Reducing SD by trying different powders and primers in 223AI

[Dwubyd]

Update:
The 223AI is back from the gunsmith with a new barrel. 1 in 8 twist 26" Cheetah. I have run about 130 rounds through it. I just can't seem to make the 80gn ELDMs work. Today I was fire forming some Lapua with junk loads - Rem primers that were left over from testing, some 30 year old 52gn BT pills and fire forming from 223 cases.....and it shot great! A couple of .4" groups. Now I am thinking the 80 ELDMs are too long for the 1 in 8 twist of the new tube. I will try Berger 75 VLDs and 80 VLDs. The Berger stability calculator has them at 1.5 and 1.37. The 80ELDMs are at 1.2 in the stability calculator.

Anyone else tried heavier bullets in a 1 in 8 twist?

 

[Chilly807]

I didn't have much luck with the 75 ELDM, and I'd expect the 80 ELDM to be worse from a stability point of view. My barrel is also an 8 twist, and it's a 223, not a 223AI.

Hornady "match" bullets in general haven't impressed me, maybe I'm a bullet snob. I've been called worse..

I use 80 Match Kings and 80.5 Bergers, but it will also shoot the 85.5 Berger Hybrids. I got them as a backup in case I had trouble finding the Sierras or the 80.5 Bergers.

Accuracy is a bit looser with the 85.5's, as they're not quite as stable as they should be in an 8 twist barrel. Berger says they'll work in an 8 twist, and they will, but it's not ideal.

The 80 Sierra is the more accurate bullet in my rifle, but there are a few problems with it. It either has a thicker jacket, or a longer bearing surface.. pressure builds sooner than it does with the 80.5 Berger Fullbore bullet. If you don't need speed, it's fine. I get more speed with less pressure using the 80.5 Bergers.

In order to shoot 800m F-TR with the 223, I need to be supersonic at the target (Shotmarker system), so speed matters. A longer barrel in 7 twist would make life easier, but I'll run this one until it's done or I get fed up, whichever comes first.

 

[Dgd6mm]

I shoot HM scores at 600 yards in FTR. My rifle is a Savage .223 running a Hornaday 80eldm. Benchmark 26" 1-8" twist barrel throated for this bullet.

 

[Dwubyd]

I shoot HM scores at 600 yards in FTR. My rifle is a Savage .223 running a Hornaday 80eldm. Benchmark 26" 1-8" twist barrel throated for this bullet.

What does HM scores mean?

 

[Dwubyd]

Chilly, how fast are the 80gn Sierras and Bergers coming out the end of the tube? I only need 2850-2900fps.

 

[jelenko]

What does HM scores mean?

For 600 yards, it's means you lose no more than 1.5% of the total points. Usually that means 98.5% of all shots are 10's or X's. The 10 ring is 1 MOA; the X ring 1/2 MOA.

 

[Chilly807]

Chilly, how fast are the 80gn Sierras and Bergers coming out the end of the tube? I only need 2850-2900fps.

I'm at a disadvantage with a 24" barrel, the rifle is a 223 Tikka T3x Varmint. It has a stock SAAMI chamber with a fairly short throat.

The 80 Sierras are going about 2675 fps, and the Berger 80.5 is at 2750 fps. Both are supersonic at 800m, I think the BC is slightly higher on the Sierra bullet.

Add a couple inches of barrel length and you should be right around 2850 I think.

Both loads use N140, and neither is above Viht's recommended max charge.

Both are jumped 15 thou off the lands.

I think you'd easily get 2850-2900 with either bullet in 223AI, but it'll be easier to get speed with the Berger.

 

[Dwubyd]

This week I tested about 6 different projectiles from Berger, Hornady and Sierra. The ones in the yellow boxes did best. The Berger 73gn BT Target pills showed most promise and the 85.5 hybrids were also good.

I was having trouble with the brass fire formed in the old barrel sticking in the new chamber. Seems to have been alleviated by using new brass. SDs were in the range of 8-15 for 5 shot groups.

Now I have to choose between the 85.5 and 73 grain pills. My preference is the 85.5s for their higher BC and hence better long range ballistic performance. The 85.5s were "marginally stable" according to Berger's stability calculator. They also say on their website that a bullet with lower SG number will have a lower BC. So maybe the drop in BC due to the lower SG will outweigh the advantage of the higher quoted BC. I suspect the only way to find out is to ping them at paper and see which is least affected by wind.

 

[L.Sherm]

I was having trouble with the brass fire formed in the old barrel sticking in the new chamber.

I'm betting the old barrel was fatter at the back end, new one is tighter.

 

[hunter67]

I ran 8208 in my 223ai with excellent results. Stupidly accurate, but I was not shooting matches, but the pdogs did complain out to 600.