I am baffeled and need some help please

[Trapper]

I have a Savage Model 12 with a Varmint contour 6.5 Grendel barrel. I do alot of shooting and reloading for pistol and rifle calibers, but with this one rifle I find that 2-3 rounds out of 50 become FTF. The primers have firing pin dents in them but no bang. I had the trigger pull set at 2 1/2 # and then moved it to 3# and I still get the 1-2 FT. I was wondering if it is possible to change the weight of the bolt internal spring that the firing pin goes through. I can't find any information about the weight of the bolt firing pin spring pressures, so I am hoping someone can point me in the right direction. I have tried several primer mfgs. and have the same problems. Any ideas?
Thanks in advance for any help offered.

[earl39]

Need a little more info. Is this factory ammo? Is it russian ammo? Reloads? Primer might not be seated good. I was having this problem with 7.62x39 in an ar using russian ammo and seated the primers a little more with a hand primer and cured the problem.

reread your post and it appears you reload. How do you seat your primers? What brands have you tried? Have you segregated the brass that didn't fire to see if it is the same brass each time? Primer pocket could be too deep. Have you pulled the bullets on loads that didn't fire to ensure they did have a powder charge. Do you tumble your brass? Primer pocket plugged. Wet tumble? Might have water still in case. Have you checked your firing pin protrusion? May be set to short.

[hafejd30]

I would strip the bolt down and clean/lube it.

Is this rifle brand new and having problems? Also as stated above, what primers are you trying. If you could post a pic of the Ftf and fired primers it may help.

I'd guess a weak firing pin spring or to little firing pin protrusion. I've never had this issue but I do believe there are aftermarket firing pin springs available through brownells/midway etc

[Dennis]

Either a headspace issue, weak firing pin spring, worn firing pin, even a badly worn sear could cause this.

I have experience this twice in recent years and found the problem to be one of the above. My case, I replace the sear in one, and the firing pin in another. It took care of my issues, but I almost put the gun up due to this issue. I didn't give up, it's to simple to give up, just worked with it, asked a lot of questions, and Bingo, I found the issues finally.

[LongRange]

like earl said a little more info would be good...
is it a factory rifle or something you re-barreled?

...also like hafe said the inside of the bolt maybe dirty/greasy causing the pin to slow down before it strikes the primer so id start by cleaning the bolt...i think its pretty rare that a firing pin spring is bad(but its possible)i fired over 10,000 rounds on a precision target action(not including hundreds of dry fires)and never had a problem.
but before striping the bolt pull it out of the action and check the pin protrusion by pushing the cocking piece over into the fired position and measure with your calipers...its a crude way to check but will give you an idea...it should be .035 to about .055 and in the fired position should look something like this...



to measure the pin protrusion use the rod thats at the back of your calipers...put the base of the calipers across the high part of the bolt and measure to the bolt face then doing the same thing measure to the top(highest spot)of the pin in the fired position.

if hand loading the first things that comes to mind....are you full length sizing and bumping the shoulders a little to much causing a false head space issue?
try measuring a sized case and a fired case off the shoulder and if more than about .004-.005 your sizing to much.

next and as earl said and ive seen first hand is not seating the primers deep enough or to deep? both will cause FTFs but not deep enough more so than to deep.

if its a head space issue its easy enough to figure out...as i said above measure a fired case and look up the specs on the case and compare. also but not going to tell you if it is a head space issue is to reduce your load to just a little over book minimum and jam the bullets into the lands and if all the jammed rounds fire with no issue then the cases are over sized or the barrel has to much head space.

im willing to bet its something simple but another thing to check would be when you pull the bolt is it hard to get out? when you pull the trigger back and push the bolt release does the bolt release move freely?

[Trapper]

Factory Model 12 LRP rifle with barrel change to Varmint 6.5 Grendel, and a ppg bolt head. Great advice as I have been shooting a lot of rounds through this bolt action 6.5 Grendel. I am a former Marine and my firearms are all broken down completely after each use. I was using CCI BR primers. Alot to check and see where the problem lies. Now I will start my hunt and as was suggested, stay at it until I find the problem. Thank you all for your suggestions.

[hafejd30]

Did you headspace with the ptg bolt head or add that after rebarreling?

[Robinhood]

Head space or firing pin protrusion.

Dennis how did a worn sear impact FTF?

