From what I have read and heard from my friend in Alaska, the 17/225 will propel the 30 gr at 4100 to 4300 FPS or a bit faster.
I believe he said he now gets 4100 from his 17 VLR which is a 223 case improved.
Since 1972, I have been using rifles chambered for a .17/222 magnum improved with 40 degree shoulder. This case has capacity of about 31.5 grains of water, which is similar to that of a .17/223 improved, and about 0.5 - 1.0 grains less than a .17 PPC.
During the last 3 years I have switched to using the 30 grain bullet, and found that this case will achieve 4100- 4175 fps with that bullet weight. This is similar to that being achieved by others using the .17/223 improved, and .17 PPC. The .17 BR seems to achieve about 75 to 100 fps more.
I also chronographed the Berger 37 grain VLD (BC.343) to find out what velocity could be achieved with this case. I achieved 3785 fps using a full case (30.0 grains) of WIN 785, however as expected the bullet keyholed into the target, as it requires a 1 in 7 twist barrel to stabilise it.
However, some are having problems getting the Berger 37 grain VLD to hold together and be accurate at velocities in excess of 3500 -3600 fps. About 3 years ago, Walt Berger in replying to my query on this issue, told me that he thought 3450 fps was the practical limit for the bullet.
I believe that cases with a capacity of about 31 to 33 grains are the practical limit when using the 30 grain bullet.
A case such as the .17/225, would only be practical if suitable bullets in the 35 to 40 grain range could be sourced. Hope the above helps your choice. Good luck, Brian
Originally when new in 1986, it was 25.25 inches, and about 6 months ago I had the barrel set back and rechambered for the same case, and lost about 0.6 inches in the process.(ie 24.6)
I had this done as the throat had eroded about .250 inches after about 1600 shots, velocity was down about 100 fps, and my gunsmith was available to do the job.
In my .17/222 mag imp, with the 30 grain bullet, about 27.0 - 28.0 grains of H414, or Viht N550 will achieve between 4050 - 4175 fps. I use this rifle as a principly a varmint rifle for foxes, rabbits, etc and did not want the length to exceed 26 inches.
However, it would be interesting to see what velocity increase would occur with a 27 or 28 inch barrel. Good luck, Brian.
My only experience with a long barrel, was in 1972, when I put a 33 inch Ackley Barrel on a 22/284. The rifle achieved 4,048 fps using 54.0 grains Norma 205 with the 60 grain Hornady Hp. Unfortunately, there were no suitable bullets heavier than that available in Australia at that time.
I recently had the 25.25 inch barrel chambered for the .224 Clark (64 grain capacity, same as 22/284) set back after 1500 shots and rechambered to 22/250AI.
The 224 Clark achieved 4,035 fps (55.5 IMR 7828) with the 60 grain Nosler SPBT, 3,952 fps (54.5 IMR 7828) with 69 grain Sierra HPBT, 3735 fps (57.0 H1000) with 80 grain Sierra HPBT.
I intend to build up another rifle using the .224 Clark, but next time will use a long action Rem 700, probably a 28 inch barrel, and concentrate on bullets of 80 grains and heavier. Good luck, Brian.