7mm SAUM in S/A best expected velocities

[GLC]

I have a tactical rifle project on the go at the moment, with a S/A BAT repeater (Rem Clone) rifle is going to be chambered in 7SAUM (Norma Brass) I am limited to COAL with the S/A if I want to mag feed (which I do) and I am aware that Alpha Industries make a longer AICS compatable type mag (will get COAL of 2.885 or similar) Barrel will be around 28" Bartlein 5R 1:9 twist.
would appreciate powder and Primer info if anybody has done this.
I considered the 7/300 WSM which i have alot of experience with but I seated a bullet in the case at 2.885 and it looks pretty silly as well as eating up alot of the case capacity!

My question is has anybody done this and what sort of velocities are you getting with a 180 Berger Vld?
I am hoping for 3050fps without using R17, is this too optimistic? (My QL program is on my home PC which has a problem so cannot access)
I know the simple answer would be use a L/A but i have already got the stock ($1200 worth!)
Thanks
Gary Costello UK
P.s The other question is has anybody done this with the Seekins Mag (3.014 COAL) which apparently will need some work done on the bottom metal to allow the Seekins Latch to fit AICS type bottom metal.

 

[TonyR]

Gary.
I've been doing some testing of a 7mm SAUM in a 28 inch Broughton 5C with the bullets seated for COAL of 3.111 inches and I am just touching 3000 at what QL says is max. I ran QL for your COAL of 2.885, and it gives about 3000 fps at max pressure of 65000 with Norma MRP or IMR-7828SSC, the two I have tested in my gun. I plan to test H4831SC as well but I expect lower max velocities with it. I have shot a lot of IMR7828SSC in competition and it is up to match standards. I have have good MV, SD and ES with MRP but I have also had some experiences which suggest more temp sensitivity than I like so it has not been used in matches.
Good luck with your project.

 

[15Tango]

Sure sounds like an awesome rifle, be sure to post pics when it's done!

Wayne

 

[GLC]

Thanks Tony, I suspected I was being optimistic, I shortlisted H4831,n560, R22, H4350 and R17! I am erring towards 560 and 17. I am also thinking the .284 shehanne may be another option if all I can achieve is 3000 fps, however at the max COAL it may be a bigger problem that the saum.

15 Tango

Pics will be posted once complete, I need the rifle for a big tactical match in April, in Wales, I have a KMW. Sentinel stock which is why I do not want to change to L/A, it is the nicest tactical stock I have seen.

Regards
Gary

 

[ericskennard]

Try H1000 Tony.

 

[AusFclass]

hi GCL!

i have been doing some pritty serious research myself as i should have my 7saum back next week.

from what i can see H4831sc, retumbo and H1000 are the powders of choice.

H4831sc can get around 2950fps with 59-60gr.

62.8gr of retumbo 3050 but apparenty 62.3 gives 2980 with lower es. some guys say retumbo is temp sensative so im going to try the third choice!!

im going to start with H1000 at around 60gr and work up. i think 3000- 3050fps should be possible and shouldnt have the temp sensetivity of retumbo.

there isnt a whole lot of info out there so let us know how you go ;D

ill probabaly only get into serious testing in 2 or 3 weeks so im sorry i cant give you first hand data myself.

 

[TonyR]

Eric. H1000 is on my list as is Retumbo. All I need now is some time!

 

[GLC]

I second that! some time would be very beneficial !

I was going to try some slightly faster powders, like R22 and 4350 and see if this works.
happy to pool results once tested.

My experience with H1000 is limited but i found it very dirty, which puts me off slightly, do not discount N165 either.

regards

Gary

 

[jarhead1086]

H1000 is the least temp sensitive of the group per Hodgden and some data others have posted. My velocities with H1000 were lower than I hoped (2940 with 63.0 @ 82 F). My best groups have been using RE-25 (2990 with 62.0 @ 82 F), Retumbo is a close second but I get 3070 fps with it and a very smooth recoil (66 grains though! @ 82 F). Its getting colder so I hope to see for myself what the cold does to them. QL shows H4350 too fast for the 180's. I fired 58.5 of H4350 behind some VLD 180's and got some 1/3 min groups, single digit STD DEV, and nearly 3000 fps but bought Quickload afterward and was scared of the pressure numbers it gave. I still need to try a few lighter bullets for an all weather varmint load. Going back to a stiffer charge of H1000 may be worth a try too. N560 is way too temp sensitive for me to mess with again even though it groups nice (6.5-284). I will let you all know on my cold testing.

 

[sailhertoo]

Good thread! I'm planning to build two F-Class rifles this winter in 7 saum.

 

[maxpower]

Looking though Quickload, N560 would be the only powder to get to those speeds. How stable is the temperature at that time of year in your area GLC?

