.223Rem Sierra GameKing 55gr load devalopment

Reloading for my .223Rem was something I wanted to do long, long time ago, but never found enough spare time to do it. Every time I was running out of factory ammunition I just went to the shop and bought what I thought to be the last box.

Shooting roe deer with .223Rem

Just when I got my Tikka M595 I got some varmint ammo with it. As I don’t shoot many foxes I used it for zeroing and target shooting. It was a mixture of 40, 50 and 55gr hollow points and BTs. I needed roe deer ammo and surprisingly, there was agreement among Scottish deer stalkers. πŸ˜† All agreed Sako 55gr is best. I bought a box and it was shooting below 1″ and I just needed to test it on roe.

My first doe dropped on the spot as well as the second one. The third made 10m. After butchering carcasses I was also very pleased to find little meat damage. Sure, there was some bruising occasionally, but not too bad. No worse than from .243 or .308 and bullet was doing little muscle damage, but internal organs were a mess.

To be honest I also had one strage reaction to the shot, but it was when I shot a doe that spotted me and started running away. She looked back and I shot her aiming behind the shoulder. She ran 30-40m and stood. I shot her again and she dropped. As I examined the carcass both shots were good and maybe 1″ apart. So she would have gone down anyway, but was full of adrenaline and was running away, so not really caliber problem, but see for yourself.

Load development

My objective was to develop a load that would perform as well as Sako 55gr or better. My Tikka M595 really likes Sako ammo and would consistently shoot 0.5-1″ groups with it. The bullet is just a simple Soft Point so looking at what was available in local gun shops I decided to go for 55gr Sierra Game Kings SPBTs. It is nice little bullet with a boat-tail end that I think I paid Β£19 for.

My Tikka has very short 17.5″ barrel and after some research I went for Vihtavuori N130 powder. According to my data it should perform better than N120 and N133 with 55gr bullets in a short barrel. I looked up Vihtavuori load data and Sako load and decided to start from 20gr and load in 5 increments up to 23gr. I could just copy Sako load and they several years ago gave exact powder loads for their ammo, and they also use Viht powder, but in comparison with Viht data it looked hot at 24.2gr. I know Vihtvuori changed their load data to be more conservative over the last couple of years, but if I could not find good load in the 20-23gr range I could still go up to 24.2gr if safe.
I never claimed to be an expert in reloading so do not know if this approach makes sense… πŸ™„ I thought I could try a shortcut in load development by copying Sako’s COAL. So far my usual loading process consisted of two steps: find safe and accurate powder weight to suit a rifle and then find most accurate load by varying cartridge overall length. I thought I could skip second step if I copied Sako’s COAL. Both Sierra and Sako bullets look the same, so why not?

I measured all remaining Sako ammo to ogive using Sinclaire hex nut. Sinclaire hex nut is little cheap comparison tool. Much cheaper and easier to use than anything else I could find. Fist thing I noticed was that Sako’s COAL varied a lot… πŸ™„ I had only a few Sako ammo left so I just took an average as my target COAL for reloads and it was 2.835″ measured to ogive with the hex nut.

I used my once fired Sako brass and only neck sized it with Lee collet die. I chacked randomly several cases and they never needed any trimming, so I just used Lee chamfer tool and cordless drill to prepare case mouth for loading.

I never had any problems with CCI primers, so went for CCI400 small rifle primers. I used Lee Auto Prime to prime all cases.

This time I had to be precise with 0.7gr load increments and could not rely on Lee scoops πŸ˜† so used RCBS 5-0-2 model scales. I scooped the powder and used RCBS powder trickler to measure accurate loads. I loaded 25 neck sized cases. I loaded 5 different loads, 5 rounds each.


I went to try my loads. Weather was not great so I hid myself under a sitka tree and fired all 25 rounds checking spent cases for any pressure signs. I found none. I am sure there were one or two fliers in some groups, but one group looked great at 0.5″. It was 21.5gr load and the next one 22.3gr also was about 0.9″ and one bullet could be a flier. I could work out another load around 21.5gr and 22.3gr, but it suppose to be a hunting load and 0.5″ group is great for me anyway. I don’t think I can shoot any better. All my shots are below 200m and 0.5″ is very accurate in my book. I loaded remaining 75 bullets and they should last for a while.


LOAD 20.0gr 20.7gr 21.5gr 22.3gr 23.0gr
Group 1.0β€³ 1.4β€³ 0.5β€³ 0.9β€³ 1.7β€³


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  1. Very good thank you. I am going to try that exact bullet but use Vit133.
    Not wishing to diss you, but were you aware that you flinch when shooting?

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