NX 100 Precihole, problem in velocity

[sathya.sniper]

Posting this on behalf of a Friend.
need some info regarding the PRECIHOLE problem,
My friend bought a precihole Scorpious (Nitro piston) .22 cal (Rust free version)
initially it was damn powerful enough, I don't have a chrony but used audacity and measure the fps and it was around 580 fps
he might have crossed 1000 or 1500 shots now and there is a remarkable decrease in power.
So measured the fps in the same method and found that the fps has reduced to 430 fps. (in same condition and same pellets)

As per my knowledge there are only two reasons for this prob.
1.Seal (it is ok i did check it by closing the breech while cocking)
2. Leak in gas piston
Is there any problems like air leak in the gas piston of precihole.
if so how can it be rectified.
Experts please shed some light.

I am planning to buy a NX100, But after seeing this problem again into the same state in which i was earlier. to buy precihole or not :headslap:
Suppose if there is a problem in nitro piston will there be customer support from precihole. I mean if I send the old nitro piston will they send me a new one for payment atleast.


Thanks in advance.
Regards
-Sathya

[Basu]

Guess , if the cocking effort remain same , then the culprit is piston seal which might have lost is exact shape due to heat produced by high velocity firing.
I am keen to know about weight of the pellet.

Basu

[AnandNair]

Check and replace the Breech seal and the Piston seal. Unless you feel a drastic drop in cocking force there may be no leak from piston.

[bennedose]

There is no way I can seriously answer the specific question of the Precihole. However, I can only point out that I have a 14 year old Maruti 800 which, like most other cars has a "gas ram" to hold up the rear hatch. Over the years the gas ram has lost its power to hold up the hatch in the sense that while new - the hatch had to be raised only halfway up and it would spring open and stay open. Now the hatch has to be lifted 90% of the way and the hatch weakly rises up to its full extent and threatens to come down easily.

To me this indicates that "gas rams"/"nitro-pistons" have a finite lifetime. Perhaps the gas simply leaks out leading to a loss of expansive power after compression.

Mind you this is speculation. Perhaps Precihole need to be contacted?

By the way - did you use the exact same brand of pellet to measure velocity on both occasions? Velocity can vary with pellet weight.

[bennedose]

Here is some relevant information
http://www.airgunsofarizona.com/blog/20 ... iston.html

[brihacharan]

Posting this on behalf of a Friend.
need some info regarding the PRECIHOLE problem,
My friend bought a precihole Scorpious (Nitro piston) .22 cal (Rust free version)
initially it was damn powerful enough, I don't have a chrony but used audacity and measure the fps and it was around 580 fps
he might have crossed 1000 or 1500 shots now and there is a remarkable decrease in power.
So measured the fps in the same method and found that the fps has reduced to 430 fps. (in same condition and same pellets)

As per my knowledge there are only two reasons for this prob.
1.Seal (it is ok i did check it by closing the breech while cocking)
2. Leak in gas piston
Is there any problems like air leak in the gas piston of precihole.
if so how can it be rectified.
Experts please shed some light.

I am planning to buy a NX100, But after seeing this problem again into the same state in which i was earlier. to buy precihole or not :headslap:
Suppose if there is a problem in nitro piston will there be customer support from precihole. I mean if I send the old nitro piston will they send me a new one for payment atleast.-Sathya

NX 100 Precihole, problem in velocity
Postby bennedose » Wed Jul 02, 2014 9:07 am
Here is some relevant information
http://www.airgunsofarizona.com/blog/20 ... iston.html
Regards
bennedose

> Excellent 'info' bennedose....
> I have an NX100 (Gas Ram) & till date put through 1500+ pellets of assorted weights / brands (14gr, 15gr, 19gr) in Round Heads, Wad Cutters, Hollow Point & Pointed...
> This AR is functioning perfectly well with grouping of 3/4" at 30ft...
> Re: the NX100 in question the possibilities could be:
1. Improper fitment of breech seal
2. Gas leak from Ram
> However I suggest that the matter be taken up with Precihole - am sure they will rectify any of these issues...
Good Luck!
Briha

[thunderbird1]

Is it due to the fact that the gun is totally out of lubricants? I believe some amount of dieseling happens in all air guns and once the lubricants in compression chamber ( cant call it a combustion chamber !) is used up velocity may drop ...

[Basu]

Dear thunderbird1,
Do you mean to say 430 fps is actual velocity and earlier 580 fps was caused by dieseling ??
Have you tested any model of Precihole ARs which delivered only 430 fps at muzzle ??

