High SD/ES with AR and 55gr class bullets

[NVScout]

I have a 16”. Craddock barrel and found an accurate load of benchmark and 55gr Nosler BT but it has horrible deviations .... like SD’s In The mid 20’s to 30’s. This same barrel shoots 75 grr BTHP extremely well .5-.7 5x5 with SD’s in the low teens but I am using 8208 for the 75’s. Is there a better powder you guys have found that works for the 55’s that give accuracy and good deviations ? I’m using 13 LC brass and BR4 primers, this rig is primarily for predator use and would like to find a varmint bullet that shoots well. I have shot 50, 53, 55 and 60 gr bullets in Hornady , Sierra and Nosler. The Nosler 55’s have shown the most promise.

 

[nso123]

I have had luck with 52s and Reloader 10x, although it was in a bolt gun.

 

[Onyx Z]

Try magnum primers (CCI 450's/Wolf/Tula). For 223, they tend to provide more consistent ignition with extruded powders like Benchmark, XBR, Varget, etc. The Wolf/Tula primers seem to get the lowest ES/SD for some reason.

Are the loads compressed or near compressed?

 

[Rimfiremike]

Try magnum primers (CCI 450's/Wolf/Tula). For 223, they tend to provide more consistent ignition with extruded powders like Benchmark, XBR, Varget, etc. The Wolf/Tula primers seem to get the lowest ES/SD for some reason.

Are the loads compressed or near compressed?

^^^
This... Tula/Wolf and cci450 primers are very good for consistent, accurate loads. Rem 7 1/2 are okay if you can't find the above.

Haven't seen the Tula or Wolf available for a couple/few years now though...

 

[NVScout]

Try magnum primers (CCI 450's/Wolf/Tula). For 223, they tend to provide more consistent ignition with extruded powders like Benchmark, XBR, Varget, etc. The Wolf/Tula primers seem to get the lowest ES/SD for some reason.

Are the loads compressed or near compressed?

Not even close to being compressed.

 

[rweaver00geo]

whats your barrel twist rate and powder charge for your benchmark load and are you using the nosler boattail orange tip or the black flatbase varmageddon. Are you crimping, I normally do not. I use a lot of benchmark in several guns with a variety of brass and 55 grain bullets and with minimal work up get a good shooting load. I use rem 7 1/2 primers 90% of the time but also worked up some good loads using plain wsr and the CCI5.56 primers

Ok just saw the pics above the powder charge's seem right on, maybe play with the seating depth. Even that middle group is all you need to hit a yote at 300

 

[FCS]

H322, AA2015 or N-133 would be my first pass with a 55.
GM205MAR have worked well for me in ARs.

How much Benchmark are you using?
Virgin brass or fired brass?

What blank was used: Krieger Criterion or Bartlien or ???
What length is gas system?
Buffer weight?

 

[NVScout]

whats your barrel twist rate and powder charge for your benchmark load and are you using the nosler boattail orange tip or the black flatbase varmageddon. Are you crimping, I normally do not. I use a lot of benchmark in several guns with a variety of brass and 55 grain bullets and with minimal work up get a good shooting load. I use rem 7 1/2 primers 90% of the time but also worked up some good loads using plain wsr and the CCI5.56 primers

Ok just saw the pics above the powder charge's seem right on, maybe play with the seating depth. Even that middle group is all you need to hit a yote at 300

It’s a 16” mid length rock creek 8 twist. They are the 55 BT’s not the varmegedons. I’m using a JP silent capture and don’t recall how I have it setup spring wise. I do know I went heavy on the spring due to going into battery problems.

 

[supercorndogs]

How far are shooting these 55s? Far enough that you would be worried about it?

 

[NVScout]

How far are shooting these 55s? Far enough that you would be worried about it?

Just depends , it could be 300-400 on squirrels.

 

[rweaver00geo]

Normally I shoot more of the varmageddons since im a cheap ass and the BTips have become a lil expensive. But for example with the varmageddons Im experiencing SD's in the teens and I would expect the same or better with the BT. I would bump up your charge a few tenths provided you havent seen any pressure signs yet and seat them as long as you can in the mag. With benchmark and my 16" RRA I'm running 3000 fps. . Im where your at and go up to 25.5 grains. IMO a magnum primer is not needed and dont crimp, that increased my SD's in a test.

 

[NVScout]

Normally I shoot more of the varmageddons since im a cheap ass and the BTips have become a lil expensive. But for example with the varmageddons Im experiencing SD's in the teens and I would expect the same or better with the BT. I would bump up your charge a few tenths provided you havent seen any pressure signs yet and seat them as long as you can in the mag. With benchmark and my 16" RRA I'm running 3000 fps. . Im where your at and go up to 25.5 grains. IMO a magnum primer is not needed and dont crimp, that increased my SD's in a test.

