Finally found my 7mm Rem mag load!

[jonboy]

There are two kinds of rifles once you get past "shooter" and "club" grade. There's the one that shoots any load you put into it very well and simply prefers certain choices. Then there's the one that shoots it's pet load(s) great and doesn't like much else.

Then theres type 2 sub-type A) (Jon Boy's 7 mag-LOL) that looks like it's going to be "decent" then teases you with the occasional .450" groups then no matter what bedding floating or loading you try still seems to elude you for consistent great accuracy but does so well as a hunting rifle either way -that you put up with it (5 deer and a bobcat last year) I've tried several factory loads (most shooting under 2" with some holding at 1.5" "generally" But something was going on and I just couldn't find it. I did find some federal 175gr that shot great but the ammo was so inconsistent that it was hard to read if that was any better than the 150's (federals cheap stuff REALLY stank last year in most deer calibers...we had the misfortune of ordering hundreds of dollars worth at the store...a mistake we didn't repeat this year)

So I started hand-loading for it. From corelokts to Hornady SST 139gr BTBT I got some tiny groups with less recoil at around 63gr w/ H4831SC But still seemed finnicky....still the occasional 1.5" to larger group would open up. If I let it cool between shots It would generally stay at the smaller end of that. So I float it and play with shims and bedding. No major improvements.

Finally...dumb luck strikes! They are out of 139gr SST's at my wholesaler the other day so I try the 154gr with 60gr H4831SC Instead of seating to crimp I decide (for pressure reasons...OAL didn't seem to help with 139's) to seat to max 3.290" with a good firm factory crimp in neck sized brass. First group just under .5"@100 yards!! Heated it up with a group of H4350 trials (never had any luck with it with 139gr...nothing new here either...horrible!) Now with a hot as heck gun it prints several more under and right at or just over 1" groups and these were not really fired under ideal conditions. A few were seat more like 3.275-3.285 and they seemed marginally less accurate. So I have some more slow cold fire tests to run but if it shoots this good twice I FINALLY found my load!

Best I can figure is the old theory that somehow a boat-tail bullet leaving the case seems to somehow "center itself" better as it goes past free-bore and hits the lands in the throat area. And while the 139's (still being Hornady after all) had great consistent weight and diameter etc they simply were not long enough to allow the "effect" (whatever exactly that is) to occur. Then again it could be simple harmonics and the slow H4831 liking pushing a heavier pill down the bore...I don't know (doesn't seem like it though after all that bedding playing). I really had the feeling this load was shooting better than me after that first group.

Never give up on a rifle! It just has always handled and shot so well in the field I knew it had to have at least one pet load somewhere! I was getting ready to try the ultra-slow powders next! Now I just need a 120gr varmint load and we'll call it good enough. Assuming it repeats the performance the other day next time...need more H4831SC Really love this powder BTW Does great in .270 as well. Meters well with the shorter grains over H4831...same data applies. That was dumb luck to...they were out of H4831 last time I bought so I tried some.

Also for the magnum reloaders -I have found rem or fed cases neck sized shoot great (federal seems a little tougher but neither has failed yet after MANY loadings of a 20 round test lot of each (5-6 reloads at LEAST on the fed cases!...some have at least 9 on them...I can't believe the necks are not cracking yet!...but my loads are not that hot either) The routine I've found works best with the belted mag cases is to simply full length resize and trim OAL on every third reload.

People often mistake a little hard bolt lift as "that spot I can't resize just in front of the belt is bulging" but in fact I have never seen it yet (at least with lee dies which run towards max dimensions anyway). But at about 3-4 reloads and somewhere around the neck to just a finger width behind it seems to start getting a little snug...I would say from bumping the shoulder back but the collet die doesn't do that (go figure) Head-space is "dead on" between my dies and the chamber of my rifle though the contours are bit different in the neck size only cases and full length of course.

I have never had any hard bolt handle lift or extraction issues since I started doing the FL every third reload...I knew they were not pressure signs as they were all the same loads at the time I noticed it shot under the same conditions. Your mileage may vary. But if that pops up on your rifle as an issue try the above regiment...neck sizing is easier on brass and less of a pain so I do it when I can. To tell you the truth I've never seen a huge difference in accuracy other than in rifles with very sloppy chambers...like old enfields ect. (they LOVE collect die ammo!) But I like the "idea" that it's custom fit to my rifle-LOL The mag cases are so $$ I like trying to make them last better than an extra 150 FPS myself. So I run below max and neck size as much as possible. I really didn't notice it until the case had 5-6 reloads on them but after that the pattern seemed pretty clear. I have quit trying to figure out what causes weird rifle idiosyncrasies like this...I'm just happy to have a work-around for them



"In the absence of true genious...dumb luck will do nicely"-Jon Boy

[jonboy]

