7 rem mag load development work up

[h4everything]

Guys finally got my reloading stuff all set up again after moving getting married what not.

I am working up a load for my 7mm rem mag, Rem 700LA, trued and blueprinted, 23" bbl 1 in 9" twist hart bbl, threaded running a YHM 30 cal can, NF 5.5-22 scope, A-5 stock, might put up a pic someday. Using a 550 press, RCBS dies, Lyman electric powder thrower for all charges,

Using 162 AMAX bullets and 162 Hornady 162 HPBT. My goal was to get a load that was accurate and up to 3000 fps and maybe shoot a mile someday. (yes I know we have all heard that, but we all have to have dreams)

Right now I am using 4831SC Nosler custom brass and federal match rifle magnum primers. started @ 62 grains, see below chart for data but shot a .432" 4 shot group, (running short on brass), also had loads @ 62.5 (had some chrono issues no data), 63.0, 63.5, and 64.0 grains. The suppessor made very little difference in the velocity. I was getting some pretty bad accuracy, 1"-1.5". Could this been to the huge extreme spreads that I had? I am most likely the main problem. I shake like a dog shitting a peach seed.


I plotted the data in excel and got a linear relationship.

charge , ave vel ,ES ,SD
62 , 2622 , 27, 14
63 , 2733 , 60, 21.8
63.5 , 2770 , 20 ,8.4
64 , 2808 , 39, 15.2

My one nice group

What the average group looked like. Some with more vertical stringing.

There was a lot of rambling there but my main questions are why am I having the big spreads, and is the linear relation close to valid? Can I get 3000 FPS with 23" bbl w/ 162 bullets and 4831? I want to stay with a Hodgon extreme powder to stay away from the temperature extremes. I was thinking that H4350 would be too fast. I am getting very slight primer flatten @ 64 grains 4831.

Thanks for the help.

Jason

 

[ChadTRG42]

Re: 7 rem mag load development work up

Your 62 grain load does shoot very well. What kind of group did the 63.5 load do? It gave pretty good numbers. If it shot ok, I'd load up some at 63.2, 63.5, and 63.8, and see what they do. You could go over max of 64, but I wouldn't go too much past it. Try 3 or 4 rounds of 64.2 and 64.4 and look for pressure signs when shooting. If you get pressure, stop, then pull the bullets from the case. I don't think you will get 3K fps before you get to pressure. You should be able to get more velocity and it still shoot well.

 

[mscott]

Re: 7 rem mag load development work up

Have you tried Retumbo? I got some pretty good velocity with it and it's an Extreme powder like you are wanting. I haven't tried the 162s yet, but will when I can find some.

 

[7mmRM]

Re: 7 rem mag load development work up

Try Retumbo, RL19, or RL22.

 

[cinosbus]

Re: 7 rem mag load development work up

Seat close (.015") to the lands and try more like 66 grains. Worked for me in a stock BDL.

 

[Clark]

Re: 7 rem mag load development work up

7mmMag 162 gr Hornady moly SST plastic tip #2845 bullet I am using 68 gr H4831sc or 68.3 gr Re22.
From a 26" barrel, I measure a hair over 3000 fps with either.
With a 10 pound 6X scoped and with sling rifle, the best I ever do is 1.5 moa.

I have some actions on the bench right now to become 7mmMag.
I shoot ~ 60 different rifle, pistol, and shotgun cartridges, but I am becoming a 7mmMag fan.

 

[h4everything]

Re: 7 rem mag load development work up

I am beginning to wish I left the bbl longer than 23". I am going to start getting to the max loads and see how far I can go.

What brass are you using?

 

[Clark]

Re: 7 rem mag load development work up

I am using Winchester brass.

 

[craigp40]

Re: 7 rem mag load development work up

H4, I would seriously consider moving to a slower powder like mentioned above. Using Retumbo or RL-25, you should be able to easily get over 3k with no problems or pressure. Hell, I'm hitting just shy of that with 175 SMKs. Also, I've found the 162 Amax likes to be seated close to the lands.

I think your thoughts on the 23" barrel are probably correct too. Unless going with 23" was done to meet a specific need, you're better off with 26"+ in magnum chambers.

 

[h4everything]

Re: 7 rem mag load development work up

I went with the 23" bbl because it normally has a suppressor on the end of it.

Do you think that my 23" bbl is long enough to utilize the slower powders? I think I will give them a try.

I have loaded some more up today getting up to 67.5 grains of 4831. I have heard of people going up to 68 so I will see.

Thanks for the advice guys. I will keep you updated.

Jason

 

[kyreloader]

Re: 7 rem mag load development work up

I would also give H1000 along with Retumbo a try due to those both being Extreme powders.

 

[Brians708]

Re: 7 rem mag load development work up

My hunting stick likes ( 22" SS Rem take off barrel w/ custom brake)
Hornady brass
66 grains of H4831 SC or LC ( No pressure signs)
WLRM Primers
162 Horn, SPBT Interlock, seated at 3.333

Runs about 2980 down here in Texas.......
Given it's a hunting stick... It shoots 3 shots at 1/2 moa or less out to 500yrds, throw another 2 rounds in there and it will work up to 1 moa but not over. The finely tuned Timney trigger helps on this rig. The brake makes her feel like a .243 w/ 60 gr boolits

 

[h4everything]

Re: 7 rem mag load development work up

Well I was able to get to the range againg today to work on my loads. The weather was about the same as last week. so temperature wasn't a big factor. I am still using 4831 and trying to make it work. I am still measuring each charge with my lyman electronic powder thrower. I am getting some pretty large extreme spreads. I would think that the more powder that is in the case ie the fuller it is it would have less of an ES and less SD than a half full case of powder but i am still getting some huge ES. I was with a buddy that was in a hurry so I had to hurry and I got my rifle pretty hot. Shot about 20 rds pretty quick. got the can hot enough to sizzle. Would the heat cause some problems with that?

My accuracy is still in the 1.25" to 1.5" range. I think I am the main cause of that though.

charge ave vel ES SD
62, 2622, 27, 14
63, 2733, 60, 21.8
63.5, 2770, 20, 8.4
64, 2808, 39, 15.2
64.5, 2803, 94, 36
65, 2826, 31, 13.9
65.5, 2892, 129, 44.5
66, 2890, 55, 22
66.5, 2925, 52, 27
67, 2923, 52, 27.4


I did load 1 round each at 67.5 and at 68 grains and the 68 grain was over 3000 fps and just had some slight primer flattening. I think I am reaching a maximum velocity no matter what. Is it possible that I won't ever see pressure signs due to the fact that my bbl is only 23" and the powder isn't fast enough?

No target pictures today. Too embarrassed.