Hangfire/FTF/Whatever you call it with custom action 6.5x47 Lapua

[dkhunt14]

Yes. This is happening with virgin brass and with F/L sized brass. I size my brass for a 0.001" - 0.002" shoulder bump.

If you seat a used primer in a sized case and let it stick out about half way. Now close bolt and let bolt seat the primer. That will tell you how much excess headspace you have by how much is still sticking out the case. Try to use one with no cratering or sand the crater off. Matt

 

[randyc]

I had same problem with 6.5 x 47L. I was bumping the shoulder back to far on resizing. Reset die and try,should cure problem.

 

[243winxb]

Replace the firing pin spring...

It should increase pin velocity.

 

[carlsbad]

did you check the headspace with a no-go gauge?

I would replace the spring. It is easy and cheap to do if you have the tools. I've had to replace light springs to fix FTF issues recently. Everyone wants a light spring for the smooth cocking feel.

--Jerry

 

[TikkaSporter]

Replace the firing pin spring...

Looks like I will need to purchase a tool to do this unless there is a trick/method to removing/replacing the spring without the tool (like the 'shoelace trick' for removing the firing pin assembly). Either way this looks like an inexpensive option to try remedying this. Would I want to get a regular strength spring (24lbs?) or a high strength spring (28lbs?)?

I also thought about just purchasing a whole new firing pin assembly (maybe a Gre-Tan with regular weight firing pin) and installing it, then keeping the other as a spare.

Or maybe swapping out the firing pin assembly with one in another rifle I have (if the pin diameter is compatible) and seeing if I still get the same problems... The other rifle uses Federal 210 large primers, which seem to have a softer cup. Thoughts on this?

 

[TikkaSporter]

I'm not sure I believe that headspace is the issue, at least on it's own. Maybe when combined with other things like a weak spring, etc it could be a factor. This has happened on both fired/re-sized brass and on virgin brass. I was pretty careful to only minimally bump the shoulder and have not had this issue on other rifles, even when bumping the shoulder 0.003" - 0.005" on them (gas gun).

That said, I'll watch the Wheeler videos again and see if I can figure out how to remove my ejection plunger to test headspace. I don't currently own a no-go gauge.

 

[M-61]

Do you have a GO gauge?

 

[243winxb]

The other rifle uses Federal 210 large primers, which seem to have a softer cup. Thoughts on this?

Hardness may change between lots.

Federal primers may have Nitroglycerin in them. others don't.

https://www.federalpremium.com/downloads/msds/F4001_Small_Arms_Primers.pdf

 

[butchlambert]

You don't have a lightweight firing pin do you?

 

[TikkaSporter]

You don't have a lightweight firing pin do you?

It looks like a regular steel firing pin (doesn't look anodized, not fluted, looks like all one piece/metal, magnet sticks to it). I have a call into Northwest Precision to verify. I was told they use 'regular strength' 24lb springs.

 

[TikkaSporter]

I haven't got to handle one of those actions. It could relate to any or all of the answers to the following questions...

3. Does it have enough pin fall? The back of your calipers is close enough for this purpose. Just measure the cocking piece protrusion in battery, and then fired, do the math. Or just close it, if it closes easy it's likely not enough if it's a Remington.

Tom

Well if I'm reading this right I measure at the back of the bolt shroud. These are rough measurements because I didn't take the rifle out of the stock and was working around a cheek piece, but I get + 0.049" cocked and - 0.204" fired, for a pin fall of 0.253"?

 

[rardoin]

did you check the headspace with a no-go gauge?

I would replace the spring. It is easy and cheap to do if you have the tools. I've had to replace light springs to fix FTF issues recently. Everyone wants a light spring for the smooth cocking feel.

--Jerry

^^^^ Order a GreTan spring. I had to do this in a new Borden action. It solved the primer ignition failure issue. the increased force required to close into battery does not affect the gun in the bags.

 

[TikkaSporter]

That should be enough.

Does it happen to be cerekoted?

Tom

It is coated. I assume with Cerakote.

 

[TikkaSporter]

Ordered a new spring and a firing pin/spring replacement tool today.

 

[Alex Wheeler]

If you have a full weight small tip pin, with enough fall, which it sounds like you do, I dont think your spring could fatigue enough to cause light hits. On an action with short fall and light pins, like a Bat, yes. That being said, if a new spring fixes your issue I bet you $100 you have a binding issue with your pin. When you change your spring, assemble the bolt without a spring first and make sure the pin has no drag over its travel. Also look at the cocking piece cut in the action. If you have a Kelbly trigger they can drag as well. I would like to see one of these primers that wont go off. When you say you can hit the primer multiple times and it still wont fire, that sounds more like a bad primer lot to me.

