Saturday I took the day and fitted and chambered the barrel to my 224 AM test rifle. Took most of the day. Ran into a bit of a problem when I loaded up some rounds to live fire test the rifle. Seems the brass I was using was a bit thicker in the neck then the cases I used to draw up the reamer print off from.
They were to tight when chambered. As such Sunday morning I got up and took 1.5 thou off the neck thickness and this worked perfectly. Got a couple cases formed and then had family things to attend.
This is not a major issue, in fact a good thing. If someone wants a tight necked chamber the reamer is good to go. If they do not want to neck turn, I am ordering a properly sized neck reamer for that purpose.
Anyway, don't have any hard data yet but a fireforming load of 60.0 gr of AA8700 under the 100 gr ULD RBBT did a fine job of forming the cases and is still a very mild loading.
Don;t have the Sako extractor fitted to the bolt yet but tip the rifle up and the fired case fall out. Must be a pretty mild load!!
Comparing case capacitied with the parent(22-270 WSM) and the 224 AM I came up with 87.2 gr vs 92.5 gr for the 224 AM. Not that I am concerned about case capacity as there is more then enough!!
This pic shows two 22-270 WSM fireforming loads on the left, two formed 224 AM cases in the middle and a 22-250 AI loaded round on the right for size comparisions.
You can see the body taper is reduced in the 224 AM cases. Also, the seating depth of the 100 gr ULD RBBTs in the fireforming loads is deeper then it needs to be by about 50 thou just to give a pressure cushion for the first loads. Not alot of data for a 100 gr .224" bullet with a 60 gr powder charge!!
There is not a dramatic visual appearance change from the 22-270 WSM to the formed 224 AM. Slight shoulder angle increase and a shoulder diameter increase of around 15 thou.
This week I have to get back on customers rifles but hopefully will get the rifle bedded and barrel break in started during the week. Possibly be able to get some chrono numbers next weekend.
I was actually a bit suprised that there were no ignition or pressure issues at all forming these cases using the slow ball powder. Just have to find out what burn rate will work best now with the 100 and 107 gr ULD RBBTs. I have Ramshot Magnum, Magpro, 8700 and WC872 to try. That covers a pretty wide range of burn rates so I am sure one of them will produce top performance. We will see.
More to come, just a short update.