 

[bighorn06]

I can go higher but my tuned load for my Light gun with H 1000 produces 3000 fps with 180 hybrids. 2900 with Retumbo and 180 vlds. Just started with a heavy gun. It has about .070 less free bore than the LG and 2" more barrel. Otherwise they are the same. The HG gets 2980 with the same Retumbo load and the 180 vlds and 3065 with H 1000 and 175 XLDs. My gunsmith says the dirty of H1000 and Retumbo is grafite and is a good thing. At 20 degrees today I shot a 5 shot, 1000yd group of 4" with the LG trying a new load. Good luck with your new build. I will be building more 7mm SAUMs. Mike

 

[TheBlueEyedBear]

BigHorn,
Curious as to which brass type you are using.??

 

[bighorn06]

I use both Remington and Norma. The Norma seems a little better to work with, but I can't complain about the Remington. Just don't go too long without anealing. I learned my lesson the hard way. My brass grew after bumping back and wouldn't you know it was at the one match that I drove a long ways to. Mike

 

[TheBlueEyedBear]

My appology for all the questions: Do you turn necks?
I am expecting delivery of my new 7SAUM in the near future. I recently found some Norma 300SAUM brass at Sinclair and bought a couple hundred pieces. I was planning to neck the cases down with a forming die to 7mm and then expanding .001, then neck turning to skim. Was wondering what method you use. Do you have a tight neck or no-turn?
Thanks.

Barry

 

[GLC]

Max Power

at the moment it's cold, down to - 5 degrees, however if we are really lucky in the summer we can get up to 25-30 degrees C or 75-80 degrees F, i use N560 in my 6x47 swiss match, which has never exhibited any temp issues however this is only 41 grains of powder.

i see some guys getting the velocities i am looking at with various powders, I have my new 7SAUM barrel on my F open gun and am just starting with some loads and bullets so the thread is helping, this is a BAT 8.5 Octagon action, Bartlein 30" 4 grove 9 twist barrel.

Bighorn 06

interesting regarding the "dirty" H1000 and Retumbo, can you explain more? I presume your smith is referring to the graphite coating the barrel however from my perspective the more i have to clean the bigger the pain!


Has anybody had decent results with R 17? a max load indication would be interesting.

 

[bighorn06]

I hate to try to explain something that I don't know well, but grafite is a dry lube and my gun likes to be shot dirty. It does reach a point at which I feel it is too dirty for optimum accurcy, some where about 30-50 shots. Maybe I just get tired and sloppy. My barrel is easy to clean, but then it is a Broughton 5C and that is one of their tributes, and also My smith had my barrel nitrided recently.

 

[AusFclass]

ive been playing around with my 7 saum and soing some load testing.

i have used h1000 and only found it slightly dirty when running lighter loads. bronze brush and some butches bore shine and 2 maby 3 patches and the carbon is gone.

trying to figure out where the top end is i pushed it up to 68gr of h 1000 with berger 180 VLD and ended up getting 3111fps still with easy bolt lift but the cci br2's looked fairly flat. i droped it back to 67gr for 3080fps and it really hammered at 300yds BUT after 3 firings one in 5 rem cases are starting to loosen up. still easy to chamber but primers are getting loose.

65gr of h1000 is probably going to be reliable top end with h1000 i think and that gets about 3040 fps.

i did very limited testing with 4831sc but i just couldnt seem to get to the 2980 node without getting much higher pressure than what h1000 would. in my gun it just didnt seem to look like it wanted to shoot but some say its THE powder to use so maby more testing is needed.

 

[wooger]

This is a timely thread, I'm picking up my 7 saum in a couple of weeks and will post results. My gunsmith has recommended RE17 so I'm going to work that powder into the load development.

 

[Wild_Bill]

Hi i am on my 3rd 7mm SAUM barrel the first two were 30" 9 twist barrels and with a MAX load of retumbo i can get over 3100fps and a 175gr MatchKing the barrel length is Key also the use af a drop tube the max load listed by ADI is 66gr with a 175gr Projectile you will get high pressures if you try using that much with a 2.8"oal i have it throated way out and have gained a lot of capacity. In rem brass i use 1gr more powder than in Norma brass and at 1200 yards they print in the same group. at a practice recently i fired 2 shots at 1182yards with Rem brass then another shooter Alan Blane fired a third shot on a new steel plate. after getting the plate and measuring the 3 shot group it was 2.670" centre to centre with 2 different shooters and cases. This is the cartrige i use for long range F Class from 1000 to 1200 yards and has helped me win 5 state championships in just over 12 months so it definatly is king of the hill if you ask me.

I have never had any issues with temp sensativity with AR2225/Retumbo and am running .5gr more than the max ADI load with Norma Cases and 1.5gr More with the rem cases but throating the factory length throat .120" makes a lot more case capacity. also the primer choice is critical aswell.

I am just chambering my Rock creek 9 twist 5r barrel and will be using it in the nationals in early March so hopefuly it will also hammer. I stop shooting the barrels in competition at 2000 rounds not because they are not shooting i just dont want to have one die in an important match i still shoot them for club practice to 3000 rounds my first was a mand lapped MAB the seccond a Lawton i rechamber at around 1000 rounds.

Cheers Bill
Australia