Very similar results with mine. Next is new firing pin spring. Congrats. Accuracy on a CZmtr can be a rabbit hole.

 

Is this what is being done on the PETE'S PILLARS reshaped firing pins for 457s? I couldn't figure out the reason until this post. I even contacted PP to ask but they were pretty dismissive which turned me off, especially after ordering a lot of stuff from them.

 

Interesting, this is a reprofiling to achieve better/consistent primer ignition?

what are ya aiming for when ya do this, what shape? And does it work for all 45X series rifles, or just the 457?

thanks!
SK

 

Kidd - I have no idea what Pete's Pillars does, could be the same idea. I have read that it can reduce flyers and stringing. I cannot at this early stage attest to either, but based on my limited shooting thus far I would say that I am encouraged.
Squirrel -Yes I think the idea is to get better and more consistent ignition as the striker isnt crushing the rim so all of the force hits where the primer compound is located. I think it works in a 455 but the striker is completely different. People a lot smarter than me figured this out and are many threads and you tube videos on it. The approach i took was to file some, put a fired piece of brass in the gun and pull the trigger, evaluated the hit and did that process over and over again.

I am attaching a picture of what mine looks like; although I am debating about taking a tad more material off. Again I took a risk of ruining my firing pin so unless you are willing to buy a replacement you may be best leaving it alone.

I am sure there

 

Jesse48 - let me know how the new firing pin spring works out for you

 

Got any pics showing the rim of a fired case???

Would be heap big plenty help for those who want to give it a try.

 

So below are before and after brass. The one on the bottom is before I reprofiled the striker, note how the impression extends all the way through the rim. The one on the top is after profiling. See how the rim is untouched. I previously said I was thinking about taking some more material off the striker in order to move the strike further from the rim, but I am afraid that I could be taking too much off. Since I have see great improvement in SD's I am thinking to leave well enought alone for now and see if I feel my flyers and stringing has been reduced.

 

Here is a shot of my 50 yd target from today. I don't think the reprofiling did any harm, I now need to get some time to shoot some groups at 100 and 50 to see if it has improved my results.

 

Nice! I’m excited to see your results!

I just claimed a 452 in the classifieds, and I’m interested in seeing if the same thing can help with that rifle

 

Excellent testing, frigatebird. I didn't chrony my rifles when I did that mod. After a few 'touches' with a file I got the strike looking about like yours. Did this also reduce your ES ? I'm working on a couple diff lots of SK-RM and will have some chrony data soon. The weather has been pretty poor lately - too Hot or too Windy or too Rainy.
I've done the 'profiling' to several rifles, including my CZ 455 & 457-VMTR. You just need to analyze where the FP is striking and how to change it. Note - some FPs cannot use this mod since the FP is 'too loose' in it's channel. It even worked on my Savage 64, but due to the rifle's 'accuracy-issues' the results are inconclusive 😉 And I haven't chrony'd that rifle lately.

 

Just FYI, a mod like this won't turn a average shooting rifle into a great one. But, it can help to turn a already great shooting rifle into a even better one.

 

IMO any actual measurable increase in accuracy is certainly worth spending the price of modified firing pin...

 

Not sure it's significant enough by itself to actually measure it's value. Is it worthwhile? Providing everything else is good, I think it is.

 

As this is really more about ignition of the cartridge, than any particular firearm, I'm thinking about a couple of tight shooting 10/22 clones. There are some "improved" firing pins available for them that I use, but now I wonder if they hit the outside edge or not. As for use with the CZ, I found some mentions of concern that a profiled firing pin may be less reliable with 22 mag or 17 hmr. If so, swapping calibers would require an extra step of changing the firing pin or a complete bolt.