Basu

[bennedose]

This topic interests me a great deal because I have been toying with the idea of buying a Scorpius for a few months and this thread prompted me to use Google chacha for some research. I tried to find information comparing springers with Gas Ram/Nitro-pistine air rifles. I avoided manufacturers websites as they are naturally interested in promoting their products.

It turns out that most of the information seems to appear in internet discussion forums and the discussions start off from around 2009 or so when I guess gas rams became available in the west (not sure of this). The advantages listed for gas rams over springers is "quieter", "can be left cocked", "they remain effective over a wider range of temperatures". None of these three reasons has any great bearing on India so I do not accept these reasons as valid for me personally.

Another "advantage" of nitro piston seems to be that they are claimed to be "longer lasting" than springers. But here my bullshit meter starts ringing alarm bells. Nitro pistons have not been around for very long and unless thousands have been owned and operated for many decades like springers it cannot be claimed that nitro-pistons are longer lasting.

In fact many forum discussions show that people still feel their springers are good enough - with many having used springers for decades without servicing.

There have been complaints about Nitro-pistons - such as loss of power. One site says that nitro pistons that lose power will do so very early (a few days) or else they will last forevere. But here again my bullshit meter starts ringing. My Maruti 800 has been with me for about 5000 days. The hatch which uses a gas ram to stay open may have been opened once a week - that is just 700 times. OK let me simply multiply that by 3 and say it has been operated 2000 times. It has lost power already. What does this say about the longevity of gas rams?

After going through internet discussions I am not at all sure that i should invest in a NX 100.

In fact I may be able to service a springer and squeeze more than 12 fpe out of it. In India the law does not restrict us to 12 fpe. In fact our law only asks that our air rifle passes the Deal wood test. There is no way i can fiddle with a nitro-piston rifle to change its power setting.

I am waiting and watching.

[thunderbird1]

Dear Basu
I own an NX 100 and its performance improved to initial state after re-lubing. Ofcourse, the drop was over 1500 shots and I didnt bother with lubrication as oil was seeping out from the trigger area for the first 200 shots and moreover when the velocity dropped I felt the gun became more tame and accurate... I re-lubed this as I collected around 8 empty deo cans from my friends and I wanted the pellet to penetrate it with a nice bang..

[Basu]

Dear sathya,
I wish to bring you in here under given observations of thunderbird1 .

Basu

[sathya.sniper]

Hello,
My friend contacted Precihole factory and their customer support was excellent.
> They asked is there any oil leak in the back end of the receiver.
I did not knew it, But my friend has regularly wiped off some oil at the back end of the receiver.
> Also the cocking effort was very less compared to a new rifle.

> They have said to send the entire rifle and they have assured to change all the required parts and service the rifle for free of cost.
So my friend has planned to pack it and send it to precihole factory.

Thank you all for your kind and useful information
I really feel very happy that there are so many members to help heart-fully.

Regards

[AnandNair]

> They have said to send the entire rifle and they have assured to change all the required parts and service the rifle for free of cost.
So my friend has planned to pack it and send it to precihole factory.
Regards

IMHO.. Precihole should not expect everyone to ship back the entire rifle all the time. It is high time they make Pistons, springs, and other kits available to enthusiasts and those who can maintain the rifles themselves.

[bennedose]

Dear Basu
I own an NX 100 and its performance improved to initial state after re-lubing. Ofcourse, the drop was over 1500 shots and I didnt bother with lubrication as oil was seeping out from the trigger area for the first 200 shots and moreover when the velocity dropped I felt the gun became more tame and accurate... I re-lubed this as I collected around 8 empty deo cans from my friends and I wanted the pellet to penetrate it with a nice bang..

The reply from Precihole suggests that oil leak and loss of power are connected and that it is a known problem for Precihole that requires factory servicing.

Thank you everyone for this feedback. I will be watching this space with interest before I invest in a NX-100

[brihacharan]

Hi Guys,
> Just had a word with Tech.Director of Precihole.....
> They have till date sold 2500 NX100 out of which "Only 4 nos." were reported to have this problem...
> This works out to only 0.125%!!!!!
> They have recalled them & will be rectifying these....
> I was told that "Shooting Clubs" have put through over 12,000 shots without any problem so far...
> IMHO - ARs whether Spingers or Gas Rams are mechanical devices - minor aberrations can occur & its unfortunate that some have had this experience
> BTW - my Scorpius NX100 has gone through over 2500 pellets of various brands, weights & shapes & am still counting
Cheers
Briha