Author Topic: synrod .25 problem (Read 6165 times))

Archer97 · « **on:** January 05, 2014, 11:21:02 AM »

Ok, so my friend ordered a new synrod and it and the pump came in yesterday. We mounted the scope, and pumped it up. To find that the pump gauge and gun gauge were reading two different things. We filled the gun to 3000 and went to sight it in. Loads of power ands great accuracy. but the gun was losing between 50 and 100 psi for every shot. Both of us, being new to pcps, figured it was just the cold air making us lose shots so quick. But we also noticed the the gun had a loud ping and we had heard this gun had a depinger. So this morning after shooting maybe 30 rounds yesterday and filling the gun 4 times back up from 2000. We went to discharge a pellet to fill the gun again. With the magazine out and a pellet in the gun. We shot. Only to hear an ear splitting blast of air and have the pellet fall way short of its mark. And we saw the breech oring pushed back onto the bolt. So what the heck is happening to this gun? Might it be an easy fix or should he send the gun back?

Archer97 · « **Reply #1 on:** January 05, 2014, 12:00:18 PM »

Well he decided to send it back but still what happened?

Norm_m · « **Reply #2 on:** January 05, 2014, 12:21:00 PM »

To me it sounds like the bolt had been push in but not push down in the locked position.
When the trigger was pulled the air went in two direction, some out of the barrel but with the resistance on the pellet traveling down the barrel the path of less resistance was towards the bolt. When ever a PCP is fired and the bolt is either not pushed in or not pushed down in the locked closed position the largest amount of air when come out of the breech and the breech O ring will come out. If the bolt had not been pushed in the breech O ring could have come out and hit you or someone near you and caused serious injury. Always wear safety glasses!!
If the bolt had been pushed in and locked in the down position it would never have happened.

IMO there is nothing wrong with the Marauder and all you need is a new breech O ring

I've been there done that not once but several times! Most of the time it was when I was shooting the gun to degas it and pulled the trigger before I got the bolt closed

Norm
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Archer97 · « **Reply #3 on:** January 05, 2014, 12:26:20 PM »

Ok so that solves the oring issue. But why was the shot count so bad and why was it pinging so bad if it supposedly has a depinger installed?

Norm_m · « **Reply #4 on:** January 05, 2014, 02:25:06 PM »

A .25 caliber will use a good amount of air on each shot. How much is determined by what you plan to do with it and how you tune it to get the best shot curve for that purpose.

I have my .25 SynRod set for high power and get 16 good shots. The stroke setting is all the way CCW back for the longest stroke and the Pre-load is turned in 5 turns CW. The velocity screw is backed out 4 1/2 turns CCW from all the way in for full flow through the valve port.

I'm sure I will improve things once I decide to do a few mods to the valve and transfer port.

Norm

FuzzyGrub · « **Reply #5 on:** January 05, 2014, 03:03:51 PM »

50 psi a shot for a 25 cal tuned to 16 shots @ 40 or so fpe, is about normal. The stock out of the box tunes that I have seen, haven't been that great. I doubt there was anything wrong with gun (outside of a tune), unless it was loosing pressure while sitting.

PS: The new depinger does not work as well as other aftermarket ones.

Archer97 · « **Reply #6 on:** January 05, 2014, 03:14:29 PM »

Ok, so a new oring and a tune doesn't seem all that bad. But why would the pump and fu. Gauges be telling us two different readings? The gum would be reading 3k and the pump would be reading 2400?

FuzzyGrub · « **Reply #7 on:** January 05, 2014, 04:17:50 PM »

Quote from: Archer97 on January 05, 2014, 03:14:29 PM

Ok, so a new oring and a tune doesn't seem all that bad. But why would the pump and fu. Gauges be telling us two different readings? The gum would be reading 3k and the pump would be reading 2400?

It is very common that they don't match, but 600psi is a bigger diff than "normal".

Archer97 · « **Reply #8 on:** January 05, 2014, 04:21:20 PM »

Is it a serious problem? Which gauge should we trust?

