.280 Ackley and 150grn Swift Scirocco II

[TimeOnTarget]

Can anyone help me with some load data for the combo above? I would really like to use the 150 Swift Scirocco II and be able to push it to 3000fps with accuracy but im having a hard time finding load data for this caliber/bullet combo.

Anyone have quickload that would care to provide some info for me? or personal experience would be great also.

The rifle is a Cooper Excalibur with a 26" tube. Nosler Brass.

 

[TimeOnTarget]

Ok, Ill ask this question differently,

Im having trouble finding a bullet that i can get close to the rifling but still fit in the magazine.

Any of the high BC bullets are way to long. The only bullet that i have tried that i can get within 30 thou of the lands is he 140AB. The 160 AB i can get to about 50 thou off the lands.

Everything else ive tried are a mile from the lands.

Suggestions?

 

[varmintH8R]

I have a Cooper M52 in 280AI that I am working up a load for. Here is where I stand:

I have the same mag length constraint you have. I actually filled the inside of the mag catch notch in the magazine with epoxy as rounds were sticking in it nose-first. It actually worked pretty slick. I still can't get to the lands with long bullets. . .

I have worked up loads using 160ABs and 160 TSXs. Both in front of 57gr H4831SC. No pressure signs, and there will be room to increase. The ABs were at max mag length leaving them 47 thou off the lands. The TSXs could be seated to the lands, but my experience is that they like to be at least 30 thou off so that is where I started.

I only loaded 10 of each as this was an initial work-up. I fired 3 shot groups only and got very good results. My worst group was 0.64" with the TSXs, but both projectiles averaged just under 0.5" across 3 groups each.

So, my initial concerns about loading right up to the lands proved to be unnecessary . . . I was even more pleased as my fireform loads SUCKED for accuracy.

 

[varmintH8R]

Also, a question for you. Are you using Nosler 280 rem brass or 280AI brass? I read an article that the SAAMI spec for Nosler 280 AI was 14 thou shorter than the original PO Ackley design, creating a potentially unsafe case-stretch issue. Cooper told me that their reamer is the PO Ackley design, but they seemed a little non-committal. If you have actual measurements I would be very interested in your experience.

Thanks

 

[yawn]

Iv got some 2000 rounds through my excalibur 280ai. Nosler brass has been fine with over 10 cycles and no issues at all. I shoot 162 amax single shot for longer ranges (though its still .040 off as thats as long as I can extract a loaded round) and the ttsx 140gr for a mag length load for close stuff. It s one of the least fussy rifles Iv ever had so as above try them at mag lenght and see how they go. You shouldnt have any trouble getting that speed wit a 26" barrel.
Re: the differnt chamber specs , I read an article a while ago that compared the go-nogo gauges for both the PO Ackley and the SAAMI and no actual difference could be found other than they seemed to be indexed off slightly different positions on the shoulder.

https://gunsmithtalk.wordpress.com/2012/07/17/280-ackley-improved-emperical-headspace-test/

 

[varmintH8R]

Yawn,

Thanks for the post and the excellent link. If I can get away from fireforming my next batch of brass that would be fantastic.

 

[TimeOnTarget]

Thanks for replys guys. Im using Nosler Brass, BR2 primers.

VH8R, Standard tsx and not ttsx correct?

I had really good groups out of 160 AB using 55.5 IMR 4350, i didnt measure them but i would be inside of 1/2". but was only getting 2800fps on my chrony.

The 1st load i ever made up was 59.5 IMR 4831 and 140 AB, This load also shot very well but i couldnt get it to group again to save my life yesterday.

MY chrony is an older shooting chrony so maybe its accuracy is in question.

I've taken the dremel to front of my magazine and thinned it down. Hadnt thought about filling that mag latch cavity with epoxy, but i am now!

Thanks for the help guys. Looking forward to more replys.

 

[varmintH8R]

You are correct, good old fashioned non-tipped TSXs.

I know it borders on heresy, but 2800fps out of 280AI isn't that bad with 160's. I would bet with the longer barrel and 160gr pills you could probably get some utility out of a slower powder. I would be interested to see your chrony results using H4831 or even IMR7828 (Hodgdon.com lists a load for it).

Let us know how it progresses! It is COLD here so I am shooting vicariously through LRHers.

 

[TimeOnTarget]

You are correct, good old fashioned non-tipped TSXs.

I know it borders on heresy, but 2800fps out of 280AI isn't that bad with 160's. I would bet with the longer barrel and 160gr pills you could probably get some utility out of a slower powder. I would be interested to see your chrony results using H4831 or even IMR7828 (Hodgdon.com lists a load for it).

Let us know how it progresses! It is COLD here so I am shooting vicariously through LRHers.

Thanks VH8R,


Me also,

Not to cold here, 25F right now, Middle of a blizzard though. snow and gusts to 40mph. I cant even see my 100yd target right now, to much blowing snow.

