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Reducing SD by trying different powders and primers in 223AI

Dwubyd

I am reloading a 223AI PRS rifle and my next challenge is to reduce my ES/SD. I have ES of up to 50 fps (5 shots) and SD of 15-20. I notice that Mr Freedom Seed recommends sorting out SD by focusing on combustion - things like powder, primer, neck tension and case volume. I am using ADI and Starline brass. He says don't even worry about grouping until you have combustion sorted out. I have 1.5 thou neck tension, so that is covered.

My next step is to try different primers (currently using Federal 205, going to try CCK BR4, Rem 6 1/2 and Rem 7 1/2). I will also try a different powder (ADI Benchmark 2).

I welcome suggestions on what steps to take to reduce ES/SD.
 
Dwubyd said:
I am reloading a 223AI PRS rifle and my next challenge is to reduce my ES/SD. I have ES of up to 50 fps (5 shots) and SD of 15-20. I notice that Mr Freedom Seed recommends sorting out SD by focusing on combustion - things like powder, primer, neck tension and case volume. I am using ADI and Starline brass. He says don't even worry about grouping until you have combustion sorted out. I have 1.5 thou neck tension, so that is covered.

My next step is to try different primers (currently using Federal 205, going to try CCK BR4, Rem 6 1/2 and Rem 7 1/2). I will also try a different powder (ADI Benchmark 2).

I welcome suggestions on what steps to take to reduce ES/SD.
Click to expand...

Do a search and you'll find a few posts that might help such as this one:

Getting the ES/SD down on .223s

While I have been able to get my extreme spread in muzzle velocity below 20 fps in most other calibers I can’t seem to do the same with my .223s that I use for PRS style competition Using a bolt action rifle. I use all the same tricks (weighing the powder to +/- .02 grain, lubing the case...
forum.accurateshooter.com
 
Focus on what your target tells you not numbers from a chrono. Yeah 50 ES is high
but you say 1.5 nk you have sorted out, what does that mean? 1.5nk is the answer.
I think your on the right track by switching primers to get it down but focus on group shape to get you started and not numbers.
Seating depth can also affect E.S.
Believe the Target!!
I've seen 0 E.S shoot like crap.
 
Thanks guys.

Sherm, what I meant by "neck tension is sorted" is that when I got the rifle it came with 300 brass that had neck tension of around 6 thou. I bought a larger bushing to reduce the neck tension to 1.5 thou, which should eliminate that as a potential problem.

I hear what you are saying about believe the target. Of course, at the end of day that is what actually matters. However, as you say a 50 ES is a bit high, so my goal is to get that down, and then I will try varying seating depth and amount of powder.

I am shooting Monday, so I will report back after that.
 
neck thickness can vary in unturned brass, so when you run the brass through the die, the difference is pushed to the inside of the neck, "think of the hole where the bullet goes" if this varys, so does the "grip" on the bullet! try either turning the necks or an expander mandrel right before loading & see if that helps?
Best of luck getting it sorted out & good shooting!:)
 
I use Gordon's Reloading Tool (free download) to find powders that look promising. I can quickly find the charge that yields the max allowable pressure for the cartridge. It will tell me what muzzle velocity to expect and where along the barrel that burnout occurs. As I reduce the charge from the max charge, I can see that burnout marches toward the muzzle. I find the lowest charge weight that allows burnout to occur inside the barrel and make note of the corresponding velocity. (Anything lower than that is just blowing unburnt powder out of the barrel). I like powders that give me a wide range of loads between these two extremes that I can then explore with a ladder test.
 
An ES of 50 is high for sure. FWIW my best F-Class and ELR load has an ES of 45 and it shoots ridiculously well. All my attempts to shrink the ES resulted in increased vertical dispersion at distance. So I just turned the chrono "off". So as stated above, if its shooting well you might have a great load despite what the chrono is telling you.
 
223 (not necessarily AI) can be a problem child when it comes to getting consistent velocity. Maybe a situation caused by less than ideal combustion in a relatively tall, narrow case?

