Firing Pin Lock Time

[onehole]

Guess this is aimed at the "Smithys" but see what comes up,,,,,,,,,,,,,I love my RPA,s super quick lock time and a good deal of this comes from its short firing pin stroke,,,,,,,,A lot of other bolt actions have at least twice perhaps three times the length and timing of this short stroke,,,,,is there anything that can be done to "speed" up the lock time of others generally? I,m thinking,,lightweight firing pin,,,stronger spring,,short stroking or bushing existing pin??? etc etc,,,,anyone had any similar work carried out and on what please,,,,who done it?,,,,,,,,I think there is a kit or conversion available for remmys?,,,,,,,,,thanks,,,,,O

[Big Al]

The concept of fast lock time is one thing but I do wonder if it really makes any difference in practice rather than theory?

[jcampbellsmith]

It's an area that David Tubb has done some work on and at one time he sold 'enhanced' parts. Not sure what he has available now. Regards JCS

[andybrock]

Without sophisticated measuring equipment how would you know if you've improved lock time when its measured in milliseconds?

[Davy]

I discussed this with Robert Chombart a while ago, you can improve the calculated lock time by changing to a Belleville stack as opposed to a conventional compression type spring, the Belleville has the advantage of not being under compression when de-cocked plus it gives a reasonable calculated lock time improvement. There is also the obvious advantage of not having a spring partly compressed at all times and the resultant loss in energy.

 

The other area to look at is firing pin diameter, a 0.0625" firing pin tip requires around a third less impact energy than a 0.0800" one to perform optimal primer ignition meaning you can reduce the ignition energy (Spring) accordingly. A bi-product of this is the reduction of mass in motion and modification to the firing pin spring will reduce lock time and in some cases can allow a lighter trigger pull weight and a lighter re-cocking. Concepts that are easily proven.

[baldie]

Having owned several RPA,s and also a Tubb 2000, I can confirm that a faster lock time makes a very real difference downrange.

 

Wont make a lot of difference to a good shot with a good technique, but it will improve a shooter with a sloppy follow through, no end.

[Montey]

I have an RPA still and I can't say that a faster lock time is a good thing. It shoots realy well (243) but the bolt fit is sloppy and the mag feed very pore.its been back to RPA twice now because of the inability to feed from a short mag.

I would rather have a slower lock time and a proper mag feed or AI set up.

[Chris-NZ]

Poor feeding and lock time are two totally different and unrelated things.

 

My RPA CG-2000 has a very tight tolerance bolt. The later models were maybe much bigger tolerances?

 

My clubmates (one now deceased) built the Millennium action which is the next improvement on the CG-2000. We got my professional engineer buddy to calculate the lock time. He started from the mass measurements and known characteristics of the Belleville washer stack. Obviously some guesses needed to be made about friction. I think he used a spreadsheet/iterative technique and the lock time thus calculated was in the low ones. This is a good decade ago so I can't be more specific sorry.

 

... just discovered this old doc on the Net:

 

https://www.google.co.nz/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&ved=0ahUKEwiN_oHXisPPAhWq6YMKHe2YAOMQFghTMAk&url=http%3A%2F%2Fbusseltonrifleclub.squarespace.com%2Fs%2FRIFLE_NZ_WORLD_CHAMPS.pdf&usg=AFQjCNGkI9VQzJ7JMCVDZ4NzuMyKUzSnbA&sig2=R2fx2tmLJ2O-8JzZpgF8rQ&cad=rja

 

Gives a fair bit of detail

[Davy]

I have a similar spreadsheet that applies to the later single shot rear locking M41 and the single and repeater front locking M59 and M66 versions and it makes for interesting reading. Accuracy improvements relating to lock time are best seen when shooting off hand however lock time is a small part of action design and ultimate rifle accuracy. Chombart who patented such an ignition system apparently got the idea after seeing the German field guns as a child in occupied Normandy.

[Chris-NZ]

Yes, Robert is certainly an interesting and intelligent guy. I met him years back when he attended our Nationals. This was when the lads were getting underway with building the Millenniums.

[Montey]

I agree lock time and poore feeding from the mag are two difrent things my point being that lock time isn't that important in the real world in my option.

[brown dog]

Looking at it another way: I find I have to work hard to shoot ARs really really well. I've convinced myself that this is because of the AR lock time (weeks,not days) being unforgiving of my sloppy technique -something that faster lock time rifles let me get away with.

[The_Dogge]

I notice a similar thing shooting a CZ542 offhand, compared to shooting a Sako Finnfire in the same manner. I have them both set up with a very similar weight and stock setup, and from the bench the CZ shoots well, but the Finnfire is much more "forgiving" to shoot. I'm sure there are a number of factors, and I have no evidence the lock time is significantly different, but it may be an important factor.

