7mm SAUM slow node.

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ben_g
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7mm SAUM slow node.

#1 Postby ben_g » Fri Feb 14, 2020 1:34 pm

G’day all.

I’m sure this question has been answered in the depths of a thread before. But I cannot search the answer I am looking for.

Have a 7mm SAUM that I usually run around 2930/40fps with 55.8gr of 2209

I have a heap of brand new brass and a brand new barrel and want to initially run the barrel in the low node of around 2840fps. Can anyone give me a guesstimate of the charge of 2209 I might need to get there (180 hybrids).
Sorry Rod if you reply...... I am sure I’ve asked you this question before and ive lost the info........

saum2
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Re: 7mm SAUM slow node.

#2 Postby saum2 » Fri Feb 14, 2020 1:41 pm

Hi Ben, I ran my brass in with 2225 it’s a bit slower with 62gns slower than 2217 and colder for yr new barrel. I used 2225 because I had it spare

ajvanwyk
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Re: 7mm SAUM slow node.

#3 Postby ajvanwyk » Fri Feb 14, 2020 2:30 pm

52.8gn off 2209 provided me with a very long and stable node at 2785. Had to be there a while back when shooting in NZ with low energy limits. I could not get a good node at 2840 mark.... 2880 was another good node in my first barrel but that was 55.8gn of 2209, jumped 20thou...
Albert
Rosedale Rifle Club
Victorian Rifle Association

BRETT B
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Re: 7mm SAUM slow node.

#4 Postby BRETT B » Fri Feb 14, 2020 5:25 pm

54.5-54.8 of 2209 should get you around the 2870 mark with 180 and I can tell you there is a very good node around 2870-2900. If you are using the new 2209 (BTI) then drop it a touch more.
What bareel and grove type? 4Gor 5R?
BRETT BUNYAN F CLASS OPEN SHOOTER W.A.

ben_g
Posts: 224
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Re: 7mm SAUM slow node.

#5 Postby ben_g » Fri Feb 14, 2020 6:21 pm

It’s a 5r barrel 8.5twist.

Current batch of powder achieves around 2930fps with 55.8gr

v63800
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Location: Alice Springs

Re: 7mm SAUM slow node.

#6 Postby v63800 » Fri Feb 14, 2020 7:21 pm

hi, guys
bit off topic but whilst on the subject of 7 saum is it a free recoil proposition or shouldered with the extra 4-5 g of powder compared to straight 284

ben_g
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Re: 7mm SAUM slow node.

#7 Postby ben_g » Fri Feb 14, 2020 7:42 pm

I shoot my SAUM the same as I shoot my 284 and dasher which is with some shoulder pressure.

I don’t feel that the SAUM recoils significantly worse than a 284, they feel about the same to me. Maybe a bit of a sharper push.

John T
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Re: 7mm SAUM slow node.

#8 Postby John T » Sat Feb 15, 2020 6:18 pm

Hello Ben et al.

Ben, thanks for an interesting topic.

Brett, what is 2209 BTI?

Regards,
John T.

williada
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Re: 7mm SAUM slow node.

#9 Postby williada » Sat Feb 15, 2020 6:27 pm

Brett asks a good question.The 5 r's tend to run a little quicker. Bloody energy limits spoil the show and bog the potential screamer groups of the SAUM at higher nodes. Given the energy limits imposed the slower barrels in standard form are more appropriate along with a faster twist to take the edge off speed. Faster powders can give better ignition where there is a slight air gap such as 2209. Harmonics can then determine the right node. Both Albert and Geoff use different combinations of components to which I have privileged information. As such there is no substitute for the horizontal charge test to determine what your barrel is doing with the powder you use. Barrels are definitely individual beasts in combination with your body mass when shouldering the rifle a tad. When mixing it with the big boys (i.e. magnum chambering) forget free recoil. Bag handling with correct shoulder pressure and position will give consistent results. All in my opinion of course. For what it is worth, in Australia I am running with a minus head space to reduce the air gap. The SAUM case is just so versatile. I am also using the same cases prior to the last worlds when I did considerable testing. The primer pockets are still tight. I hear Tim was having trouble with cases stretching. A problem may lie in the head space. Always got to bump back on the measured head space and don't assume it is zero or minimum head space and base calculations on that. Draw up tension alters on switch barrels with further use. If using higher tension has crush been accounted for? Just food for thought.

ben_g
Posts: 224
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Re: 7mm SAUM slow node.

#10 Postby ben_g » Sun Feb 16, 2020 6:53 am

Agree, I will need to do my own experimenting. But will knock 3gr of 2209 off and work from there.

Quick
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Re: 7mm SAUM slow node.

#11 Postby Quick » Sun Feb 16, 2020 8:18 am

John T,

The new 2209 is the new Ballistic Tempretaure Independence forumula of 2209. Its a bit faster then the old formulations of 2209.
Shaun aka 'Quick'
Yanchep, Western Australia

308 Win F/TR & F-S
7mm F-Open Shooter.

BRETT B
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Re: 7mm SAUM slow node.

#12 Postby BRETT B » Mon Feb 17, 2020 2:25 pm

ben_g wrote:It’s a 5r barrel 8.5twist.

Current batch of powder achieves around 2930fps with 55.8gr



Ben looks about right. 5R can sometimes be a tad slower than 4grove, drop it a grain or a touch more should get to to mid to high 2800. If you decide to go lower you may need to change to a slightly warmer primer to keep ignition stable !! only maybe !!
BRETT BUNYAN F CLASS OPEN SHOOTER W.A.

BRETT B
Posts: 233
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Location: PERTH

Re: 7mm SAUM slow node.

#13 Postby BRETT B » Mon Feb 17, 2020 3:06 pm

John T wrote:Hello Ben et al.

Ben, thanks for an interesting topic.

Brett, what is 2209 BTI?

Regards,
John T.

Hi John , Ballistic Temperature Independence (BTI) Is the new ADI batch being released. Initial testing has shown it to be a little faster than most old 2209 batches. it seems a little darker in colour and reminds me of what H4350 was like when we were at the Last Worlds in Canada.
BRETT BUNYAN F CLASS OPEN SHOOTER W.A.

BATattack
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Re: 7mm SAUM slow node.

#14 Postby BATattack » Mon Feb 17, 2020 6:24 pm

Tha SAUM has several good nodes. The 2900 ish node is a good one. Easy in brass and consistently accurate.

ben_g
Posts: 224
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Re: 7mm SAUM slow node.

#15 Postby ben_g » Tue Feb 18, 2020 7:17 am

BRETT B wrote:
ben_g wrote:It’s a 5r barrel 8.5twist.

Current batch of powder achieves around 2930fps with 55.8gr



Ben looks about right. 5R can sometimes be a tad slower than 4grove, drop it a grain or a touch more should get to to mid to high 2800. If you decide to go lower you may need to change to a slightly warmer primer to keep ignition stable !! only maybe !!


Thanks Brett, I will take the scales out to the range and experiment.


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