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Very Hot Topic (More than 25 Replies) Rimfire Accuracy (Read 1884 times)
Ray_H
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Rimfire Accuracy
Jun 15th, 2019 at 12:47pm
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Seeking opinions .............. does the intensity and/or depth of a successful (to fire) firing pin strike have any measurable effect on downrange accuracy?
I have chosen my words carefully. If there is any question regarding what I mean, please say so.
Thanks.
  

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JackHughs
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Re: Rimfire Accuracy
Reply #1 - Jun 15th, 2019 at 2:22pm
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Ray_H wrote on Jun 15th, 2019 at 12:47pm:
Seeking opinions .............. does the intensity and/or depth of a successful (to fire) firing pin strike have any measurable effect on downrange accuracy?
I have chosen my words carefully. If there is any question regarding what I mean, please say so.
Thanks. 


Hi Ray,

Firing pin strike is one of those evergreen topics among rimfire benchrest shooters.  Generally speaking, the best setup is to assure very consistent ignition with the lightest strike possible.

This discussion includes the relative merits of high-mass, low velocity firings pins as opposed to low-mass, high velocity firing pins and "pin around spring" as opposed to "spring around pin" designs.

This discussion also includes the shape and geometry of the firing pin nose.

The key word in your question is "measurable."  Considering all the variables in rimfire benchrest shooting, I don't know of anyone who has successfully "measured" the effect of firing pin strike on accuracy.

The evidence in favor of "not too hard/not too soft" firing pin strike is all anecdotal - prevailing wisdom as it were.

JackHughs      


  

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GT
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Re: Rimfire Accuracy
Reply #2 - Jun 16th, 2019 at 1:56am
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Ray,
I did some experimenting with this concept on a low wall.  In my case, my first firing pin arrangement was similar in face to a Winchester bolt gun, small rectangular shape and a significant impression.  Accuracy was good but not great, endured several misfires with the ammo the gun seemed to prefer.  On a whim, I made a few changes to the firing pin.  First, a fairly large round flat face (.065" diameter), second change was the material, I changed from an A2 tool steel to titanium.  The misfires with the ammo has all but ceased, and the largest performance issue now seems to be the shooter.  Measurable accuracy? From the groups shot with original design, I've changed virtually nothing else and when I do my part the rifle is capable of sub 1/2 MOA convincingly to 200 yards.  Prior to this change, besides the misfires, I recall rarely shooting any consistent MOA groups.  Like many, when I have something that shoots like this I move on to other projects and call it good.
Greg
  

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ratseye
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Re: Rimfire Accuracy
Reply #3 - Jun 16th, 2019 at 9:13am
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GT, that is astounding accuracy, at least to me. Could you give the details of your rifle, scope(?), ammo, etc. Thanks, ratseye
  
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joeb33050
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Re: Rimfire Accuracy
Reply #4 - Jun 16th, 2019 at 10:21am
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ratseye wrote on Jun 16th, 2019 at 9:13am:
GT, that is astounding accuracy, at least to me. Could you give the details of your rifle, scope(?), ammo, etc. Thanks, ratseye


Me too! I've never competed with anyone who could shoot 5 into 1/4" at 50 or 1" at 200 yards. Is it the titanium firing pin?
joe b.
  
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rafter3c
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Re: Rimfire Accuracy
Reply #5 - Jun 16th, 2019 at 12:10pm
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Over the years I have built 22RF rifles on 44, Lo Wall and Hi Wall actions and sold them quickly due to more than one reason. My last attempt at a 22RF on a BRC Borchardt action finally did it for me. Between the quick lock time and coil main spring was the important factors.
Jack Hughs post is right on in my opinion and good advise. I had questions about firing pin issues and went in different direction a bit like GT. My firing pin is round .075" OD with a flat face. My barrel is a 22RF BRC chocked with Pacific match reamer barrel of my design. My firing pin strike on rim is probably twice as hard as it should be looking at spent case. My thought was to test accuracy of barrel and adjust firing pin length as I went along. Based on conventional thought I should not be getting below results. I do plan to replace current firing pin with a bit shorter pin and check results. Based on my traditional style of BR shooting I doubt I can improve much on my results. The BRC barrel does seem to shoot a wide range of ammo with positive results even with hard hit on rim. All 22RF testing at 100 yards.
KL
« Last Edit: Jun 17th, 2019 at 9:00am by rafter3c »  
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JLouis
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Re: Rimfire Accuracy
Reply #6 - Jun 16th, 2019 at 1:51pm
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It just takes having the right equipment and taking the time and effort to accomplish what others might proclaim to be the impossible. Those are the same folks who are simply not capable and who continue to proclaim that if they cannot do it nor then could anyone else.
  
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gewehrfreund
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Re: Rimfire Accuracy
Reply #7 - Jun 16th, 2019 at 3:16pm
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joeb33050 wrote on Jun 16th, 2019 at 10:21am:
ratseye wrote on Jun 16th, 2019 at 9:13am:
GT, that is astounding accuracy, at least to me. Could you give the details of your rifle, scope(?), ammo, etc. Thanks, ratseye


Me too! I've never competed with anyone who could shoot 5 into 1/4" at 50 or 1" groups at 200 yards. Is it the titanium firing pin?
joe b.