You may find you want more than 1.5 thou of neck tension to promote a more consistent powder burn by allowing the pressure to build a bit before the bullet starts to move in the case. There's a couple of ways to get that.

I'd agree that the target has the final say as to whether a load is working or not.

If slow shots hit lower than faster ones enough to affect your scores or whatever other yardstick you're using, that's a problem that needs to be addressed. I definitely see the difference 50 fps can make at long range.

Typically you correct the problem by reducing your extreme velocity spread as much as you can while still keeping the load as accurate as possible.

As has been already mentioned, a load with excellent velocity stability that shoots like a shotgun is no good, but you might be able to improve your velocity control on an otherwise accurate load.

I put a mild crimp on all my 223 loads to achieve this, starting with about 2 thou of neck tension. That usually reduces extreme velocity spread by 30 to 50 percent over non-crimped loads.

I can't see that it has hurt my accuracy to any noticeable degree, although many would say that a crimp isn't something that they'd ever use. It wasn't my first choice either, but it works when nothing else seems to.
 
Gary, I am annealing every firing, using a gas annealer. Having said that, I just did my first anneal after getting the gun and brass 2nd hand.

OMW57, I have measured the neck thickness of the brass (ADI and Starline) and it is within half a thou of 0.014", so I have not bothered to neck turn. I do not have an expander mandrel, so I resize with a FL bushing die. I could buy an expander mandrel and a smaller bushing....

FeMan, I have found from doing an OCW test there is a load that looks promising. If I don't have any luck with different primers, powder or neck tension, I know I can always go back to that load.

Chilly, I am not excited about the idea of crimping, but if it works, I might have to try it.
 
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If you decide to try crimping, I'd suggest the Lee factory crimp die. They're not case length critical, and are easily adjusted.
If you don't go overboard with the amount of crimp you use, they don't mark the cases either.
I use just a shade over 1/4 turn of crimp after the die touches the case, it gives enough grip to reduce ES and SD without damaging either the case or the bullet.

I tried using greater neck tension instead of crimping, but results weren't very consistent even with annealed cases.

I'm using 80.5 Berger Fullbore and 80 Sierra Match King for long range, with N140 and Fed 205 Match primers. SD is usually 9-11 fps with the crimp, rather than 15-18 without it.

I've gotten lower SD on occasion, but 9-11 is about normal for those 2 loads.
 
Chilly807 said:
If you decide to try crimping, I'd suggest the Lee factory crimp die. They're not case length critical, and are easily adjusted.
If you don't go overboard with the amount of crimp you use, they don't mark the cases either.
I use just a shade over 1/4 turn of crimp after the die touches the case, it gives enough grip to reduce ES and SD without damaging either the case or the bullet.

I tried using greater neck tension instead of crimping, but results weren't very consistent even with annealed cases.

I'm using 80.5 Berger Fullbore and 80 Sierra Match King for long range, with N140 and Fed 205 Match primers. SD is usually 9-11 fps with the crimp, rather than 15-18 without it.

I've gotten lower SD on occasion, but 9-11 is about normal for those 2 loads.
Click to expand...
How do these loads shoot?
 
I use either Lapua or Winchester (sorted) for my 223AI. FWIW, mine has a Bartlein 27" 1-7 chambered by LRI and a TAC30 action.

I've shot more 80 grain VLD's than any other but also have 80.5, 82, and 75 VLD Bergers on hand and have had good results to 600 with all. I either use Varget or Re15 and CCI450's. I can keep sd's between 10-12 fps for 10 shots. I use a Redding FL bushing die and then a mandrel afterwards for .002" tension (or whatever way you want to describe it) and no crimp. I do have a Lee FCD but the chronograph said it made little to no difference and my targets preferred no crimp slightly. I get better accuracy and numbers when I load warm (a touch crunchy with my preferred powders).