 

[TimeOnTarget]

VH8R,

Here is the group that i spoke of using 55.5 imr4350 and 160 AB.

Good group, just wasnt getting the speed i was hoping for.

It is un-realistic to think that i can get 3000fps out of a 160 AB in the 280AI?

Running numbers it looks like the 140AB launched at 3200fps (which i can do but havent found perfect load there yet) will have about 10" less drop, within 1" of same wind drift, and 100lbs less energy than the 160AB launched at 3000fps(which i cant do) at 600yds. I might just run the 140AB if i can make it shoot like the 160's @ 2800.

I was only thinking of the 160AB because of my annual elk trip. otherwise its whitetail sized game.

 

[varmintH8R]

I think 3000fps is probably unrealistic with 160s. Most of the 7mm mag data I see for 160s is 2950 to 3000. Of course, "internet people" routinely experience velocities quite a bit over published data. Their 280 Ackleys are faster than 7mag, too. I love my 280AI but it flat out aint faster than a 7mag.

That being said, with a slower powder you might get a bit more speed out of that longer barrel. Worth trying - my personal preference is for heavier bullets.

I am no ballistics genius, and I'm betting this relationship is not typically linear. But, I thought it was interesting:

140 is 12.5% lighter than 160

2800 is 12.5% slower than 3200

Critters will be bummed either way, seeing the groups above!

 

[yawn]

I dont think 3000 is at all unrealistic with a 26 inch barrel. Iv been running the 162 amax at 2920 form a 23" (validated many times at long range) and the nosler brass has tight primer pockets after many cycles. Slower powders will help with the heavier bullets, RL 22, N165, N560, H1000. If you are keen on the accubonds I think Id look at the new long range 150gr nosler have just put out. Better BC than the 160 and youll be able to push it faster. I might give them a try on the next new barrel.

 

[woods]

I shoot 160 AB's almost exclusively in my 280AI and always clock them around 3030 fps. My load now is with RL17

Here is my data and if you use YOU SHOULD START LOW AND WORK UP JUST LIKE I DID

AUDETTE AB 160 0.507 RL17 3.350 1 53.7 0.030 2911
AUDETTE AB 160 0.507 RL17 3.350 2 54.0 0.030 2949
AUDETTE AB 160 0.507 RL17 3.350 3 54.3 0.030 2962
AUDETTE AB 160 0.507 RL17 3.350 4 54.6 0.030 3003
AUDETTE AB 160 0.507 RL17 3.350 5 54.9 0.030 2949
AUDETTE AB 160 0.507 RL17 3.350 6 55.2 0.030 2996
AUDETTE AB 160 0.507 RL17 3.350 7 55.5 0.030 3003
AUDETTE AB 160 0.507 RL17 3.350 8 55.8 0.030 3030
AUDETTE AB 160 0.507 RL17 3.350 9 56.1 0.030 3072
AUDETTE AB 160 0.507 RL17 3.350 10 56.4 0.030 3065

I now load at 56 gr and primer pockets are staying good

Before RL17 I used RL22 and RL25 and was able to hit 3000 fps without problem

My gun is a 26" Hart barrel and that OAL is .030" off the lands. I have a tight chamber and a .313" neck.

I tried the 150 gr SSII's and my Audette was as follows

AUDETTE SCIRR 150 0.551 RL17 3.350 1 53.5 0.030 2996
AUDETTE SCIRR 150 0.551 RL17 3.350 2 53.8 0.030 3030
AUDETTE SCIRR 150 0.551 RL17 3.350 3 54.1 0.030 3044
AUDETTE SCIRR 150 0.551 RL17 3.350 4 54.3 0.030 3044
AUDETTE SCIRR 150 0.551 RL17 3.350 5 54.6 0.030 3051
AUDETTE SCIRR 150 0.551 RL17 3.350 6 54.9 0.030 3058
AUDETTE SCIRR 150 0.551 RL17 3.350 7 55.2 0.030 3075
AUDETTE SCIRR 150 0.551 RL17 3.350 8 55.5 0.030 3110
AUDETTE SCIRR 150 0.551 RL17 3.350 9 55.8 0.030 3108
AUDETTE SCIRR 150 0.551 RL17 3.350 10 56.1 0.030 3108
AUDETTE SCIRR 150 0.551 RL17 3.350 11 56.4 0.030 3125
AUDETTE SCIRR 150 0.551 RL17 3.350 12 56.7 0.030 3174
AUDETTE SCIRR 150 0.551 RL17 3.350 13 57.0 0.030 3174


But accuracy was not as good as with the 160 AB. Perhaps a seating depth test might yield better results. I know my 6.5 rem mag likes the 130 SSII's at .060" off

 

[TimeOnTarget]

Thanks guys, I just happen to have a pound or so of RL17. I will give it a try.