Straight .284 Bullets

[walkabout]

Just about to start some load development on a new Straight .284.
It will be for 600-1200 yrds steels & paper.
I have a long action, Bartlien 8.25 twist, 28".
I'm going to use RS70 or RS60.
I have used 180 Berger Hybrids in a SAUM, they were good but they are getting expensive.
I was thinking of using either Sierra 175, 180 smk's.
Which would be better?
I have seen the new 183 smk's, any advantage?
Any real life experience with these bullets?
Cheers
Mark

[Laurie]

The old 175 7mm SMK is an excellent bullet in the 284. It is very jump and load tolerant and its BC is higher than one might imagine from a relatively short tangent ogive design - a bit less than the much less tolerant Berger 180gn VLD and a bit more less than today's favourite, the Hybrid - but not a great deal.

The 180 SMK is a VLD form but has an identical form-factor to that of the 175, so its extra 0.10 G7 BC points is entirely doew to the extra 5gn weight. It has not been a particularly well received design. I have a lot of early (non factory pointed) examples I bought very cheap and BTOs are all over the place. With measuring, batching, trimming and pointing, I've got them to shoot well at long-range in the 284 - but a lot of work!

The 175 I seat jumped, 15 thou' originally but have never had to redo the COALs - they cope excellently with any throat erosion. The 180 I put into the lands from day one and that works. How they'd do jumped I can't say.

The 183 is in a different league drag wise and with a 0.859 form factor (14% less drag than the G7 'reference projectile') / 0.337 BC is one of the highest BC bullets you can buy in 7mm. Because of their length, they need a 1:8.5 twist barrel, ideally 8.25 or faster. (I have an 8 on my 284.) I found they produced dreadful vertical if seated into the lands as per usual VLD practice but US sources report they can shoot well jumped despite being a super-VLD form. I just did some COAL based tests last week at 100 and 40 thou' 'out' looks OK in my rifle, so it'll be tried in a match at that. I suspect though that they are too 'finicky' for most shooters compared to the Berger Hybrid and the need for a faster twist barrel than most have been using will work against them too. (One has to wonder how many reports of their being impossible to get them to shoot well come from people who've got 1:9 twist barrels on their rifles.)

Whilst I said unkind things about the early 180 SMKs, recent Sierras are very consistent indeed and I'd imagine the latest iteration of the 180 in factory pointed form will be good. Recent purchase 175s and the 183s are superb in this regard, both as to BTO measurements and weights.

[walkabout]

Thanks Laurie
I think I will try the all three types.
I have just checked and I have a 8:25 twist so hopefully the 183's will work?
However I do like the sound of the 175's being easy to setup.
I don't want to drive the load too hard...been there and done that on the 7mm SAUM!
So I will go steady and see what the rifle does and the results on the target show.
I may stick to RS70, or do you think RS60 might be a better bet?
Cheers

Mark   

[Laurie]

Several people including many on this forum swear by RS60 in the 284. When it works, it gives excellent results and high MVs. I also know of cases where it has proven to be inconsistent - great results for a while, then nothing good and unable to find the sweet spot again. So, it's certainly worth trying. I've no experience of RS70. An acquaintance who tried it got very, very high MVs but couldn't achieve the desired precision. As that's a grand sample of one, others may have tried it and got satisfactory results.

After some early experimentation with hotter powders, I settled on Viht N165 which will give the 175/180 SMKs 2,800-2,850 fps MVs from a 30-inch barrel. N165 has a repuation as being a very cool-burner and hence an aid to barrel life, and it has worked very well for me in both straight 284 and the Shehane. With a 0.327 G7 BC, a relatively mild 2,830 fps MV with the 175gn SMK sees 1,580 fps retained velocity at 1,000 and 1,372 fps at 1,200 (still above the transonic zone) in unpointed form and at 59-deg F at sea level, higher still on upland venues.

[No i deer]

I've bought a box of 183s to try in my saum but if 1 in 9 isn't suitable I won't bother I will keep them  but i did hear the weekend one of the better f class shooters use them in his 9 twist and says there the best 600yds bullet he has ever used but crap at 1000yds......!