Air Arms Owners Club

Hi all. I'm still about but been busy on house remodelling duties. In one of the few downtime moments, I bought what looks to be a mint S400 MPR FT. Is there a 400 MPR FT-owning guru of this model available to answer some questions – no, not pellet choice or sweet spot or trigger related or how to get 30ftlb or anything like that? Just basic dimensions relating to barrel band, cylinder to stock clearance etc.

I've got one, excellent rifle. Had it for over 10 years and it's my choice target and hunting rifle.
Just fitted a regulator as it has quite a power curve.
Found the sweet spot of 30 shots between 160 bar and 140 if that's any use to you.
Rich

Hello there! One of the best AA rifles made and sadly out of manufacture.
Not quite sure why you need dimension data when you have one in front of you to measure. Is there something you need to do?

It will say S400 MPR FT on the bolt housing if it is one.

Ah yes, good question. Yes, I have one in the house but only one and this is the rub: I have nothing to compare it to when it comes to measurements and details.
POI is anywhere but the POA. With usual easy to fix suspects eliminated (it's the same with or without muzzle break or moderator, chrono shows a decent and consistent power curve over two fills, barrel cleaned etc), POI is still all to cock. High, low, left or right and not consistent where it places JSB or AA 4.50, 4.51 and 4.52. So...
Does this rifle have a damping pad at end of the stock between cylinder and stock as standard? With barrel band removed, is the distance between cylinder and barrel the same along their lengths from block to end of cylinder? If not, then how much does it close or open up when laid on its side or held in a shooting stance? Is the pressure gauge meant to be a stiff fit and positioned so it is set well inside the stock ie nowhere near flush with the bottom of the stock? The rifle is supposedly all standard; I can only tell by Web images; AT measures still in place; floppy trigger...
Any answers to the above questions will be welcomed.

The barrel gets closer to the cylinder as it gets nearer the valve body.
The gauge should be a close but not tight fit in the hole, it should say Air Arms and be a 22mm across flats hexagon with rounded corners. If not then it could be a replacement.

Personally I would have the barrel band on rather than floating the barrel but that’s just me.

Have you cleaned the barrel and if so have you re leaded it.

BBF

I too acquired an S400 MPR FT a few months ago and continued to use the JSB pellets as I was using in my old S400 Classic.

However, I too soon had a similar experience - reliable grouping was impossible.
Two of my fellow club shooters, who I know to be very good shots (one also an MPR owner), also tried and failed miserably.
Cleaning the barrel made absolutely no difference - although I do that every 3 or 4 tins.

The MPR owner suggested the solution was to ditch the JSBs and try the H&N Baracuda FT pellets he uses - problem solved!!

I also have a FTP900 and it too seems to prefer the H&N Baracuda FT pellets with the new Baracuda Lights performing just as well.

It's worth trying them after cleaning the barrel and releading it with the H&Ns before taking more drastic action.

Slàinte Mhath!

That's very strange regarding your rifle not liking jsb pellets.
I have an Mpr of roughly 10 year old and it's my most accurate shooter.
How old is your Mpr? Maybe the older barrels are better? I can't see the internals would be any different to the new ones so only the barrel could cause the issue.
Jsb Heavies 10.4 grain for me in 4.52mm
Literally ragged hole groups out to 40 yards and consistent kills out to 60 holding for windage.
Richard

As regards to the barrel band, I've taken mime off as I found it to be just as accurate without it plus centralizing the barrel to be exactly straight each time the band is taken off and on isn't something you can do very easily.
Having that band pull slightly to one side by even half a mm when tightening will always make the rifle shoot to either left or right.
Wirh the Mpr barrel being heavier than the s400 variants it's easily able to be free floated without any issues and the accuracy of mine is testament to this.

Hi Richard,

As I bought it from a dealer 2nd hand (or more??) I'm not entirely sure how to date my MPR although think it must be one of the earlier ones - the DOM stamped on the reservoir is 06/2007 with a serial number of 073104. Also there's no metal support at the front of the stock below the reservoir the wood of the stock just rises at the end.

I was using JSB Diabolo Exact 4.51mm 8.44 grain pellets and, as I said, the grouping at 30 yards was all over the place - over an inch in any/every direction. The H&N Baracuda FT and lights are pellet on pellet (most of the time ) over the same distance.

That said, I'll give the JSB Heavies a try and see how they perform.