, Ideal 228367 sized with round nose punch, as cast 62gr, Lyman 225462 55gr, Lee Bator 51gr, Lyman 225415 51gr, Lyman 224450 50gr, Hensley & Gibbs #4 46gr, Ideal 22596 49gr, Modern Bond A-225-525 FN 45gr, Modern Bond A-225-525 HP 44gr both size with .243 gas check, Ideal 225438 43gr, Lyman 225438 41gr.

[Larry Gibson]

NHlever

"Clumsy fingers"...that has never happened to me;-)

I agree with the 225438 being the better hornet bullet, especially when pushed past 2000 fps. The short stubby nose with almost full length bearing surface is the reason I suspect. However I've a new Savage M40 with a 14" twist and a 21" Contender barrel with a 12" twist. I haven't really had a chance to wring them out with 225415 but am still having hopes for that bullet in the 2200-2400 fps range with the M40 at least. That is an excellent killer on smal critters vs the RN 225438. If I can get decent .22 Magnum RF velocities of 21-2200 fps and 1.5 moa accuracy I'll be happy. That's the goal for a decent varmint load anyways.

Larry Gibson

[Larry Gibson]

Larry you mentioned using 228035. Isn't that a plain based boolit? At least the 22835 is and I'm assuming your was just an updated number version. ...Geo

Guess I should have mentioned that it had been a PB mould. The owner of the mould had the top faced off so a .22 GC would crip on the bottom lube shank. I think it had originally been a 78-90 gr mould. When he passed on I tried to buy that mould but the son was a shooter too and kept it along with the very sweet M99 .22 Savage Highpower his dad had.

Larry Gibson