7MM results?

[Pilgrim]

I've got a 7 X 65R rifle under construction and expect to see it in Jan./Feb. I cannot find any info on barrel twist, etc on this cartridge, but expect it will be virtually identical to the 7 X 64 as both were designed by Brenneke and the two differ by only the rim as near as I can tell. Anyway, I believe the rifle will have the standard 9" twist. Unfortunately, the rifle will NOT have the flexibility to load to velocities less than factory and still maintain accuracy. Has anyone had any luck with ~160 gr. cast at ~ 2700 fps in a 9" twist 7mm? If so, what was the formula? TIA Pilgrim

[Blammer]

Ok, I curious now, why can't you load it to less than factory velocity?

[scrapcan]

Pilgrim,

Do a search on the user name BoomBoom. A very good thread on 7mm & cast will come up. There is some good info in there. Have a read and I am sure some of the posters in that thread will be along shortly. Here is a link to the thread if it works.

http://castboolits.gunloads.com/showthread.php?t=603&highlight=boomboom

[Pilgrim]

Ok, I curious now, why can't you load it to less than factory velocity?

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I'll try to make a long story short....

The rifle that is being built is a double rifle (side by side in this instance). These rifles are regulated with a specific ammunition to place the bullets into x" (usually 2") at 50 - 100 meters. Ammunition other than that for which it is regulated may not shoot accurately at all. Usually, a handloader can develop a load that duplicates the "regulating" load and all is well. Oft times, if the regulating load is more or less standard, other manufacturers ammunition will also regulate in that rifle, but not always. For example, my 9.3 X 74R was regulated using Norma 286 gr. ammunition. A target is nearly always sent with the rifle that shows the accuracy of load Y at X range shot with that particular rifle. My rifle also shot very accurately with Sellior & Bellot 286 gr. ammunition (2 each rights and lefts into ~ 1" at 100 yards, rights on the right and lefts on the left).

However, to give you an idea how difficult these rifles can be...as I continued to shoot the rifle the accuracy (grouping) got progressivley worse. After ~ 300 rounds, instead of the accuracy noted above, the groups with the same ammunition, same velocity (w/i 1 fps per chronograph reading!), same bench at the same rifle range, same distance, same shooting set-up, same scope, same shooter put 2 ea rights and lefts into 5" horizontal spread with the right barrel hitting to the left & vice versa. I had the rifle re-regulated ($750 w/ shipping to & from the gunsmith) and now it is perfroming as before. The cause? The barrel smoothed out with the shooting of FLGC's I was using, and as it got smoother, the "dwell time" (for want of a better description) of the bullet in the barrel became less. That meant the bullet left the muzzle sooner with the smoother barrel than it had with the rough barrel. In that fraction of a second, the recoil of the rifle had not progressed as far as it had previously, causing the bullet to hit to the left (right barrel) and right (left barrel). Both barrels grouped as before, just not at the same place as originally. Over and unders are easier to regulate as they recoil in a single plane, vertically. Side by sides on the other hand, recoil both horizontally and vertically. The right barrel recoils up and to the right, while the left barrel recoils up and to the left. The recoil effect must be accounted for by barrel convergence at the muzzle. This is called "regulating" the rifle. It cannot be done mechanically as each rifle is slightly different. You can get them someplace in the ball park mechanically, but that form of regulation is not any where near as precise as a shooter sitting at a bench or "leaning bench" shooting the rifle. If you rest the rifle on a front rest like we often do with our bolt actions, the double rifle will recoil differently and thus the accuracy will be different. They are intended to be shot held in the hands, and that is how they are regulated. Hope that helps....Pilgrim

[Blammer]

yep, thanks.

[scrapcan]

Pilgrim,

Do you have pictures ofhte doubles? I would like to see them.

Also I hope you are able to find a load that will regulate to the sights. maybe with a lot of work you will find a load that will regulate at a different distance but still be usable.

Are you using the doubles for their original intentions? And good post ont he regualtion of loads to sights with a double.

[Pilgrim]

I'll try to figure out how to paste a picture. In the meantime, the site below will give you a pretty good idea of what my rifle looks like. My current rifle (except for the wood and the addition of a Leupold VXIII 1.5 X 5 scope) looks just like the rifle at the web site. The rifle on order has a color case receiver instead of the french grey. It will have a VXIII 2.5 X 8 scope. The rifle is a Chapuis UGEX (Ultility Grade Express). Piligrim


http://www.williamlarkinmoore.com/product_details.asp?id=1604

[Pilgrim]

I failed to answer one of your questions.....I've wanted a double rifle for at least 50 years. The cost of one just kept escalating a $1000+ or so more than I could afford through the years. After my second heart attack I decided enough was enough and bought it while I still had time to enjoy it. I chose the 9.3 X 74R chambering thinking I would take it to Africa. That cartridge is the minimum that some (but not all) of the African nations will permit to be used on dangerous game (lion, elephant, cape buffalo, rhino). Even though leopard is also a dangerous critter, it is often shot with rifles of lesser caliber. Because I might use it for dangerous game (cape buffalo) I had the scope mounted in "swing mounts" so it could be easily removed for use in close combat (so to speak) if needed. After contemplating where I would mount the trophys, it became obvious to me I had no place to mount them. My wife has virtually all walls covered with art/indian baskets,sculptures/etc. that she & I have picked up over the past 40 years. She has made a fair amount of the art work herself as she is a very talented professional in that sort of thing (pen & ink/water color/calligraphy). Having no place to mount the heads, I've decided I wouldn't go to Africa & shoot any of 'em. It didn't seem right to do so if there was no purpose in it, at least in my feeble mind. I'd love to shoot and have mounted gemsbock (oryx), kudu, and other spiral horned antelope, but putting them at head height in my shop seemed to be one helluva insult to the animals. A cape buffalo would also be nice, too. I'm not interested in any of the other dangerous game, except maybe elephant, but that critter is way beyond my budget (current or projected!). Anyway, the cartridge pushes a 286 gr. bullet (or boolit) at 2350 fps out of a 24" barrel. Not fast, but fast enough to be useful out to 300 yards if the rifle is accurate enough. Using a solid, it will also penetrate all the way through the head of an elephant or shoulders of a cape buffalo. Think of it as a .375 light. Mine is accurate enough, and I hope to use it for hunting in this country if I can get my bones motivated enough to get in acceptable condition for hunting. Pilgrim