Misfires with a specific ammo

[emp1953]

Greetings, I am breaking in a Winchester Model 70 Alaskan, 375 H&H. This gun is a strong candidate for a back up on an upcoming CO elk hunt this fall. I will soon do some load tuning but now have an issue with misfires. I have discharged 60 rounds of Federal Premium, 300 gr Nosler Partition, with no issues. Best group is 1.7 MOA but am confident with hand loads that I can get it pretty close to 1 MOA. This weekend, I tried Hornady Outfitter 250 gr GMX. Of seven attempted firings, 3 were misfires. Hornady customer service looked at the attached pic and stated:
"Thanks for the inquiry. At first glance we notice that the pin strikes on the primers aren't centered on the primer and do appear a little shallow. We seat the primers slightly below flush about .005" to .007" but this increases the sensitivity of the primers. Currently we don't show any other known issues with that particular lot# at this time."

In the pic, the three misfires are on top, beside an unchambered round, four normal fired cases on the bottom. As you can see from Hornady, no consideration of the fact that the gun performed without issue with another type of ammo. Winchester said to go ahead and ship the gun to their service center in Missouri. However, I may consider having a local smith give it a look. I can also try another type of factory ammo (not cheap however these days, at 4+$ per round), or try some hand loads. Any thoughts or advice? I can also get the comparators out and compare head space/case length for fired and unfired cartridges with both ammo types on hand. Could the Hornady cases be a tad short, too much room in the chamber? Both types are nickel plated cases. Any similar experiences with Hornady Outfitter ammo (which they claim is durable and dependable enough for an outfitter to use).

Thanks in advance for your help.

Back in the early 70's I bought a new, in the box and wrappings Sako military rifle in 30-06. Heavy with cosmoline. I cleaned it up and took it out with my hunting reloads and immediately had light primer strikes/misfires like your photos. Took it to my gunsmith buddy who said a Sako won't do that. He put the bolt into a solvent tank for a week. Blew it dry with compressed air gave it back to me to try. my first shot was a misfire. No more misfires after that. I never had the bolt disassembled. But I did spray it out with carb cleaner and more compressed air. The rifle has been a reliable performer for 40+ years. I had it sporterized. Since your rifle was new I'd vote for junk in your bolt first.

 

[skipglo]

Light primer strike can be firing pin drag in bolt. I agree with @LoneTraveler to tear down bolt, clean the inside of the bolt body, shine light in bolt body to make sure no corrosion, clean firing pin assembly with good degreaser to make sure not gummed up, look at firing pin hole on bolt face to insure it is free and clear on inside of bolt.

I would try the ammo again after deep clean.

X3...I agree with both! Primer strikes are erratic on all six...not two the same!

 

[xsn10s]

As a side note if you clean boltfaces on any firearms with the firing pin hole facing up you could be setting yourself up for a problem. At one time primer sealants were used on especially duty ammo. Scrubbing with a brush with boltface facing up could push the residual sealant down the firing pin hole. When mixed with cleaning solvant a tough polyner like buildup would occur inside. That has had instances of stopping the firing pin from striking properly. I make it a habit to clean out bolt bodies or semi auto pistol firing pin cavities depending on how many rounds I fire.

 

[emp1953]

I ran across a guy at the range once that had this happening. Investigation showed that he had intentionally used large pistol primers instead of large rifle primers in his reloads. It took several weeks to figure this out. Finally had to disassemble some rounds and punch out the primers and measure.

 

[lancetkenyon]

Looks like light primer strike issues to me too.
Just because one brand of ammo works, doesn't mean a slightly different cartridge primer seated a hair deeper will. Younare probably right on the edge with your first ammo as well.

 

[Tim Sharp]

Greetings, I am breaking in a Winchester Model 70 Alaskan, 375 H&H. This gun is a strong candidate for a back up on an upcoming CO elk hunt this fall. I will soon do some load tuning but now have an issue with misfires. I have discharged 60 rounds of Federal Premium, 300 gr Nosler Partition, with no issues. Best group is 1.7 MOA but am confident with hand loads that I can get it pretty close to 1 MOA. This weekend, I tried Hornady Outfitter 250 gr GMX. Of seven attempted firings, 3 were misfires. Hornady customer service looked at the attached pic and stated:
"Thanks for the inquiry. At first glance we notice that the pin strikes on the primers aren't centered on the primer and do appear a little shallow. We seat the primers slightly below flush about .005" to .007" but this increases the sensitivity of the primers. Currently we don't show any other known issues with that particular lot# at this time."

