I have a Model 70 .375 H&H that I’m getting ready for a trip to Africa. Will only be a plains game hunt but I’ll be in a DG area. I have had a gunsmith go over it doing bedding, trigger work, and installing a Williams extractor.

So I know we always hear that a DG needs to be 100% reliable. I’d like to hear how you guys test this and get to the point that you truly trust the feed and function of the rifle. I’ve done a good bit of cycling rounds through my rifle. I have some Rem. Factory 300 gr round nose ammo that really won’t work at all. About 1 in 10 times the 2nd from the last round coming out the mag will kick up and jam on the chamber. I’ve tried a couple spitzer and semi-spitzer (Sierra and Barnes) bullets and have not had a failure. The rifle feeds and eject empties no problem.

I plan to shoot the Barnes TSX so if it feeds fine then I’ll be happy. Just looking for some feedback on how you guys test.

Next question is regarding mounting a VariX III 1.5x5 scope with straight front tube. I’ve mounted it where it feels the best and of course the front ring is right over the lense. I’m using a torque wrench and am using 15-20 in. pounds so I know I’m not over tightening the screws. Any concerns mounting the scope this way?

I do not have the experience to answer most of your questions, but I would change the scope rings to offset rings, if it were me. I've never cracked a front lens with a ring, but, then, I've not put a ring on a lens. I've had a number brought to the gun counter with cracked lenses with a ring mounted on the lens, usually in hard kicking guns like slug and turkey guns. Mr. Murphy can hide in your gun case when you travel.
Bfly

It should feed your rounds of choice from the magazine or single loaded, put them into a decent group, and extract and eject every time from the shoulder.

Sounds simple, but things that work well in front of the TV or at the range do not always work so well in the heat of the moment.

I just did a 458 win mag mauser myself. My criteria was that it would feed a flat nose bullet, slip fit but not crimped in the case, flawlessly every time, every position, any speed.

I was able to achieve that with about 6 hours of trial and error, fitting and polishing.

Duane Wiebe has a good thread demonstrating the steps in doing that as a sticky on the top of the gunsmithing forum. About the only thing that i did that Duane doesn't cover is chamfering the sharp corner at the back of the chamber and polish it smooth, and on the mauser, chamfer the back corner of the barrel seat shoulder and polish it so that if a bullet or case mouth hits it, the corner won't cut into the case or bullet and grab.

First, make up a couple of dummy rounds instead of using live ammo. A lot safer. I use a partially sized case, with the bullet pushed in to the canelure. I want the bullet free to move into the case so that if I'm jamming the front of the bullet into something, it will show me that, rather than glancing off and feeding sloppily.

I do the feed fitting work with the firing pin assembly and trigger removed to make it easier on myself. No sense in overworking that piece of the action when you're really only concerned with the bolt, claw and magazine. Also, don't have to worry about grit contaminating them.

After I've got everything feeding well and polished with 220 grit paper, I use a felt tip in the dremel and polishing compound and polish the feed rail corners and edges, the feed ramp, the magazine chamfers at the feed ramp, and the barrel and action chamfers I've described above. Then, clean up with solvent, and I moly coat everlything with dry molybdenum disulphide. Reassemble the trigger and firing pin, oil and you're ready for the final testing.

With the action reassembled, I test extensively with the dummy cartridges again. Try different speeds, tilting the action up, down, sideways. Often it will feed at low speed but jam at high, or vice versa. If it does, watch where it derails, and mark the rails and case with felt tip to see whats happening and where it's rubbing. Remove material from rails, shape follower, relieve under the claw slightly, whatever it takes to get it going smoothly. It's more of an art than a following directions sort of thing.

Once it will feed a flat nose reliably, it should feed anything else. As you found, spitzers will fed when other stuff just won't.

dave

As Charles said.

You are on the right track anyway from what you have done.

Do it with a full mag, half mag, one round in the mag only and see how it goes.

Also, do it fast, slow, from the shoulder, with the rifle down at the hip etc - every conceivable way possible.

And good luck on the hunt !!!

One thing I found is that dummies and live rounds may eject flawlessly but empties may not due to the lack of weight forward when they try to pivot out. Not much fun when they bounce off the rear bridge and stay on top of the live rounds.

So, just try it all, and under duress, because the worst case is where problems will crop up.

I agree with you guys, and great post ssdave! One thing I would like to add is that I had the bottom metal and/or magazine/box (internal or not) NP3 plated. This was to add in smooth feeding, but it also tightened the feeding lip up just a bit. I found with one particular gun that the reason it would throw that second to last round in the chamber was the feeding lip of the mag was too wide. A little tweeking and a heavy plating of NP3 fixed it. Funny thing is that the bullet shape really shouldn't effect it that much, as you described above, unless the edge of the chamber is really that sharp. So ssdave gave a good answer for that.

I have a .375 Safari Express LH, one of the last ones built. Before my first safari with it, I ran about 800 rounds through it at the range and out in the country. It has a Leupy 1.5-5x20 #4 scope on it. The first time the smith mounted it, he put the ring parallel with the objective and cracked it. I went to offset QD mounts and the problem was solved.
I see no need for a Williams extracter. The MIM on mine has flawlessly extracted over 1500 rounds without a hitch, but go for it if you feel it's necessary.
I've taken it on two buff hunts, shooting Remington Factory 300 grain A Frames and killed everything I shot with it, including two buff, with one bullet each.

I practiced with handloads, 98% being 300 grain Hornady Interlocks loaded to Hornady's max figures with IMR 4350. It is an outstanding rifle. Deadly accurate and 100% dependable.