I was doing some load development in my 7mm mag using RL22 and 160 accubonds, I checked a few books and started at 65grs and went past max at 67grs. So my velocity at 65gr was 2843 5 shot average, 65.5 gr shot up to 2990av. could not figure out why? Any Suggestions? Next 66gr back down to 2886 av. and my group shrank to.250" shots, great!Then went a touch over max to 66.5grs and speed was 2933 and it opened up some, next went up to 67grs and my group for 3 shots went into .153" excellent again but the other 2 shots opened a bit, my error I think. I see that most everyone pushes their speed to 3050 alot of times,is it safe for me to go a little higher like to 68 grs of RL22? Have not seen any pressure signs like sticky bolt.My barrel is also 26 inches long and the gun is a Sauer202, What are your experiences with the first situation of a jump of velocity? And is velocity a safe way to gauge if your getting near max? Because book velocity does not match my numbers.
Thank you
Elmer
You should go back to the 65.5 gr. load and shoot it some more. Try to get a could read on the speed and group size. Anyway that is where I would start. Your speeds don't make any since to me. Was that an avg. of several shots? Your Chrono may have malfunctioned.
FYI, if you can get a 7 mag to shoot 160's anywhere near 3000 fpsaccurately you've got an awesome weapon.
__________________
"Well, If'n I had me a horse pistol like that.... I wouldn't be afraid of no bogger man." Rooster Cogburn
You should go back to the 65.5 gr. load and shoot it some more. Try to get a could read on the speed and group size. Anyway that is where I would start. Your speeds don't make any since to me. Was that an avg. of several shots? Your Chrono may have malfunctioned.
FYI, if you can get a 7 mag to shoot 160's anywhere near 3000 fpsaccurately you've got an awesome weapon.
if your not seeing the usual pressure signs, (ejector pin marks, heavy bolt lift, sticky extraction, loose primer pockets, or casehead expansion) your not over pressure so it would be safe to bump it up a bit. don't always count on a flattened primer to be ahigh pressure sign, some primers are so soft that they flatten at normal pressures.
A tech at sierra told me once that if your getting flattened primers and its not accompanied by other signs of excessive pressure then its the soft primer cups.
I use the max load velocity as sort of a guide, I only try to get it to that speed if no other signs of excessive pressure are there. usually with a custom made barrel you get around another 100 fps, sometimes 200 over published max velocity.
RR
Watch your bullets. Some loads are safe with one bulletand are not safe with anothermake of the same weight. Watch your bullet substitution with maximum and near maximum loads.
elmer- if velocity is your goal I would look at slower powders for the 160's and up. I couldn't get great speed or accuracy w/ R-22 but average around 3100fps with R-25 and 160 Accubonds in my 26" remy. They shoot sub moa too.
I was doing some load development in my 7mm mag using RL22 and 160 accubonds, I checked a few books and started at 65grs and went past max at 67grs. So my velocity at 65gr was 2843 5 shot average, 65.5 gr shot up to 2990av. could not figure out why? Any Suggestions? Next 66gr back down to 2886 av. and my group shrank to.250" shots, great!Then went a touch over max to 66.5grs and speed was 2933 and it opened up some, next went up to 67grs and my group for 3 shots went into .153" excellent again but the other 2 shots opened a bit, my error I think. I see that most everyone pushes their speed to 3050 alot of times,is it safe for me to go a little higher like to 68 grs of RL22? Have not seen any pressure signs like sticky bolt.My barrel is also 26 inches long and the gun is a Sauer202, What are your experiences with the first situation of a jump of velocity? And is velocity a safe way to gauge if your getting near max? Because book velocity does not match my numbers.
Thank you
Elmer
Your 65-66gr velocity gain seems reasonable. I am not a big advocate for people trying to build loads in such fine grandularity. REally with magnum loads, its not going to be consistent. I only see one set of velocities out of whack and thats your 65.5gr set. Rest seem reasonable. I believe you are expected way too much expecting 3050 for a 160gr bullet.
I personally know 3 people who are trying to obtain nosler's numbers for this combo, and all are little shocked they are not.
Nothing out of the ordinary not to meet the numbers.
Look for the classic pressure signs. Primers, hard bolt lift, etc. A chrony number is just another piece of data for you to make your decision on max load. use it for what its worth. If you see your velocity shoot up like incredible numbers, your gettin in dangerous territory.
Yes, but was there a abnormally high reading within those 5 that pushed your avg. up? You Chrono may have experinced a hiccup, it happens.
You velocity gains from 65 to 66 makes perfect sense. You 65.5 speeds are suspect to me.
watch for pressure and not the chrono.
Quote:
Next 66gr back down to 2886 av. and my group shrank to.250" shots, great!Then went a touch over max to 66.5grs and speed was 2933 and it opened up some
think about your statement for a second. 2886 to 2933 is 47 FPS difference. Who could ever know other than the chrono. I guarantee you a moose or elk won't. ".250" sounds pretty darn accurate. I have a feeling that you are too wrapped up in chasing velocity. JMTC
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"Well, If'n I had me a horse pistol like that.... I wouldn't be afraid of no bogger man." Rooster Cogburn
Yes, but was there a abnormally high reading within those 5 that pushed your avg. up? You Chrono may have experinced a hiccup, it happens.
You velocity gains from 65 to 66 makes perfect sense. You 65.5 speeds are suspect to me.
watch for pressure and not the chrono.
Quote:
Next 66gr back down to 2886 av. and my group shrank to.250" shots, great!Then went a touch over max to 66.5grs and speed was 2933 and it opened up some
think about your statement for a second. 2886 to 2933 is 47 FPS difference. Who could ever know other than the chrono. I guarantee you a moose or elk won't. ".250" sounds pretty darn accurate. I have a feeling that you are too wrapped up in chasing velocity. JMTC
Pressure question on max charge?
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