I've been playing some more. OAL is now 3.298-3.300 Hornady 154gr SST BT BT I started at 60gr H4831SC (CCI mag primer Fed cases) tried 61 (nothing big seemed a bit less acurate. ..63 OK now...accuracy went back to great (shot a .45" group at 100 and a couple around 1") never did get any presure signs but it has that "sound" ...that little poing that just says (this load is really a little hotter than you ought to be loading) This rifle seems to have a 3 grain cycle between accurate loads with 4831 So I backed down a grain to 62 an it sounded normal again but accuracy was back to factory...yup there is deffinately a 3 grain rule in effect saw it with the 139 gr loads as well. So I end up back at 60 grains where I started. I have found that although the lee book says OAL on case doesn't matter with the factory crimp die it does as far as accuracy is concerned. Neck sized trimmed to length (with lee case trimmer...which is min OAL) camphered inside and out in a clean case. Also Fed cases seem to be doing better work for me....I have no idea "why" that is but have seen it a few times now.

Also tried the 150 gr corelocks with 62gr H4831SC (never exceeed load seated longer) and that bullet just doesn't group for me....got a very inconsitent lot though

[jonboy]

OK the first group was after a deep bbl cleaning so I guess it was getting oil or whatever out and re-fouling the bore some. I had also beat the gun around a little and knocked it over once as I did the trigger job the other day (hence the re-adjustment going on here) Gone is the 5+ pound factory trigger pull. Shimmed and re-profiled and polished it now runs just under 3#'s on average...much nicer...no more wobble either! (that pull didn't hurt these groups either-LOL)

I also went to millet rings and a 3-9x50 nikon...I preffer a 40mm but got a great deal on it so there we have it. 60 grains of H4831SC driving a Hornady 154gr SST seated 3.300" OAL with CCI mag primers and federal cases trimmed to Min OAL with a factory crimp die applied after seating (crimp groove is out in limbo so you need this crimp for a unform start presure) Probably somewhere around 2800 FPS no scortcher...the high-end load for this rifle seems to be 63gr. but it "sounds hot" though no presure signs observed it is over max slightly. If I was going out west I'd be tempted to go with it. Around here 150-200 FPS is pretty meaningless. I think the scope was settling a bit after the last adjustment...I was getting fatigued though as I had been getting mosquito eaten and plinking .22's an hour and half inbetween 3rd and 4th group so that could be it to. Will have to do one more test and final zero the scope and that should be it! (then we tinker with the new bullet weight-LOL)

I ordered the Hornady 162gs SP BT's to try as well after seeing the 154's do so much better than the same bullet in 139gr It seems it likes the longer bullets so let's see what these do next...had great reviews on midway. (they sold out of the Amax 162gr at my wholesaler or I'd have tried it...basically the same thing as the SST in it's heaviest longest version

[Danny Creasy]

Wow, that .37" is sweet and all of em would put deer in the freezer. Way to go Jon.

Thanks for the write up.

Danny

[jonboy]

I've started playing with the 162gr Hornady Interlock softpoint boat-tail and then got (finally) some 162gr SST ballistic tipped boat-tails. Near as I can tell these are just the A-max with a thicker interlock type jacket and a crimp groove. So far the 162gr SP Interlocks are the ONLY 7mm bullet with a crimp groove in an apropriate place. In fact you need to get trimmed brass almost all the way over it to hit max SAMI OAL (3.290") Al the others you'd be hard pressed to get min OAL with trimmed brass. In tight match chamber this might actually ba a downside but in a hunting rifle the cheaper softpoint interlocks look good so far. I'm still trying charges and seatings out and some new powders.

I didn't want to go to anything as slow as 870 (generally a dirty powder) especially in a 24" bbl but have been interrested in the slower than H4831 choices like H1000 (which apears to be near the sweet-spot for load density in a lot of 7 mag loads) and the similar IMR7828 which is pretty well made for over-bore magnums. It seems like depending on bullet weight these do notably better than 4831 (way better than 4350) and at lower chamber presures as well. It probably becomes a question of whether or not you can burn enough to get those gains in a 24" bbl. My though was with the heavier bullets maybe so.

I'm playing with H1000 (just the slow side of IMR7828) now even the never exceed load of 70 grains (which almost fills the case) is below 50K CUP I'm still hunting the sweet spot charges for this rifle but I haven't matched H4831 accuracy yet...so far about a 1" group at 67 grains with the 162gr. SPBT seems best. I'm going to try 66 and 69 grains next as it was worse with 68 grains than 67 and 70gr was pretty bad...it may end up slightly over max otherwise...several people have noted 68-68.5gr as a sweet spot though so maybe I'll get lucky below max. But so far I'm seeing what several other guys at the club have found- H4831 is hard to beat in 7 mag for accuracy! You don't know till you try though. I know we have several 7 mag shooters and reloaders at the club so figured it might be interesting enough to share...so far I'm wishing I had just bought another can of H4831SC

[jonboy]

OK -I'll be durned! .620" with the cheaper 162gr SP's! 68.5gr. probably puts it around 2850 FPS -ish