I struggle to get low sd's with the 223 but all of my 223's are gas guns so there is that. The 223AI has not been nearly as hard to get consistent decent sd's.

I would not use the Remington 6 1/2 and use the BR4 or 7 1/2. The 205 is never a bad idea but I have had better luck with the 450 (more or less a cheaper BR4 IMO).
 
It'll usually hold a minute of angle all the way back to 800m if I'm doing everything else right. Maybe slightly bigger or smaller. The rifle is a Tikka T3x Varmint in 223, in an MDT XRS chassis. Original barrel.
It's not a half minute rifle and never has been, but it's good enough for casual F-class at the level I want to play at.
The 80 Match Kings shoot a little better in it than the 80.5 Berger Fullbores, I have a few hundred of the Bergers left though so I might as well shoot them up.

This was last February with the Bergers at 800m. A bit of wind left to right blew 2 into the 4 ring, and the SD creeps up a bit in cold weather until the barrel is fully warm.

(1).jpg
 
Dwubyd said:
I am reloading a 223AI PRS rifle and my next challenge is to reduce my ES/SD. I have ES of up to 50 fps (5 shots) and SD of 15-20. I notice that Mr Freedom Seed recommends sorting out SD by focusing on combustion - things like powder, primer, neck tension and case volume. I am using ADI and Starline brass. He says don't even worry about grouping until you have combustion sorted out. I have 1.5 thou neck tension, so that is covered.

My next step is to try different primers (currently using Federal 205, going to try CCK BR4, Rem 6 1/2 and Rem 7 1/2). I will also try a different powder (ADI Benchmark 2).

I welcome suggestions on what steps to take to reduce ES/SD.
Click to expand...
Check out the load map.
 
I also struggled with high ES/SD using 223AI for PRS. It didn't really start to matter until 500 yards. I had single ragged holes of 10 shots at 100, but solid over and unders beyond 500.

I tried quite a few different things, but what changed my numbers the most was switching to....... CFE223. Heresy. Ball powder metered much more exactly in the small cases. I have always used CCI BR2's.

I would say the next biggest factor was neck turning. I also use Starline, and turning necks mitigated some of my ES and SD problems.

Finally, I like to load big batches. I practice and shoot them same load. Batches that sat for a couple of months had inconsistencies compared to freshly loaded ones. I started using graphite lubrication as part of my reloading practice when seating. I try to only keep a few hundred loaded anymore.

Good luck! Don't stop trying. It is tough with these itty-bitty cases.
 
Well, I am back from a day at the range. Unfortunately, no obvious lessons from a day of making noise.

Best for the day wasn't even from my 223AI. It was a 0.2" 3 shot group from my 308 Howa hunting rifle.

Best group for the day (5 shots at 100m) was 0.43". Most were in the 0.5s and 0.6s.

I have done a bit of measuring stuff. Here is what I have found:

- Neck thickness is not what I thought. I measured 8 cases and found variations from 0.3 to 1.1 thou in neck wall thickness. 1.1 sounds like a bit too much.
- I weighed all cases I fired today and they were between 96.1 and 97.1grains except for outliers of 95.9, 96.0, 97.6 and 98.3
- I measured case length for 30 cases. Min1.744", Max 1.765". The max is a bit concerning because 223AI max length is 1.760"
- Loaded round concentricity measurements were usually 0.003" but some were as high as 0.007"

Conclusions from today's shooting:
- Rem 7 1/2 primers had high ES for velocity. Rem 6 1/2, Fed 200, CCI BR4 were all fine.
- Velocity for the loads I tested today was around 2845fps. Perhaps 100fps too slow for the Ackley version. No signs of approaching pressure limit. It might pay to push it a bit faster and see what happens to groups and ES

Next steps:
- try pushing the velocity up a bit, looking for a node
- Prepare some precision cases: Trim cases to 1.745", neck turn, group by weight, check for neck runout
- or just buy some Lapua
- try 85.5 hybrids in the yellow box
- check for bullet runout in loaded rounds
 
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