to ackley or not

[elkaholic]

I completely agree that the 7RM case is every bit as strong as the Wby and should by all rights be capable of handling 65k but ballistics labs have noted unexplained pressure spikes in the 7RM since it's intro in 1962.
After many of these reports SAAMI took note and concluded that a pressure reduction was in order to compensate for these pressure spikes.
Since the publishers of loading manuals are reluctant to publish loads which exceed SAAMI MAP (the standard used by the industry) the loads for the 7RM reflect that lower limit.
Loading the 7RM to 65k means exceeding the latest data whilst not exceeding 65k. How is that pressure determined absent proper equipment?
At the same time you run the risk of exceeding safe and sane pressures should you experience one of those anomalous pressure spikes which seem to be peculiar to the 7RM and the 243 W.

There has to have been something going on besides the case design! There is nothing about their designs which would cause anything that wouldn't occur in any other similar case. Could have been a "wrong powder issue" or any number of other things, IMO....Rich

 

[Sennaspeed]

The scientists and ballisticians are at a loss to explain why these two cartridges (the 7RM and the 243 Win) exhibit a much higher propensity to pressure spikes than other cartridges on the same basic case.
They may not be able to explain it but the pressure issues associated with these cartridges have been noted for a very long time and have been deemed significant enough to warrant a pressure downgrade from SAAMI.

Whether the pressure downgrade for the 7RM is warranted or not the fact remains that since the SAAMI limit is now 61k, ammo manufacturers and reloading manuals will adhere to that limit and more importantly, pressure tested load data will cease to be published which exceed the 61k limit.

 

[Fiftydriver]

So you have no explination for it????

If you look at the old load data that also was established under the SAAMI standards, the old data showed much higher performance levels then todays standards.

Its the lawyers alone that have come up with these anemic standards and noone else.

Do I advocate exceeding safe chamber pressures, certainly not, especially for novice handloaders. But for experienced handloaders who PAY ATTENTION to all pressure indictors, its easy to find a safe max working pressure.

The Rem Mag, IN NO WAY AT ALL, spikes chamber pressure compared to the Wby. The only thing that will do this is the difference in the throat between the two but both will easily handle the same chamber pressure quite safely. If you set up a Wby chamber with an accuracy throat which is short like the Rem Mag, they are for all intent and purpose IDENTICAL.

Again, this is a lawyerproofing step pure and simple, this is also the reason factory rifle triggers generally are quite bad right out of the box on most rifle, to keep the lawyers off the manufacturers back.

One more question for you, say you take a 7mm Wby rifle, load it with say a 140 gr Accubond to the max load used in the Nosler reloading manual, what happens with that load chronographs 100 fps slower then the book says it should, does that mean your rifle is producing 100 fps less velocity at that top working pressure listed by the reloading manuals????

 

[Sennaspeed]

The lawyerproofing argument doesn't hold water IMO.

Why would the lawyers decide to go after the 7RM and the 243 but leave the older, more popular 270 WCF at 65k?
Not only that but most of the newly introduced cartridges (the WSM's, RUM's, 280AI's and such) are all standardized at 65k and if lawyers rather than ballisticians called the shots they would likely have been 60k cartridges.

The widespread use of accurate piezo transducers have shown that the long reported pressure spike problem in the 7RM were in fact an actuality even though the cause of these spikes remains unknown to the finest minds in the industry.

 

[Fiftydriver]

Best to get back to the topic of the thread, this is a dead stick topic.

 

[buckyne]

sorry did not mean to create so much "discussion". Was just looking for some meanful input on the advantages v disadvantages of going with a totally custom chambering. The 280 is fairly hard to find ammo anyway and the ackley with the 40 degree shoulder is something I have never seen stocked.

Out hot water heater took a crap this weekend anyway so the $ I had squirreled away in my gun fund has now been re-allocated by the wife/boss.

I will have several more months to contemplate whether to go with the ackley or not. Now I just need to try and find a gunsmith near Lincoln, NE and see what he would charge for a rebarrel job. if he works on rugers....

Thanks again for all the feedback on my original Q.

