|
Post by finfurnfeather on Apr 26, 2023 18:03:16 GMT -5
Hey Folks, Just getting started in the SML game. Finished two rifles just the other day, converted mine and a hunting buddie's Rem 700 ultimates to SML using barrels/LRMP HIS system from Hanks Precision. 26" Preferred brand barrels, remage type, 1.06"x9" tapers to .882 (.75" threads). Those specs said, from everything I've learned here so far I've gathered that the wise/experienced recommend 65g IMR 4198 with a 275 pitman as a max safe load and 62 Gr IMR 4198 with a 300 pitman max safe load. Correct me if any of that is wrong My Questions, 1. Approximately what velocities should I expect with those loads from these barrels and, 2. At those velocities, what have the respective field proven ballistic coefficients ended up being? Thanks for any help!
|
|
|
Post by yoderjac on Apr 26, 2023 18:18:51 GMT -5
I'd guess you are in the 2500 fps range with the 275 pittman load.
|
|
|
Post by ballistic on Apr 26, 2023 19:34:46 GMT -5
Expect Kyle’s listed Bc values to be very accurate on BC down to 1400 fps velocity. Bullets below 1400 experience transonic issues that almost always lower the advertised Bc. Your testing might show those numbers to be closer at lower velocities -take good notes. Other bullet makers list higher Bc numbers than Kyle’s but I have found that Kyle’s bullets edge out most of those claims. Kyle has done most of the homework and his numbers are good to go or very close
|
|
|
Post by encore50a on Apr 26, 2023 19:47:12 GMT -5
I never totally trust any published BC. I may use the posted BC to start shooting, but the actual target drops to 600yds+ will allow you to adjust the BC to be more exact. I also don't use G1, but rather G8. I find it more accurate.
|
|
|
Post by finfurnfeather on Apr 29, 2023 22:04:17 GMT -5
I never totally trust any published BC. I may use the posted BC to start shooting, but the actual target drops to 600yds+ will allow you to adjust the BC to be more exact. I also don't use G1, but rather G8. I find it more accurate. I looked at the G profiles and can see why G8 would be applicable to the big flat based bullets we use for sml's. However, of the ballistics software I'm familiar with, its always G1 of G7. What software to you recommend that runs G8 and where do you find listed G8 values? Thx!
|
|
|
Post by finfurnfeather on Apr 29, 2023 22:23:42 GMT -5
3 shots-275 pittman accu 62 gr 4198 (this is at 50yds, that's all I got in the backyard, but it bodes well) 3 shots-300 Parker Black max 60 gr 4198 Got to do some shooting today. Here's some data for new guys like me so you have an idea of what to expect. Altitude 210', Temp 76 deg, 29.64 inHB, wind calm, humidity 61% all powder was IMR 4198, velocity via LabRadar 275gr pittman accu, 60gr 4198, 2532 FPS 275gr pittman accu, 62gr 4198, 2625 FPS 300gr parker black max, 60gr 4198, 2470 FPS, (of note SD was 9.3)
|
|
|
Post by encore50a on Apr 30, 2023 7:06:56 GMT -5
I never totally trust any published BC. I may use the posted BC to start shooting, but the actual target drops to 600yds+ will allow you to adjust the BC to be more exact. I also don't use G1, but rather G8. I find it more accurate. I looked at the G profiles and can see why G8 would be applicable to the big flat based bullets we use for sml's. However, of the ballistics software I'm familiar with, its always G1 of G7. What software to you recommend that runs G8 and where do you find listed G8 values? Thx! I use JBM. I can access it by my cell phone, however, I also have the Strelok app on my phone. JBM is what I use the most, and basically because of laptop use and its accurate to 1K and includes drift. jbmballistics.com/ballistics/calculators/calculators.shtml
|
|