I have a custom left-handed 416 Rem Mag built on a Montana action only 2 years old. The gun will misfire, and has since I had it built, around 5% to 15% of the time. The gunsmith who put it together has tried to repair it 3 or 4 times and hasn't succeeded. He has replaced the firing pin and spring, extended the firing pin protrusion, and generally gone through the rifle in search of the cause. The rifle dents the primers but some don't go off.
I think the headspace is excessive but he argues that because it is a controlled round feed that the extractor will hold the case to the bolt face thus this isn't a consideration. There is a noticeable amount of for and aft
play in the bolt when it is closed with no case in the chamber. Also when dry fired with no case the bolt moves forward and the handle moves slightly upward.
I cleaned all my reloading equipment with denatured alcohol as well as the cases before I primed and loaded them. I bought 200 new primers from the store. I wanted to make sure there was no contamination to weaken the primers. I used both new and once fired Rem. cases that were full length resized and trimmed to length with a Lee case trimmer. The primer pockets were cleaned with a tool then swabbed with alcohol and let dry before loading. I have been reloading for over 20 years and shooting for 50 so I don't think my technique is faulty. I guess I could put a false shoulder on the case by partially neck sizing it but I don't want to go to that trouble with a dangerous game rifle. I want it to go bang every time with even marginal cases.
Does anyone have a smith they would recommend who is familiar with Montana actions that could straighten this gun out? It is an accurate gun when it goes bang and fits me well. Any suggestions would be apprecited.

I heard similar complaints about earlier Montana Rifle actions.
I never heard that a CRF feed rifle can control excess headspace by the extractor. But I would be the first to admit I am far from being a smith myself. I would try partial full length resizing of the cases so they chamber with just a slight resistance and do that to start.

But the easiest thing to do is to return it to MRC to have it fixed.

It could be a case sizeing problem. Its got to headspace either on the belt or on the shoulder.
If you just push the shoulder back just a little,but do not reduce the taper of the case, it will not headspace on either the belt or the shoulder, and the firing pin will force the case forward. I had a 1999 do the same thing. I adj firing pin out to 80 thou, but in a heavy spring ,adj the die to just neck size with out pushing shoulder back no more problems.

JD

I think JD is on the right track ... Do you see the same problem with brass that has been fired in the rifle and then only neck sized so the shoulder has not been moved from the fired condition of the case.

If they do work 100% of the time ... the chamber is a little too long. If not, adjust the firing pin protrusion a bit longer and try again.

I have had a similar problem, but traced it back to not quite enough protrusion to properly detonate the older nickeled WLR primers. (Worked fine with CCIs ... but I have a stock of WLRs I can't bare to throw away ;>

I'll try neck sizing a few and see if the problem goes away. I'm on my way to a hunt and if that works I'll have an idea of what to tell the smith. I'm thinking about sending it to Montana Rifle company and see if they can straighten it out. Thanks for the input.
Lewis

With any belted case, when resizing size just enough of the neck and body to get a crush fit in the chamber. resize it down a little at a time, trying it in your rifle until you get that crush fit...Then go shoot it, that will probably fix it..Your chamber is probably a tad to large and you need to fireform to it..That is your gunsmiths fault btw...

If this works, then you can size it down just a barely tad more to get a bit less than a crush fit so that all ammo will feed as its a dangerous game rifle..

I would be inclined to demand a new barrel and a proper chamber, if the above works cuz he run the reamer in to far! or at the least shorten the chamber but that could effect the inletting if its a custom rifle.

I suggest you fire some factory ammunition before you ship the gun off for inspection or repair.

If the factory ammunition misfires also, the problem lies in the gun - weak firing pin spring, insufficient firing pin protrusion, headspace, whatever.

If you're unwilling to deal with it, sell the gun to me.

George

I had exactly the same problem with my LH MRC 1999 in 308 Win. except I had more misfires with factory ammo than my handloads. MRC sent me a new (heavier) firing pin spring which did nothing to correct the problem. They finally asked me to send them the rifle which they returned in two weeks and I have had zero misfires since. I don't know what they did to fix it but I got the impression during several phone conversations they had already dealt with this problem more than a few times. I would advise sending your rifle to MRC for repair.

I agree with George - if you have this problem with factory ammo, the gunsmith needs to fix it or pay to have it fixed by someone who knows what they are doing.

You might be able to "fix" the problem if it is a headspacing issue by fireforming and neck sizing, but if you are somewhere and don't have your home-brewed ammo, you have a rifle that will fail to fire one out of every six shots. If this is the case, then follow Ray's advice and demand a new barrel which has been chambered properly.

Listen, we all make mistakes and problems do occur. An honorable person accepts and corrects their mistakes and does not make excuses. You are getting excuses.

what George S posted, +1!

Have you tried any other brand of primers? I'd put nothing but Federal 215's thru that big a case.

Rich
DRSS
Knowledge not shared is knowledge lost...

First insist your gunsmith replaces the Montana FP spring and checks fp protrusion as well as make sure nothing is interfering with/slowing down the firing pin travel. look for bright marks in the bolt sleeve and in the action itself. Use dyechem if necessary. Fp protrusion should be about .060. 95 percent of these malfunctions are the result of the above. If the above checks out then Borrow a no -go guage for a .416 Rem Mag ( REMOVE THE EXTRACTOR)_and see if the bolt closes easily on it. IF so you have excessive headspace. It takes a whole lot of excessive headspace before a gun won't fire. Usually you will see incipient headspace separation marks on a fired case if this is the cause. If the claw extractor is strong enough to hold a case against the boltface when the bolt is removed from the gun and a case is inserted in the bolt and held horizontally and shaken a few times, then it will almost always fire despite headspace. A old fireforming trick I've used myself many times. You can also seat some bullets out until they lodge in the rifling and then ajust the OAL until your just able to close the bolt with some feel on a loaded case( use a load 10% below max for this experiment.. You now have zero headspace and have moved the case off the belt recess in the chamber. Compare the OAL of this loaded round to a loaded round that won't fire, if the zero headspace round still wont fire, the problem is in the fp or spring. Make sure your not seating your primers too deeply. .001 below the case head is usually plenty. I've seen some folks death seat the primers. Try another brand of primer(fed 215's are good) and also try other brands of cases while your at it. Finally if your gunsmith can't/won't fix this simple problem take it to someone else.-Rob

I ran out of patience on my 1999 .450 Ackley. Same situation, 5-15% misfires but only with Hornady basic brass. The FP was rubbing in the shroud but relieving that, checking protrusion, and replacing the FP spring, still not 100% boom.

Rifle shot like gangbusters but $&^#( the misfiring.

Please let us know if you get your .416 remedied.

Sounds like headspace to me. The belt is too far forward in the chamber. Do what Rob said. If holding the case back against the bolt face makes it work you know you need to set it back and chamber properly.

My bet is it isn't headspace. It takes a whole lot of headspace to make a gun with a .060 fp protrusion fail to fire. This much headspace usually results in case head sparations.
MY bet is weak FP spring or SOMETHING is rubbing in the FP bolt sleeve enough to slow down the FP velocity. FOLLOW MY ADVICE and solve the problem.-Rob

Lewis50,

Have you gotten anywhere with that .416, or should we start talking price yet?

George

........Funny this topic should come up .....A 1999 Montana that I had has started doing the same thing........Oddly enough it is a 416 also ....