The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading 7mm Load data too conservative?Go | New | Find | Notify | Tools | Reply | |
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I've loaded for a plethora of cartridges:223,270,30-06,300's,338's,375's, 416's,458's. I recently decided to try the 7mm Rem Mag. A few things seem weird about this cartridge. 1) Why is the max COL 3.290 when every other magnum cartridge based off the H&H has a max COL of 3.340 and the actions are made for 3.340? 2) The load data seems very mild and doesn't seem to get very close to the velocities this cartridge should be capable of. I normally don't make a habit of going over published loads, but it seems I have to if I want any velocity greater than what a 280 does. I started experimenting with higher charges of RL22 and the 140 TTSX. I went up to 66.5 grains, which seems to be about the max listed. I went up in 0.5 grain increments finally at 68 grains, I was able to reach 3100 fps. I worked up to 69.5 and hit 3200 fps. I know traditional pressure signs aren't the most reliable way to tell pressure, but in my experience, you will start to get stamping marks on the case head from brass flow when you get overpressure along with a slightly resistant bolt lift. at 69.5 grains, the primers aren't flattened or flowing, the case heads are unmarked, and the bolt lift is easy as with factory loads, and the cases extract just like unfired rounds. Has anyone else had to go above max published loads to get close to 7mm mag velocities? | ||
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Why are you concerning yourself with published OACL when you know they'll generally shoot tighter groups and higher velocities if seated closer to the lands... provided they fit and feed. Moving the bullet out frees up case space for more powder and higher speeds. Yes, I've gone above published data with IMR7977 and a 150 BT Nosler to reach the rifle's potential. My son just used the load and killed a B&C desert ram in Utah. Zeke | |||
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the main reason the COL thing bothered me is I initially increased my COAL to 3.340+ and the velocities I got were WAY down. like 200-300fps less than what I got with 3.290. So basically at that COAL, any load data in the manuals were WAY lower velocity. 7mm-08 or under velocity. This means a lot of load development in un-charted territory (we're talking going 10 grains or so above anything published) to make up the velocity from the 2.290 COL. So the main thing about this that bothers me is if they would have designed it with the 3.340 COL, at least there would be available data that gets you close to what the 7mm rem is supposed to do. It's just the most time consuming cartridge I've ever loaded for and I've learned I have to load this cartridge differently by going way over published loads and using a lot more components to get there. I eventually gave up and went with the standard 3.290 just to make things easier on my self. it's shooting just as accurate at this COL as it did at 3.34 or 3.4 COAL but I still have to go over max loads to get even close to factory velocities that the 7mm rem is supposed to get. | |||
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I understand. Of course whenever you increase case capacity you'll generally need to add more powder...and then some, to increase your velocities. It really all boils down to how much tinkering you want to do and your time constraints. It sounds like you're on-track for what you're looking for anyways. Best of luck, Zeke | |||
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Thanks. I did figure out my time with the 7mm was better spent on just upping powder charges, while chronographing, to find the velocities I'm looking for, then going back and testing for accuracy after I've determined the loads are safe. My main curiosity was if others have been finding they need to go go over max published loads to get velocities anywhere near what the 7mm was supposed to get. | |||
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I have not worked with the 7mm Mag but years ago I worked up loads for a 30-378 and used a combination of loading data that was published. I shot a number of animals in Africa with those loads. According to most current loading data, my load that I have used for 15 years is about 10grs over the max. When I developed the load, one source had a load that was 1gr above mine. When I called Barnes about the data in their #4 manual, the technician told me that for #4 they had all the lawyers on the range monitoring the data. He advised that I use #3 and work up carefully. | |||
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With mine, I load 68 with 160 partitions and 66 with 175's. I know the 175's went 2907 fps, the 160's just a touch over 3000. These were in Win brass which holds a bit more than Rem. I think I loaded 70 with 140's for 3200 fps. A shot not taken is always a miss | |||
