7mm SAUM big surprise

[toddc]

I recently built a 7SAUM on a Savage LA. Most stuff I have reloaded for has been what most consider to be way overbore so I'm a little new to the EFFICIENCY game.

The big surprise is this. My speeds are nearly 200 FPS over book.

In the past I have never been lucky enough to exceed book without some scary issues and in fact most of the time I have ended up under book.
This build does have some unique qualities that may be influencing this but I am still wondering.
The 2 variables that could be giving me false data are the chrono and the scale.
The scale threw loads on 3 different guns that matched book data including the SAUM with 2 powders.
The chrono matched book with 2 of the powders in the SAUM and matched previous data and book data on an Edge and a Creed in the same session.
The build is as follows.

Savage LA action.
27" Mcgowen 9 twist
I set headspace short, the fired brass only grew 2 thousandth over a virgin brass reading off of a RCBS precision mic check.
Brass is Norma and was virgin.
175 ELD-X
COAL was long at 3.10
Primer Fed 210
H-1000 61-65 . 65.5 is book max.
61gr ran 2890 and 65 ran 3043.
I also ran 7828 which pretty much matched book speeds.
The H-1000 load at 61 matched book max speed and the 65(still .5 under MAX) made 3043 which is about 200 OVER and close to RUM territory according to book anyway.
Some of the factors that COULD have given these results are the long COAL, 3" longer tube and short headspace.
I can see maybe 60-75 FPS with the barrel length (usually a longer barrel seems to MATCH book not EXCEED it).
I can see the COAL giving me a hair but this is RUM territory. COAL may be giving me a little but 200 FPS? Without more powder?
The short headspace may be increasing pressure but I wouldn't think it would produce the speed.

No pressure signs AT ALL. Nothing.

Velocity increased in a linear fashion and wasn't tapering at all.

Load was slightly compressed past 63 or so but nothing crazy.

I can't write this off as a fast barrel since the 7828 data was spot on (not a big believer in 200FPS from magical barrels anyway).

COAL may be giving me a little but 200 FPS? Without more powder?

I have read the 7SS thread and seen that some speeds in it seem really stout but I never get that lucky.

Am I worried about nothing? Has anyone run a SAUM up in these ranges? Looking at my brass I have more room but 200 FPS over book with 3" of extra barrel seems like an internet story. Reloading data shows this thing is outrunning everything but the RUM.

Since brass looks good should I just consider myself lucky and start accuracy testing? I'm just not very experienced with these smaller cases. I load for the Creed but its an AR so I just loaf it. The Edge is really the tamest thing I load for otherwise and if I was getting 200 FPS over book with it I would need a mallet to get my bolt out lol.

Sorry for the novel but I wanted to state all of the facts so that someone can make an informed call about this. I know a lot of guys get over book speeds with the RM, STW, WSM and RUM but 200 over seems like a lot. Thanks to all who answer.

 

[climb-101]

my 338 lapua is similar with the 300gain match king. i kept getting slight pressure signs when i first started loading for it. i kept backing it down till they went away i'm down around 81.5 grain of h1000 (below anything in the book) but there coming out at a little over 2700ft/sec. according to the sierra it should take 90.3 gains of h1000 to be at that speed.


the gun shoots well and consistent. last 5shot groom over the chronograph was only 12ft/sec different. i figure in just get a little more bang for the buck since i have to use less powder.

 

[toddc]

my 338 lapua is similar with the 300gain match king. i kept getting slight pressure signs when i first started loading for it. i kept backing it down till they went away i'm down around 81.5 grain of h1000 (below anything in the book) but there coming out at a little over 2700ft/sec. according to the sierra it should take 90.3 gains of h1000 to be at that speed.


the gun shoots well and consistent. last 5shot groom over the chronograph was only 12ft/sec different. i figure in just get a little more bang for the buck since i have to use less powder.

Wow. I have 0 experience on the LAPUA but have burnt 5 Edge barrels to dust which is very similar. 81.5 of H-1000 is very light for that case. 90 is the go to Edge load and usually makes 2850 with a 30" tube like clockwork as recorded by many guys on here. Just shows how complex internal ballistics can be I guess.

