7mm Improved


Well-Known Member
Feb 26, 2003
How much case capacity can be gained by Ackely improving a case? I am interested in:

7mm RUM AI
7mm WSM AI


The 7 wsm has a 35 degree shoulder with is better in some aspects than the 40 degree ackley version. I would get the wsm and never look back. Thanks Reed
..Second that.. I personally don't see enough gain available to justify the additional expense and hassle..
.. But if yer hell-bent on it, check with Richard over at Richard's Custom Rifles.. I think he's messed with these a bit.. Good luck.. d:^) JiNC

So I am just interested in what can be gained by improving these cases. What happens when you take out the case taper and make the shoulder steeper? How much volume can you can you gain?

There are lots of 300/338 RUM improved dicsussions on this site. Lets hear about the big 7mm cases.


[ 02-12-2004: Message edited by: dwm ]

On a 7 RUM I feel you would gain only a few grains (2 or 3) by blowing out the shoulder and increasing the shoulder angle by 5 degrees.

I did some preliminary measuring on someone's 300 Tomahawk, which is a similar improvement to the 300 RUM. I'll have better measurements by tomorrow evening. Stay tuned.
Thanks Len, this is what I was looking for.


[ 02-13-2004: Message edited by: dwm ]
I have many AI's, 22-250AI, 308AI, 30-06AI, 6MM-06AI. At this point in time, I have not shot the 308 yet, just did this one a few months ago and being in Wisconsin, I really haven't had the weather for shooting. But I will say so far the only one that has dissapointed me had been the 30-06AI. I gained next to nothing, maybe 50fps on it and it kicks like a mule. The 22-250AI is just awesome. In the HEAT of summer I have chronographed some of my loads at over 4100fps, 55grain bullet and the gun shoots like the no tomorrow. I will tell you as well, in my opinion, having been around many production guns, that a custom chamber, cut nice and true on a lathe, versus being mass produced at a factory, definately has some merits. Accuracy tends to be a bit better, but then again that is provided all other aspects of the rifle are there, ie bedding, load etc. The 6MM-06AI, is another fine shooter and has plenty of zip. It is really awesome on groundhogs at long range and can zip a 105 A-max at around 3700fps. I would say the Ackleys are worth a good look depending on caliber. Try it, if you don't like it I am sure you could always find someone to buy it. It is fairly easily done on a production barrel also, which in most cases cuts the cost down at the local gunsmith shop. I ahd one done by Howard Wolfe, back in PA and it only cost me, at that time, $50.00 so, I really don't feel that I lost anything there.
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