Factory Sporter Bench Tecniques / Tips

M

mrh1958

New member
I have been shooting factory sporters from the bench lately and having problems with consistency, usually get 3 or 4 and sometimes 5 into a nice group, the rifle I am shooting now has been bedded, floated ,re crowned, headspace is at .047" , tried all the usual match ammos from SK to Eley Match, all do about the same. Using a bald eagle rest and Protektor rear bag and have tried the rest at different positions. Also have tried 2 different scopes with same results. Very likely could be me causing the problems but any advice appreciated.
 
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Friend mrh1958

mrh1958 said:
I have been shooting factory sporters from the bench lately and having problems with consistency, usually get 3 or 4 and sometimes 5 into a nice group, the rifle I am shooting now has been bedded, floated ,re crowned, headspace is at .047" , tried all the usual match ammos from SK to Eley Match, all do about the same. Using a bald eagle rest and Protektor rear bag and have tried the rest at different positions. Also have tried 2 different scopes with same results. Very likely could be me causing the problems but any advice appreciated.
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Friend mrh1958:

The difference between the kind of results you're getting and what we do in big time RFBR is small, when you look closely at the big picture of things.

The first 95% of rimfire accuracy comes really easy.....

The other 2 or 3 percent above that, that we've obtained with what we do in RFBR, costs several fold more than that first 95%.

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If I knew something that would be guaranteed to help you, I'd tell you in a heart beat.....but I don't.

There are so many factors involved in producing the kind of accuracy we work with in big time RFBR.

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If there "may" be anything at all, from your post, that might be a correctable issue, it is the .047" headspace.......

And it wouldn't be an issue, as long as you have consistent ignition...

Depending on the kind of rifle you have, and how its ignition system works, there could be an issue with .047" headspace....

Since the firing pin must travel further forward to produce a footprint in the case with .047" headspace, there is the possibility that the firing pin may be bouncing against its mechanical stop in the breech bolt when trying to produce ignition....

If this happens, you will most certainly get flippers....

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Finally, "factory" rifles are not all alike, even from the same maker and same model....

If you had ten factory rifles of your model, and you could shoot them all, one of two would stand out from the others.....

Whoever is lucky enough to purchase one of those "special" rifles, is going to win most of the factory match contests..

And the problem with factory class rifles, is that there's really not a lot one can do to help their accuracy.....

In other words, if there was something one could do to the 8 out of 10 that have less accuracy than the one of two "special" examples, then of course the folks who have the one or two "special" examples can do that to theirs too.....

So those one or two "special" examples are always going to win, most of the time.....

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How do you determine if your firing pin is bouncing off of its mechanical stop when you fire the gun?

I would have to know the kind of rifle you have, and even then I might not be able to tell you.......

Some actions, like the Turbo, are very easy to determine this....

Some other actions, with the firing pin head enclosed in the bolt shroud, are very difficult to run this test on...

Your friend, Bill Calfee
 
Friend mrh1958

mrh1958 said:
Thanks Bill, I will look into correcting the headspace and see if I get any improvement
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Friend mrh1958:

The rifle is yours, so you can do what you wish....

.047" headspace is not really an issue, IF, you have proper ignition.....

The prudent, and inexpensive thing to do is to determine if your ignition is functioning correctly.

Chances are, if your ignition is not functioning correctly, you will still have the same problem if you correct the headspace.

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Let's say you have the headspace corrected.....which could be most costly, if done correctly.

And your issues don't improve....

Then you will still have to determine if your ignition is functioning correctly...which costs only a little of your time..

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If your ignition is functioning properly, changing your HS from .047" to something else will not make your rifle shoot better.

Good luck with your rifle.

Your friend, Bill Calfee
 
The firing pin has been reshaped to strike inside the rim and is quite deep, I assume its correct, I doubt the headspace would help but I may try it just so I know headspace is correct, thanks.
 
Friend mrh1958

mrh1958 said:
The firing pin has been reshaped to strike inside the rim and is quite deep, I assume its correct, I doubt the headspace would help but I may try it just so I know headspace is correct, thanks.
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Friend mrh1958:

I'll start by saying this:

From this point on, my post, or posts, will be for the CYA audience....

This is a very important issue, and is a good subject for CYA folks interested in advancing rimfire accuracy to have a thorough understanding of...

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For CYA friends:

If you find yourself with a set of circumstances similar to friend mrh1958, the first thing that must be done, is to make sure the ignition of your action is functioning properly.

I've highlighted a sentence from mrh1958 in bold yellow...

Two things scare me to death, and doubly reinforce the need for the ignition to be evaluated.

The first is about striking inside the rim.

How far inside?

If the footprint is too far inside the rim, one will have inconsistent ignition, and possible failures to fire, no matter how deep the foot print is.

The second thing that scares me is, (the footprint) "is quite deep".

How deep?

Remember, the deeper the footprint, the closer the firing pin comes to striking its mechanical stop.

