Bullpup Design: Why must the hammer be behind the magazine?

[Bunyboyz]

The main issue I see with reversing the hammer set up is cocking the rifle.  If I'm following correctly you mean kind of like an airforce style hammer that fires towards the back of the gun.  Airforce limits their guns to single shot and the cocking lever goes forward instead of back which would be hard to replicate on a multishot rifle. 

Yes, you'd have to cock the hammer forward, but why would that prevent using a mag?  As long as the probe pushes a pellet out, then pulls back, the mag's spring will still do its thing.    So, you'd push the arm forward, tensioning the hammer spring and pushing a pellet into the breech, then you'd pull the arm back & lock it, so the magazine advances & the next pellet is ready to be loaded by the probe.

The only possible problem is that it might be possible to fire the gun without pulling the lever back, so the next round wouldn't load.   It wouldn't hjurt anything, and eventually you'd get used to it.     I think ......   

How would it seal if the probe retracted again?

Insert video of the guy from India who made an full auto Airforce it used maybe a marauder style mag. 

- I always wondered about running a remote bottle like I did it paintball. But with an Airforce rifle. You’d think it’d be pretty simple but maybe only enough flow for .22 .25.  Esspecially with a plenum.  Maybe one day I’ll get a round to it.  Imagine a talon with a say 38 cubic inch 4500 bottle that you wear on your side or reverse Fanny pack style. Running a remote line you can get a pretty solid sight picture as I remember.

[Rallyshark]

The design issues of a bullpup that lead to the high scope mounting generally has nothing to do with where the hammer is or most anything else in the breech block.  It has to do with sight picture.  They don't have the long upward angled butt stock to bring the action/barrel higher  and closer to eye level.  The high rails and rings are needed to get the scope up to eye level, so you don't strain your neck trying to get a sight picture. 

To change what you wrote, " They don't have the long upward angled butt stock to lower the cheek weld position."

A regular rifle has the exact same height limitation, if you remove the long butt stock and move the trigger forward.

I just don't see your point.

You are correct, you don't see my point, LOL!  The cheek weld needs to raised to make shooting comfortable, unless you don't have a neck.  On a rifle raising that cheek weld(and action) puts your sight picture in line with the bore easier, since the butt stock can accommodate it.  On a pup, there's no butt stock to bring the action/bore/cheek weld up, but the cheek weld still needs to be higher, so you end up having to use a very high off bore sight picture.   I guess if you want to be technical, a rifle has that limitation, but it has 10-12 inches of material prior to the action to bring things up.  If you remove the long butt stock and move the trigger forward, you no longer have a rifle. 

The point is still the same though.  You cannot have a bullpup with a scope mounted close to the bore and shoot comfortably, without having a pretty weird lowered butt padd/stock configuration. 

I used to get concerned about the high off bore scope mounting of the pups, but now, I couldn't care less about it.  It used to drive me nuts that I couldn't get the scope closer to the barrel.  You will get used to it though, and know where your holds are for various distances.

You must not do a lot of pesting, (or you have a second gun for that)  in which case I agree with you.

But fo me,  trying to go from a 6 yard target to a 50 yard target is practically a nightmare, using a bullpup.   I ran the numbers for if I get the MTC 12X SAWT scope that I'm lusting after.   Unless I'm calculating wrong (I'm not sure, and no one here has been able to help with this)   wiith a 21 yard zero,  the holdover at 6 yards is 10.5 mil dots !    That's simply not workable.   Even if I used the turrets, it would be ridiculous.

What I might do is mount a cheap red dot on offset mounts, just for sub-20y shooting.  But I'm having a very hard time figuring what red dot would be best for that, short of a super expensive prismatic / holograpphic type.  It's bloody confusing......

I do, and have done quite a bit of pesting/hunting.  I will say, a 6 yard shot isn't something I've ever encountered often.  At that point, who even needs sights?  I have done some shooting at 10-15 yards though.  I think your calculations may be off a bit on that holdover.  Either way, I wouldn't recommend sacrificing my entire setup, so I could make a 6 yard shot. 

