284 shehane question

[macguru]

Can you get 180s up to the mid 2900s in the 284 shehane chambering without stressing the cases too much, or do you still run them a bit slower and get lower pressures than a straight 284 ? In other words, is it worth the trouble (over a straight 284) ?. I am trying to convince myself I do not need to bother with a saum/magnum boltface etc ; i suspect 2850 is just fine but it would be nice to have a bit more ???

[lewis reynolds]

Just from my personal 2850fps mark is all i can push before opening up primer pockets on the blue box brass. I was give some older cardboard box brass from rocket Rod Davies that was much tougher. Some people have a theory that 2213sc is a little less brutal on the brass compared to 2209 but i never had great results with 2213sc so my testing was limited.

[Brad Y]

With adi powders your cases won't last long at those velocities. The 2800fps mark is proven for accuracy and case life. If you want to run faster build a SAUM.

[DaveMc]

OK - basically as stated by the guys above - if you get a slightly weaker batch of brass you will open up the pockets in 1-2 firings at 2950. even with good brass only expect 3-5 shots. (some barrels will be better than others of course).
Most people I know run their Shehane at 2800-2850 and get great case and barrel life but no harm in having a box of hotter loads for the odd occasion.

I did run one barrel at 2920 with hybrids (jumped) and 2213SC for 1800 rounds before rechambering and brass lasted well (200 cases so 9+ reloads still going strong) it is sitting in the cupboard again waiting for me to get back to it.

As Matt P will no doubt tell you (and I'm not arguing) the 280ai should do it with ease if you feel the need to go that way.

[AlanF]

I'd agree with Dave's assessment. But I do think that 2209 in particular is hard on primer pockets. For that reason I'm now restricting its use to 168VLDs. I generally use a slower powder (N165) for the 180s and the difference in pocket life is noticeable.

If I was doing it again with the 284 case I would still go Shehane, because it will do the same with less pressure than the standard case, and there is another advantage with the Shehane that is not often talked about. That is ease of extraction. Its not logical because the Shehane differs by having LESS body taper. But I've seen a discussion about it on a US forum - Shehanes are generally easier to extract than identical performing loads in standard 284s. I haven't used both myself, but often had stiff extraction with a standard 6.5-284, but have never had it once with the 284 Shehane. So despite not being able to explain why, I think it is a fact. Another one of those "go figure" things that shooting presents us with from time to time .

[Matt P]

At the recent QRA Queens, I went back to the 284 as my 280ai hasn't been behaving itself, anyway to cut a long story short I found a load at 2750 that holds x ring elevation @1000 and is easy on brass. Now the difference in drift between the 2870 (280AI) and 2750 (284) is less than I (and most mortals !!) can read.
Matt P

[AlanF]

That's interesting Matt. Care to reveal some specs (barrel etc)?

[Matt P]

Hi Alan
I rechambered an old trueflite 9twist 2weeks ago it's now 28" long (4th chamber)using 50 grains of 2209 with 180VLD Bergers jammed 14 thou for 2750 with an ES of 9. I had only shot it at 700m prior to the Queens. Unfortunately I don't have any powder left of that batch so it will have to start all over with a new batch
Matt P

[AlanF]

Sounds like yet another "go figure" .

[RDavies]

Just from my personal 2850fps mark is all i can push before opening up primer pockets on the blue box brass. I was give some older cardboard box brass from rocket Rod Davies that was much tougher. Some people have a theory that 2213sc is a little less brutal on the brass compared to 2209 but i never had great results with 2213sc so my testing was limited.

You were not given those good old cardboard box Lapua cases, I asked if you could fire form them for me. Now they are fire formed, can you drop them around to me now you are done.

[lewis reynolds]

rod is this a similar story to the 284 barrel you gave me that was no good for fclass course it didnt go 2 strings without cleaning then when you seen it shoot at 900 requested that we share it?

[RDavies]

rod is this a similar story to the 284 barrel you gave me that was no good for fclass course it didnt go 2 strings without cleaning then when you seen it shoot at 900 requested that we share it?

Oh piss of Lewis, you accidently PULLED those 9 shots into the X ring, beginners luck.

[macguru]

At the recent QRA Queens, I went back to the 284 as my 280ai hasn't been behaving itself, anyway to cut a long story short I found a load at 2750 that holds x ring elevation @1000 and is easy on brass. Now the difference in drift between the 2870 (280AI) and 2750 (284) is less than I (and most mortals !!) can read.
Matt P

Matt, I know its theoretical but I ran the numbers and the wind deflection for a berger 7mm 180 vld at 1000yds (starting at 2750fps) 5.7moa
and ............................................................................the wind deflection for a berger 6.5mm 140vld at 1000yds (starting at 2950fps) is IDENTICAL 5.7moa

(this was sierra bullets software, 100m altitiude 10mph crosswind)

If you send them away at low 2800s there is a 5% advantage to the 7mm, if you send them down at 2950 there is a 10% advantage 5.1moa
so clearly technique and skill play a bigger part here ....
Note that the gap is a bit wider to the 6mm, using vlds 6.5 moa deflection, a bit less with hybrids (not sure but they are about 6 moa deflection) both at 3020fps MV

Andrew

[AlanF]

Andrew,

I scrubbed an old 6.5-284 barrel out a couple of weeks ago. It had done 1500 rounds which is pretty much the expected quota for that chambering. I decide to load 140Hybrids at about 2980, something I'd never tried in it. Not only do I think it was as good in the wind as my 7mm 180VLDs at 2830, it hasn't dropped a point in 4 shoots! So its definitely earn't some more outings. And I still have all the dies - hmm.

Alan

[macguru]

Alan,
Thats spot on with what I found , the 140 hybrids at that speed would be the same drift as your 284 at low 2800s. The velocity numbers I quoted were mine for the 260ai rifle I used at the qld queens, chambered by Matt. In my load development the vlds at 2950 gave the best results. I am hoping that, as it does it with 5-6gr less powder than the 6.5-284, that i will get longer barrel life