 

Could you attempt to measure lock time by recording the sound of dry firing and looking at the sound trace with suitable software? Mounting the microphone on the action you could possibly see the click of the sear disengaging and the larger noise of the firing pin hitting home. may need a snap cap to provide something to hit at the right position.

[onehole]

Wow thanks for the mixed response,,,,,I think Baldie is where I am thinking on this,,,,,,,,,,,I remember my days of field target shooting,,,,most were very conscious of the relatively low velocity pellet,,,"barrel time" and even more so of lock time ,,,ie the timing of the hammer stroke and many were "tuned" by short stroking and made quite a difference. We have some similarities in the 22RF ,,,,again barrel time demands excellent follow through process and firing pin lock time can vary enormously from one rifle to another.,,,,RF barrels can be shortened to help,,,,,,,,Anyway back to centrefires I,m convinced a high speed lock time can only help ,,,I observe my RPA firing pin as almost instantainious compared with the leasurely timing on my Howa pin and was toying with the possibility of reducing its stroke by half and the most effective way of doing this? It may not be possible? I would imagine the whole pin is hardened?

Probably best left alone but if it could be a simple fix I would certainly have it done,,,,,,,O

[Davy]

What would be interesting is putting a high speed camera with acoustic trigger to fire it, I have identical actions with both conventional spring and Belleville stack and it would give a definitive answer for this particular action. I will speak to the chap who does our high speed photography

[baldie]

Many a good shot started life on the air rifle field target circuit. Those who were good, and mastered the PCP went on to make good rifle shots. The ones who mastered the springer went on to make stellar rifle shots.

 

Nothing shows up poor technique or bad follow through, better than an air rifle.

[Chris-NZ]

..,,I observe my RPA firing pin as almost instantainious compared with the leasurely timing on my Howa pin .

 

Let alone an M98. You feel there's time to make a cup of coffee watching that drop..

[Leeman]

Yes, Robert is certainly an interesting and intelligent guy. I met him years back when he attended our Nationals. This was when the lads were getting underway with building the Millenniums.

 

Chris,

 

you may or may not know this but a mate of mine in Cambridge, shoots at Otorohanga has a Milennium in 223, as supplied by John and Tony, or at least he did the last time I emailed him, came with the green Robertson stock, lovely rifle and I was led to believe the only one in existence.

 

Richard.

[Chris-NZ]

They did very few with a small boltface from memory Richard. I recall being round there once while he was working on a .223 version so that may well have been it!

 

My gunsmith/buddy has opened several Millenniums up to handle some big bangers, ie bigger than 7RUMs. Handle it easily. Actually Tony did some destruction testing with a cosmetically-imperfect action- stuffed a case 3/4 full of pistol powder behind a 185 projectile. The barrelled action was mounted on a sled and they fired it with a string hiding in a ditch. The brass flow was impressive but the action was left unharmed, other than having to restore the extractor which was somewhat displaced..

 

My gunsmith has a spare nice F-Class stock with the Flexibed bedding block in it and sitting at Tony's widow's place is a Millennium with my name on it. I'm tempted but the action isn't ideal for F use because of the high recocking effort which will upset the gun on the bags. Might bite the bullet one day and build another varmint gun ;-)

[Leeman]

 

 

My gunsmith has a spare nice F-Class stock with the Flexibed bedding block in it and sitting at Tony's widow's place is a Millennium with my name on it. I'm tempted but the action isn't ideal for F use because of the high recocking effort which will upset the gun on the bags. Might bite the bullet one day and build another varmint gun ;-)

 

I knew a few that used them for FO and it would be even less of an issue with a modern wide FTR bipod, I use a Quadlite from time to time and whilst it's noticeably stiffer than twin lug actions or a Barnard I used to have, it's quite manageable.

[Chris-NZ]

I agree the action isn't so bad for an F-TR gun but this would be in FO shooting off a Farley. My son has actually got down on the CG-2000 and it's now been converted to F-TR with a 32" Broughton, 8-32 NXS and Mystic bipod. Seriously accurate rig.

[gbal]

There is not a lot of decent evidence on lock time and accuracy (accuracy,since the main factor is the shooter-is there any movement of the muzzle between sear release and primer ignition-thereafter it's 'barrel time' and not a function of lock time,which complicates actual measurement.

Dvorak Instruments did use a 'trigger scan' methodology,in the research development phase of the Savage Accu Trigger,so it is possible to get some data.