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I read here on AR once that 7 Mags are not hard to load for, and you can load accurate rounds. But the problem comes when you start trying to load accurate rounds that are at magnum velocities. I have found that to be true at times. I don't have the data right here but I have seen book loads that were 300 fps low to the book from my 7 Mags. One thing though is that some powders reach up there fast. I shot some RL 25 that was at book and sending 160 AccuBonds at about 2970 fps out of my 7 Mag but I had a very sticky bolt here in Texas in the 90F and up. I did not see any other pressure signs on the brass but I didnt like it. It was probably a load to go back to but new brass is better in my rifle than the once fired and the next batch of RL 25 was entirely different it seemed, so I threw that whole mess away. It would have been a little better in the 1X fired brass I believe. Anyway it is just an example. | |||
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Blame it on SAAMI.They have set the pressure on the 7mag @ 61,000psi.Most magnums go up to 65,000psi.I've been loading for the 7mag since 1994.My loads all exceed what I usually see in the modern manuals.The Lee reloading manual shows most of the modern loads are below 60,000psi.I like this manual because it is a copy paste version of all the loading manuals,but it also list the pressures of the loads,where most manuals don't.Here is a list of the SAAMI pressures for different cartridges. http://www.lasc.us/SAAMIMaxPressure.htm | |||
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That is kinda crazy(7mmRM @ 6100psi) when the 270 win is 6200psi. On paper(looking at powder capacity) the 7mmRM should be FAR more powerful than a 270 or 30-06, but it is not far ahead of them according to the manuals. I had a 7mmRM and have been looking for an excuse to get another but the published data leaves me with little reason to as I already have several 270s and 30-06s. Jason "You're not hard-core, unless you live hard-core." _______________________ Hunting in Africa is an adventure. The number of variables involved preclude the possibility of a perfect hunt. Some problems will arise. How you decide to handle them will determine how much you enjoy your hunt. Just tell yourself, "it's all part of the adventure." Remember, if Robert Ruark had gotten upset every time problems with Harry Selby's flat bed truck delayed the safari, Horn of the Hunter would have read like an indictment of Selby. But Ruark rolled with the punches, poured some gin, and enjoyed the adventure. -Jason Brown | |||
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BTW, is this list correct? It lists the 270 Win max as 65000psi. I have always thought that it's max is 62000psi. Jason "You're not hard-core, unless you live hard-core." _______________________ Hunting in Africa is an adventure. The number of variables involved preclude the possibility of a perfect hunt. Some problems will arise. How you decide to handle them will determine how much you enjoy your hunt. Just tell yourself, "it's all part of the adventure." Remember, if Robert Ruark had gotten upset every time problems with Harry Selby's flat bed truck delayed the safari, Horn of the Hunter would have read like an indictment of Selby. But Ruark rolled with the punches, poured some gin, and enjoyed the adventure. -Jason Brown | |||
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Well I kinda see it that way too.Unless your rifle is really screwed up I see no reason why the 7mag cannot be loaded up to around 63,000 - 65,000psi and do it safely without any problems.I used to load mine with IMR-4350 and it did quite well with that powder,but these days,Reloader-22 has been my go to powder.Seems like it just makes my loading easy,gives me good velocities and great accuracy. My loads with Reloader-22 69.5grs with 140gr bullets @ 3200fps 68.0grs with 150gr bullets @ 3160fps 66.0grs with 160gr bullets @ 3065fps 64.0grs with 175gr bullets @ 2861fps Now I could play with it more and squeeze a little more out of it,but I'm satisfied with my results and I'm getting great accuracy so I left it at that. | |||
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I'm having a lot of trouble believing that seating the bullet 50 thousandths longer is making it go 300 fps slower. | |||
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I've been loading for the 7Rem Mag for 25 years, and my loads are very close to yours, and I always reach for RL22 first. | |||