I think the problem here is way too much reading, and not enough shooting and doing.  I don't mean that to sound derogatory in any way.  I know it is very easy to research things, until you're blue in the face!  I've done it too, only to find out what I thought I wanted wasn't actually what I really wanted.   Trust me, your life will be easier when you spend less time trying to re-invent the wheel, and just learn to use the wheel that's already there   If you're likely to find yourself with a lot of shots under 10 yards, maybe a second small sight would be useful, but I wouldn't compromise my entire setup for it.  Close shots are easy, so spend your time getting good with the longer ones. 

I think you're selling yourself short on your own abilities here.  Don't waste your time worrying too much about the close stuff, you'll be just fine making those shots.  It is as simple as setup the close target, and take a shot, then you know your hold at this distance.  Easy as it gets.  You'll also find that 1 mil, or MOA difference in holdover at that distance is miniscule, and not nearly as important as it seems(unless you're hunting bugs).  You're making things much harder than they are  

[JungleShooter]

Allan,


🔶 I'm getting similar numbers for the needed POI correction at 6 yards: 😟
With the specs you gave me, and a zero at 21y:

▪Bugbuster: hits low by 8.2mil = 28moa = 1.8"
▪MTC 10x30: hits low by 9.0mil = 31moa = 1.9"
▪MTC 12x50: hits low by 9.8mil = 34moa = 2.1"



🔶 The scope heights of 2.75", 3", and 3.25" seem awfully high.... 🤔 
That's why I asked what gun this was.

I assume we're talking about a bullpup that has a very high scope rail.

➔ You could lower the scope by using extremely low rings, and just making sure that the objective bell (front part of the scope) will not be over the scope rail but the barrel — where it will have space to be mounted lower. 👍🏼  There are some very low mounts out there.


However, the MTC prismatic scopes have an extremely thick scope tube, with special scope mounts, so that won't work. 😟


For my bullpup, a Diana Skyhawk (Artemis P15) I used very low scope rings and got as low as 2.4" — and that is with a dovetail-to-picatinny adaptor. I could get as low as 2.15" if I bought yet another set of rings that are even lower. And go further down if I used dovetail rings ➔ 1.85".



🔶 I have seriously considered have a shop make me a new rail, lower, and picatinny style.
But the benefit would be too small to justify the expense.



🔶 The way I set up the gun now is as follows:
▪I try to set my scope to obtain a large point blank range (PBR). Depending of how large you allow the kill zone to be that could  be quite a long PBR.

▪Then I write myself a dope card to memorize — for the closer ranges (closer than the PBR).
I write that elevation dope not in mil (or moa) to click on the scope. Instead, I write the dope in inches (or centimeters) to hold over on the kill zone. 
At such close ranges that is fairly easy, but requires some practice. 😊
Note that the amount of clicks at extremely close ranges is extreme, but the actual holdover in inches is not!


🔶 I have been looking at a cheap little laser to mount on the gun for those extremely short range shots, with a simple squeeze switch.


Matthias

[Scotchmo]

...
Current scope: Lowly Bugbuster.  2.75" above bore-center  ...
...
New option #1:  MTC SWAT 10x30.   3" above bore center.   
...
New option #2:  MTC SWAT 12x50.   3.25" above bore center.   
...

Why so high? My FT rifle is a Diana Skyhawk (P15 bullpup). The scope (Athlon Helos 6-24x50) center-line is 1.93" above the bore-line. How low do you want to go?

[Cableaddict]

Why so high? My FT rifle is a Diana Skyhawk (P15 bullpup). The scope (Athlon Helos 6-24x50) center-line is 1.93" above the bore-line. How low do you want to go?

That's just how it is on my rifle, which is a Flashpup.  Even after I ground-away the rear picatinny rail and the left-side corner of the breech, I need to use high mounts in order to not get pain in my neck from cranking it sideways, if shooting for long periods.

