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bobmullen-
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Mike B.
Interesting …
You must have a 1:7 or a 1:8 twist to be able to successfully stabilize a 223 caliber cast bullet.
It will be interesting down the line… to see how many others also want the same mould type as a new inventory run.
https://noebulletmolds.com/site/product-category/bullet-moulds/224/225-72-rn-b1/
Personally I sort of wish that particular mould had an RG option …
It might be interesting to see if there are any other forum members that are of the same opinion…
Maybe with something like a 225-46 RG version… as that HP pin design is already made up in that caliber.
https://noebulletmolds.com/site/shop/bullet-moulds/224/225-46-wfn-a1/225-46-wfn-a1-rg4-cavity-gc/
3 – 5 grains lighter is a potential starting point for a new RG design option.
Of course the meplat would have to go from an .090 RN meplat to a ~ a .170 WFN meplat version
An RG option @ ~ 65 or possibly even 68 grains should still be heavy enough to be optimally stabilized by the fast twist barrels…
I will have to do some dimensional thoughts on this subject… to see what the software will predict for the nose bob plus the aforementioned WFN RG pin design … for a new group buy… on this thread.
Take Care, & Stay Safe…
I’m glad that you find the 1:9 twist works with your rifle using this mould
You may want to read the attached article on that particular bullet weight … especially the attachment on bullet weights vs twist….
Unfortunately the forum is still not allowing attachments to be included so the link to the article will have to do.
https://www.nrablog.com/articles/2017/3/how-to-pick-the-right-round-for-your-ar15-barrel/
Take Care, & Stay Safe…
rsterne
If you are referring to the round nose profile as being short for it’s weight, then you must also take into account that there is also more bearing surface in that particular cast bullet design than in a more normal spitzer bullet designs.
If that were not the case the long 140 & 160 grain 6.5’s would not tend to be as accurate, & the latest trend toward 90 grain in the 223 – 5.56 caliber to fly farther & not be as easily deflected by the wind… thus needing a faster and faster twist to stabilize the heavier bullet designs to make the projectiles fly farther and hopefully a bit more accurately…
Thus bullet and pellet designs tend to naturally want to evolve… Even if the current design is accurate there is always someone out there that wants to see if the envelope can be theoretically be pushed a tiny bit further.
It all tends to depend on what one is trying to achieve with the load combination that one is trying to put together.
Round nose bullets of the same bullet weight do not tend to fly as far as, most of the more aerodynamic & longer by comparison bullet designs… Otherwise the military would not have gone away from round nose versions towards the more aerodynamic spitzer designs …
So one ends up with a trade off — or for lack of a better definition … A balancing act between bullet weight, bullet design aerodynamics, vs what the end result is … that one is looking for…
Each individual tends to have a preference … Just as some rifles might tend to prefer one bullet design and load over another…
There is no right or wrong answer here…. Its just being able to obtain what one wants to take the next step into the unknown…
If one is happy with what one has … then I am sincerely happy for that individual… IF one wants to experiment and gets their kicks that way … then I am also sincerely happy for that individual also.
Take Care, & Stay Safe…
I was not referring to any other qualities of a RN design compared to a Spitzer or Pointed…. However, the RN tends to be shorter for a given weight, and hence does not need to be spun up as fast to be stable…. A 9″ twist may work fine for the 72 gr. RN, but a Spitzer of the same weight, and particularly if it has a boattail, may well need a faster twist rate…. Two excellent Twist calculators you may find helpful are:
http://www.geoffrey-kolbe.com/barrel_twist.htm
http://www.jbmballistics.com/cgi-bin/jbmdrag-5.1.cgi
and here is a bullet length list….
https://www.jbmballistics.com/ballistics/lengths/lengths.shtml
As an example, a Barnes 70 gr. in .224 cal is from 1.030-1.037″ long, compared to only 0.75″ for the NOE 72 gr. RN…. Berger 70 gr. are 0.976″ long, Hornady 70 gr. are 1.047″ long, Nosler 70 gr. are 0.965″ long, Sierra 69 gr. are 0.900-0.972″ long, and Speer 70 gr. are 0.808″ long…. Even the US Military 62 gr. M855 is 0.907″ long…. Plug any of these lengths into the calculators and you will see that anything over 0.90″ long is marginal in a 9″ twist, but a 0.75″ long bullet has tons of stability….
Bob
ericstevens
I don’t know how many times that I was told that I couldn’t do something because someone else didn’t think it feasible. That negative kind of thinking and regurgitation of nonsense by non-doers prevents lots of folks from exploring the limits.
I’ve had the NOE-225-70 for quite a while. It didn’t take long for me to develop a load that shot very well from my 9″ twist Stag despite a chrome lined bore, M4 profile, and non-free float forearm.
Linked is a 10 shot group from a clean bore at 50 yards. It is literally 8 of 9 shots that could be COVERED with a penny, and this is with conventional lube. These were sized and lubed in a .227″ die and taper crimped behind the front band so as to fit in the 2.26″ max magazine length. The load was 15gr Reloader 7 (Made in Sweden) in FC cases with F205 primers, lube ahead of the GC and first lube groove. The older lot of “made in USA” Reloader 7 shot similar groups at 16.3gr. It is full function with carbine length gas.
Mike B.
ericstevens
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