In the pic, the three misfires are on top, beside an unchambered round, four normal fired cases on the bottom. As you can see from Hornady, no consideration of the fact that the gun performed without issue with another type of ammo. Winchester said to go ahead and ship the gun to their service center in Missouri. However, I may consider having a local smith give it a look. I can also try another type of factory ammo (not cheap however these days, at 4+$ per round), or try some hand loads. Any thoughts or advice? I can also get the comparators out and compare head space/case length for fired and unfired cartridges with both ammo types on hand. Could the Hornady cases be a tad short, too much room in the chamber? Both types are nickel plated cases. Any similar experiences with Hornady Outfitter ammo (which they claim is durable and dependable enough for an outfitter to use).

Thanks in advance for your help.

Not saying this is what you need, but this video may be worth a watch. I had a M70 doing the same thing. Greg Tannel video.

 

[F&H1821]

Help me out a bit on headspacing. Does shoulder position not matter at all, with only the belt determining precise placement of the cartridge in the chamber? If so, how do I measure head space based on the bolt?

As a side note if you clean boltfaces on any firearms with the firing pin hole facing up you could be setting yourself up for a problem. At one time primer sealants were used on especially duty ammo. Scrubbing with a brush with boltface facing up could push the residual sealant down the firing pin hole. When mixed with cleaning solvant a tough polyner like buildup would occur inside. That has had instances of stopping the firing pin from striking properly. I make it a habit to clean out bolt bodies or semi auto pistol firing pin cavities depending on how many rounds I fire.

FYI, both types of ammo that I am currently shooting have primer sealant. Hornady markets it as a key addition to their "outfitter" ammo, making it durable in though conditions. It is clearly obvious on the Federal premium loads.

 

[xsn10s]

Help me out a bit on headspacing. Does shoulder position not matter at all, with only the belt determining precise placement of the cartridge in the chamber? If so, how do I measure head space based on the bolt?

FYI, both types of ammo that I am currently shooting have primer sealant. Hornady markets it as a key addition to their "outfitter" ammo, making it durable in though conditions. It is clearly obvious on the Federal premium loads.

On belted magnums when you reload you can "headspace" you can bump the shoulder a couple of thou when you resize. So that's when a comparator comes into play. But after a few loads you may need to size for the belt. So FL size or get a body die. You could FL size each time but you'll likely stretch the brass faster and get less firings out of it.

I load most all of my ammo now. So I haven't bought ammo other than rimfires for twenty years. That's why I'm not aware if ammo manfacturer's still use primer sealant.

On your new rifle if you haven't cleaned out the inside of the bolt it'll have some original packing grease in it. That's true in any firearm. So I clean them out. But I've been to armorer's schools so I'm comfortable doing it. If I wasn't I'd take it to a trusted smith or amrorer. Since Winchester said they take a look at it that's a viable option. I simply offered the ammo checks so you could rule out the ammo.

 

[F&H1821]

On belted magnums when you reload you can "headspace" you can bump the shoulder a couple of thou when you resize. So that's when a comparator comes into play. But after a few loads you may need to size for the belt. So FL size or get a body die. You could FL size each time but you'll likely stretch the brass faster and get less firings out of it.

I load most all of my ammo now. So I haven't bought ammo other than rimfires for twenty years. That's why I'm not aware if ammo manfacturer's still use primer sealant.

On your new rifle if you haven't cleaned out the inside of the bolt it'll have some original packing grease in it. That's true in any firearm. So I clean them out. But I've been to armorer's schools so I'm comfortable doing it. If I wasn't I'd take it to a trusted smith or amrorer. Since Winchester said they take a look at it that's a viable option. I simply offered the ammo checks so you could rule out the ammo.

No problem on my end cleaning out the bolt. In fact, I disassembled the M70 bolt last night and there was a lot of oil or lube in there, likely anti rust preventative. Would it be OK if I simply give it a bath in my ultrasonic cleaner, disassembled, and with standard parts cleaner? Then blow it out with compressed air and light lube with ballistol or CLP? Actually, I was down at FTW for the SAAM class back in '19 and on the last day, during our final "exam", my new Fierce Fury 300 Win starting giving me misfires, and I had a retired Seal instructor right there with me. [Sidenote -- still finished 2nd in that class!] I should take the bolts off all my guns and do this. The main elk gun will be a new Nosler 33 M48 Long range carbon, also under break in and load development. I disassembled that as well, and while it had little noticeable lube or oil, an ultrasonic dunk with light oil after may be a good preventative. Sound OK to do?

