Alpha Trooper spring mod

So I'm up to my third mod now (Longshot, Recon and now the Alpha Trooper).

I have removed the air restrictor, improved the o-ring seal, padded the plunger - all the usual stuff. Results were pretty good - an extra 12-15 feet or so.

I then replaced the spring with a Recon/Longstrike aftermarket spring. Re-assembled - first shot was fine. The extra power and distance was very impressive. Unfortunately I couldn't re-cock the gun - the handle would only go to half way back along the gun and would stop - couldn't force it - it's as if there's some sort of spring/catch that's blocking it and preventing it from re-loading. Reverting back to the stock spring fixed it.

This aftermarket spring that I have is not massively stronger than the stock spring (supposedly 1 and a half times to twice as strong) but I'd still like to use it if possible.

Can anyone point me in the right direction as to what to look at next, to enable the stronger spring to reload? The padding is only about 10-20 mm thick and just to recap, the stock spring works fine.

I thought it may have been the bolt catch but wasn't sure.

Padding is useless. You should try to be 'reinforcing' the actual plunger where you put the padding. You use a washer and 3 day epoxy. That will STRENGTHEN rather than absorbing. That you can do both.

As littlebro said, padding the plunger is virtually useless. If the blaster can't cock, then it might be because the padding is to thick to allow the plunger to move all the way forward, so try removing it. If that still doesn't work, it may be the spring having too many coils to properly compress,which means that you will have to use another different aftermarket spring, or just revert to the stock one.

Firstly, like they have said, make sure the padding added to the plunger is not too thick.

Secondly, where did you get the aftermarket spring from? Because you may be experiencing the same problem that I had with my AT as well. I used one from Black Tactical, the problem is the spring is thicker than stock spring, so when it is compressed the spring expands and gets stuck inside the end of the blaster case (where a stock can be attached to). So you need to file/sand/dremel the ridges and reduce their height by 2-3mm, that will give the spring more room when it is compressed.

Thanks for the input.

I used epoxy for the padding anyway, so I've got the best of both worlds as I used a pretty reasonable amount of epoxy to hold it in.

Just to re-iterate:

The blaster does cock the first time after being assembled. However it won't RE-cock after firing the first shot. I had a similar problem on my Longshot and removing the bolt lock fixed this, but I don't want to run under the same assumption this time around as they are different after all.

The stock spring works fine even with the padding, and the padding isn't all that thick anyway (probably 10mm max, maybe less).

The spring is an Ebay one - this one to be exact - http://cgi.ebay.com.au/Nerf-Recon-Longstrike-Performance-Spring-/150548958518?pt=LH_DefaultDomain_0&hash=item230d6acd36

It's stronger compared to stock but not over the top like the ridiculous one I bought for the LS. This one feels like it's only about one-and-a-half to two times the strength of stock.

I read on another page somewhere (I think it was on nerfsg) that the bolt lock could be the cause, or to try filing near the boltsled but it sounds a bit hit and miss to me. There's something binding inside the mechanism which is preventing it from being cocked.

The spring is almost exactly the same dimensions as stock (thickness, length, you name it).

I had the same issue with my raider and I didn't have padding or anything. Some times the spring gets fatter as it is compressed. Try putting the stock spring in and if it works you'll have to make room for the new spring.

killerbunny wrote:I had the same issue with my raider and I didn't have padding or anything. Some times the spring gets fatter as it is compressed. Try putting the stock spring in and if it works you'll have to make room for the new spring.

I've already done that, but thanks anyway (stock spring works fine)

Try doing this.

Will definitely try that killerbunny, thanks.

I'm disappointed with myself for not thinking of reading the Raider mod guide and finding that info out for myself!!!! I didn't realise that the Raider and Alpha Trooper are so similar.

Thanks for the advice all - I performed the grinding at the rear and it improved things. Unfortunately if I don't cock the bolt back perfectly it gets jammed up. So it works 50% of the time. It requires quite a bit of force to cock it and I am concerned that it could tend to wear the gun out...

So it looks like there's something else causing it to jam as well.

I have just finished modding an AT, and experienced similar issues. I used an aluminium recon plunger and aftermarket spring. Remove the three pieces as shown in the image, cut a piece of plastic biro to use as a spacer for the trigger release (as once you remove the little piece behind it with the two springs, it no longer sits in the correct position for the catch to release). Trim the plastic as shown in the raider mod, and a little bit of plastic from the opening where the plunger travels through in to the tail cap. I'm not sure if this was an issue due to the after-market spring or the aluminium plunger, but the three procedures combined have eliminated any jamming problems.

Hope this is of some help

clunk07 wrote:

I have just finished modding an AT, and experienced similar issues. I used an aluminium recon plunger and aftermarket spring. Remove the three pieces as shown in the image, cut a piece of plastic biro to use as a spacer for the trigger release (as once you remove the little piece behind it with the two springs, it no longer sits in the correct position for the catch to release). Trim the plastic as shown in the raider mod, and a little bit of plastic from the opening where the plunger travels through in to the tail cap. I'm not sure if this was an issue due to the after-market spring or the aluminium plunger, but the three procedures combined have eliminated any jamming problems.

Hope this is of some help

If you fill that part in near the trigger, you'll lose the ability to slam fire.
I had this problem too, and I may have a fix. Is the spring shorter than the stock spring?

Thanks for identifying the error in my mod fix. I hadn't tested slam-fire, as it isn't a firing mode that I use regularly. Guess I had better check things more thoroughly before posting.

In regards to your question, yes, the replacement spring is shorter than stock, when both relaxed and compressed.

Well first of all, sand down those tabs in the stock attachment part of the shell that killerbunny identified.
And second of all, this little tab here amy be your problem:

This lock keeps the bolt sled in place in the forwards positions so that it is not possible to re-prime the blaster with a dart chambered, to prevent double feeding. When fired, the plunger tube moves forward and connects with this part, pushing it down, and allowing the gun to be re-cocked. Now, if your spring is too short, the spring will supply not enough, or no force at all, to push the peg down, and therefore, prevent the re-priming of the gun.
The solution? The most probable is the use of a spring spacer, as seen here in this Recon:

You can use any material you wish, so long as it creates a bed for the spring to sit on. This not only increases performance, but also compensates for the lack of spring length.
Hope this helps

Tried that already, and it made no difference with my problem. Maybe I didn't use a big enough spacer, I only used some e-tape, cut in half vertically (ie: half the width). I will still try this though, but maybe with the stock spring to start with.

This problem shouldn't happen with the stock spring, only the new spring. Hmmm, this is a pickle.

I've just gone and pumped approx. 200 rounds through my AT, and while I have no slam-fire, there are no issues with the cocking mechanism. Although, after that many rounds, it is becoming quite hard to cock. I really have to focus on cocking it each time, and physical strength isn't an issue, maybe the Recon spring isn't the ideal fit, or it could be the aluminium plunger. I may try strengthening the stock plunger with a washer and epoxy, and try that.