The 1/4 inch at 50 yds is not all that uncommon, but frequent 1" groups at 200 yds with a 22 is fantastic to say to least the least!
  
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Ray_H
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Re: Rimfire Accuracy
Reply #8 - Jun 16th, 2019 at 4:00pm
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Thanks for the input folks.
My initial query was predicated by occasional misfires. (CPA action, stock CPA firing pin) and Eley Tenex ammunition. Increasing firing pin pressure by tightening the mainspring screw helped for a few dozen rounds. But, my accuracy seemed to fall off. I figured time for a complete cleaning. Lo & behold ...... I found a broken firing pin. Now I go back to testing at original reduced firing pin pressures until reliability is restored.
The titanium firing pin intrigues me, and I'll pursue that with CPA.
JackHughes - You, besides being a helpful friend are a mind reader. Since there is no schuetzen action here in FL, I find myself  getting into RFBR (ARA & IR50/50) with a new Holeshot by Jerry Stiller, Lilja, Harrell's, TM stock, etc. Quite different from schuetzen, but helpful to my shooting ability in general. Life is good.

  

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joeb33050
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Re: Rimfire Accuracy
Reply #9 - Jun 16th, 2019 at 5:12pm
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We all have shot teeny groups, now and then, in the past.
Averages over a lotta groups tell another story. Like this:
5-shot groups.
GECO semi-auto is $23 per brick.
  
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Re: Rimfire Accuracy
Reply #10 - Jun 16th, 2019 at 5:44pm
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Hi Rafter, perhaps it helps you getting those good groups because you are firing with the barrel on the rest.
After reading some years ago how Michael Petrov got his rifle to shoot minute of angle I tried it with my 22rf BSA Martini and lo and behold my groups were not as good as yours but were minute of angle with RWS.
« Last Edit: Jun 16th, 2019 at 5:59pm by Nero »  
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rafter3c
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Re: Rimfire Accuracy
Reply #11 - Jun 16th, 2019 at 7:06pm
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Hello Nero,
Your place looks very nice. Getting a 22RF rifle to shoot competition quality is a challenge. Much harder than CF in my opinion. You look to have a shooter there.
Ken
  
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Schuetzenmiester
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Re: Rimfire Accuracy
Reply #12 - Jun 17th, 2019 at 3:46am
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Nero wrote on Jun 16th, 2019 at 5:44pm:
After reading some years ago how Michael Petrov got his rifle to shoot minute of angle I tried it with my 22rf BSA Martini and lo and behold my groups were not as good as yours but were minute of angle with RWS.


How did he do that?
  

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Re: Rimfire Accuracy
Reply #13 - Jun 17th, 2019 at 8:17am
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Rafter, that is a very fine looking Borchardt rig you have there and your targets show it to be quite accurate as well. Nero, I am a big fan of the little Martini and yours is also very nice. I have been working with a Model 8 and a Model 12 and find they shoot measurably better from a barrel rest as opposed to a fore arm rest. Dampened barrel harmonics perhaps? Joe, I put in as much time, money and effort possible to find the highest levels of accuracy that I can achieve. I am seeing 10 shot fifty-yard groups from my Model 8 that occasionally go a little under a half inch but GT is where I want to be. My hats off to him and anyone else in that league.  I would still like to know what his rig looks like. ratseye
  
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Re: Rimfire Accuracy
Reply #14 - Jun 17th, 2019 at 11:36am
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Once upon a time I spent a lot of time and money wringing out a couple of rimfire rifles searching for the most accurate.  I probably went through 20 different kinds of .22 ammo from Remington bulk to Eley in price.  I was shooting 10 5-shot groups at 50  yards using the "Proove-It" targets produced by a guy whose name I now forget who ran a .22 web site for a couple of years.  Best results were with a stock Remington40x single shot using a batch of Wolf ammo.  That got me an average of 0.37 inches for the 10 groups.

Oddly enough, an old Stevens 416 training rifle (that's the bolt action manufactured from 1937-1948, most of which ended up with U.S. Property markings during WWII) would do 0.51 inches for the same ten 5-shot groups with the ammo it liked best.  Both were topped with the same Redfield 3200 24x scope.  There's a lot of $$ difference between a 40x and a 416 for not a lot of accuracy difference and you'd need to be shooting high end benchrest competition to make the difference worthwhile.

My Parkerrifled lined BSA Model 13 with an old Weaver 10xAO is currently getting 0.47 inches for the same ten 5-shot groups with Wolf Match Target ammo.  My Walther Sportmodell Meisterbuchse is getting 0.78 inches with an old Weaver V-9 AO set to 9X.  I'm not sure when that rifle was manufactured, but I'm guessing post WWII.  Both would probably produce smaller groups with a higher power scope and somebody who actually can read wind and has better technique would shrink the groups on any .22 I own.

All of this is to say that until you are trying to extract the last 0.1 inch of group size out of the rifle, you probably are wasting your time fooling with the machine until you've identified the ammo that shoots best in the rifle and perfected your benchrest technique.
  
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