[Dennis]

Head space or firing pin protrusion.

Dennis how did a worn sear impact FTF?

It didn't allow the firing pin to fully lock in place. So it didn't have enough force to strike the primer. It appeared that someone previously might have worked on the sear which caused this problem. I had the action and use it for about a year, it started misfiring a few rounds, then within 3 months, it wouldn't fire any round.

It drove us nuts for a few weeks before we realized the problem. We replaced the sear, firing pin, pin spring, and it's been shooting fine ever since.

Dennis

[earl39]

I would look closely at pin protrusion if you didn't at least check it after putting in the PTG bolthead. Combine that with headspace and shoulder setback and you have stacked tolerances that can cause problems like you have.

[Robinhood]

It didn't allow the firing pin to fully lock in place. So it didn't have enough force to strike the primer. It appeared that someone previously might have worked on the sear which caused this problem. I had the action and use it for about a year, it started misfiring a few rounds, then within 3 months, it wouldn't fire any round.

It drove us nuts for a few weeks before we realized the problem. We replaced the sear, firing pin, pin spring, and it's been shooting fine ever since.

Dennis

That is intriguing.

[jonesturf]

I had burrs in the firing pin hole on my ptg bolt head. Remove the firing pin or visually inspect and see if any are there. That could ruin your day in a heartbeat.

Sent from my SM-N920V using Tapatalk

[earl39]

Trapper have you found a cause yet?

[Trapper]

Earl, I went over everything suggested except for resizing the brass as mine were already reloaded, but I did measure them. The firing pin is sticking out at .045 and seems to be hitting the primers hard enough. This time I had one FTF and I think I am going to change the primers from the CCI-BR4's to Federal SRP and see if that helps. The rifle shoots great, but the FTF is a puzzle, nice way of saying pta.
Thanks for all the help guys.

[BillPa]

Something else to take a close look at.


The red line represents a bent pin, the yellow line represents a pin turned off center. Both conditions can pad the pin fall when passing through the bolthead retaining pin and or through the bolthead past the vent. Those that are bent are easily straightened, those off center should be replaced.

Bill.

[sharpshooter]

It's the bolt head...

[short round]

It's the bolt head...

Would it have any thing to do with PTG bolt head being made for large diameter firing pin, being used with small dia firing pin?

[Robinhood]

What happened with this Trapper?

[sharpshooter]

Would it have any thing to do with PTG bolt head being made for large diameter firing pin, being used with small dia firing pin?

Exactly.....the pin is totally unsupported in the cocked position and droops off center, then bounces around like a pinball before the tip actually finds the hole. That robs it of energy.

[yobuck]

I would imagine a good gunsmith could bush the firing pin hole?

[earl39]

Would like to know what happened with this also

[Trapper]

Hood, My friend the gunsmith, took the bolt apart ,cleaned it his way and put everything back together. We had 2 FTF in 25 rounds, He took the bolt back out and told me to pull up a stool and shut up. He cleaned the bolt again and ran Qtips up through the inside of the spring over and over and each time he did it, a small piece of the cotton would stick in the same place on the spring. He dremeled the burr off the spring, and put the bolt back together. We went out to the bench and shot another 25 rounds with no FTF. I don't know how that little burr messed with the firing pin, but so far no FTF's. I'll be at the range tomorrow for 50 rounds of the 6.5 and we shall see. By the way, he took the PTG head off the bolt and measured it from every angle and said that they do good work. He's retired from the military where he was an armourer for many years. I would have ended up replacing the spring, for no apparent reason except just because I couldn't figure it out. Helps tp have you guys like ya'll making suggestions and being lucky enough to have a friend that knows rifles like he does. Thanks to all for their suggestions, I'm lucky I am already bald, cause I would have pulled my hair out.
Thanks everyone again for all their input,
Trapper

[Robinhood]

Glad to here it is functioning like it should.

[sharpshooter]

I wouldn't be surprised if it started doing it again.

[Trapper]

Sharpshooter, I will defer to your diddy at the bottom of your profile. I will be replacing the firing pin, just for peace of mind, but this rifle is to heavy to hunt with and tote around, and I am not good enough to be a serious competitor with. I built it to try out the 6.5 Grendel in a bolt gun, as I already had an AR from Alexander Arms. Thanks again for all the help
Traper