FuzzyGrub · « **Reply #9 on:** January 05, 2014, 04:25:16 PM »

Quote from: Archer97 on January 05, 2014, 04:21:20 PM

Is it a serious problem? Which gauge should we trust?

Most go by the pump, but unless you have a known accurate to compare to, it is a guess.

Archer97 · « **Reply #10 on:** January 05, 2014, 04:36:00 PM »

But If we go by the pump the gun would be deep into the red. Is there sn easy way to find out which is right?

Nomadic Pirate · « **Reply #11 on:** January 05, 2014, 04:49:47 PM »

What pump ? if it's a Hill Go with the pump gauge, I wouldn't trust the gun one

Archer97 · « **Reply #12 on:** January 05, 2014, 05:01:06 PM »

It'd the Benjamin pump that came with it.

Nomadic Pirate · « **Reply #13 on:** January 05, 2014, 05:22:26 PM »

Than, I wouldn't trust either

Archer97 · « **Reply #14 on:** January 05, 2014, 05:28:09 PM »

Is there any way to find out which is right?

Nomadic Pirate · « **Reply #15 on:** January 05, 2014, 05:35:23 PM »

Cross check with an other pump or rifle ? or borrow a scuba tank with a gauge ?

Archer97 · « **Reply #16 on:** January 05, 2014, 05:42:06 PM »

There is a scuba shop near us. They're not open very often but would they be able to tell?

Booger · « **Reply #17 on:** January 05, 2014, 07:04:51 PM »

Quote from: John B on January 05, 2014, 12:54:29 PM

regarding the oring, I agree with user error (bolt not locked down) and installing a new oring would take care of that.
Really need hard number regarding air use but you said 50-100psi per shot, 3,000 to 2,000. With decent adjustment the .25 only gets about 16 shots.
Ping. Stand back 10', still hear it? Does it hurt anything?
John

Thank you for this post! My .25 Marauder was professionally tuned and got 32 shots from 3000 to 2000. It was only shooting about 700 fps, so I decided I wanted a little more power. I adjusted my rifle to shoot between 820-840 fps and now I get 20-24 shots from 3000 to 2000 psi. I am happy with my shot count to fps adjustment.

BrewCityMusic · « **Reply #18 on:** January 05, 2014, 09:13:35 PM »

I'm with Manny on this one - if it's a Benji Pump and the factory gauge, there's really no reliable way to decide which is right until You get it on a Nitrogen or SCBA setup with some DECENT gauges (for example, my .25 MROD reads 3300-ish when the rest of the gauges on my Nitro setup all read 3k even) ...

As to shot count, my .25 is set hot and I get 20 "no questions asked" through the same big hole at 30yds before I get a tiny bit of drop, at 50yds the groups (if I do my part and do it well) hold solid in a dime off sandbags through 2 full clips before I get a drop in POA - You'll have to make the decisions we all eventually do RE shot count vs accuracy at whatever range You generally shoot at, if You do a lot at 50yds or more then to keep things consistant You're likely going to have to suffer a slightly lower shot count. Keep in mind the weight of your pellets are going to have a say in how things perform too ...

mtsheron70 · « **Reply #19 on:** January 06, 2014, 10:19:44 AM »

Quote from: Archer97 on January 05, 2014, 03:14:29 PM

Ok, so a new oring and a tune doesn't seem all that bad. But why would the pump and fu. Gauges be telling us two different readings? The gum would be reading 3k and the pump would be reading 2400?

Was it the Benjamin pump he got with the gun?

If so.........simple, quality! Get a Hill pump and never look back! Or best yet, go to a tank and while the initial investment is shocking, it makes for so much more ease and going through pellets!

As far as issues on 50-100 psi per shot............maybe the setting from factory was set way hot! I have my M-Rod in .25 using about 32 psi per shot. I dialed it down just a tad from the factory.

Still getting great ft/lbs of energy. But I don't use this or any of my rifles to hunt. Just kill the steel you might say!

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synrod .25 problem

Author Topic: synrod .25 problem (Read 6165 times))

Nomadic Pirate

Nomadic Pirate

Nomadic Pirate