Image credit
- Title
- File:Frommer Stop 32 ACP Sn 149082 L DSC0291.jpg
- Author
- Self Loader(attribution required)
- Licence
- CC BY-SA 4.0
- Source
- https://commons.wikimedia.org/wiki/File:Frommer_Stop_32_ACP_Sn_149082_L_DSC0291.jpg
How Muzzle energy is calculated
E = ½ · m · v²
Inputs
- m4.6 g70.99 grverifiedsourcePublished as 71 grains.
- v274.3 m/s899.9 fpsverifiedMeasured with a 101.6 mm barrel, not this arm's 95 mm. Velocity outside the sourced range is not projected.
1 of 2 inputs link to their source.
How Muzzle velocity is calculated
nearest sourced barrel length, no extrapolation
Inputs
- v at 101.6 mm274.3 m/s899.9 fpsverifiedsourcePublished as 900 ft/s.
Assumptions
- This figure belongs to a 101.6 mm barrel. It is shown because it is the closest measurement that exists, not because it applies here.
1 of 1 inputs link to their source.
How Loaded mass is calculated
m_loaded = m_empty + m_magazine + n · m_cartridge
Not calculated: m_magazine has no sourced figure yet. Nothing is substituted for a missing input.
Assumptions
- One magazine, filled to the stated capacity. Spare magazines, optics, slings and lights are the owner’s, not the arm’s.
2 of 4 inputs link to their source.
How Free recoil is calculated
E_recoil = ½ · m_firearm · v_recoil²
Inputs
- m_firearm0.61 kg1.345 lbestimatedsourceFrom the infobox; no inline citation is given there.
- v_recoil2.068 m/s6.786 fpsestimated
Assumptions
- Propellant gas momentum is excluded: ARMAG does not record charge weights. This is therefore a lower bound on the real free recoil, consistent between entries but smaller than a figure that includes the gas term.
- Free recoil: the arm is unrestrained. Stock design, muzzle devices, stance and shooter mass are not modelled, because none of them is a property of the arm.
1 of 2 inputs link to their source.
How Capacity is calculated
as published for the primary chambering
Inputs
- capacity8estimatedsource8-round detachable box magazine, from the infobox, uncited there. The pistol was designed around a proprietary, hotter-loaded 7.65mm Frommer cartridge not carried on this site, but the article states it also fires standard .32 ACP ammunition.
1 of 1 inputs link to their source.
Derived figures
Computed from the sourced values above. Open ƒ on any figure for the formula, its inputs, and the assumptions it makes.
How Momentum is calculated
p = m · v
Inputs
- m4.6 g70.99 grverifiedsourcePublished as 71 grains.
- v274.3 m/s899.9 fpsverifiedMeasured with a 101.6 mm barrel, not this arm's 95 mm. Velocity outside the sourced range is not projected.
1 of 2 inputs link to their source.
How Sectional density is calculated
SD = mass(gr) / (7000 · diameter(in)²)
Inputs
- mass4.6 g70.99 grverifiedsourcePublished as 71 grains.
- diameter7.85 mm0.3091 inverifiedsourceC.I.P. G1, maximum bullet diameter.
Assumptions
- Reported in the conventional lb/in² so it is directly comparable with published figures.
2 of 2 inputs link to their source.
How Power factor is calculated
PF = mass(gr) · velocity(fps) / 1000
Inputs
- mass4.6 g70.99 grverifiedsourcePublished as 71 grains.
- velocity274.3 m/s899.9 fpsverifiedMeasured with a 101.6 mm barrel, not this arm's 95 mm. Velocity outside the sourced range is not projected.
Assumptions
- A competition classification defined by the IPSC and USPSA rulebooks, stated in their units. It describes a scoring category, not an effect.
1 of 2 inputs link to their source.
How Magazine dump is calculated
t = (n − 1) / (rpm / 60)
Not calculated: rpm has no sourced figure yet. Nothing is substituted for a missing input.
Assumptions
- Cyclic rate held for the whole magazine, no stoppages, trigger held down. A theoretical figure for comparing mechanisms, not a measured one.
1 of 2 inputs link to their source.
How Sight error at 1 mm is calculated
θ = atan(misalignment / sight radius)
Not calculated: sight radius has no sourced figure yet. Nothing is substituted for a missing input.
Assumptions
- Shows what a stated aiming error costs. The misalignment is the reader’s figure; the site does not claim how well anyone aims.
No input on this calculation carries a clickable source yet.
Specifications
Every row here is generated from the schema, so a figure recorded on this entry cannot be missing from the table, and the same rows, read the same way, are what the comparison shows.
Identity
- Type
- Pistol
- Action
- Self-loading
- Fire modes
- Semi-automatic
- Operating system
- Long recoil
- Roles
- Designed in
- Austria-Hungary
- Produced in
- Introduced
- 1912
- Production
- 1912–1940
Dimensions and mass
- Mass, empty
From the infobox; no inline citation is given there.
- Magazine, empty
- not recorded
- Length
From the infobox, uncited there.
- Length, folded
- not recorded
- Width
- not recorded
- Height
- not recorded
- Barrel length
From the infobox, uncited there.
Sights and rifling
- Sight radius
- not recorded
- Sight height over bore
- not recorded
- Rifling twist
- not recorded
- Twist direction
- not recorded
- Grooves
- not recorded
- Sight graduation
- not recorded
Operation
- Cyclic rate
- not recorded
- Trigger pull
- not recorded
- Effective range
- not recorded
- Units produced
- not recorded
- Launch price
- not recorded
Scale
A to-scale outline against family siblings. The dimensions are sourced; the shape is a representative outline for the type, and says so.
- Frommer Stop165 mm6.496 inheight not recorded
Representative outline: the dimensions are sourced, the shape is not. Overall length, and barrel length where recorded, are drawn from this entry's own figures; the profile is a generic one for the firearm type and says nothing about this arm's actual contours. Frommer Stop records no height, so its outline is drawn at the type's proportion. That height is part of the shape, not a measurement.
Detail
The Frommer Stop is a semi-automatic pocket pistol Rudolf Frommer designed in 1911 and Fegyver- és Gépgyár (FÉG) manufactured in Austria-Hungary from 1912. Unlike most blowback pocket pistols of its size, it uses a long-recoil, straight-pull, rotating-bolt locking action, with the barrel and bolt riding on independent return springs. This is a mechanism more commonly associated with far larger, harder-recoiling weapons than a compact pistol of this class.
It was designed around a proprietary 7.65mm Frommer cartridge, a hotter-loaded, heavier-bulleted round not carried on this site, and later a similar proprietary 9mm Frommer loading for an export variant produced from 1912 to 1929. Both proprietary rounds were dimensionally compatible with existing commercial ammunition (the standard .32 ACP for the 7.65mm pistol and .380 ACP for the 9mm export version), and the pistol fires either commercial cartridge as well, with correspondingly less energetic recoil, ejection and rechambering than its intended proprietary loads. It saw military and police service through both World Wars and the regional conflicts that followed Austria-Hungary’s collapse.
Mass, length and barrel length figures on this page come from Wikipedia’s infobox, which carries no inline citation for any of them, so all are recorded as estimated rather than verified. No manufacturer specification sheet was reachable for a pistol this old. No published twist rate was found for this entry, and no photograph of the export 9mm variant appears on this site.
References
This entry's own bibliography. Every citation key on this page resolves into this list.
- Frommer Stop · Wikipedia · 1372447860 · read 2026-09-24 · CC BY-SA 4.0
Last verified 2026-09-24 · review status: draft