I had about 1" groups at 67gr of H1000 and nothing special at 68 (worse) and about 1-1.5" best groups at 70gr (do not exceed load) At 71gr. I had bad groups and some light intermitent hard bolt opening though no other presure signs observed...I pulled the 72gr loads and did not fire them. Now just as others noted at 68.5gr it suddenly becomes a tack driver for no known (or at least understood) reason! It seems like the sweet spots for H1000 in 7 mag with a 162gr. pill seems to run around 65.5-66-ish on the low side and 68.5gr on the high side...and even though 70gr do not exceed load is like 2K under max presure for 7 mag I did see some light intermitent presure signs begining just above it. I think that is about all the H1000 you can burn before the bullet gets gone in a 24" bbl. ...that probably is why I got intermitent hard bolt lift signs (some shots presure dropped before it got that high as the bullet left the bore...probably also why the accuracy went to crap)

So if you want to break 3K FPS with a slow powder in 7 mag you probably need to be concentrating on the 139-140gr bullet loads (and you can really bust that mark with H1000 or IMR7828 there but I'm out of 154gr nearly the 139's right now to play with it much with H1000) In a rifle that likes the 139gr you can probably hit close to 3200fps...but you'd beter get the interbond version if you are going to deerhunt with em IMHO. For more moderate loadings the H4831/SC is the accuracy winner and gets you to good hunting load velocities with a fairly economic charge weight. I just didn't ever find a bullet this rifle liked with H4350...which is odd as it does so many things well in so many calibers usually.

Now all that said most of these BT bullets in other than extreme long distance shots (which we have darn few of around here) actually are more reliable and hold together better right around 2800-2900 FPS and under anyway. So if you want to fly over 3K I'd say you are going to need a good (more expensive) bonded BT bullet like Hornady or Nosler offer. Me -I decided to just go heavy and slow it down to 2800-2850-ish with SP's - I saw some SST shot deer last year and while I'd love it for long shots at sheep ect it just plain blows up too much on anything inside 100 yards (90% of the shots I get) on anything I'm going to eat. Very accurate though.

I also wanted to see how it felt with some heavier bullets and how fast they would "really" fly with slower powders without redlining it in a 24" rifle. (just in case I ever go out west for some bigger game animals) I'll probably use they cheaper hornady 162gr SPBT bullets this deer season and work up a similar load with a Nolsler partition 160 or 175gr for that purpose after season. (just a little tougher bullet though these hornady interlocks would probably do fine as long as you don't push them too hard...considering the expenses involved in that type of hunt a premium bullet sounds like a reasonable call to me. I'll add that load to when I get to it) For white-tails the $20 per 100 SP's seem fine. I really like the 154gr SST's accuracy but I aint spending $40 for a box of the bonded version I'd actually trust...for white-tail anyway...the interbond version might just make a great "do it all" bullet in 7 mag though.

The 154's are the best accuracy and all around winner in my rifle though I'd step up to the interbond version if I was really going to hunt with the (SST hornadys ballistic tip) and the same in the Nolser. The velocity was no scorther with H4831SC but based on previous expirience with this rifle and different loads I'd say it's likely the sweet spot for the H1000 loads with the 154gr will be right around 70gr or so which would give you some speed...but then again that hasn't been proven out yet so H4831SC would be my starting point...even if I had to go a little over max to find my hunting load (63gr grouped well for me...60 did quite well on the conservative side)

Bottom line on powders is anything Heavier than 154gr I'd go to H1000 ....everything else H4831 was great to work with. While H4831 is great I think H1000 more parallels what H4350 does in .270 for the 7 mag (fills her up to like 90%)

Bullets...Hornady SST makes a great work up load and plinker bullet...very accurate but I'd have gotten the bonded versions for hunting season based on deer I've seen shot with the SST non-bonded version. Sierra and Nosler both offer great bullets as well though I have not yet played with them in this caliber the gameking BTSP has killed many deer for me in .270 win. and the Nolser partition is one of the best big game bullets guides who know reccomend in Alaska and out west for bigger game with overbore magnums. Barnes X seems to have a good reputation but I haven't played with them. For white-tail anything you pick is likely going to be "good enough" with beonded in the premium and heavier in the cheaper categories doing better at holding together on up close animals.

It seems like 7 rem mag is just a very versatile performer overall with tons of bullet and powder choices. I have played mostly in the medium weight area until now and still have to find a varmint load in the 120gr range but so far it's just a like a .270 win. (my favorite all around deer round) with a lot more options. I'm probably a few months away from having all my loads and bullets picked out for this rifle for varmint, medium, and big (well North American big) game. And so far all of these loads have fostered great confidence. This rifle is very finicky due most likely to the light bbl. contour (though that's why it's so handy so I can live with the trade-off) I haven't yet found anything this rifle can't do well if you play with the loads enough. Just really a heavy beefed up slightly more versatile .270...though the .270 is deffinately more efficient if whitetail are the biggest thing you ever plan to hunt. I like the 7 mag though....I believe I'll keep it-LOL! ;D