375 H&H Feeding Problem Remedies

[Ironduke]

Issue: Last round from the internal box magazine pops up and out of the action, leading to a jam.

Facts: Howa 1500/Weatherby Vanguard long action receiver originally chambered for the 300 Weatherby. I sent the rifle to a competent smith for rebarreling to 375H&H. The rifle now shoots GREAT. It's a sub-MOA rifle with several loads of mild to heavy 375H&H ammo.

Sadly, when feeding from the magazine the last round will pop out of the action instead of cycling. The nose of the cartridge either jams into the receiver or pops out of the ejection port so the bolt pinches the side of the case. It's just a bummer.

Solutions: I could rechamber the barrel to 357 Weatherby. That cartridge has the same shoulder diameter as the 300 Weatherby, which should fix my feeding issue since I think the issue is the narrower shoulder on the H&H case. I think the gentle sloping of the H&H case doesn't allow the receiver feed rails much purchase. I could still shoot 375H&H ammo in a pinch. I also pick up 100-150 fps in velocity with this solution.

Option 2: I could have a smith weld more material onto the feed rails. Then file off the material until feeding reliability is achieved. This would fix the issue and still allow 375H&H ammo without having to worry about 375 Weatherby ammo.

Thoughts from experienced gunsmiths?

Paul

[John Taylor]

The follower is not the right one for the cartridge.

[waksupi]

The follower is not the right one for the cartridge.

That's where I would look, too. Followers may look the same, but there are many minor variations.

[LAGS]

On some rifles that the caliber was changed.
I put Dykem or black felt pen ink on 5 dummy cartridges.
I loaded the magazine and watched how each one felt thru as you cycled the bolt.
Then looked at each casing for the marks to see what the difference was on each case.
Especially the casing that failed to feed.
Since it was the last casing to feed.
I looked closer to the magazine follower as the place I needed to modify.
Put ink on the follower and feed rails to see where the casing was hitting.

[Larry Gibson]

"Solutions: I could rechamber the barrel to 357 Weatherby. That cartridge [the 357 Weatherby] has the same shoulder diameter as the 300 Weatherby, which should fix my feeding issue since I think the issue is the narrower shoulder on the H&H case. I think the gentle sloping of the H&H case doesn't allow the receiver feed rails much purchase."

That, indeed, is the problem. You will have to rebarrel to 357 Weatherby, not "rechamber" but I'll assume it was just a reversal of numbers? The old 375 Weatherby [or the 375 Talor] was/is an excellent 375 cartridge. It should feed fine in the rifle. A new follower made for the 375 H&H taper may also work.

[405grain]

"I could have a smith weld more material onto the feed rails."

That's not going to happen. Trying to weld on the feed rails is a very bad idea, and I doubt that any gunsmith would take on that task.

[John Taylor]

If it only happens on the last round the feed rails are fine. It could be the follower is not wide enough allowing it to go to one side or the hump is in the wrong spot or not high enough.

[Ironduke]

"Solutions: I could rechamber the barrel to 357 Weatherby. That cartridge [the 357 Weatherby] has the same shoulder diameter as the 300 Weatherby, which should fix my feeding issue since I think the issue is the narrower shoulder on the H&H case. I think the gentle sloping of the H&H case doesn't allow the receiver feed rails much purchase."

That, indeed, is the problem. You will have to rebarrel to 357 Weatherby, not "rechamber" but I'll assume it was just a reversal of numbers? The old 375 Weatherby [or the 375 Talor] was/is an excellent 375 cartridge. It should feed fine in the rifle. A new follower made for the 375 H&H taper may also work.

Yes. I meant 375 Weatherby. I don't type as fast as I think! So yes. Going from 375H&H to 375 WBY would be just a rechamber, though P.O. Ackley wrote that properly rechambering to an improved cartridge is properly done by setting the barrel back by a thread to clean up the chamber and ensure perfect headspace. So barrel removal for the work would be likely I think.

[Mk42gunner]

Since it seems the feed rails are okay, I would try building up the follower a tiny bit to get the appropriate side pressure on the last round.

If your follower is metal, you may be able to use a small blob of solder or weld metal to do this. Or if it is plastic, you can try building it up with an epoxy.

A very thin steel follower may be reformable to get the correct shape, kind of like doing sheet metal body work on a car.

It may be best to try to get a replacement follower to try to modify, since the one you have kind of works now.

In any case, I don't think you will need to build up the follower more than ten or twenty thousandths of an inch.

Robert

[waksupi]

Rather than welding or grinding, you can build up either rails, follower, or both with JB Weld. It can be easily shaped, and if it doesn't work, you can remove it.

[Gtek]

If it were me I would pull firing pin/cocking piece assembly from bolt and place rifle in a rest or across your lap. Load magazine to full capacity and slowly manipulate bolt and watch cartridges as they move forward, As stated above you will probably find fix on follower or internal box rails (lips) if it has them.