Twist Rate, Pill Weight and Stability

Calibres, cartridges, ballistics tables and ammunition information.

Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 22 Oct 2018, 11:08 am

When I first tried Nosler 70gn RDF projectiles in my Howa .223, 24", 1:9 twist, fluted bull barrel, I had not long started reloading and certain things that seem obvious now I've learned about them were not then.
One of which was pressure signs.

I worked up the most accurate load, which allowed 2.5 - 3 inch groups at 400 and was feeling pretty smug about it when I came across an article on recognizing pressure signs when reloading, by Greg Dykstra from Primal Rights.

After reading the article I went hunting for any signs on my brass and found that these most accurate rounds loaded at ADI's maximum recommended 25gn of 2206H, were seriously cratering the primers.

I tested downward in 0.1gn increments until there were no more signs of pressure at 23.9gn, but the accuracy had completely degraded.

I then decided to see if going any lower might help, and tested down to the minimum of 23gn with depressingly deteriorating results.

The only conclusion seems to be that my 1:9 twist can't stabilize them at safe pressures, meaning they are, for all intents and purposes, useless in my rifle.

I would appreciate any opinions.

For those not familiar with the article:
http://www.primalrights.com/library/art ... g-pressure
fideles usque ad mortem
User avatar
Gaznazdiak
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 1973
New South Wales

Re: Twist Rate, Pill Weight and Stability

Post by bladeracer » 22 Oct 2018, 12:06 pm

If it's only showing pressure on the primer and not on the case head I wouldn't worry about it.
You can try different powders, and play with the seating depth, but some rifle/bullet/powder combinations prefer higher pressures.
You can also try primers with harder cups.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 5408
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by No1_49er » 22 Oct 2018, 12:09 pm

Increased velocity is not always conducive of increased accuracy, at safe pressure/s.
Have you contemplated trying different powder/s?
It's interesting that Berger's Reloading Manual shows (admittedly for a 70gn Match VLD) a min load of 20.5 and max of 23.0 (AR2206H = H4895). That equates to a compressed, or close to it, load.
A stability calculator suggests that your bullet will stabilize correctly at your twist rate and velocity. Look for a result that is GREEN for go/good http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
Proud member of "the powerful gun lobby" of Australia :)
No1_49er
Sergeant
Sergeant
 
Posts: 444
Queensland

Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 22 Oct 2018, 1:04 pm

Thanks guys, I have been thinking of getting some Trailboss next time, I 've seen many on here who are happy with it.
It would give me an excuse to make some more noise :D

Thanks for that link No1_49er
fideles usque ad mortem
User avatar
Gaznazdiak
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 1973
New South Wales

Re: Twist Rate, Pill Weight and Stability

Post by bladeracer » 22 Oct 2018, 1:23 pm

Gaznazdiak wrote:Thanks guys, I have been thinking of getting some Trailboss next time, I've seen many on here who are happy with it.
It would give me an excuse to make some more noise :D

Thanks for that link No1_49er


I love Trailboss, but it has a very real velocity limit, so fairly limited distance for hunting bullets. For close-up work though it's excellent.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 5408
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 22 Oct 2018, 2:11 pm

I don't even try to shoot past 250m anymore Blade, I have had a couple of crawl offs, I hate doing that so I'd rather risk losing the opportunity by closing on them to ensure a head/neck shot.

Is that inside the Trailboss window?
The biggest thing I'm shooting is rabbits, haven't seen a fox around here for a couple of years.

Last time I went looking for pigs in the scrub down the back and all I saw was rabbits, and me "armed to the teeth" with the12g Breneke's.
fideles usque ad mortem
User avatar
Gaznazdiak
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 1973
New South Wales

Re: Twist Rate, Pill Weight and Stability

Post by bladeracer » 22 Oct 2018, 2:52 pm

Gaznazdiak wrote:I don't even try to shoot past 250m anymore Blade, I have had a couple of crawl offs, I hate doing that so I'd rather risk losing the opportunity by closing on them to ensure a head/neck shot.

Is that inside the Trailboss window?
The biggest thing I'm shooting is rabbits, haven't seen a fox around here for a couple of years.

Last time I went looking for pigs in the scrub down the back and all I saw was rabbits, and me "armed to the teeth" with the12g Breneke's.


For rabbits, it probably doesn't matter if the bullet fails to expand from a .223 with a head/neck/chest hit.
I can't access my log but I think .223 will max out on Trailboss around 2200fps or so.
If you can push a 55gn varmint bullet to 2200fps it'll be dropping below the 1600fps design velocity around the 180m mark.

You should be able to load down below that level though with AR2206H, so try it first and see if you're getting the required accuracy at those velocities with that bullet.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 5408
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 22 Oct 2018, 3:31 pm

:drinks: Thanks Blade,
fideles usque ad mortem
User avatar
Gaznazdiak
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 1973
New South Wales

Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 22 Oct 2018, 3:45 pm

Just had a thought though, I'm well pleased with the current load for the 50gn ballistic tips, don't want to mess with that, but is it worth trying trail boss with the 70gn pills?
At 100m they still punch holes in my track plate bullet deflector at 23gn 2006H, they just produce a group twice the size.

