7 saum unexpected velocity

[rscott5028]

I only use benchrest/match primers. I don't know if they make much difference. But, I sleep better.

You may be able to reduce your ES/SD with some extra case prep and by tweaking seating depth. Consistent neck tension is a biggie. If your neck wall thickness varies a lot, you may want to neck turn just enough to shave the high spots, and then get a bushing die or collet die that will allow you to size necks to about .002 below caliber.

I'm not sure I believe the actual velocity readings. But, it really doesn't matter if your drops confirm what you need to know.

Either way, your long range groups will tell you if high ES/SD is going to cause you grief due to vertical stringing. So, keep taking notes and collecting data.

-- richard

 

[elkaholic]

I think i am getting closer to finding my rifles happy place. I set up today with the chrony at 10ft from the muzzle. I brought my 6 dasher as a baseline for the chrony speeds. It shot a nice little ragged hole with velocity for 5 shots being 3083,3086,3097,3071,and 3068. This is normal for this gun and the jbm trajetory matches these numbers well.

Now for the 7saum.i loaded 5 180 vlds at the original 54.5 grains of h4350 and the velocitys were 3057,3000,3093,3123,and 3118. These produced a 100 yd group around 3/4".

I also loaded 5 180 vlds with 52.5 grains of h4350. The velocitys came in at 2941,2923,2917,2919,2953. This produced a 3/8 inch ragged hole a 100 yds. Extreme spread of 36. I had 5 more rounds at 52 grains with almost identical results.

This seems like a lot of speed for 52.5 grains of powder but if the trajetory matches it i guess that will be ok.

Would you guys accept an extreme spread of 36 or change primers or any other tricks to lower the extreme spread? Accuracy seems to be good here. I really dont want to wear this barrel out before i get it tuned.

I may not have read everything so forgive me if I missed something. Have you weighed your brass and sorted to two grains or less? Do you have consistent neck thickness? Have you annealed your brass? Are the lengths consistent? Have you checked your runout? If you have done these things as well as played with seating depth, you might try a different primer to see if that makes a difference. If you haven't yet done all this, a primer change will not likely tell you much.....Rich

 

[XTRTITAN]

The last time i shot was the second firing on new remington brass. They have been sorted within 2 grains and necksized with a forster non-bushing neck die. It seems like there is more neck tension than i am comfortable with. Does anyone make a collet die for a 7 saum?

I havn't turned the necks yet but it is on the list of things to do. Flash holes have been deburred but not uniformed. Dont know if uniforming makes a difference.

Dont have a concentricity gauge but i have been rotating the case as i am seating to reduce runout. I have been looking at the hornady concentricity gauge but dont like how it measures from the rim of the case instead of the body. Anyone have any experience with this product?

I dont have any match primers to try right now. Which ones would you purchase to try? (reg or mag. And which brand)

thanks again

 

[JARHEAD1371]

I had some similar issues with my 7SAUM. My advice to you is leave the chrony at home. They aren't nearly accurate enough to pay that close attention to what they spit out. Double check your scope height for your drops, if it's off your velocity will be off as well even with the drops matching. I have my 7SAUM zeroed at 300 yds and I'll find a load that groups the best, then strech it out to 600+. If the load still maintains a good group, it's a keeper. I'll then shoot it out to 1000 yds, gather my data, and imput it into Exbal and have it calculate the velocity. But as long as the load shoots for me, I don't really care how fast it's going.

180 Hybrids
62 gr H4831sc
CCI BR2 primers
Norma brass
3047 fps
My best 3 shot group with this load was .5" @ 604 yds

 

[elkaholic]

I agree! b.c., velocity, etc. is what you use to get you on paper. The data you get from your own rifle, scope, load combo is the data that works!.......Rich

 

[rscott5028]

[...]Dont have a concentricity gauge but i have been rotating the case as i am seating to reduce runout. I have been looking at the hornady concentricity gauge but dont like how it measures from the rim of the case instead of the body. Anyone have any experience with this product?[...]

I have the NECO and the Hornady.

The NECO will frequently detect .003-.005" TIR in situations where the Hornady only registers .000-.001". The NECO is also configurable to measure a variety of other things such as case wall thickness and case head squareness, etc. I highly recommend the NECO.

My Hornady is shiny, like new, and in the box with all the paperwork. I will gladly sell it. Perhaps someone else knows better than I how to get the most from it.

-- richard

 

[XTRTITAN]

I will look into the neco. Sounds like that might be the way to go.

 

[k8hvntn]

Say, me and my buddies have found not to trust the crony too much. too many variables ( sunny, cloudy, distance. height in which the bullets fly through the crony.
use the crony to get an estimate and most important to check ES. than go shoot a couple groups at a few distances. (I perfer 400 and 800) use the farthest distance you shoot really accurate and the midde of that dist too. test the ammo and get your moa's at those distances. Than go to Jbm and play with the speeds to get what matches your findings. Really does not matter what the crony says if when you dial you do not hit!!!
I shoot a Saum with the 180 Hybrids myself love the load. my gun seems to have a good speed node at 2850. I have found that 52 grains is what my gun likes 1/4 in. I have also found that with 4350 to use standard primers. better groups and ES. Try it. might work for ya.
A MUST TRY!!! h 4831sc I use 61 gr. and is near max. (think 62) this load is also a 1/4 load and has an ES of 6. I've talked to a lot of saumers (new word HA!) and this is thier load also.

fYI 3150 Is not un heard of with 4350. I know of two custom savages and a rem that are flying 3150. Lucky bastards!!! Well un tell their guns burn out earlier... LOL suckers.

Good luck, the saum is a great cartridge, keep working it.

 

[LDHunter]

I've been shooting SAUM's since Remington introduced them and have found Varget to be a great powder for them and I use "standard" (non-magnum primers). My favorites have been the Federal Gold Medal Match primers.

Watch out for case lengths. Remington produced a few batches of cases that were a lot longer than the published "trim to" lengths.

I've also found that best accuracy has often occurred at about 1-1.5gr above published maximum loads. I don't in ANY way recommend that you exceed published maximum loads but I kept hearing of people doing it with their SAUM's and decided to try it and after careful load development, found that they were right in my rifles and I've owned a few SAUM's over the past few years.

Velocities are hard to believe and I've been called a liar a few times so I no longer post them because it seems to hurt the feelings of other magnum owners. LOL

By the way every SAUM I ever owned had a 22 inch barrel except an LTR chambered in 300SAUM which had a 20 inch barrel and for some CRAZY reason I sold that rifle and it was the most accurate "magnum" rifle I've ever owned... Wish I had it back...

 

[4xforfun]

Everyone told me the velocitys I was getiing out of my 30", 300 wby comp/hunting tube with both the 210 VLD (3275 fps) and the 230 Hybird (3195 fps) were impossable also!! When I convinced them that the speeds were correct, I was called reckless and ir-responsable by the wizzards of smart on the internet!!

Sometimes what it is is what it is. My drops have been comfermed with three different programs with both bullets out to 1500 yards. I had 7 firings on that Norma brass...the only PSI sign I ever had with the brass was that it started to expand in the web area. It fit fine in the shell holder on my press. What got me measuring was that it started to fit tight in the shell holder in my priming tool after the fifth firing. The brass was (otherwiae) fine...the PP's were still tight, the OAL hadn't changed, and I saw no sign of weakening of the brass above the belt. I tossed em to prove I wasn't reckless !! What the hell...brass is cheap and I have lots of it.

Get rid of that verticle, keep watcing your brass for PSI, and enjoy life!!!


Tod