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I recently decided to try some 162 grain Hornady Amax bullets in my 7mm RM for just target shooting. I had RL-22 to try as well.I checked my Hornady 7th Edition and got a maximum charge of 62.9 gains of RL22 for 3000 fps. So I loaded some up in fully prepped once fired Winchester brass with WLRM primers at COL of 3.290 inches and the chono and decided to give it a shot. From my 26 inch barrel on my Model 70 Laredo the data was as follows 60.5gr RL22 - 2509 fps Actual compared to Book of 2900 fps 62.5 RL22 - 2602 fps Actual compared to Book of 3000 fps 62.9 RL22 - 2618 fps Actual compared to Book of 3000 fps - Maximum Load per book Federal GMM 215 primers in the same loads were found to be some 20 - 30 fps faster. So you see how much variance there is in 7mm loads. I also shot my hunting (control) load of 2950 fps with the AccuBond 160 and it chronoed at 2956 fps. I decided to use 7828 SC and get around the 2850 -2900 fps range with the Amax and find an accurate load and just use that in my 7 Mag. I want to save my Winchester 780 powder and my AccuBonds for hunting loads. | |||
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Shortage of 160 Accubonds there too? I've had a few 7 Rems, and loaded for three more. I've never seen a cartridge that had more variation from gun to gun and load to load. Some are truly pathetic, and others seem to aspire to greatness. Some of the slow ones can be corrected by upping the powder charges and some can't. The only one I have left is a Kimber with 26" barrel. It does 3000 with 160 Accubonds and 64 grains of old style 7828. Old as in square metal can old. (I found a ton of it a few years ago at a give away price). It tops 3150 with 66 grains and 150 ballistic tips. Loads are max in the Hodgdons website but not in other sources. Pressures are mild, but since I'm beating the hodgdon book speed, brass life is great and accuracy very good I just leave it alone. | |||
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It's all about pressure. Seat bullet near lands, reach pressure, and you'll likely get near the same velocities, at least that's the way it's worked for me in my 7RM's. | |||
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Here is a good read that can explain some of the variation from rifle to rifle.It can be something as simple as seating depth distance to the lands,taper of the lands,barrel twist or the barrel itself.What might be safe in a rifle with a lot of freebore,may not be in a rifle with a short throat.Learn each rifle and keep good notes. http://www.hornady.com/ballistics-resource/internal | |||
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Published loads these days are conservative to the extreme. However, brass like Remington and Winchester is softer than 20 years ago. My usual practice is to work up the load for accuracy then gradually increase that load to see how close "my accuracy load" is to the slight ejector mark stage. As a very general rule and assuming an accurate rifle, calibres with a large case capacity in relation to the bore will maintain top accuracy at higher pressures. In other words if you had pressure testing equipment and loaded a 308 and 300 RUM or 300 Win to the same pressures then the difference in velocity from the 308 would be x f/s However, if loaded up to the point just before accuracy is lost then the velocity gap to the 308 would be greater and because the 300 Win/RUM loads will be at higher pressure. | |||
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The Hornady bullets have a shorter bearing surface than most and usually need a bit more powder. A shot not taken is always a miss | |||
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^^^^ Thank you JS. Yes I see that. I almost always use Nosler or Sierra but the Amax looked like a good paper punching bullet. But I took those stated loads right from Hornady's 7th Edition manual. And the velocities were low by 400 fps for maximum loads at 2600 fps vs 3000 fps. Which was illustrative for this thread. With RL 25 and the Nosler 160 AB I have had the very sticky bolt at max loads. So for now anyway I am looking at 7828SSC to punch paper with the AMAX and Winchester 780 for the 160 AB hunting loads in my rifles. The target loads just need to go 2850 to 2900 or so anyway. | |||
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I have developed my own loads for calibers that did not have reliable modern loda 20 years ago - 6.5X55, 280 Ack Imp, 9.3X62, etc. I followed the strict principles of measuring case expansion with a jig I made up so that every round was measured exactly at the same place every time. I was successful in developing accurate max loads. I even got a bit hot on a few occasions & opened up primer pockets after 8 or 10 reloads. But I was ultimately happy with my safe near max loda that were very accurate. During this period (15 years ago) I also started to check the fired primers for hat brims - a clear indication of hot loads pushing the primer out & recoil setting it back in. I started to measure the fired primer diameter. This was a real eye opener as the primers got slightly larger until you could measure a tiny hat brim. I started dropping some loads down a grain after this study. I always check this for every new rifle, caliber or new load now a days. Strangely I have never read anything about this idea of measuring fired primers to indicate pressure / safety / primer popping out etc. "When the wind stops....start rowing. When the wind starts, get the sail up quick." | |||