 

[Jud96]

From my experience the books seems a little slow most of the time. For instance, my .243 load with an 87gr V-MAX. According to the book I should get 3200-3250 fps with IMR 4350, I am making a chrono and drop data confirmed 3370fps. I have a 26" barrel and the books have 24" but 2" can't be giving me an additional 120-170 fps I wouldn't think. My go to load now uses IMR 4451 and gets the 87 going 3430fps with only .5gr more powder than 4350. My only pressure signs are slightly flattened primers, this is where I call it max.

The odd thing is though, with 70gr bullets in the same rifle, I am running 3600fps a grain under max according to the books but the same speed as them or slightly faster. Odd that one load at max is way faster and the next one is the same as the book. My Dad has the identical rifle to mine and we literally shoot the same loads with the 70s and 87s and even use the same dope card! Pretty wild that worked out like that.

 

[climb-101]

i have know idea as to what causes someone to have a fast or slow barrel. might need some one to chime in that has more experience.

 

[toddc]

From my experience the books seems a little slow most of the time. For instance, my .243 load with an 87gr V-MAX. According to the book I should get 3200-3250 fps with IMR 4350, I am making a chrono and drop data confirmed 3370fps. I have a 26" barrel and the books have 24" but 2" can't be giving me an additional 120-170 fps I wouldn't think. My go to load now uses IMR 4451 and gets the 87 going 3430fps with only .5gr more powder than 4350. My only pressure signs are slightly flattened primers, this is where I call it max.

The odd thing is though, with 70gr bullets in the same rifle, I am running 3600fps a grain under max according to the books but the same speed as them or slightly faster. Odd that one load at max is way faster and the next one is the same as the book. My Dad has the identical rifle to mine and we literally shoot the same loads with the 70s and 87s and even use the same dope card! Pretty wild that worked out like that.

A 120 FPS like you experienced with the 87 V-max is a lot less energy difference than 200 FPS with a 175. I have run lighter stuff a bit over book and it worries me a little less than a 175. The 300 SMK when I get very high gets really scary. The energy difference of 300 gr 200 FPS faster is massive and there is a lot more things that can go wrong Doesn't take as much PSI over time to yield a 120 increase with 87 gr. If I was 200 over with a 300gr I would already have made a big donation to the church and been pulling bullets out of remaining loads. Also bearing surface on those smaller bullets is much shorter and easier to get over book.
I'm not terrified of my results, curious more than anything. I am also thinking some of it is that there just isnt a lot of SAUM data.
And BTW thanks for the info.

 

[Jud96]

A 120 FPS like you experienced with the 87 V-max is a lot less energy difference than 200 FPS with a 175. I have run lighter stuff a bit over book and it worries me a little less than a 175. The 300 SMK when I get very high gets really scary. The energy difference of 300 gr 200 FPS faster is massive and there is a lot more things that can go wrong Doesn't take as much PSI over time to yield a 120 increase with 87 gr. If I was 200 over with a 300gr I would already have made a big donation to the church and been pulling bullets out of remaining loads. Also bearing surface on those smaller bullets is much shorter and easier to get over book.
I'm not terrified of my results, curious more than anything. I am also thinking some of it is that there just isnt a lot of SAUM data.
And BTW thanks for the info.

I was just sharing that the book numbers are not always set in stone. And you are most likely getting higher speeds because you have a longer barrel, longer OAL, and a custom barrel. Most custom barrels have a much smoother finish than factory and this can contribute to some added speed.

I don't think your 7 RSAUM pushing a 175 at 3000fps is magic, this is a pretty normal speed for one. Heck guys get 2800 with a .284 and some match shooters with 30" tubes get 2900+ with plain old .284 Winchesters. I can tell that book is slow just by the fact a 7mm RUM is only moving a 175gr at 2900 haha. Realistically it should push it close or over 3200fps.

 

[toddc]

I was just sharing that the book numbers are not always set in stone. And you are most likely getting higher speeds because you have a longer barrel, longer OAL, and a custom barrel. Most custom barrels have a much smoother finish than factory and this can contribute to some added speed.

I don't think your 7 RSAUM pushing a 175 at 3000fps is magic, this is a pretty normal speed for one. Heck guys get 2800 with a .284 and some match shooters with 30" tubes get 2900+ with plain old .284 Winchesters. I can tell that book is slow just by the fact a 7mm RUM is only moving a 175gr at 2900 haha. Realistically it should push it close or over 3200fps.

