Should I seat the pellet in my TAU-7 barrel?

[pirellip]

Hi All,

I was wondering if I should push the pellet a few mm into the barrel as I load it.

I've modified the end of a pen to do this in a repeatable manner, and it does not dent or harm the pellet from what I can see.

My though was this would produce more consistent shots, as the pellets are now of even size (kinda like sizing the pellets)

Also I thought the more expensive guns push the pellet in as the bolt is closed, am I right on that?

thanks.

[Mark Briggs]

Pirellip - interesting question. I don't really know the answer, but will mention that group testing I performed with my TAU-7's produced good groups with pellets seated only using the thumb to push the pellet skirt flush with the breech face. This same technique is used with Steyr LP-1 & LP-10 pistols, again producing excellent results in group testing. The resolution of tactile sensors of the thumb allows us to 'feel' seating consistancy down to probably something less than 0.002", which is pretty consistant.

I guess what I'm trying to say is that my limited experience (sample size of about 10 air pistols on which I've done concentrated group testing) leads me to believe that your method of seating the pellet will likely do no harm, but will also not be likely to provide you with any measureable benefit. My lazy-man's approach to shooting says that if it doesn't produce benefit then it's likely not worth expending the effort to do.

Just my opinion, probably worth less than the cyber-paper it's written on... ;-)

[pirellip]

great to hear from a fellow Canadian!

So if I read correctly, the LP10 and other 'high end' pistols don't push the pellet in as the bolt is closed?

If that is the case, I don't see much point in doing this, except perhaps I'd get a bit more velocity, so to maintain a similar velocity of non-seated pellets, I could turn it down a bit... but I like your lazy idea.

[RobStubbs]

great to hear from a fellow Canadian!

So if I read correctly, the LP10 and other 'high end' pistols don't push the pellet in as the bolt is closed?

If that is the case, I don't see much point in doing this, except perhaps I'd get a bit more velocity, so to maintain a similar velocity of non-seated pellets, I could turn it down a bit... but I like your lazy idea.

LP10's and some other pistols don't push in the pellet, but others do. I don't believe it makes any difference which method is employed. The pellets should be seated flush in which case a perfect seal in the barrel is made, it won't affect the velocity, over poking in the pellet further.

Rob.

[Fred]

[quote="RobStubbs"] The pellets should be seated flush in which case a perfect seal in the barrel is made, it won't affect the velocity, over poking in the pellet further./quote]

Rob,

Have you done any testing to support this statement? I did a limited amount of velocity testing some years ago, comparing thumb-seating vrs deeper seating with the tool marketed by Beeman for that purpose. I found that invariably, in my admittedly small sample, the velocity of deeper seated pellets was on the order of 3-5% LESS than the velocity of thumb-seated pellets. I agree with Mark's reasoning, but would go further and venture that thumb seating could actually be a superior method (not that either method has any significance in shooting performance).

FredB

[RobStubbs]

Rob,

Have you done any testing to support this statement? I did a limited amount of velocity testing some years ago, comparing thumb-seating vrs deeper seating with the tool marketed by Beeman for that purpose. I found that invariably, in my admittedly small sample, the velocity of deeper seated pellets was on the order of 3-5% LESS than the velocity of thumb-seated pellets. I agree with Mark's reasoning, but would go further and venture that thumb seating could actually be a superior method (not that either method has any significance in shooting performance).

FredB

Fred,
Nope but there's no logical reason that it should make any difference - as your 'sample' suggests. You cannot get any more contact than by seating the pellet into the barrell flush. If there really is any decrease in velocity when pushed in, then I can only think some of the energy dissapates before reaching the pellet. Anyway a few % is insignificant - unless someone cares to do detailed and statistically meaningful experiments.

Rob.

[Spencer]

Hi All,

I was wondering if I should push the pellet a few mm into the barrel as I load it.

I've modified the end of a pen to do this in a repeatable manner, and it does not dent or harm the pellet from what I can see.

My though was this would produce more consistent shots, as the pellets are now of even size (kinda like sizing the pellets)

Also I thought the more expensive guns push the pellet in as the bolt is closed, am I right on that?

thanks.

Pirellic,

Are you currently shooting around 520 (in which case there are more important considerations, like technique and training), or 570+ (when this might be of interest)

Spencer

[pirellip]

I do have a chrony but I haven't tested to see what fps I'm getting

What should I be at 520-570? I use RWS Meisterkluglen pistol pellets, I don't think I'm that high, I believe I'm under 500fps currently.

[Fred]

Rob,

You may not happen to have thought of a "logical reason," but that does not justify making the definitive statement, "it won't affect the velocity." At best you could say that you see no reason for velocity to change. I chose not to speculate about the cause for the observed data because that's something I don't know. I do know that the data was repeatable and quite noticeable, even if it is not significant in terms of firing performance.

There are, in fact, several possible factors involved here that might explain the observed difference. The rifling in airgun barrels does not extend all the way to the breech end; there is a gently beveled lead-in section. Therefore, the depth of seating certainly does affect the amount of "contact", and seating the pellet fully into the rifling reduces the pellet's initial resistance to the air or CO2 blast. Thus it would get a "push", instead of a crisp "snap", from the air blast. This is analogous to the effects of different degrees of crimp on firearm cartridges. Crimp most certainly does affect velocities, with heavier crimp tending to increase velocity because it allows more gas pressure to build.

