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G&P sentry (vltor)


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I just got one of the last Magpul Sentries in Hong Kong.

 

Externally it is fantastic. I took out the gearbox and did the teflon tape mod. I haven't opened the gearbox yet though.

 

So the spring is M100? Can it take a M120 while still using the same motor? Should I upgrade any internals?

 

Can someone give a detailed rundown of the internals, no pics needed, but some would be nice.

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I can't do pictures, however - my MRP came out of the box at 360-70fps, and so did my latest M4, both later than 2008. 8mm bearings, polycarbonate piston, metal (unsure of type) nozzle... It has most of the usual trimmings - I'm not great with internals, but i know the factory guts in mine put out 1000rpm @ 360-370fps or so. I imagine someone can give a more detailed breakdown, but i reckon the latest G&P gearboxes could probably do 390-400 without changing parts other than the spring. One of said gearboxes has now done >40,000 rounds after a quick downgrade.

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Actually there's a lot of different teflon tape mods. The 2 main ones that I think are worthwhile are:

 

1. hopup teflon mod: Where the end of your rubber sleeve meets the barrel, not the end where the BBs go, the other end. This is a place where airleaks happen. Wrap it up in white teflon tape. You should only be able to wrap twice or so around and still be able to insert the assembly into the hopup chamber, if you can get many more wraps than that, then your hopup chamber is not of high quality because it is not fitting to the hopup tightly enough.

 

2. inner barrel teflon mod: You've probably noticed that there's about half a millimeter or so clearance between your inner barrel and outer barrel. This is bad because it allows the inner barrel to vibrate. Metal on metal contact makes this really bad. If you have a longer barrel, it gets even worse.

To solve the issue, wrap teflon tape around the inner barrel at NON EVENLY spaced sections. Just enough so you can barely slide the barrel into the outer barrel.

 

Mod1 increases your consistency and FPS

Mod2 increases your accuracy, especially on full auto

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Oh... Doh...

 

I've been doing this for a little while but have used electrical tape (because I have plenty) which in truth can be a little 'thick' especially with Mod2. I will try and get some Teflon tape if that is thinner and easier to work with than the tape I already have.

 

Great minds think alike ;-)

 

Thanks for the info...

 

J.

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I've been running a Sentry for the last couple months and have had a couple issues with it.

 

Number one, with a 7.4V LiPo, the trigger contacts were arc welding together and not always coming apart when I released the trigger. Basically the gun was deciding all on its own how long it would like to fire after I released the trigger. Problem: Someone in the factory forgot to apply any sort of lube to the trigger contacts. Fix: Just a bit of silicone spray.

 

Number two, generally poor hop performance. Fix: replaced hop bucking with Guarder enhanced.

 

After doing a little bit of work on the hop-up I decided to just replace it all. I installed a Madbull Ultimate Hop, Element H-Nub, and Vanaras 6.03 300mm tightbore (which is just a touch too long, but good luck finding a proper 280mm). The wings on the sides of the Madbull had to be slightly thinned out with a file to properly seat the hop into the outer barrel.

 

Number three, after these accuracy upgrades, I had a air leak between the gearbox and hop-up (the gun was shooting around 150 fps with a SP100). I replaced the original G&P alloy air nozzle with a Guarder enhanced and the muzzle velocity went right back up to 320fps. The gun now has excellent accuracy.

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Hey,

 

My experience last sunday with my new G&P Sentry was amazing.

 

I love this AEG.

 

I have two other G&P's and both have seen a variety of upgrades and improvements. However I am not touching this one, not even with a tightbore. The only things i may do is install one of Infected's (which are on their way!!!!) MOSFETs as I am now running on Lipos (7.4v).

 

Thankfully the Sentry was running at 348fps (35fps site limit) so that was very pleasing :-) also it shot amazingly straight for a stock barrel, added to the fact that once the hop was set in the morning it never needed adjusting throughout the day (~5000 rounds later). I've had lot's of tightbbore barrels (TK, Element, Madbull etc) and to be honest the stock barrel on the Sentry was outstanding as was it's range.

 

Over all i am extremely happy with the G&P Sentry and based on my experience I would certainly recommend it to anyone.

 

J.

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OK

Some big updates:

 

First:

Upgrades of TM Hopup rubber, Element WHITE H nub (don't use the black, gave me bad results) and Promy 300mm TBB gave pretty good results for accuracy. Any inaccuracy was mostly caused by one thing: grease from the cylinder gets shot out of the nozzle into the hopup unit getting it all messed up.

 

Second:

Gun broke!!!

I took it apart and the piston had completely lost its teeth. The first teeth (the big thick plastic one) had a section completely burned through by the sector gear. Sector gear itself was completely fine.

 

Shimming was OK done, but it could have been better. They used some sort of black grease, pretty evenly. I added some white lithium after replacing the piston for good measure.

 

Piston and cylinder assembly seemed to have very good compression.

 

Odd thing about the cylinder: it seems to be wider at one end than the other. If you have the cylinder head on one end it has a lot of play. On the other end it's airtight. I guess this is why it's not ported. When I blocked the cylinder head's air nozzle and compressed the piston, there was no resistance until the piston was 80% into the cylinder. But once there was resistance, it was like hitting a wall. This makes me thing that the cylinder's diameter is not uniform through its length.

