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I've wanted a modertor on my Steyr AUG since I bought it, but thought it was the "standard" AUG thread of 13x1 LH thread, but recently discovered if actually 1/2 x20, so easy to get a moderator for.

I've just used it for the first time with a Wildcat Evolution, and it seems that the rifle hates it.... at 50yds the group size with the moderator was disappointing... I took the moderator off and the group size halved.

I expected the change in POI, but not the difference in group size... is the moderator disrupting the barrel harmonics to the extent its messing up the groups..?

I did check and theres no signs of "clipping" on the moderator..

Any ideas..?

The only time that I have seen this was when the mod worked loose..... groups go to hell.

I have seen one rifle give different group sizes with different moderators so I guess weight and harmonics do come into the equation.

I’ve a couple of rifles that wouldn’t wear a mod for love, nor money!! One Browning, one Remington. The barrels on those guns just, as you say, “didn’t like it”!

Conversely I've seen groups tighten up with a mod too, turning an average rifle into a good performer. I guess it works much like a barrel tuner, as it's not adjustable it's a bit of pot luck.

breacher wrote:I have seen one rifle give different group sizes with different moderators so I guess weight and harmonics do come into the equation.

They have to really Bri. When you consider that a barrel tuner is a weight that you move up and down the barrel to tune the harmonic.

The problem is that you cannot move a moddy up and down, and it will change slightly in weight as it picks up fouling (although I doubt you would notice a change...you might in the extreme).

Other than perhaps adding weight somewhere changing the harmonics through contact with the barrel I cant see a remedy if this is the problem (and even then where would you put the weight, its not like balancing a rotor blade!!).

Thanks All... so yes, it looks like the AUG doesn't like the moderator.. or at least the Wildcat one.

I'll just have to leave it as nature, and Steyr, intended..

(May be a good excuse to buy another .223.. )

Does the Evo have the same derlin type bushing on the back that needs to be cut to fit your barrel thickness like the Predator does? If so it could be that. It just needs reaming out so that it doesn't touch your barrel.

I had the same problem on my AUG with my Wildcat Predator. The shop i bought it at did a p***-poor job of reaming out the rear bushing (the hole through was at an angle and putting loads of pressure on the barrel). Once i'd bored it out a bit everything was good in the world! Except i was astonished at the amount of POI difference putting the mod on had considering how little of the AUG barrel protrudes from the receiver and its thickness, probs dropped around 5" @ 100m!

Its worth it though, the AUG suppresses lovely!

Thanks BS, thats worth a check... I did give them the barrel diameter 107mm from the thread shoulder, as they specified, and theres no resistance to screwing it on, but I'll try fitting it and doing the "fiver test"

You're doing well to only get a 5'' drop at 100yds... I was getting a good 4'' at 50 yds!

Blackstuff wrote:Does the Evo have the same derlin type bushing on the back that needs to be cut to fit your barrel thickness like the Predator does? If so it could be that. It just needs reaming out so that it doesn't touch your barrel.

I had the same problem on my AUG with my Wildcat Predator. The shop i bought it at did a p***-poor job of reaming out the rear bushing (the hole through was at an angle and putting loads of pressure on the barrel). Once i'd bored it out a bit everything was good in the world! Except i was astonished at the amount of POI difference putting the mod on had considering how little of the AUG barrel protrudes from the receiver and its thickness, probs dropped around 5" @ 100m!

Its worth it though, the AUG suppresses lovely!

there is no need to use a Delrin bushing on the Evo, it doesnt serve any purpose other than acting as a guide for the barrel when screwing the mod on (it may help in the event of a drop but I'm not sure I would count on that ! its not supposed to touch the barrel)