The H&N FTT 14.66gr pellet has been one of the favorites for many Prods. In the 5.53 head size, but have seen some that say 5.54 or 5.55 head size has worked well. Might want to give them a try. With a 0.110" TP, heavy hammer spring, and BSB o-ring buffer, you can get 24 shots @ 16FPE or 16 shots @ 20FPE. Might get a little more above 20FPE but will be down to 8 shots or less. PS: Is your MM barrel the newer hammer forged barrel or an LW?
Ok, got a question. I am putting a 16" Gaska barrel on it, along with a .118 port & a 7 lb spring I got from Normand. The O rings I bought are"70 Buna-N #113 3/32 Width". I would like about 700 fps with the jsbs. If that is possible. Well questions,1. How many O rings should I use?Assuming these are for a BSB buffer, and 18.1g JSB, I would say 3 O-rings. 2. Where should I start with my Hammer Spring & Hammer adjustment?Hard to say, given your variables (barrel, spring, TP) which I haven't used. The throw adjustment is critical. For just a very rough starting point, 3/4T on throw from full CCW, 5T on Preload from full CCW, on a 3K fill. I did not get any baffles, I read some drill a hole in the shroud near the breech.3. Should I drill a hole in the shroud? I assume you have a shroud to match the new barrel. My experience on prods, trying the near breech hole, with and without magic sponge, did not appear to make a noticeable difference. Your results may vary. If someone wants some of these orings, PM me. I have a hundred pak. I doubt I ever use them all. I will mail half of them to one person and they can mail some to others. They are so cheap may not be worth your time.
Quote from: Nutcracker on February 13, 2015, 12:59:39 PMOk, got a question. I am putting a 16" Gaska barrel on it, along with a .118 port & a 7 lb spring I got from Normand. The O rings I bought are"70 Buna-N #113 3/32 Width". I would like about 700 fps with the jsbs. If that is possible. Well questions,1. How many O rings should I use?Assuming these are for a BSB buffer, and 18.1g JSB, I would say 3 O-rings. 2. Where should I start with my Hammer Spring & Hammer adjustment?Hard to say, given your variables (barrel, spring, TP) which I haven't used. The throw adjustment is critical. For just a very rough starting point, 3/4T on throw from full CCW, 5T on Preload from full CCW, on a 3K fill. I did not get any baffles, I read some drill a hole in the shroud near the breech.3. Should I drill a hole in the shroud? I assume you have a shroud to match the new barrel. My experience on prods, trying the near breech hole, with and without magic sponge, did not appear to make a noticeable difference. Your results may vary. If someone wants some of these orings, PM me. I have a hundred pak. I doubt I ever use them all. I will mail half of them to one person and they can mail some to others. They are so cheap may not be worth your time. See above:
696-711-698 for 23 shots with Es of 15. 19+ FPE, it looks to me you are getting 3-4 FPE with the 4" of extra barrel. How is the accuracy?Hammer preload: If you are turning CW and it stops, your spring is too long and binding. The prod preload dis-engages the threads at max preload. With 3 orings and 1.5 turns on the throw, you might not be engaging the buffer. But, if you are happy with the string, shoot it for now.
I was a little surprised that it was not until around 2500 psi that it started getting close to 700. I thought it would be higher???
Quote from: Nutcracker on February 18, 2015, 10:21:22 PM I was a little surprised that it was not until around 2500 psi that it started getting close to 700. I thought it would be higher???Sounds like your spring. What is a "7lb" spring? The spring I use (as suggested by FuzzyGrub) is 1.5" x .30" x.042". I think they have like a 10lb or 11lb load capacity.
Yes it is 7 lb, but is longer than the one I took out. If I put a 10 lb spring in, will I get more shots around 700 fps or will it just start giving me 700 fps nearer 3000 psi?
Quote from: Nutcracker on February 18, 2015, 11:15:30 PMYes it is 7 lb, but is longer than the one I took out. If I put a 10 lb spring in, will I get more shots around 700 fps or will it just start giving me 700 fps nearer 3000 psi?Hopefully FuzzyG will answer, but here is my guess. It will move the string up in pressure, but it will also allow you to get more FPS out of it at those pressures, with less "preload". I think with the 10lb spring and 3K you can see almost a 20 shot string at 800fps, with the ability to turn it back to 700fps and see your same #'s.
The springs from McMaster Carr showed up this morning. Man that company is fast. Was 10 below this am, got to 10. So tried a few shots. With the new spring. 5 CW on HS , 1 CW on HT. 3000 psi 18.1 JSB650 660 670 672 663 670 685 680 693 671 682 687 677 (2500) 679 685 691 688 691 698 692 690 687 686 681 675 672 674 670 670 669 660 657Then tried 6 CW HS, 2 HT. ( figure that was way to much on HT, but it was so cold. 707 710 717 723 725 725 726 734 732 725 723 713 708 689 688 678 ( 2000)Will split the difference tomorrow and see what happens.