 

Big point is: the Sentry that I got came with the OLD G&P white piston which is distinguished from the new one by having 3 metal teeth rather than 4 on the new model. I replaced the old broken piston with a new model and noticed that Angle of Engagement was almost perfect! Reshimmed it and put it all back together, seems to to work great now. Cleaned out some grease from the nozzle, thorough cleaning and now the hopup performance is phenomenal, the BB goes straight for about 40-50 meters and then drops like a rock. Very consistent too. Even without upgrading the spring, the gun can bottom a can.

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Thinking about getting one of these bad boys next month, just a quick question though.

Can any one confirm that the vltor lower receiver takes Magpul PTS PMAG's and feeds them with no problems? I currently run the PMAG's and i dont want to change to another mag.

 

Cheers :)

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Thinking about getting one of these bad boys next month, just a quick question though.

Can any one confirm that the vltor lower receiver takes Magpul PTS PMAG's and feeds them with no problems? I currently run the PMAG's and i dont want to change to another mag.

 

Cheers :)

 

I have not encountered a SINGLE AEG wher PTS P-Mags didn't work.

 

They feed great in everything.

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And just to confirm, PTS PMAGS fit in EVERY single G&P lower i've ever tried them out in. Perfectly, in fact. Seeing as G&P are (far as i know) the licensed manufacturer of Magpul lowers, i imagine that's why they fit so well.

 

As for the Arc welding, Tony's sentry had the same issue - No idea as to why, but it was easily fixed.

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What batteries is everyone running their guns on?

 

I've stopped using the 11.1V lipos since they chew through G&P polyacetyl pistons in less than 10,000 shots. Not to mention the trigger contacts burn through real fast.

 

7.4V lipo still gives a decent RoF

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Nothing more vicious than an 8.4 1600mah NimH pack for us 3 at least. Both me and Jack (the reviewer) use 7.4 800 or 1200Mah lipo's in the stock tube, and Tony (other guy who had one) runs an 8.4 1600mah crane stock pack.

 

Putting an 11.1 in a stock gun is never a good idea, in my experience... Piston rape almost always ensues.

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Piston rape indeed, especially considering that on stock the gun comes with a old G&P polycarbonate piston (the kind with 3 metal teeth instead of 4).

 

The mechanic suggested a full metal teeth piston to handle the stress from high RoF. But I've heard bad things about full metal teeth ones, like how they destroy your gears...

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Hi guys,

 

im seriously digging this gun, price is right as well. However what worries me is people seem to be using 8.4v NIMHs or lipos. I want to get the best out of the gun and use a 9.6v, which battery will fit? Stick type in the buffer tube?

 

I've been using a 9.6v nunchuck battery with good results, it fits right into the vltor stock - there are 2 panels that come off and you pop the battery sticks inside.

 

Since you said you want the best out of the gun..In my experience with the sentry, I'd just go for the lipo..because my 9.6v nimh always 'jams' the gearbox when the battery is dying, forcing me to put in another battery just to clear the chamber + release the spring. Plus, with the 9.6 nimh the gun whines and has slower trigger response..it just felt like the gun wanted a stronger battery.

 

So I've also been running an 11.1 1200mah 20c lipo, so far no arc-welding but I am still under 10k shots fired. If my only issues in the future are piston wear and trigger contacts, I'll be happy.

Edited by veratek
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Im surprised thats your experience on a 9.6v, i would have thought it more than adequate. Hmm, what about a 10.8v nunchuck, im not sure i want to go down the lipo road with airsoft yet. I have some lipos from my rc aircraft but electronics in the planes have a lvc which prevents a damaged lipo. How can you tell when your battery is reaching this point?

 

 

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I've been using a 9.6v nunchuck battery with good results, it fits right into the vltor stock - there are 2 panels that come off and you pop the battery sticks inside.

 

Since you said you want the best out of the gun..In my experience with the sentry, I'd just go for the lipo..because my 9.6v nimh always 'jams' the gearbox when the battery is dying, forcing me to put in another battery just to clear the chamber + release the spring. Plus, with the 9.6 nimh the gun whines and has slower trigger response..it just felt like the gun wanted a stronger battery.

 

So I've also been running an 11.1 1200mah 20c lipo, so far no arc-welding but I am still under 10k shots fired. If my only issues in the future are piston wear and trigger contacts, I'll be happy.

 

Consider yourself lucky. I've burned through both the original piston and a replacement with the 11.1V The silver coating on the copper trigger contacts... burned through those too. And I think I'm still well under 20K rounds.

 

For reliability, I'd stick with a 7.4. I replaced the annoying loops that connect to the motor with proper promy gold clips. Gives a good RoF on that setup.

 

Oh and for anyone who is buying this rifle, like most new G&Ps, this thing comes stock with DEANS CONNECTORS

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Not in the UK it doesn't... They're still fitted with mini Tamiya's over here.

 

As for batteries, you really don't need more than a 7.4 1200 lipo. Fits perfectly in the stock tube, VERY snappy trigger response and a RoF of around 1100RPM. Seriously, a 10.8 or 11.1 is quite likely to ruin the gearbox in a short space of time unless you set it up for a ridiculous RoF.

 

As for lipo's killing themselves, i'm the dumbest twit going when it comes to batteries - I don't look after them at all and i haven't killed one yet. I'm using 7.4 800's and 1200's on a Turnigy balance charger - All i do is change the battery as soon as the RoF drops even slightly, which stops them running flat.

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