Twist Rate, Pill Weight and Stability

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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
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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.
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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
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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
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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.
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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.
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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.
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Re: Twist Rate, Pill Weight and Stability

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

:drinks: Thanks Blade,
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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.
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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..
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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.
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Re: Twist Rate, Pill Weight and Stability

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

Any pics of the primers?
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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:
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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.
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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
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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:
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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.
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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.
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Re: Twist Rate, Pill Weight and Stability

Post by marksman » 23 Oct 2018, 7:45 pm

Gaznazdiak wrote: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.


I would suggest that your firing pin hole is a bit sloppy causing the cratering
the edges of the primers are both rounded, no pressure
rem 7.5's are a good primer and are supposed to be a thicker cup but they measure 20 thou and the cci's 25 thou
honestly try the cci br4 or 450 mag primers with that load
check out these primers from factory ammo

Image

the hornady has rounded edges on the primer but a very slight crater, but I would consider it mild and safe
the s&b is totally flattened and probably has an enlarged primer pocket, this I would say is on the edge but I must assume it is safe as it is factory
I would never load to this level of flattened primer even though I don't believe in looking at primers for pressure
measure the case head its much more reliable
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Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 24 Oct 2018, 9:50 am

As nobody was able to offer an explanation that definitively disproved pressure, I did some googling and much more reading.

Every source, without exception said that a common cause is ill fitting firing pin, but every source also said that if factory loads or your minimum loads do not cause cratering and hotter hand loads do, pressure is the only logical culprit.

So erring on the side of prudence and safety, I can only go by the majority of opinion.

Thanks to those who took the time to offer some advice on this problem.
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Re: Twist Rate, Pill Weight and Stability

Post by SCJ429 » 24 Oct 2018, 6:30 pm

You can get the bolt firing pin hole bushed if you are concerned about it. Was it a Remington action?
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Re: Twist Rate, Pill Weight and Stability

Post by marksman » 24 Oct 2018, 6:47 pm

its good to see that you will make your own mind up and err on the side of caution Gaz
you did it your way :thumbsup: :drinks:
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Re: Twist Rate, Pill Weight and Stability

Post by marksman » 24 Oct 2018, 6:48 pm

SCJ429 wrote:You can get the bolt firing pin hole bushed if you are concerned about it. Was it a Remington action?


+1 or change to a thicker cup primer :lol:
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Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 24 Oct 2018, 8:37 pm

Virtually new (less than 800 fired) Howa action.

I'm using CCI BR4 now, it might be worth making a couple of 25gn loads with them to see if they are more robust that the Remingtons.
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