Help

[phutch30]

So went to the range this am. 65 grains R22 gave me 2886 on a 3 shot string. Group was around 3/4". No real difference in primers (pressure) between 63 and 65grains. Im heading back up to try a couple more wsorking up to 66gr. Group size hasnt varied very much between 62.5 and 65 grs, maybe 1/4" differnce from largest to smallest. These have all been seated the same depth, which is way off the lands. Im also going to run 6 different seating depths at the same charge of 63grs imr 4831 to see if I can shrink the group size while keeping the 3000 or so velocity.


Heres a question. In every manual I have, they lists R22 as a faster powder than IMR 4831 (equal charge). What Im seeing is IMR is faster. 63grs of IMR 4831 with partions and Accubonds gives me between 3015-3335 while 63grs of R22 is 2780 and 64 grs 2880. I understand theres usually a difference between posted and what we get in our rifles. But generally the published velocities are from a 24" barrel and Ive always shot 26" so Im usually close. But with R22 its not close.

Any ideas?

 

[OU812]

From the data I have from my friends 7mm rem mag, 160 accubonds and RL-22 you seem to be right on par (slightly more) with the velocities we were getting and his rifle has a 24 inch barrel. 65.5 gr gave 2940fps and was super accurate so we stopped there.

What primer are you using? We were using Fed 215's.


Bill

 

[SJB358]

I am with Bill on this. Keep pushing incrementally up with RL22. Almost every 7mm Rem Mag I have shot or did load work for would push just about any 160 grain bullet to 3050 or better without undue pressure and plenty of safety margin. It will get it done. I would creep up to 66-67 and start watching your 7RM come alive if you want a little extra speed.

 

[OU812]

From your first post.

"I did some loads up with r22 to work up velocity and check accuracy. With 63.5 and 64grs I got 1/2" groups, but at 64 grs of R22 im only getting 2880fps (5600' elevation/70 degree temp).

So went to the range this am. 65 grains R22 gave me 2886 on a 3 shot string. Group was around 3/4".

Either you hit the top of the bell curve with 64 gr of RL-22 and your velocity is falling off with an increase or something is wrong with your chrono readings. According to the info you posted you only gained 6 fps with a whole 1 grain increase on powder charge weight. Hope it's just the chrono reading of the 65 gr was wrong.


Bill

 

[phutch30]

Im using fed 215 primers.

65.5 grains R22 gave me 2976 average 3/4 group
66 grains R22 gave a 2 shot average of 2687 (something was funky so I didnt shoot the 3rd round)

I think Im jut going to stick with IMR4831 and seating .10 off the lands seems to be the trick.

I loaded up five different 3 round loads with 160 accubonds starting at .010 and running out to .050 off the lands using 63 grains of IMR 4831. I throughly cleaned after every other group and fired one foul round
Results (i did not subtract .284 from the groups so they are a little better than posted)
.010 1.08" (3035 3 shot ave)
.20-1.23"
.25-1.4
.030 -1.5
.040-1.5
.050-1.6ish (3040 3 shot ave)

Im going to take the first load and play with it. Im sure I can shrink it to 1/2". Going to have to mill out my clip to accept this length.

I also loaded up two 3 round loads with partions with 62gr and 62.5grs of IMR 4831 seated .010 off the lands. The 62.5 load averaged 3025 and had a .787" group without subtracting the .284bullet dia. If I can duplicate it next trip Ill be more than happy.

120 loaded rounds, 4 different powders, 2 different bullets and Im basically right back to my old pet 7mm load. Shoulda just done that first. LOL but didnt because without machine work the rounds wont fit my clip.

 

[phutch30]

If I wasnt getting the same consistant velocity with 63 gr of 4831 that Ive got with 2 different cronos I would agree something is wrong with the crono. 5 years ago this load on a different crono gave 3035 and on this crono over several days this same load has been consistantly within 10fps at different temps.

Im just going to stop scratching my head over R22 and go with 4831. With a little tweaking from where im at now I"ll be happy

 

[OU812]

4831 is a great powder and if your getting the speed you want with groups your happy with can't see any reason to change what is working so well.

Bill

 

[phutch30]

I know. Ive always used 4831 before this. I was just trying to work with what limitations I had, like rounds fitting my clip, before going gorrilla on the clip and making it fit my rounds. Much like my last 7mm seating depth made a very big difference.

 

[SJB358]

I know. Ive always used 4831 before this. I was just trying to work with what limitations I had, like rounds fitting my clip, before going gorrilla on the clip and making it fit my rounds. Much like my last 7mm seating depth made a very big difference.

Sometimes you can find a 2nd seating node the bullet will shoot well at too. I had to run the 160 AB's back a LONG way off the lands to get accuracy back. Might be worth trying.

 

[phutch30]

After subtracting the .284 from my groups, Ive got the accubonds shooting at .647" w/63grs IMR4831 and the partitions at .521" w/62.5grs imr4831. Both at .010 off the lands. Ive tried moving seating depth in and out a little as well as +/- 1-2 grains with no increase in accuracy. My try turning the necks and weight sorting the brass for the heck of it to see if it makes any difference. Im thinking Im pushing my abilty to hold the scope x-hairs on the exact spot to get any tighter.

 

[OU812]

After subtracting the .284 from my groups, Ive got the accubonds shooting at .647" w/63grs IMR4831 and the partitions at .521" w/62.5grs imr4831. Both at .010 off the lands. Ive tried moving seating depth in and out a little as well as +/- 1-2 grains with no increase in accuracy. My try turning the necks and weight sorting the brass for the heck of it to see if it makes any difference. Im thinking Im pushing my abilty to hold the scope x-hairs on the exact spot to get any tighter.

Those 2 groups sound more than adequate to me unless your hunting mice and even then I'll bet they would get the job done in some why or fashion. Good shooting.


Bill