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Even the loading books disagree on max loads, why? because there are many varibles from gun to gun without going into great useless detail.. I load to absolute max when starting with a new gun, to get there I start with new brass and review all the book minimum loads and begin loading at about 5 percent below book max or perhaps at book starting loads, whatever that might be. I look for high pressure signs as I go, some times not just one but perhaps a couple, depending on the sigh in question, for instance a flat primer which alone may be a poor indication or pressure but when combined with another such as a extraction mark then its time to back a grain or two. I have found primer hardness is a factor in using primers for a pressure sign, so flat primers don't mean much to me, but a primer leak or crater is a sigh to pay attention to.. A sticky bolt and it alone is a good reason to back off a grain or two, but again one sticky bolt can be perhaps pressure or not, so its time to inspect the case carefully and run it through the resizer, check the trim length, and prime it, looking for a loose primer or excessive streatching. I also work with the chronograph as I go, and excessive velocity is postitive cut back time, and keep in mind a 100 FPS means isn't much of a loss, so better safe than fast.. I find a good load that's max, then I reload that load a number of time, up to about 14 or 15 times with the same case, and if the case is still good and has been trimmed about 4 times then its usually good to go. Books have been written on the subject, but its still flyin by the seat of your pants to a degree and for the experienced otherwise best to load at 2 grs. below max for your rifle and call it good, and it will still kill as predicted and shoot well enough to go hunting. The worst I have had is a blown primer on a couple of occasions, two I think, over some 60 years of reloading, and one bolt I had to hammer open and the case was in half, It was the result of a misprint in an Ausstralian reloading book with old H450 or some such powder.. Todays reloading books due to frivoulous law suits, tend to underload in many cases, and also due to the number of old Mausers mod. 95 and 96 with some metric calibers mostly such as the 7x57, 8x57, 9.3x62 to a lesser extent, and probably a few others for various reasons. IMO a reloading book is simply a guide, a good place to start, and compare..I have about every damn reloading book printed and its total confusion as I delve into them on a new caliber, but it does give me an idea of what is needed, and where to start.. Ray Atkinson Atkinson Hunting Adventures 10 Ward Lane, Filer, Idaho, 83328 208-731-4120 rayatkinsonhunting@gmail.com | |||
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One other thing you need to do when working up loads is to mic the LOADED rounds neck OD to be sure they haven't thickened up. Many reloaders forget to do this and when this happens you can get pressure signs very early on, powder weight wise. 7mmRM SAAMI specs call for a neck OD of 0.315"...my loaded neck measure ~0.310" and 0.314" fired so this is a fairly tight necked chamber compared to other factory necks I've measured....I also polished the dies so the body is only sized ~0.0015" Measure YOUR OWN brass and don't rely on printed numbers...QL has a set of numbers and MY brass has ANOTHER set...I have WW, REM, Norma, Federal, a few RWS I picked up somewhere and Hornady and they ALL measure different weights with MY R-P hitting 86 gr and WW hitting 82 gr for one bunch and 84 gr for another 20. I'm working with my 7mmRM right now using up some very ancient 175 gr Hornady and Sierra SBT's and RL-22 and 25. Powder weight for the Horn is 6 gr OVER a particular manual and the Sierra takes one more gr due to less bullet bearing area for the 22 and 2.5 gr more for 25 for ~2915-2930 fs...3.30" COAL for the Sierra and 3.31" for the Horn. I've reloaded 3 cases 13 times each, trim ~0.002" each firing but haven't developed "the RING" yet...that's about 0.030" total so I might hit 15 before these 3 die. My Oehler 33 chrono results are fairly close to QL's predictions...~50 fs lower for both 22 and 25 with pressure running ~55KPSI...at 92%-96% volume so to get any more velocity I will have to go to Norma MRP or Viht 560(none to be had in this area  ) and get up into the 63-65KPSI range for an additional ~100 fs or so. Not good for brass life for a few more fs. If 2900fs/3300ftlbs doesn't get the job done I should have had a bigger tool.Last group I fired went onto 1/4" at 75 yds so I packed up and went in for coffee. This is a cheap Sav 110 NS barrel that has shot better than a few of my varminters from the gitgo with any weight bullet I feed it...mostly with RL powders at ~90%+ and ~55KPSI...The 300 WM Sav 110 NS I bought with it, does similar...oorah!! . | |||
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Well I did work up to 69.5 grains of RL22 and it did indeed spit the 140 TTSX out at 3200 fps. | |||