The bump to the left was a 62gn ADI SS109 penetrator with 25gn, also at 100m.
Attachments
70gn RDF@ 200M.jpg
70gn RDF@ 200M.jpg (446.55 KiB) Viewed 725 times
fideles usque ad mortem
User avatar
Gaznazdiak
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 1973
New South Wales

Re: Twist Rate, Pill Weight and Stability

Post by Oldbloke » 22 Oct 2018, 3:57 pm

I think typically 1700fps is about as fast as you will get with trail boss. Just have a look in the ADI manual. Yep, AR2206H in this case would be better option..
Hunt safe, look after the bush & plug more pests. :thumbsup: Better to load on the mild side. :o The greatest invention in the history of man is beer. :drinks: "Often the written message doesn't convey all of the information"
User avatar
Oldbloke
Field Marshal
Field Marshal
 
Posts: 5296
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by bladeracer » 22 Oct 2018, 4:22 pm

Oldbloke wrote:I think typically 1700fps is about as fast as you will get with trail boss. Just have a look in the ADI manual. Yep, AR2206H in this case would be better option..


You can get well above 1700fps, my standard reduced load is 8.0gn behind 52gn bullets at 1870fps.
ADI only list 4.0gn for a subsonic load, they don't offer any supersonic TB loads.
Case capacity is around 10.0gn from memory.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 5408
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by Oldbloke » 22 Oct 2018, 4:30 pm

Any pics of the primers?
Hunt safe, look after the bush & plug more pests. :thumbsup: Better to load on the mild side. :o The greatest invention in the history of man is beer. :drinks: "Often the written message doesn't convey all of the information"
User avatar
Oldbloke
Field Marshal
Field Marshal
 
Posts: 5296
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by marksman » 22 Oct 2018, 5:02 pm

yes that would be a good idea, show the primers and tell us what primers are you using

primers are not a good indicator of pressure, especially in small rifle, primers are not primers
cratered primers can be caused by a sloppy firing pin hole, an edge protruding around the firing pin hole ect
my advise would be to try a different primer with a thicker cup, cci 450 mag or cci br4's

as blade said check the case head for expansion to see pressure :drinks:

and by the way I rate the guys at primal rights very highly :thumbsup:
User avatar
marksman
Colonel
Colonel
 
Posts: 2029
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by bladeracer » 22 Oct 2018, 5:18 pm

Gaznazdiak wrote:Just had a thought though, I'm well pleased with the current load for the 50gn ballistic tips, don't want to mess with that, but is it worth trying trail boss with the 70gn pills?
At 100m they still punch holes in my track plate bullet deflector at 23gn 2006H, they just produce a group twice the size.

The bump to the left was a 62gn ADI SS109 penetrator with 25gn, also at 100m.


It's worth trying different powders, but probably not Trailboss if you're still wanting velocity to be able to reach out a bit. The 70gn should have sufficient BC to also hang onto 1600fps out to similar range, if you can launch it at 2000fps.

I think AR2206H and AR2208 are likely to give the best results in .223, but BM8208, AR2219 or even AR2207 could be worth trying.
Practice Strict Gun Control - Precision Counts!
User avatar
bladeracer
Field Marshal
Field Marshal
 
Posts: 5408
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 23 Oct 2018, 11:22 am

OK, I had to find where I'd stashed an example of the cratering to get a couple of pics.
The pics are both Remington Small Rifle, the cratered was 25gn and the uncratered was 23gn of 2206H.

I have since run out of these and I'm currently using CCI BR4
Attachments
25gn.JPG
25gn.JPG (83.66 KiB) Viewed 689 times
23gn.JPG
23gn.JPG (103.04 KiB) Viewed 689 times
fideles usque ad mortem
User avatar
Gaznazdiak
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 1973
New South Wales

Re: Twist Rate, Pill Weight and Stability

Post by marksman » 23 Oct 2018, 12:31 pm

its not IMO pressure, the edges are still round, the primer is not flattend out at all, the primer has not enlarged
no pressure :unknown:
User avatar
marksman
Colonel
Colonel
 
Posts: 2029
Victoria

Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 23 Oct 2018, 5:14 pm

I'm not trying to be argumentative here marksman, I appreciate your input, but if you look closely at the pics the uncrated one has an even, round profile from the outside edge and over into the pin impression, whereas the cratered one is distinctly flattened around the crater.

The pin impression on the uncatered is also far deeper than the other, which looks to my barely tutored eye to have flowed under force into the firing pin hole in the bolt.
fideles usque ad mortem
User avatar
Gaznazdiak
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 1973
New South Wales

Re: Twist Rate, Pill Weight and Stability

Post by Oldbloke » 23 Oct 2018, 5:17 pm

marksman wrote:its not IMO pressure, the edges are still round, the primer is not flattend out at all, the primer has not enlarged
no pressure :unknown:


Agree 100% maybe warm, definatly not hot. Fairly normal really.
Hunt safe, look after the bush & plug more pests. :thumbsup: Better to load on the mild side. :o The greatest invention in the history of man is beer. :drinks: "Often the written message doesn't convey all of the information"
User avatar
Oldbloke
Field Marshal
Field Marshal
 
Posts: 5296
Victoria

Next

Back to top
 
Return to Calibres, cartridges and ballistics