FredB

[Bill177]

That problem is taken care of in the Pardini air pistols - a probe seats the pellet as the breech closes. Thus, the pellet is consistently and properly seated EVERY time.

The Steyr LP2 uses a similar mechanism to seat pellets. I shoot a K2.

[Mark Briggs]

Ok, time to chime in again...

Firstly, Pirellip, there is a legal consideration regarding velocity - you should be aware of this and set your gun accordingly. Under Canadian law your air pistol muzzle velocity cannot exceed 500 fps, otherwise it is classified as a restricted firearm. Obviously the classification of your airgun as a restricted firearm brings with it a whole mess of trouble. The safest path is to keep your muzzle velocity below 500fps and leave it there. The up-side to doing this with the Tau-7 is that you'll get much better mileage per fill of Co2, and your accuracy won't suffer from slowing things down.

I'll also throw a word in about the "probe seating" method used by many top-end airguns. Bill177 brought up a valid point about the probe seating providing consistant results. This is true, and many top-notch airguns use this technique. Morini CM162, Walther LP300, Pardini's, Feinwerkbau's, to name a few. There are also some top notch airguns that DON'T use this technique, starting with the Steyr LP-1 and LP-10, and running the gamut down to the TAU-7. I've tested about an even number of each type and can honestly say that I've been able to detect no advantage of one design over the other when performance is measured using group size as the single criterion. The choice of which technique is "better" is, I believe, very much a matter of personal preference rather than technical superiority of one design over the other. Before anybody decides to flame me for having made such an unequivocal statement, please do keep in mind that my two primary pistols are a Morini CM162 (probe seating) and a Steyr LP-1 (thumb seating). That's not to say I'm an expert on the subject (far from it), but rather to point out that I have some experience with both types.

[Spencer]

I do have a chrony but I haven't tested to see what fps I'm getting

What should I be at 520-570? I use RWS Meisterkluglen pistol pellets, I don't think I'm that high, I believe I'm under 500fps currently.

Not velocity in fps, but score out of 600...

Spencer

[JulianY]

Sorry Fred some more logic ;)

The tau 7 was designed without a "seating device", so one can conclude the designers we satisfied with this arrangement. So i would stick with the design as it is. I am not keen on pushing non pellet things in to barrels, but more to the point you are in effect shortening the barrel by pushing it in further ! Not that this will make much difference but the air pressure drives the skirt in the the refiling and this will no happen further down the barrel

Going back to Spencer's comment. The main point what ever you decide is consistency and extra 3fps is meaning less especially compared to the fundamentals o technique.

JY

[RobStubbs]

Rob,

You may not happen to have thought of a "logical reason," but that does not justify making the definitive statement, "it won't affect the velocity." At best you could say that you see no reason for velocity to change. I chose not to speculate about the cause for the observed data because that's something I don't know. I do know that the data was repeatable and quite noticeable, even if it is not significant in terms of firing performance. <snip>
FredB

Fred,
With respect mate, I'll choose my own wordings. You're being entirely pedantic and dragging the whole subject off topic. As you yourself illustrated, but not proved, the seating method is irrelevant in the great scheme of things.

Rob.

[pgfaini]

I might as well add my own 2¢ worth. My 162E pushes the pellet into the rifling, you can feel it as you close the loading lever. In my opinion, this causes a slight loss of velocity, due to the fact that these hollow pellets, are made to seal the (smooth)bore when inserted, and the rush of air pressure expands them further against the bore, as thay move forward into the rifling. Upon reaching the throat of the rifling, there's enough pressure to engave the rifling into the pellet without allowing any air loss.

Pushing the pellet into the rifling, without something to support the hollow skirt, must surely compress the skirt against the lands, allowing some air to escape in the grooves. This is probably negligable, and offset by the gain consistant resistance of the projectile gives.

This method is called "breech seating" in the sport of Schuetzen Shooting, and has long been the preferred method of loading these accurate lead bullet target rifles. Using a tool designed for the purpose, the bullet is pushed into the chamber throat, which has a gradual taper, and into the rifling. The cartridge case, primed, and loaded with powder, is then inserted into the chamber behind it. Usually, for uniformity, the same cartridge case is reloaded, and used for every shot.

Paul

[Fred]

Fred,
With respect mate, I'll choose my own wordings. You're being entirely pedantic and dragging the whole subject off topic. As you yourself illustrated, but not proved, the seating method is irrelevant in the great scheme of things.

Rob.

"Pedantic"? If correcting a false statement made with little thought and no concrete evidence is pedantic, then I guess I'm guilty.

"Off topic"? No way. The original poster assumed that deeper seating would increase the velocity, and you stated that there was no difference. Seating depth vrs. velocity is clearly part of this topic.

I chose to share some information on this topic that I thought might be interesting to other TTers. This was addressed to you, because it was you who gave an authoritative sounding, but incorrect, answer to the original poster. The intent was to inform, not offend. I'm sorry for any offense taken, but I'm not sorry for any correct information shared.

FredB

[pirellip]

Thanks for all the insight on the matter, I do have a chrony, but just bumped up my velocity to around 485fps from 435 (without breach seating the pellet)

btw, the velocity was very consistent not more then 7fps variance over 60 shots

I'm going to give it a try at this velocity setting without breach seating the pellet, I'll just push it flush with my thumb for the next while, as mentioned before, I'm not over 570 in my scores yet, so I don't think it really matters

thanks for the input everyone