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Had to resurrect this one. Do the brass manufacturers not use the same basic brass for the 7mm Remington and Weatherby, and for that matter, the 264 and 338 Win Mag, which are rated at 64K psi. If so, what would be the problem with loading to 64 or 65K psi? | |||
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The older manuals had loads that would approach 64-65K psi, the new ones have been "lawyer proofed" somewhat. | |||
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Regarding the max pressure discrepancy for the 7mm vs other cartridges on based on the same case and even smaller cartridges such as the .270 Win. I've observed John Barsness write on many occasions that the 7mm rem gets eratic pressure behavior (read extreme spikes) at the top end of the what SAAMI considers safe for any modern cartridge, about 65ksi piezo. In his recent book, The Big Book of Gun Gack, he again writes about this over a few paragraphs explaining that it is a function of throat dimensions and erosion over the life of a barrel. The conservative load data trend seems to be a function of keeping a safety margin built into the 7mm rem. | |||
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Interesting! It even lower then both the 264 Win mag and 338 Win Mag? Now I understand how or why the 7mm WSM and 7mm RSAUM can meet or beat 7mm Rem velocities. I am also curious what PSI 28 Nosler is at since Nosler stated it's faster then the 7mm RUM. | |||
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Is this just a problem encountered by the 7mm Remington Mag, or over bore cartridges in general? Also, why wouldn't the various reloading Manuals warn of that so you know why pressure levels are kept under 59kpsi for the most part. Seems like the lack of information is dangerous in its own right. | |||
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Not the 7mm Wby, but a .300 Wby: Speer data was shot with RP brass, and calls for seemingly low powder charges. Why? Empty primed brass weights: RP primed avg 265 gr WBY (early '70s) primed 228 gr IMR 4350 charge weights needed to fill case: RP primed 85 gr WBY (early '70s) primed 93 gr Now to add some perspective, my RP .300 Win brass - unprimed - weighs 245 gr, and has an IMR 4350 capacity of 83 grains - that's just two grains less than the RP .300 Roy. Internal capacity is just one basis for data discrepancies. | |||
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I think that issues such as this only came to light with the transition from CUP pressure measurment to piezo transducer measurement. Whereas CUP only shows the max pressure achieved a transducer shows the behavior under the pressure/time curve. I've used transducers in oil wells that have resolution of 0.01 psi/sec which is overkill for the application. And I know there are lab transducers that blow that resolution away which is where the ballistic labs see the erratic behavior of cartridges like the 7mm Rem. I've heard reference to the .243 Win having a similar problem at max pressure as well. | |||
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Makes sense. Thanks. | |||
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DavidReed, "And I know there are lab transducers that blow that resolution away which is where the ballistic labs see the erratic behavior of cartridges like the 7mm Rem." First I've heard of 7mm Remington Magnum displaying erratic behavior. I've never had that problem in the last 25 year's of reloading and I only follow Nosler reload data. I wonder if this erratic behavior would apply to 7mm STW, 7mm Dakota, 7mm Remington Ultra Mag and 28 Nosler? Could you go into more details? | |||
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I believe any cartridge is capable of erratic behavior as well as every rifle is different.There are many factors that can cause it.Throat,seating depth,brass,primers,bullets,neck tension,rifle barrel,differences in powder and how it responds at different pressures and the list goes on and on.Years ago,the 7mag only competed with the Weatherby 7mag,then along came the introduction of the 7STW.Any time something new comes out,it has to shine when compared to the previous leader of the pack.It's much to do about marketing and the all mighty dollar.I own both calibers.You really have to add about ten more grains of like powder to get the 7STW going 100-200fps faster than the 7mag.It is a great cartridge too,but look what happened to it when Remington introduced it's 7mm Ultra Mag.It quickly went the same direction as the 7mag.Heck the Weatherby,which is nearly the same case capacity as the 7mag,now runs neck and neck with the book loads for the 7STW.I've loaded for several 7mags in the last 20+ years and have never noticed any pressure spike problems.I do have one that wears a 24" Douglas barrel that shoots a load at a half a grain less and still beats the 26" Remington by about 50fps.So that goes to show you how each rifle is different. | |||
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