 

The asumption-on the face of it reasonable enough-is that any delay between trigger release and bullet exit can be detrimental to 'accuracy' because,in theory,faster lock time reduces any off target barrel movement.This is especially so in Long Range shootingn(where there is time for the deflection to appreciate ) and has bothered muzzle loader shooters ever since the flint lock flash pan preceded the release of shot from the muzzle by a perceptible margin,and had to be factored in,especially to wing shooting.Perhaps something of this remains in air rifle shooting,especially with springers?

In more modern cf rifles,3-8 milliseconds is the norm for sear release to primer strike. Old Mause 98s were quite slow,as a military service design choice.

 

OK,there is some very direct evidence of the utility/desireability of fast lock time in modern rifle development.

David Tubb redesigned the Remington 700 bolt etc to his 'Speedlock' version,essentially lightening the firing pin to reduce lock time,with a few other modifications and claimed a correlation between such reduced lock time and scores,but note importantly-when shooting off-hand at distance on windy days (this was in "Across The Course" competition modes.His final lock time approached 40% faster.

Put into what may approach selling hype,this might mean the bullet is leaving the muzzle before the standard Remington 700 firing pin has initiated ignition.

 

So,around 2004, Remington put it's considerable research and marketing expertise into the Remington EtronicX cf rifle,essentially a 700 with electronic ignition of special primer cartridges.

Remington claimed this electronic trigger and ignition system reduced 'lock time' to 27 micro seconds (about a 100% reduction from the conventional 700).

 

Perhaps you have seen/heard of these Etronic Xs being fired-they seemed on the lock time theory to offer a very substantial advantage-at least for some shooters/styles.But few will have experienced them.

Alas-the idea was a flop commercially (partly it was cost-rifle doubled the price) and there were primer issues/battery issues esp in the cold,and supply shortages....it just faded away...perhaps a victim of the relatively poor batteries then available etc....electronic triggers are useable in some target handguns.

 

So,not for the first time,when shooters had the choice of a potentially superior tool,they took to it not-as said,there were other factors.like cost-though cost per se has not deterred custom rifes at many times the price of a standard 700....with relatively standard ignition,a few claiming to be a tad faster...

 

Flint lock experience,air gun follow through,and eg Brown Dog's observations are relevant-any gains from fast lock time are only likely to be possible-even if small-in modern rifles that are essentially shoulder fired without rests ( ie the aim error is based on human muscular/physiological factors-"wobble").

 

For the Bench Rested rifle is well capable -if set up properly -of sub moa when the very light trigger is pinched by thumb and forefinger as the only human contact with the free recoiling rig.There really isn't much room for shooter induced wobble.The fclass bipoder is probably fairly immune too,tho' less so.The field varminter -even with bipod-is perhaps a bit more vunerable,and the offhand shooter most of all-though there are very few measured accuracy tests this factor alone-some indoor target electronic target/aim point analysers can give a muzzle wobble trace out,but not for lock time alone. So it largely remains just a possible variation in a fair old raft of other factors diminishing both precision and accuracy.

 

We might as well speculate on the relative merits of a heavier barrel-somewhat more stable for a few seconds,but then very much not so for the non pumping iron biceps shooter,and a short barrel-faster 'barrel' time.....good luck with those,other than as 'campfire' discussion-or forum topic! :-)

 

There may be a small correlation theoretically,between lock time and accuracy-and smaller with good modern designs (I have an RPA,can't say I notice a quantum difference,rested) but for most it will be small,very small,and vanishingly so- asymptotic- the better the rifle rest used.

 

gbal

[onehole]

Again thanks for even more input and I acknowledge all the other relevant factors brought to the fore,,,,,however,I,m sticking with how it feels behind the trigger and as I have mentioned the RPA seems to get it over and done far easier within a heartbeat [that's another thing!] ,,,,,Anyone remember the Sporstmatch GC2 pneumatic?,,,,now that was quick!!!..........atb,,,,,,O

[baldie]

I remember that beautiful rifle Dave, I also know the chap who one blew up on very well. That stopped production.....permanently.

[Andrew]

Many a good shot started life on the air rifle field target circuit. Those who were good, and mastered the PCP went on to make good rifle shots. The ones who mastered the springer went on to make stellar rifle shots.

 

Nothing shows up poor technique or bad follow through, better than an air rifle.

We never had spring piston air rifles but I grew up shooting the likes of the 71/84 Mauser, 1892 Krag Jorgensen, Trapdoor Springfields, Remington Rollingblocks and 1903 Greek Mannlicher: These make a 98 Mauser seem FAST.~Andrew