If the firing pin occasionally strikes its mechanical stop while trying to produce ignition, you will have fliers.

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CYA friends, if any of you have similar circumstances to friend mrh1958, the first thing you have to, is to check how close your firing pin is coming to its mechanical stop, when the gun is fired.....

I had a standard I used for years of .005".....( the firing pin never coming closer to its mechanical stop than .005" )

But I have changed my standard........which is now .010"......

Sometime back I had a rifle causing flippers....I checked and found I had my .005" clearance, just fine........but since I could find no other issues with the ignition, I increased the clearance to .010".....and the flippers stopped, dead.

And since that time I've worked with the .010" clearance......

Your friend, Bill Calfee

PS:

CYA friends, mrh1958's footprint placement and his footprint depth may be perfect, and, he may not have any mechanical stop issues, but the point I'm trying to make is this; we do not know, for sure, without actually measuring the firing pins mechanical stop distance.....

If his footprint location and depth are correct, and his mechanical stop clearance is also correct, then changing the headspace will most likely not cure the issues he's having....

This is a very important issue and I'm glad mrh1958 has brought it up...bc
 
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Bill thanks for the info and interest in this topic, here is a couple of photos of the fired cases showing the footprint of the firing pin, hopefully there good enough to see if it's correct.

IMG_7135_zpsqavaxhlw.jpg


IMG_7209_zpsqhd7cpxc.jpg
 
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Friend mrh1958

mrh1958 said:
Bill thanks for the info and interest in this topic, here is a couple of photos of the fired cases showing the footprint of the firing pin, hopefully there good enough to see if it's correct.

IMG_7135_zpsqavaxhlw.jpg


IMG_7209_zpsqhd7cpxc.jpg
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Friend mrh1958:

Excellent pictures....

I'll say this, those footprints are textbook perfect as far as the distance inside the rim the pin should strike....

I apologize for sounding like a broken record, but, you need to check your firing pin to its mechanical stop distance....

Think about this:

The brass at the rim is .007"-.008" thick......so rolled over you have .014" to .016" of brass........

With rims that are .039" thick, minus say .016", leaves you .023" to completely close up the rim...

By the looks of your pictures, those footprints are "at least" .023" deep...........

Look how the brass is cratered-in around the footprint....

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There's a distinct possibility that you're over-driving the footprint....


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Two thing will cause flippers......

The firing pin making contact with its mechanical stop, in the breech bolt, or, the breech face of the barrel if you have a Swindlehurst or 541 Remington...

And second, doing more than "just barely" closing up the rim.......remember, there's a steel anvil behind that rim......not soft brass like our centerfire friends have in their primers.....

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Lastly, you may be "just barely" closing up the rim, and, you may have at least .010" clearance from your mechanical stop....

But, there's only one way to know, for sure.........measure it.

Your friend, Bill Calfee
 
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Will do the measurement thing Bill, thank you for your thoughts and help on this matter, another point of interest about the firing pin , when you place a fired case in the chamber and "dry fire" its almost like its very weak or soft, no metal to metal sound
 
Friend mrh1958

mrh1958 said:
Will do the measurement thing Bill, thank you for your thoughts and help on this matter, another point of interest about the firing pin , when you place a fired case in the chamber and "dry fire" its almost like its very weak or soft, no metal to metal sound
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Friend mrh1958:

All rimfire actions have a quiet sound when snapped with an empty case.....

I'm not sure you can determine your firing pin/mechanical stop relationship by listening......

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Friend mrh1958, your ignition may be perfect, as is.....your footprint is most certainly in the correct location...

But, there are some things we can't afford to take for granted....

I can't imagine taking a new barrel blank and cutting it to X length and fitting it, without a thorough evaluation....

Although some folks probably do it that way, and every once-in-a-while, they get away with it...

I also can't imaging blueprinting my ignition, and not determining "exactly" where I'm at by careful measuring....

These two things simply can not be left to blind luck.

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Some things:

We always determine the depth of our footprint, and mechanical stop issue, by using once fired cases.....

Viewing the footprint of a fired round doesn't tell much......

In your case, with .047" headspeace, your fired round footprints will have the depth exaggerated because the case head is blowing back around the firing pin tip more than normal.....

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Finally, you've never said what kind of action you have......( you don't have to, of course)

I lot of folks think I'm kinda nitpicky, cough cough, but one has to be, if, one expects to win big RFBR Nationals.....( or even to have a good club gun)

A friend of mine, who's deceased, gave me the best piece of advice I've ever had, he said, "Bill, a chain is only as strong as its weakest link"..

He was referring to my work on custom hunting rifles 40 years ago....

But, the same thing applies to a RFBR gun....

If me, or someone else, is ever going to build a gun that turns another 12,000 PSL score, no link can be even remotely weak.

Your friend, Bill Calfee

PS: If you run into any issues running your mechanical stop test, I'll be glad to help, if I can......bc
 
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