I went higher but it started to open up at 25.3 . I’m going to run a depth test Next time out and will go from there. I was just mainly curious if other powders might have a better outcome

 

[supercorndogs]

50FPS is about .1 vertical at 400y.

 

[NVScout]

50FPS is about .1 vertical at 400y.

Cool, I never really ran the number. But that still didn’t answer my question of other powders that may help with SD’s

 

[rweaver00geo]

N135 may be your answer check out this video on you tube I do not have any personal experience with that powder again Im a cheap ass and benchmark for me gets the job done and single digit SD's might not be possible but in the teens...YES.
Also IMO trying a different primer or brand of brass is an easy way you could get lucky. Im sure some others will chime in and I hope they do because maybe I will learn something too, but SERIOUS ATTENTION TO DETAIL with sorting, weighing out brass and bullets and a case prep will help. I Aint got time for dat lol

 

[rweaver00geo]

 

[NVScout]

Loaded up 25.2 with BR4, 205M and 450’s. Will post results later

 

[MarinePMI]

27grs of CFE223 seemed to work well for me with 55gr BTs. Meters well out of a Harrels too.

 

[NVScout]

Any

27grs of CFE223 seemed to work well for me with 55gr BTs. Meters well out of a Harrels too.

what kind of deviations and what primers ?

 

[MarinePMI]

BR-4's and 9fps SD's in a string of 5 shots. LC or NT (Lapua) brass. The powder meters really well...

It's a warm load, but performed well in the summer heat of the prairie dog towns, without any flattened primers or other pressure signs.

 

[rweaver00geo]

BR-4's and 9fps SD's in a string of 5 shots. LC or NT (Lapua) brass. The powder meters really well...

It's a warm load, but performed well in the summer heat of the prairie dog towns, without any flattened primers or other pressure signs.

I have recently been trying out the NT brass and have had mixed results what are your opinions? case cap is low imo

 

[MarinePMI]

My experience has been good thus far (sitting on 2k of it now). The case capacity reflects my expectations, as it is marked "5.56", and IMHO means it duplicated NATO (LC as the case may be) case capacity specs.

As far as durability, it's been pretty good. It seems to have the same strong case head as LC, in that I'm running 75gr ELDM's over a charge of 24.5gr's of XBR @2940fps, and no pressure signs. Primer pockets seem to be holding up well.

 

[NVScout]

My experience has been good thus far (sitting on 2k of it now). The case capacity reflects my expectations, as it is marked "5.56", and IMHO means it duplicated NATO (LC as the case may be) case capacity specs.

As far as durability, it's been pretty good. It seems to have the same strong case head as LC, in that I'm running 75gr ELDM's over a charge of 24.5gr's of XBR @2940fps, and no pressure signs. Primer pockets seem to be holding up well.

Is there any way you could measure h20 capacity of the NT brass?

 

[rweaver00geo]

This might warrant its own thread but with 8208 and a 75gr hornady I only tested it in LC brass and only up to 23.6g. With 8208 and nanno brass I only tested the 68gr hornady up to 22.8 so looks like Im on the weanie end of the charge weights. i have not measured the case cap with h20 but it is the heaviest brass I have used when compared to Winchester, WCC, Hornady, PMC, Rem, LC and Aquilla. With it weighing 4 grains more than LC I assumed it had a reduced capacity. I dont have any Lapua to check it against. So far durability has been good Imo also.
OK
Back on topic
NVScout Im curious on your primer test? I did one with 71/2, CCI556, and WSR. I will try and post some when I dig thru my records.

 

[NVScout]

This might warrant its own thread but with 8208 and a 75gr hornady I only tested it in LC brass and only up to 23.6g. With 8208 and nanno brass I only tested the 68gr hornady up to 22.8 so looks like Im on the weanie end of the charge weights. i have not measured the case cap with h20 but it is the heaviest brass I have used when compared to Winchester, WCC, Hornady, PMC, Rem, LC and Aquilla. With it weighing 4 grains more than LC I assumed it had a reduced capacity. I dont have any Lapua to check it against. So far durability has been good Imo also.
OK
Back on topic
NVScout Im curious on your primer test? I did one with 71/2, CCI556, and WSR. I will try and post some when I dig thru my records.

I ended up doing a primer test with 205AR, 205M, BR-4 and 450’s. The BR-4 was the winner but still poor spreads and inconsistent accuracy with the 55’s. I went back to the 75’s and decided that they just work to well not to use.....