17-223 load development help?

[spencerhenry]

I recently acquired a BHW barrel in 17-223. 9 twist, 20", rifle length gas system, threaded 5/8-24.

My brass is random headstamp 223 run through pacific durachrome 17-223 dies, set for full length sizing.

Primers are Winchester small rifle.

Loads tried so far:
30gr sisk, 20.0 to 22.0gr of IMR 4895 in .5 grain increments
30gr sisk 21.5 to 23.0gr of 8208 in .5 grain increments
27gr kindler 21.5 and 22.0gr 8208 seated to 2.180 coal (base of bullet to base of neck)
25gr sisk 22.5 to 24.0gr W748 seated to 2.135 coal (base of bullet to base of neck)

So far the best group has been over 1.5" with most groups in the 2.5" to 3" range!

I have tried with and without a sandstorm suppressor attached. From bags at 100 yards, the scope is one i have used in the past on a 223 that shot consistently .5 moa. Rifle started out as an unfired colt 6724. Gas block is a PRI adjustable, first few groups were gas closed off, shooting single shot. Some groups with gas open shooting self loading, and some groups in between.

suggestions?

 

[pacificman]

For me the .17 caliber seemed to be the fussiest cartridge to find the perfect load for especially
wanting accuracy and extreme velocity. I now will load for accuracy and just let the velocity be what
it will be. I had good results with H4198, Benchmark, and RL-15 with the .17 calibers that I have
owned in the past. I also used 30 and 25 grain Berger and Hornady V-max bullets with great results.
I remember trying several different powders to achieve the load I wanted...You might consider a
OCW...(optimal charge weight) ladder test with what you have. Seems like with what you have tried
already you would have better grouping. You might want to check scope, rifle, a bit more thoroughly.
Ya might want to have a look in barrel with bore scope too. Just some suggestions for ya.

 

[fredo]

Are you 100% certain that your barrel is a 1:9 twist???

My 'smith & I experienced the unfortunate instance of where a barrel was incorrectly stamped.
Built a beautiful rifle, but it was on a 1:10, not a 1:9!
I only figured it out after carefully measuring twist rate, myself. That said, 25gr would shoot lights out, but 30s wouldn't stabilize. 2-3" groups with 30s, but the 25s shot in the same hole.
I felt horrible the smith, as he was out his time & effort to re-barrel on his dime. The barrel maker would not compensate him, despite it being their error.

Anyhoo, that's kind of a stretch, but your lowsy groups reminded me of that negative experience.

Beyond that, what are the reamer dimensions? Have you measured how much those bullets are jumping? Not familiar with the bullets you're using, but possible that excessive freebore is inhibiting accuracy? IMHO, freebore should be "0" on a .17-223...

 

[boltfluter]

Segregate your brass for starters.

Paul

 

[spencerhenry]

the barrel is a 10, i was thinking 10 and typed 9.
that may be the issue with the 27's and 30's but, the 25gr sisk are shorter than the hornady 25gr hp by .020, but i am not convinced that those are an accuracy bullet.

there is a lot i can do with the brass, but i doubt that matching headstamps will take a 3" group down to under an inch.
i am going to anneal the first 65 or so that have been fired, sort them, and prep them. i know that will help, but the question is how much.

 

[fredo]

There ya go, then. A 1:10 is NOT friendly to >25gr .172 cal. bullets...

Even though those 25 Sisks are shorter, they might have a longer bearing surface. Remember, bearing surface length is what dictates required twist, not overall bullet length.

Dont' bother annealing, yet. Plus, you're runnin' a brass munchin' AR, so I wouldn't get too fussy over brass, anyway!

Stay with 25grainers that are proven to work in a 1:10, and see what ya get for accuracy. Then go from there...

Good luck!