How much powder do you have left?
The reason i ask is that my best results in the Howa 223 varmint barrel have been with BM2 (best consistent 0.6moa) and BM8208 (using now and getting 0.4moa pretty consistently). I wont go into my loads as i don't use that weight bullet and even with the 55s you are best to find your own load by progressively working up, as Blackened explained above. My personal approach is as follows, but everyone will be slightly different. Start at bottom of load spec and test up in 0.3gn, say 21 through to 22.2gn, 3 x 3 shot groups. You will find one load that is much better and one either above or below it that is not as good but still better than others, say 21.6 best & 21.9 2nd for example. Test 0.1 grain either side of those two with further 3 x 3 shot groups. Pick the best of the lot and confirm with 3 x 5 and maybe 1 x 10 shot groups. Using this technique i have 3 loads for 3 different bullets that all shoot less than 1moa and all with in 1moa of the one scope zero in my Howa 223rem. Also have a trailboss load that shoots about 1moa but it is on a different zero. Not saying to follow this, just sharing my process. (by the way, i don't mix up the loads because they are in different head stamps and have obviously different bullets. One other thing: be anal about weighing each load during testing). No point testing if you are "throwing" each load and they are 0.2gn different with in the batch, 0.2gn can make a huge difference in 223rem!
However, it sounds to me like the rifle itself needs a little tuning. If you haven't done it yet, use your best existing load and tune the rifle with it and see if the groups shrink. Then start looking at tuning the load further.
What i did to tune my Howa 223 HB to achieve close to 1/2moa with tuned load and around 0.9 moa with Rem factory 55PSP:
1/ Glen Couglan trigger job (ebay trigger dude) $60.... bargain, 2lb, no creep, crisp as!
2/ Tune action torque (mine like 5inch pound more on the front 35"lb rear-40"lb front, or something close): start 35 both, shoot a few 3 shot groups, do the front one 5"lb, shoot some more groups, do the rear 5"lb, do some more groups repeat up to around 50"lb. Assess your targets and choose the best looking setting then confirm with 5 & 10 shot groups. Cost = time and ammo
3/ Full length bedding of action. Cost = time + about $30-40 using kit and instructions from this dude :
http://www.ballisticstudies.com/Knowled ... dding.html(or you can pay a gunsmith to do it).
Might seem like time and money up front but less in the long run than losing confidence in the rifle and yourself, wasting money looking for a load in a rifle that isn't tuned very well. You'll end up selling the rifle. losing money, buying a new rifle, spending money looking for a load for it.... and so on.
Also, with a Hogue stock, you may find that the fore-end (notoriously flexy) may be touching the barrel if you are using a rest up the end of the fore end. To fix this i stiffened the fore end using instructions from the web link above. In the end, i jest got sick of the Hogue stock (wanted a prettier gun) and bought a Boyd stock, pillar & full length bedded it. Not suggesting you need to go that far, just what i have done.
Also, sounds like you don't have load data on hand: here is the link to ADI load data:
http://www.adi-powders.com.au/handloade ... ifle%2EaspGood luck with it!