The MTC SWAT scopes make the problem worse by including an angle-adjustable mount, which adds another 1/4" or so.
Why so high? My FT rifle is a Diana Skyhawk (P15 bullpup). The scope (Athlon Helos 6-24x50) center-line is 1.93" above the bore-line. How low do you want to go?
-------------

That Diana is an excellent design. the breech is short, and then the butt falls away immediately.  They thus were able to mount the picatinny rail very low, and you are able to use lower mounts than on most bullpups.   It's actually a pretty unique design.    A 22" barrel in a 29" gun, and with a low cheek-weld, no less!  Geez, I might have to buy one.
 
Where the heck is the hammer spring located in that thing?

[Scotchmo]

Why so high? My FT rifle is a Diana Skyhawk (P15 bullpup). The scope (Athlon Helos 6-24x50) center-line is 1.93" above the bore-line. How low do you want to go?

That's just how it is on my rifle, which is a Flashpup.  Even after I ground-away the rear picatinny rail and the left-side corner of the breech, I need to use high mounts in order to not get pain in my neck from cranking it sideways, if shooting for long periods.

...

That Diana is an excellent design. the breech is short, and then the butt falls away immediately.  They thus were able to mount the picatinny rail very low, and you are able to use lower mounts than on most bullpups.   It's actually a pretty unique design.    A 22" barrel in a 29" gun, and with a low cheek-weld, no less!  Geez, I might have to buy one.
 
Where the heck is the hammer spring located in that thing?

The hammer spring is in the normal location (below the breech/barrel).

The Skyhawk stock was longer than it needed to be, but I did not want to cut the nice Minelli laminated wood. I made a stock (3D printed) with a shorter back end. I could have gotten a P15 with a simpler stock and saved some money. I also swapped the barrel for a 24" Lothar Walther.

1.93" high is a tight squeeze. I tried lower but I could not squeeze my face into position.

[Dairyboy]

Well I'll come at this from a different angle. Have you ever shot anything at 6yds with a scope at 10x or 12x? I can't imagine that being easy in the slightest. I guess what are you shooting at that distance? I got my bullpup fairly close to the barrel. Taipan Veteran.

[JohnnyPDX]

I just lowered the shoulder pad instead of having neck vertebrae removed, close call.

Simple solution and the ergonomics are fantastic. I do A LOT OF PESTING and rarely do I need to take close shots. I am hitting startling at 50 yards and only holdover two mil dots for a 10 yard shot. That's not so difficult, geeze.

[Ribbonstone]

Do dislike the forced high scope mount of most bull pups….for that matter, non-bull pups like the standard AirForce rifles and kin.  A 3 way between bore center, scope center, and face-fit.  Can only win 2 out of the 3, take face fit and scope alignment to your eye….the height will just be-what-it-be.

Mil dot scopes normally have up and down dots.  Gets hyper-critical when some dumb critter pops up at like 5 to 10 yards...and it’s embarrassing to miss the shot, likely because you didn’t pre-test or a long range mind really not worthy at telling 5 yards from 8.

Have to admit...no matter what the air rifle…can easily miss those shots.

[JohnnyPDX]

...and it’s embarrassing to miss the shot, likely because you didn’t pre-test or a long range mind really not worthy at telling 5 yards from 8.

Have to admit...no matter what the air rifle…can easily miss those shots.

I can miss those shots with ANY rifle!

[Lani52]

The AF guns work better with Talon Tunes angled tank adapter to lower the tank and thus the scope.

But with the bullpups, it might be easier to get a surgeon to remove your cheekbone.  Sure that sounds drastic, but your either dedicated to the Darkside or not.

Regards,

Roachcreek

[JohnnyPDX]

The AF guns work better with Talon Tunes angled tank adapter to lower the tank and thus the scope.

But with the bullpups, it might be easier to get a surgeon to remove your cheekbone.  Sure that sounds drastic, but your either dedicated to the Darkside or not.

Regards,

Roachcreek

I am dedicated to The Darkside but also permanently attached to my cheek bones and vertebrae.

