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Discussion Starter · #1 ·
I finally picked up some AA1680 for the M375. I had heard lots of great words about the velocity. I took some loads out for a test drive last week and was amazed at the the speed, but dissapointed with the accuracy. I was shooting 200gr Sierras and 36,37,38, & 39 grains (still 1-1/2 gr below max in the book). The 39 gr load was kicking 2365, but all over the place. 37 gr was down around 2200, but descent(not spectacular) grouping 1-1/2 @ 50. I plan on working with bullet seating and more precise charges.
My question is what are the rest of you all getting from AA1680 in terms of vel/accuracy?
I'm really pumped about the speed possibilities, but can't give up the accuracy.
By the way, 20" bbl w/peep sights.
Thanks
 

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Duckbill,
I had the same experience with the 1680/200g Sierra load. Velocity was good, but accuracy was terrible. :cry: I next tried a Hornady220g/Re-7 combination and got great accuracy with a little more than 200 fps less velocity.
I still have some of the Hornady loads left, and I haven't tried a Re-7/200g cobination yet. So, I don't know if it was the bullets or the powder that gave such poor results. I hope it was the powder, because I have quite a few Sierra 200g's left.
My 375 load work has been on the back burner lately. Let us know if you get any better results from a different combo.
Best,
TnNuc
 

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Discussion Starter · #3 ·
Hey Tennessee,
I, too, have had great accuracy with RE7 both with the 220 HDY and 200 Sierra. It was the velocity that I was after. I'll keep ya posted on my progress. Thanks
 

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Duckbill,
Glad to hear you got good results with the Re-7/Sierra combination. I suspected it was the 1680 powder. I tried it later with various 7.62X39 loads and got equally bad results. The 1680 did, however, perk up the shrubs in the front yard.
Later this summer when I get some more time I'll try some Sierra/Re-7 combinations.
Later,
TnNuc
 

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Discussion Starter · #5 ·
Shot some more today with the AA1680. I played with the seating a little. I actually made some progress. I was getting descent grouping with some faster loads. Speeds of 2335 did good and 2279 did good. The groups were like 1-1/2" but both had 2 touching. I think I can tweek them from there.
 

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Duckbill --

AA1680 has worked great with Hornady 220's usin gRem 9-1/2's and 39.0g powder - 2230fps, 3.4fps Standard Deviation. I used this load to put 18 shots into 2" at 100 yards using the factory rear sight and a Williams FireSight front, and 3 shots into 2.9" at 200 yards. After mounting a scope I put 2 shots into 1.65" at 200 yards (both shots from a cold barrel, an hour apart).

Success with the Sierra 200g bullet has been more problematic. Here are the results of my work-up loads. Groups were 5 shots each, 100 yards, iron sights.

Code:
Wincheter brass @ 2.010"
Remington 9-1/2 primer
Sierra 200g bullet @ 2.533" (crimped in cannelure)
AA1680 powder

Charge  Velocity   Group
37.0      2316      6.3
37.5      2365      5.9
38.0      2363      4.5
38.5      2396      2.2
39.0      2430      4.9  
39.5      2433      5.8
40.0      2452      3.4
40.5      2413      6.4
41.0      2443      7.6
As you can see from the work-up data, the velocity increases were inconsistent and there wasn't much of a charge range where accuracy was acceptable. Still have a bunch of these bullets but will have to work up loads with a different powder - H4198 will most likely be my first choice, as Hodgdon lists a 2480fps load and I prefer loads that are both accurate and fast.
 

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Discussion Starter · #8 ·
Thanks Coyote,
I thought you had done some extensive work with the AA1680. I'll keep tinkering with them and let you know if I make a "break thru". I'm low on 220's, but I've got quite a few 200's. So I'll keep playing with them for a while.
 

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Duckbill: What type of crimp are you curretly using with your 375 Win. loads? Have you considered different types of crimp dies ie... Lee factory crimp vs other crimp dies. Just a thought.

Maybe bullet tension has something to do with the load accuracy.™
 

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Discussion Starter · #10 ·
7-30, Good thought...I've not been putting much crimp at all. I was going to ask about that, actually. I'll try giving them a little more "squeeze".
Thanks
 
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