 

[TikkaSporter]

If you have a full weight small tip pin, with enough fall, which it sounds like you do, I dont think your spring could fatigue enough to cause light hits. On an action with short fall and light pins, like a Bat, yes. That being said, if a new spring fixes your issue I bet you $100 you have a binding issue with your pin. When you change your spring, assemble the bolt without a spring first and make sure the pin has no drag over its travel.

Will do. I appreciate the suggestion. I talked with Greg Tannel on the phone about this before I ordered the spring. He mentioned that if there was much of an alignment/drag issue with a small tip firing pin, the pin would likely have broken within a few hundred rounds. I've put about 100 rounds through this action, plus another 200 - 300 rounds of dryfire, plus whatever was put through it before I bought it (used).

Also look at the cocking piece cut in the action.

What am I looking for here?

If you have a Kelbly trigger they can drag as well.

It has a Timney 510 trigger and I haven't been able to rule this out as a potential cause (sear drag). FWIW this is the second Timney 510 that I've used in it, both experiencing misfires. I read somewhere that this is why the Timney 510U is required in some R700 clone actions (Defiance).Design change to prevent this?

I would like to see one of these primers that wont go off. When you say you can hit the primer multiple times and it still wont fire, that sounds more like a bad primer lot to me.

I'll see if I still have one that hasn't been de-capped/replaced and will post a picture. I've read a lot online about bad primer lots and misfires, especially with regards to the two styles of primers I've has this issue with (CCI 450 & BR4). That said many of these online accounts noted that if the 'bad' primer was fired in a different rifle, it worked fine. This leads me to believe it is more a combination of the primer and the firing system. So far I've had this happen with 3 different lots of primers, all CCI.

 

[TikkaSporter]

New spring from Gre-Tan and firing pin disassembly tool arrived today. I have it all apart now.

There's a big difference in the two springs. The new spring has ~ 27 coils and is ~ 3/8" longer than the old spring (uncompressed). The old spring is noticeably easier to compress and has ~ 37 coils, despite being shorter.

Without the spring and with the firing pin and cocking piece together, there is some drag when I slide them in the bolt shroud assembly. Not excessive, but not smooth either. Is this normal? If not, how do I remedy it? Polish the OD of the back of the firing pin with emory cloth or lapping compound? Polish the ID of the bolt shroud channel where the firing pin travels? Lube?

Pics:

 

[TikkaSporter]

Refer to post 38. Is that paint? The photo is dark.

Tom

Where? On the shroud, cocking piece, back of the firing pin? It's coated for sure, but I can't be 100% sure it is paint. If it is, it's fairly thin.

Hopefully I didn't do anything wrong. I chucked up the very back of the firing pin (the part that sits inside the cocking piece and doesn't slide) in a drill. I put some lapping compound on my fingers, spun the drill at a medium speed, and used my fingers w/ the lapping compound on the part of the pin that slides through the bolt shroud and was dragging. When complete, most of the coating was removed in this area (some of it was already worn away to start with). After doing this the rear of the firing pin slide smoothly inside of the bolt shroud.

After replacing the firing pin spring, my trigger pull was ~ 1/2lb more than it was prior. I adjusted it back down to 1 lb, 10 oz.

When I get some daylight that doesn't involve work, I'll put some rounds through it.

 

[savagedasher]

New spring from Gre-Tan and firing pin disassembly tool arrived today. I have it all apart now.

There's a big difference in the two springs. The new spring has ~ 27 coils and is ~ 3/8" longer than the old spring (uncompressed). The old spring is noticeably easier to compress and has ~ 37 coils, despite being shorter.

Without the spring and with the firing pin and cocking piece together, there is some drag when I slide them in the bolt shroud assembly. Not excessive, but not smooth either. Is this normal? If not, how do I remedy it? Polish the OD of the back of the firing pin with emory cloth or lapping compound? Polish the ID of the bolt shroud channel where the firing pin travels? Lube?

Pics:

Springs are the same as as a bar if you unwind the spring it will give you a bar leingt the longer the bar the softer the spring if the diameter of the wire is the same . That depends on the temper also when you compress a spring . To installed leingt being shorter will be stonger . Larry

 

[TikkaSporter]

When I get some daylight that doesn't involve work, I'll put some rounds through it.

Put 23 rounds through it today after work with no misfires. Tried the two rounds I had left that didn't go off with the old spring. One of them fired, the other didn't. Encouraging.

I ran some rounds through the chronograph and either my Magneto is lying to me, or my ES/SD is now horrendous. I'm leaning towards a chronograph/false data issue since some of the velocities were just plain unbelievable.

I two rounds out of 12 show velocities over 3150 fps (6.5x47 Lapua, 130 gr Berger AR Hybrids, 41.2gr H4350, 22" barrel). No pressure signs on the fired cases, just not buying it. So a 300+ fps ES if you believe those two rounds.