[JungleShooter]

But with the bullpups, it might be easier to get a surgeon to remove your cheekbone.   
Sure that sounds drastic, but you're either dedicated to the Darkside or not.    
Regards,

Roachcreek

Now here is a word of truth from one of the heroes of our sport!   
Thanks for clarifying this once and for all:

Airgunning is far more than a hobby — it's a style of life — that necessarily has an impact on life, like: 
▪the allocation of unheard portions of your salary (unheard by your better half)
▪the allocation of large chunks of your time
▪use of real estate (gun cabinets, shooting ranges, pellet shelves, etc.)
▪the size and location of one of your cheek bones

Matthias

[Hobbyman2007]

Why not just go with a picatinny offset mount and a red dot . Much cheaper route than trying to reinvent the reinvented wheel.

[Cableaddict]

The Skyhawk stock was longer than it needed to be, but I did not want to cut the nice Minelli laminated wood. I made a stock (3D printed) with a shorter back end. I could have gotten a P15 with a simpler stock and saved some money. I also swapped the barrel for a 24" Lothar Walther.

1.93" high is a tight squeeze. I tried lower but I could not squeeze my face into position.

That's bloody impressive!

But IMO you now have a trigger that's too close to your body, for a really comfortable hold. 
Well, maybe. that's where we get back into the discussion of what constitutes an optimal bullpup hold,  and how that might change with and/or effect bullpup design.

--------------------------------------------

Here's what I did with my Flashpup:  It's not perfect, but it works WAY better than stock:

https://www.dropbox.com/s/j804e8wirqpuxx0/MODIFIED%20PUP%2C%20LEFT%20SIDE%20%20.jpg?dl=0

Note that I initially ground-away as much as I could at the top & side of my breech block, then added foam. - But even with high scope mounts, I still found it somewhat uncomfortable.   

So now I've moved my scope way back, (as in this picture) and am putting my cheek at the very back, where it's marked.  I should be able to put medium rings back on,  maybe even low one.    This is not a perfect ergonomic solution, but works fine if using a sandbag or other support. The trigger is a bit far away now, but that's better than too close. 

For off-hand shooting,  this head position works best with a special "bullpup hold" that I read about once online.
I highly recommend this hold, BTW: 
Basically, you hold the rifle to the left,  “At 90 degrees to your chest.”  You keep your left elbow down & tucked tight. (as close to your body’s centerline as possible-comfortable.)  And you keep your right elbow down & tucked, If possible.
 
With this hold, and because of a bullpup's typical weight distribution, it works great.  You also get a lot of steady support from your arms.
And to the point, it has the added benefit of letting you keep your head (and hence your scope) way back.

Of course, I'd still prefer to just lower the back-half of my breech block,  but that's not exactly a DIY project.  LOL....

[Cableaddict]

Why not just go with a picatinny offset mount and a red dot . Much cheaper route than trying to reinvent the reinvented wheel.

Yes, that's probably what I'll end up doing.

But that doesn't change the fact that bullpup air rifle design can still be improved.    Having you scope closer to the bore is an advantage, no matter what your target range.

[Nomadic Pirate]

The Eastern Europeans got it right, with the loading done from the top of the magazine you can shave a good inch of distance from the center of the bore to the scope.

[Doug Wall]

One thing to keep in mind is that the valve/transfer port needs to be as close as possible to the barrel/pellet. If you move the valve to another position, and have a long "transfer port/tube", you will loose a LOT of efficiency.

[mackeral5]

As others have posted, lowering the buttpad location of a bullpup can help with cheek weld/scope height.  Typically this isn't pretty, but it does help with ergo. 

For example, this little BP shoulders and cheek-welds perfectly for me.



Regarding the P15/Skyhawk stock comparison....  I recently borrowed a Skyhawk for a few weeks, it is amazing at how much better the ergonomics of the Minelli stock are vs. the OEM P15.  However, it makes the gun so much larger....really takes away from IMO the P15's best trait---being short and lightweight.

[sb327]

We need little periscopes for our scopes. Adjustable for eye to cheek height. Head tilt, etc. 

Just dreaming...... 

Dave