 

Modacam will do the re-profiling for $33.50

 

Modacam will do the re-profiling for $33.50

View attachment 616739

Cool, just looking at the CAM rendering there, I believe I can do that to mine, albeit maybe having a small radius at the bottom instead of a sharp corner, by using a small ball endmill.👍🏼

 

As PWN said, this won't make a poor rifle more accurate. The issue addressed is ignition and this improves that, tho it may not be easily measured. Frigatebirds tests indicate there is an increase in speed so that shows there is a change from this. There are many threads covering this mod.
As well, some have tried 'lightening' the FP by taking away mass. This is to increase 'speed' of the strike but I don't know if that is 'a thing' as to being effective. the reduction in mass may not give much of an increase in speed ?
On my 457-VMTR I didn't notice an increase in accuracy, but I'm not that great a shot anyway. I normally shoot in the 0.3xx-.5xx range but I haven't had a 'calm day' out here since last August. Maybe some better days to come.
Here are pics of my work. The pin can be filed down just a bi more IMO, but as the case shows the strike is away from the rim a bit. The Green strikes are the 'After' hits.

 

As PWN said, this won't make a poor rifle more accurate. The issue addressed is ignition and this improves that, tho it may not be easily measured. Frigatebirds tests indicate there is an increase in speed so that shows there is a change from this. There are many threads covering this mod.
As well, some have tried 'lightening' the FP by taking away mass. This is to increase 'speed' of the strike but I don't know if that is 'a thing' as to being effective. the reduction in mass may not give much of an increase in speed ?
On my 457-VMTR I didn't notice an increase in accuracy, but I'm not that great a shot anyway. I normally shoot in the 0.3xx-.5xx range but I haven't had a 'calm day' out here since last August. Maybe some better days to come.
Here are pics of my work. The pin can be filed down just a bi more IMO, but as the case shows the strike is away from the rim a bit. The Green strikes are the 'After' hits.

View attachment 616751

View attachment 616752

Thanks for posting this analysis and pics @Fasteddie01 ! Much appreciated and good to see the results of this mod. 👍🏻

 

Did you shim your bolt when you added the Mullerworks barrel ? Just curious and very interested in your project !

Kelly

 

FastEddie - I had some weird velocity results in the data from prior to reprofiling the striker with several shots being 40 to 70 fps below the average. I have no idea if those are accurate or if the chrono got them wrong. The ammo I am using is good ammo but not the best so I guess there could be that much random variation in it. I have never really looked at rimfire data before. So my Pre ES was 108.1 and my post ES was 41.7. If I take out those 3 really low velocities my pre ES drops to 83 and the SD drops to 11.34. I am now thinking that those may be more reasonable results. Either way a significant reduction in both ES and SD. Would be interested to see the results you are getting.

Groupshooter - No I have not looked at shiming the barrel or the bolt mainly becasue I have been trying all sorts of ammo since I built the gun to see which one(that I can get!) works the best.

To address the question of is doing this worth it. I think its up to each individual to decide. I do not think it is a miracle cure for a poor shooing rig. I think it may improve things a tad (keeping in mind group sizes can be measured in thousandths) but I still have to be convinced of that with more time on the gun. I am constantly tinkering with all of my rifles and centerfire reloading to see if I can improve results. Its a hobby and I enjoy the challenge of trying to improve results while doing things myself.

 

I think it’s plausible that if ignition is borderline as compared to vigorous and across the entire primer mix radial width that pressure profiles would be more consistent.

 

This has been a known fact in how a rimfire firing pins strikes the rim for a long time.
Did my 452 Varmint like 15 years ago, I think it helps.

 

Read Bill Calfee's book "The Art of Rimfire Accuracy " Whole section on Ignition and firing pin profiles.

 

This was taught when I was in gunsmithing school almost 50 years ago. It’s simply a matter of not expending firing pin energy crushing the folded brass rim where there is no priming compound. If FP energy is marginal, the reprofiling might do some good, but rifles with excess FP energy, that impart a Thor-like hammer blow, probably won’t see any improvement, and the rifle has to be accurate enough to see any difference.

 

I modified the firing pin on my CZ MTR. I was having light strikes occasionally, then it happened during a match. I decided then to reprofile the fp. I don’t know if it measurably affected my accuracy but it did eliminate the light strikes.

 

You can change out the firing pin on a CZ 457 in 5 minutes or less.

 

What are your thoughts on swapping out the firing pin spring for a faster lock time?

 

Unless you're shooting offhand (silhouette etc) or position shooting faster lock time won't help much and can cause more problems (excess vibration, harder to cock, etc). The 457 should have reasonable lock time as is. With good mechanics (follow through) lock time isn't something I'd be pursuing