Re: Kirby your AM\'s
Things are going well so far, there have been a couple hic ups but that is to be expected with extreme rounds like this.
The first 257 AM that I built was using a Pac-Nor 30" 1-8" twist for the 145 gr ULD Rebated Boattail Wildcat bullets. During bullet development, Richard Graves decided to try some heavier ULDs and came up with a 156 gr ULD Rebated Boattail for the 257 AM!!!
Those bullets should be here for testing here in the next week or so.
One interesting thing I found with the Pac-Nor barrel was that it had a very loose bore, large compared to the Liljas I am used to working with. As an example, when I chamber a 25 cal Lilja barrel I generally use a reamer pilot bushing in the .2502" to .2504" range. The Pac-Nor took a .2514" bushing easily so they are a full 0.001" larger in bore diameter then the Lilja barrels.
With the 30" barrel using the 130 gr Wildcat BCFBHP bullet, I did reach 3750 fps but this was a very hot load using AA8700. A top comfortable load easily reached 3650 fps out of the very fast 1-8" twist barrel.
Just for reference, the 257 STW pushes these same bullets to 3450 fps in a 1-10 twist Lilja 3 groove 30" barrel.
I just finished putting together a 30" Lilja 257 AM with a 1-10 twist on a 29.5" barrel. We have had a bit of cold weather move in and it hit just as I finished up this rifle. I was able to take it out and at least fireform some brass with this rifle to see how it shot at 100 yards. With virgin brass and bullets seated .150" off the rifling, this Lilja barrel is already printing 1/2 moa three shot groups at 100 yards. That was shooting in 0 degree weather with heavy gloves and coats so I suspect this rifle will play with the 1/4 moa level easily in better shooting conditions.
I have not been able to chrono any loads because of the weather to compare the Pac-Nor barrel with the Lilja.
The 6.5mm and 270 Allen Mag Reamers came in and I will be building a 270 AM here possibly this week. I have the barrel and stock, just waiting for the action to get in.
The 6.5mm AM will be put together shortly after that.
I have received the quote from Redding on the dies and have OKed the making of the full length sizing dies. They will run about $65 to $70 for a Full Length sizing die and I wil be supplying BR style In-Line seating dies of either Redding or Forster brand in all these rounds cut with the same reamer as the chambers.
These will take roughly 16 weeks to get produced so this is the longest wait so on the rifles. I am just being a little creative right now with some dies that allow me to load the ammo.
I have found that with the extreme minimum taper of these rounds, the cases will require a near full length size for easy feeding. Not enough to bump the shoulder but enough to reduce the body diameter slightly to allow easy chambering.
The 257 AM as produced what I was expecting so far. I am happy with the accuracy and the velocity with a full 200 fps edge over the 257 STW with the 130 gr bullets.
I did shoot some 115 gr Ballistic Silvertips just to see what they would do. I only tested one load and they hit 3800 fps easily in the 30" Pac-Nor with 8700 fps and the five shot string had an extreme spread of only 15 fps so wven with this light bullet weight the powder is burning consistantly with the help of the AMs shoulder design.
We have also started design work on the 7mm AM. I can not give out much details but I will say it will out perform the 7.21 Firebird from Lazzeroni and it will be able to be housed in a Rem 700 action as well.
Another little bit of information, Richard Graves of Wildcat Bullets is designing bullets in the 180 to 200 gr Range for a ULD bullet in the 7mm AM!
This will probably be released sometime this summer, mid to late. Will just have to see what the finances allow.
SO so far, we are meeting every goal so far. There is still alot of testing to be done but it is going very well.
Temps here are supposed to remain in the zero to 10 degree F range for the next 15 days so there will be no chono testing but I will be doing some accuracy testing and hopefully I will get one of the 257 AMs out after some yotes here soon.
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