700 Firing Pin Assembly & ES/SD

[MikeMcCasland]

Hey Guys,

I've been troubleshooting an ES/SD "issue" on a rifle I use to 'informally' shoot F-Open with. It's a 6.5CM used for 1k competition, and I've been unable to get my SD below ~15 FPS. I'm following all of the standard reloading best practices (FX120i weighed powder, AMP annealed brass, .002 bump, sorted brass, etc.). I am getting these SDs with two different brands of bullets too.

To date, I have tried 3 different brands of primers and have subsequently moved to Federal match primers from the CCIs I was using before. That said, I have to wonder if I'm not dealing with a rifle-caused ignition issue at its core.

This rifle started life as a Remington 700 BDL in 30-06 that I purchased on my 18th birthday. That said, it's been worked over since then. The action is now blueprinted and it wears a 30" HV Krieger barrel. In the past it's shot out 4 different barrels (to include the factory tube) on the stock bolt.

In my quest for ever lower vertical (and consequently SD) at 1,000, I decided to purchase a Gre-Tan standard weight firing pin assembly; I know I could have gotten away with a replacement 24lb firing pin spring, but what the heck.

That said, I was curious what kind of change you'd expect to see with regards to load performance? Would swapping to a Gre-Tan potentially throw the load out of tune? Would you expect to see POI differences?

I'm shooting a match next weekend, and trying to decide if I should keep it stock, or toss in the GreTan prior to.

Any feedback you have would be appreciated.

Thanks!

 

[Dusty Stevens]

If its standard weight you cant go wrong getting a new spring

 

[MikeMcCasland]

If its standard weight you cant go wrong getting a new spring

I purchased a Gre-Tan pin assembly, in standard weight/standard spring. Just not sure if it'll throw my load out of tune, put me off paper at 1k, or solve my ES/SD problem and have the same POI.

 

[Fast14riot]

What's the pin fall distance?

 

[MikeMcCasland]

What's the pin fall distance?

I'd love to tell ya, but I don't have a way to measure it.

 

[Fast14riot]

Not even a set of calipers to get a close measurement from the back of the bolt?

 

[MikeMcCasland]

Not even a set of calipers to get a close measurement from the back of the bolt?

Did my best to measure from the back of the bolt, and it looks like .240", but I don't have a ton of confidence in that measurement; not sure how to do it outside of eyeballing with calipers.

It should be obvious, but acting timing/ignition is one area I don't have a ton of knowledge.

 

[Liven The Dream]

When the chips are down
Carlsbad on this Site does GREAT Bolt work . He did my 700 Bolt for my F/TR Rifle ( small firing Pin bush job ? Improvement Yes ...
Do you have a Std. or Small Firing Pin ?

Good Luck

 

[MikeMcCasland]

When the chips are down
Carlsbad on this Site does GREAT Bolt work . He did my 700 Bolt for my F/TR Rifle ( small firing Pin bush job ? Improvement Yes ...
Do you have a Std. or Small Firing Pin ?

Good Luck

Standard firing pin/pin diameter.

I'm getting it bushed next rebarrel.

 

[carlsbad]

SD is the worst part of my shooting performance so don't consider me an expert.

But I don't think that the firing pin assembly will have a significant effect on SD so long as you have adequate pinfall and full ignition every time.

I always recommend a solid firing pin vs a fluted one. More weight is better. You have a long action so your firing pin is heavier yet.

If you have never changed firing pins/springs after shooting out 4 barrels, you may have significant wear on the firing pin and spiring causing inconsistent performance.

bushing can't hurt. Smaller primer dents are easier to make.

I don't think changing the firing pin assembly would affect load development or POI.

I would swap out the firing pin assembly and go for it.

I might put a regular weight spring on it since easier cocking makes for more consistent shooting and you probably don't need a heavy spring.

--Jerry

 

[Dusty Stevens]

If it does affect it then it was real bad

 

[WayneShaw]

If the gun is proper, you need to look at the loads, brass, and every aspect of them.

 

[MikeMcCasland]

If the gun is proper, you need to look at the loads, brass, and every aspect of them.

Short of H4350 not being able to deliver low SDs in a 6.5CM, I don't think it's the load.

I'm weighing powder to the kernel, sizing via bushing die .003 lower than bullet diameter, then mandrel expanding back up with a .263 carbide mandrel. Brass is Alpha brass (it's ultra consistent), that's AMP annealed every firing. Shoulders are all within +/- .0005 on the bump of .003". I'm not wet tumbling these, and I'm putting carbon in the neck to replace whatever gets burned off in annealing.

Seating is done on a Forster comp die, and run-out is checked on a 21st century gauge. I don't have the exact figures, but these are averaging probably .0015 bullet runout.

Seen it on Sierra 142s, Berger 140s, and Hornady 147s. That's why I'm thinking it's something in the gun.

 

[Chuckhunter]

Did my best to measure from the back of the bolt, and it looks like .240", but I don't have a ton of confidence in that measurement; not sure how to do it outside of eyeballing with calipers.

It should be obvious, but acting timing/ignition is one area I don't have a ton of knowledge.

Mike I had an ignition problem drive me crazy for a long period of time, only because I didn't know it was an ignition problem. Went over everything I could from all the screw, checking bedding, changing scope and I was very close to chambering up a new tube when I decided to change my firing pin spring. Took it to my smith and when he disassembled the firing pin he noticed a slight groove in the bolt shroud and determined it was caused by the pin that holds the cocking piece in place somehow wasn't completely flush on both side. So he put in the new spring and made sure the pin was flush by sliding a razor blade over each pin hole on both side of the cocking piece. I was struggling to shoot under 8 inches at a grand even under good condition. Long story short first match after pin fix shot a 4.631. IMO a pin weight between 18 & 20 lbs. is plenty and I like at least .250 FP fall. Oh yeah my extreme spreads and sd's returned to the single digits.

 

[DaveTooley]

One thing you haven't mentioned is making slight adjustments in seating depth.
I was never one to chase SD's. The target tells all.

 

[MikeMcCasland]

One thing you haven't mentioned is making slight adjustments in seating depth.
I was never one to chase SD's. The target tells all.

Hey Dave,

I've done lots of seating depth work, and it shoots tight groups at 500. My problem is vertical at 1k, which I'm attributing to SD.

At the range now...should have a verdict shortly.

 

[DaveTooley]

When you get time tell us about the bullet and has any work been done on the meplat. Variations in BC caused by the meplat start to show up the other side of 600 yds.

 

[MikeMcCasland]

When you get time tell us about the bullet and has any work been done on the meplat. Variations in BC caused by the meplat start to show up the other side of 600 yds.

No work on the meplats of any of the bullets I've tried. Today I was messing with some 147 Hornadys (I know...I know.....Hornadys). The load I'm planning to shoot at 1k next week had a 20 shot group that was about 3/4" inch; SDs were 13 FPS....so it wasn't a rifle related ignition problem.

Back to the drawing board.

Edit: For those who search for a similar topic in the future, swapping the stock pin assembly for a GreTan did nothing for POI. It does have more solid looking primer strikes, and gave me a slightly better feeling trigger (felt like less sear engagement). Bolt also opens up more smoothly.