Some guys do run 284s at 3k with 30" tubes so I see what you are saying, but they are running well over book powder wise. Yeah I would agree the RUM should hit 3200. Book was about 3100. However that's with 50% more powder. I'm just not used to efficiency I guess. 22-284 and 6.5 Ultras aren't known for that quality.

 

[toddc]

Idk just checked this and the rig is definitely humming compared to this data, and these guys are usually on the cutting edge of what is possible.

http://www.accurateshooter.com/cartridge-guides/7mm/

 

[Jud96]

Idk just checked this and the rig is definitely humming compared to this data, and these guys are usually on the cutting edge of what is possible.

7mm Cartridge Guide within AccurateShooter.com

Your loads are fine. Those 7mm SAUM loads on there are with 4350 and 4831, not slow enough to take advantage of the SAUM. Even with H4831 the guy achieved 2960fps and a 180. Your 175 at 3000 using H1000 is right in line from what I've seen. Might be a tad faster than average but guys on Snipers Hide are running around 2940-2980 with 26" barrel, 180s, and H1000.

 

[toddc]

Also with the COAL and total lack of pressure signs this thing should have more in it. Even .5 to book max should net close to 3070. From the get go I had planned on going over max since the COAL is long. Now I am wondering if going over because of the COAL might be a bad idea. From the research I did before this build I was hoping for an easy 2900 and hopefully sneaking into the 3000 flat area with over max load due to COAL. Then it beats max at 5 FULL GRAINS under max. Not .5 but 5. hats something you don't see every day especially not with the stuff I am used to playing with. A 338 Edge with 300gr pills 200 FPS over with a load .5 under max is either a fairy tale, defective chrono or bad scale.

 

[toddc]

Your loads are fine. Those 7mm SAUM loads on there are with 4350 and 4831, not slow enough to take advantage of the SAUM. Even with H4831 the guy achieved 2960fps and a 180. Your 175 at 3000 using H1000 is right in line from what I've seen. Might be a tad faster than average but guys on Snipers Hide are running around 2940-2980 with 26" barrel, 180s, and H1000.

Hope you are right. Might see how nutty it can get then. Always have before. I usually just load till something won't open or stuff flys out of action. Just trying to get a lil smarter in my old age.

 

[toddc]

Your loads are fine. Those 7mm SAUM loads on there are with 4350 and 4831, not slow enough to take advantage of the SAUM. Even with H4831 the guy achieved 2960fps and a 180. Your 175 at 3000 using H1000 is right in line from what I've seen. Might be a tad faster than average but guys on Snipers Hide are running around 2940-2980 with 26" barrel, 180s, and H1000.

I wasn't looking at the SAUM data I was looking at the WSM which should outrun it. That's where the H-1000 data was. Yeah I wasn't surprised to be outrunning the 4831, 4350 and 7828 with H-1000. The WSM data kinda made me wonder. I've never doubted pressure signs before and just ran to what my brass looked like, but i'm trying to turn over a new leaf and be a lil less nuttier than my usual squirrel turd level.

 

[Jud96]

Also with the COAL and total lack of pressure signs this thing should have more in it. Even .5 to book max should net close to 3070. From the get go I had planned on going over max since the COAL is long. Now I am wondering if going over because of the COAL might be a bad idea. From the research I did before this build I was hoping for an easy 2900 and hopefully sneaking into the 3000 flat area with over max load due to COAL. Then it beats max at 5 FULL GRAINS under max. Not .5 but 5. hats something you don't see every day especially not with the stuff I am used to playing with. A 338 Edge with 300gr pills 200 FPS over with a load .5 under max is either a fairy tale, defective chrono or bad scale.

.338 Edge data is with long barreled, long throated rifles just like your 7mm SAUM is setup. 99% of the book data with a 7mm SAUM is with a 700 Remington with a 22-24" barrel running at short action OAL. I'm guessing you have a 26-28" barrel and you are a loading a lot longer than book specs. Thus you are gaining 200fps over book data. Same thing with a .300 Win Mag, book said 2850fps with a 24" barrel loaded at 3.4" using a 200gr bullet. I loaded mine at 3.650" and shot them through a 26" tube and got 3050fps. No excessive pressure either. Same with the 190s, everyone runs them at 2900 in a .300 WM I pushed mine to almost 3150fps before getting extractor marks. If there's no pressure signs and everything is working, roll with it.