 

[Derek M.]

sorry did not mean to create so much "discussion". Was just looking for some meanful input on the advantages v disadvantages of going with a totally custom chambering. The 280 is fairly hard to find ammo anyway and the ackley with the 40 degree shoulder is something I have never seen stocked.

Out hot water heater took a crap this weekend anyway so the $ I had squirreled away in my gun fund has now been re-allocated by the wife/boss.

I will have several more months to contemplate whether to go with the ackley or not. Now I just need to try and find a gunsmith near Lincoln, NE and see what he would charge for a rebarrel job. if he works on rugers....

Thanks again for all the feedback on my original Q.

Although there's a chance I may eventually build a 280AI, I honestly don't think Ackley improved much of anything in terms of field results. Stick with the 280 and no worries. You can buy custom loads online from Nosler, and others for 280AI, however.

 

[Buttermilk]

I personally like Ackley 'ised cases.

I've had the 280AI in the past and plan to own another one.

Currently shooting the 30-280 AI.

I say go Ackley. Nosler makes brass and also provides ammo.

Regards
Rog

 

[elkaholic]

Although there's a chance I may eventually build a 280AI, I honestly don't think Ackley improved much of anything in terms of field results. Stick with the 280 and no worries. You can buy custom loads online from Nosler, and others for 280AI, however.

If you don't think the A.I. is a big enough improvement over the .280, build a .280 Sherman. You can use the Nosler A.I. brass and easily form to the Sherman case. I have no doubt that 3150' can be achieved with a 160 in a 26" barrel....Rich

 

[elkaholic]

I personally like Ackley 'ised cases.

I've had the 280AI in the past and plan to own another one.

Currently shooting the 30-280 AI.

I say go Ackley. Nosler makes brass and also provides ammo.

Regards
Rog

Hi Buttermilk.....what are you getting for velocity with your 30/.280 A.I.?

 

[outofayr]

Now I just need to try and find a gunsmith near Lincoln, NE and see what he would charge for a rebarrel job. if he works on rugers.....

When you get ready for your build, PM me. I can give the name of a smith here in Lincoln to do your rebarrel if you want to keep it local. No reason to, though, as you can ship it off to any number of good smiths to have the rebarrel done. Unless your barrel is shot out, or is a poor performer, you can even have your barrel set back a thread and rechambered to the AI version. This is usually a pretty inexpensive option compared to a full rebarrel.

Have fun with your build,

Brian

 

[Dalebow]

I just ordered the Dakota Hunter Model V, Nesika action with jewell trigger, Lilja #4 contour, 24" stainless, fluted tube, B & C stock, Olive with black web, sunny hill bottom metal, coated in stainless colored Fcoating. I am excited about the 280 AI, my buddy has a remington in 280 AI and he is getting 3060 out of 59grains of reloader 19, 150gr TTSX and some great groups.

I am getting over the magnum blasters and finding a love of the standards and slightly improved. I am starting the 338-06 build you guys suggested.......I rarely shoot over 400 yards and 500 max for me on critters so no need for the 10# cannons anymore. I dont care if you want to carry a the 10# rifle and shoot 100yards, I will always be in awe and support you but Iam really loving the AI rounds, really thinking about the 257 roberts AI next for lightweight deer roundgun)

 

[elkaholic]

I just ordered the Dakota Hunter Model V, Nesika action with jewell trigger, Lilja #4 contour, 24" stainless, fluted tube, B & C stock, Olive with black web, sunny hill bottom metal, coated in stainless colored Fcoating. I am excited about the 280 AI, my buddy has a remington in 280 AI and he is getting 3060 out of 59grains of reloader 19, 150gr TTSX and some great groups.

I am getting over the magnum blasters and finding a love of the standards and slightly improved. I am starting the 338-06 build you guys suggested.......I rarely shoot over 400 yards and 500 max for me on critters so no need for the 10# cannons anymore. I dont care if you want to carry a the 10# rifle and shoot 100yards, I will always be in awe and support you but Iam really loving the AI rounds, really thinking about the 257 roberts AI next for lightweight deer roundgun)

What length barrel does your buddy have?........Rich

 

[Dalebow]

he has a #5 Lilja, 24"