donmarkey Posted August 13, 2014 Report Share Posted August 13, 2014 Response to dr Hess in feeding issue. Feeding issues are the hardest thing to try to explain without being there in person. The most helpful thing I can say is grab an original 98 and some military ammo, load the magazine up and work to bolt and analize what the bolt, extractor, and feed rails are doing at each part of the loading. You will see the rails direct the shoulder of the case and the extractor grabs the rear all at specific times. Now lay your new round next to the military round. Is it longer? Fatter? Different shoulder location? The round still need to move correctly, so if the shoulder is forward the rail needs to be adjusted so the case is in the same orientation as the original. Same goes for the overall length, if the oal is longer the. You need to have the rail basically do their thing that much sooner to prevent the tip from slamming into the barrel tenon. I start working on feed issues in this order, some are irrelevant to dr Hess's issues so skip those. 1 Mag box, if the mag box isn't 100% sized right everything else is a moot point. Use the cosine rule and get the box right or at least the taper angle right. The overall width can be fudged. 2 extractor fit. 3 rail to box fit. If you modify to mag box, the bottom of the receiver needs to be cut to match. This I consider the feed rails 4 feed lips. Just as in a clip the thin edge of the feed lips guides the round. This is what need to be shaped to the new case by the adjust a little, test, adjust, test and so on method. No real blueprint to use here. 5 follower. This needs to hold the case the same as a round under it would. Clear as mud? Don Quote Link to comment Share on other sites More sharing options...
Dr.Hess Posted August 13, 2014 Report Share Posted August 13, 2014 Thanks, Don. I'll try it. Thing is, this is a 7mm Spanish Mauser action with a 7mm Mauser (7x57) barrel and it doesn't want to feed cartridges as long as the magazine, which I thought it should. No caliber change at all. It is like when the shoulder pushes against the side of the receiver, the angle it happens at isn't enough to push the tip of the bullet into the chamber and it hits the barrel at 3 O'clock instead if the OAL is too long. Anyway, I do have 17 factory (East Europa, Prvi, or something I think) loads left here somewhere. I'll measure them and watch how they feed from the left side of the magazine. Quote Link to comment Share on other sites More sharing options...
Spiris Posted August 13, 2014 Report Share Posted August 13, 2014 I'd like to add that a fatigued magazine spring can cause feed issues, and the shell may be coming out high and is not being directed by the feed ramp. The original military round for that caliber was a heavy round nose of 175gr that was guided by the feed ramp. You can try tweaking the original mag spring to put more upward pressure at the back of the shell as it feeds. Investing in another mag spring shouldn't be too costly, if you want to go that route. I wouldn't think that the feed rails need adjustment with the original cartridge, unless someone has been messing with it. Spiris Quote Link to comment Share on other sites More sharing options...
Dr.Hess Posted August 13, 2014 Report Share Posted August 13, 2014 I have some other magazine springs around that I can try. As far as I can tell from my google-fu, this receiver was made in 1904. I think by 1904 they used a spitzer bullet and not a round nose in 7mm. Round nose bullets have to be loaded significantly shorter than spitzer/pointy nose to feed. The original barrel was on the receiver (matching serial number to the receiver) when I bought it, so I don't think it was ever anything but a 7x57. That's not to say that someone hasn't been messing with the feed rails in the past 110 years. It was modified by the Spanish by scrubbing the crest off the ring and adding a vent hole to the ring and the bolt, probably between 1916 and the mid 30's and probably not at the same time. The vent holes are very professionally done and the crest scrubbing was a quick and dirty job. Quote Link to comment Share on other sites More sharing options...
donmarkey Posted August 13, 2014 Author Report Share Posted August 13, 2014 Also does it feed the same with one round or three in the mag? It should, if it feeds any different then the follower could be wrong. And or weak spring as stated earlier. Don Quote Link to comment Share on other sites More sharing options...
AzRednek Posted August 14, 2014 Report Share Posted August 14, 2014 Back in the 70's when myself and friends got together on weekends shooting mil-surps. Best I recall nearly all the Spanish 7MM surplus ammo were all round nosed. Been way to long to try and remember the year of manufacture but my best guess is 30's and 40's. I can't say for sure all the round nose ammo was Spanish, possibility some of the 7MM ammo we were shooting may have been from South America. Seems to me I recall one of my shooting buds having some 1950's pointed 7MM he got with a 7X57 chambered FN-49. I'm guessing but I think the ammo and rifle were from Ecuador. Hitler helping his buddy Franco. Re-built a bunch of both German and Spanish manufactured Mausers. If the metal was painted chances are good it may have been one of them. The few I've seen the barrels were re-lined. Using a magnifying glass look for a tiny Nazi eagle proof mark stamped on the under side of the receiver. The Spanish rifle I had I didn't discover the Nazi mark until the paint peeled off. If yours is a German rebuild no telling if they did anything with the rails. Quote Link to comment Share on other sites More sharing options...
AzRednek Posted August 14, 2014 Report Share Posted August 14, 2014 BTW Don, good to see you hanging around again, you and your expertise has been missed. Quote Link to comment Share on other sites More sharing options...
CaptnC Posted February 8, 2017 Report Share Posted February 8, 2017 Hey guys...I have two builds working right now. 6.5X55 and a 308...both cases hang in the exact same spot. The cases have heavy scrapes about 1/2 ahead of the case heads. From what I can see they are having trouble getting past the extractor...maybe the tension on the follower is weak and not pushing the case head under the extractor Quote Link to comment Share on other sites More sharing options...
Racepres Posted February 8, 2017 Report Share Posted February 8, 2017 Very Nicely done Don!! Helps considerably. I would add that sometimes, oddly, A different bolt acts differently...Go Figger!!! Quote Link to comment Share on other sites More sharing options...
donmarkey Posted February 8, 2017 Author Report Share Posted February 8, 2017 Hey guys...I have two builds working right now. 6.5X55 and a 308...both cases hang in the exact same spot. The cases have heavy scrapes about 1/2 ahead of the case heads. From what I can see they are having trouble getting past the extractor...maybe the tension on the follower is weak and not pushing the case head under the extractor Have you tuned the extractor? How does it snap in by hand? What is the defection amount? Quote Link to comment Share on other sites More sharing options...
CaptnC Posted February 10, 2017 Report Share Posted February 10, 2017 "Defection amount" is that the amount the extractor moves as you force a case under it by hand when the bolt is out of the gun? Quote Link to comment Share on other sites More sharing options...
donmarkey Posted February 12, 2017 Author Report Share Posted February 12, 2017 The amount the exactor defects with the case under the rim compared to no case. Don Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.