 

[xsn10s]

No problem on my end cleaning out the bolt. In fact, I disassembled the M70 bolt last night and there was a lot of oil or lube in there, likely anti rust preventative. Would it be OK if I simply give it a bath in my ultrasonic cleaner, disassembled, and with standard parts cleaner? Then blow it out with compressed air and light lube with ballistol or CLP? Actually, I was down at FTW for the SAAM class back in '19 and on the last day, during our final "exam", my new Fierce Fury 300 Win starting giving me misfires, and I had a retired Seal instructor right there with me. [Sidenote -- still finished 2nd in that class!] I should take the bolts off all my guns and do this. The main elk gun will be a new Nosler 33 M48 Long range carbon, also under break in and load development. I disassembled that as well, and while it had little noticeable lube or oil, an ultrasonic dunk with light oil after may be a good preventative. Sound OK to do?

I use a ultrasonic cleaner sparingly with assemblies. For single/ stripped parts it's probably fine. I just use a brush and a good solvent and then wipe clean. Lightly oil and GTG. In doing that I haven't had any issues with my firearms.

 

[spladi]

Greetings, I am breaking in a Winchester Model 70 Alaskan, 375 H&H. This gun is a strong candidate for a back up on an upcoming CO elk hunt this fall. I will soon do some load tuning but now have an issue with misfires. I have discharged 60 rounds of Federal Premium, 300 gr Nosler Partition, with no issues. Best group is 1.7 MOA but am confident with hand loads that I can get it pretty close to 1 MOA. This weekend, I tried Hornady Outfitter 250 gr GMX. Of seven attempted firings, 3 were misfires. Hornady customer service looked at the attached pic and stated:
"Thanks for the inquiry. At first glance we notice that the pin strikes on the primers aren't centered on the primer and do appear a little shallow. We seat the primers slightly below flush about .005" to .007" but this increases the sensitivity of the primers. Currently we don't show any other known issues with that particular lot# at this time."

In the pic, the three misfires are on top, beside an unchambered round, four normal fired cases on the bottom. As you can see from Hornady, no consideration of the fact that the gun performed without issue with another type of ammo. Winchester said to go ahead and ship the gun to their service center in Missouri. However, I may consider having a local smith give it a look. I can also try another type of factory ammo (not cheap however these days, at 4+$ per round), or try some hand loads. Any thoughts or advice? I can also get the comparators out and compare head space/case length for fired and unfired cartridges with both ammo types on hand. Could the Hornady cases be a tad short, too much room in the chamber? Both types are nickel plated cases. Any similar experiences with Hornady Outfitter ammo (which they claim is durable and dependable enough for an outfitter to use).

Thanks in advance for your help.

The indentations on the no fires do look very lite/shallow. The ammo with no misfires likely have softer primer metal therefore more likely to ignite. If the gun were mine I would clean the firing pin and its bore in the bolt. Like you said affirm headspace is not to great. lastly replace the FP spring.

 

[emp1953]

Thank you!

try it with your fired ammo, the ones that misfired.

 

[Jon Bischof]

No problem on my end cleaning out the bolt. In fact, I disassembled the M70 bolt last night and there was a lot of oil or lube in there, likely anti rust preventative. Would it be OK if I simply give it a bath in my ultrasonic cleaner, disassembled, and with standard parts cleaner? Then blow it out with compressed air and light lube with ballistol or CLP? Actually, I was down at FTW for the SAAM class back in '19 and on the last day, during our final "exam", my new Fierce Fury 300 Win starting giving me misfires, and I had a retired Seal instructor right there with me. [Sidenote -- still finished 2nd in that class!] I should take the bolts off all my guns and do this. The main elk gun will be a new Nosler 33 M48 Long range carbon, also under break in and load development. I disassembled that as well, and while it had little noticeable lube or oil, an ultrasonic dunk with light oil after may be a good preventative. Sound OK to do?

I experienced light strikes with my Model 70 during sub-freezing weather. To insure that it never happens again, I cleaned the bolt and firing pin thoroughly and installed a new Wolff extra-strength spring. You don't need to lube the inside of your bolt or firing pin channel. Perhaps you could lightly oil it and then try to wipe, swab it all out. You won't get it all out even if you try with dry wipe and swab, so it will be protected, but not enough left to freeze up and get gunky.

I highly recommend ordering the Wolff extra strength spring. You will NEVER have light strikes again. It also doesn't hurt accuracy to have the stronger spring.

 

[wonderman4]

Judging by the fired Winchester primers, the cases are not formed to the chamber yet. During firing, the case gets pushed forward by the firing pin, pressure builds forcing the primer against them bolt face, then the case moves back against the bolt face which flattens the primers. It appears to me that the primers are moving too far back which may indicate a little too much headspace. It ain't a biggie, just resize the cases to headspace off the shoulder.