DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 2, 4, 12-15, 17, and 21-28 are rejected under 35 U.S.C. 103 as being unpatentable over Mather (2016/0116251) in view of Farquhar et al. (GB 434220 A; “Farquhar”) and further in view of Aalto (2013/0291420).
In reference to claims 1 and 12, Mather discloses an improved firearm assembly including an improved upper receiver for a firearm, the upper receiver defining:
an external surface (figure 2, the receiver incudes a plurality of external surfaces, e.g. the external surface proximate the left-hand end of the barrel extension, or an external surface facing out of the page proximate the barrel extension);
a bore (figure 2, the interior of the receiver);
an ejection port defined at a first side between a barrel end and a buttstock end (the receiver of figure 2 is that of an AR-15 type rifle, and, thus, inherently includes an ejection port, as claimed; see paragraphs 5, 6, and 15); and
a barrel engagement portion defined at the barrel end, wherein the barrel engagement portion defines:
a threaded outer surface (figure 2 and paragraph 5 and 6, the “nipple” of the receiver includes threaded outer surface) configured to engage a barrel nut (figure 2, AR-15 barrel nut) and
an inner surface configured to engage an outer surface of a barrel extension (figure 2, the inner surface of the receiver in contact with the barrel extension);
an aft-facing surface that connects to the inner surface and is oriented perpendicular to the axis extending between the barrel end and the buttstock end (figure 2; also see marked-up figure 2, below), wherein the inner surface extends from the aft-facing surface to a forward-facing surface of the receiver, and wherein the aft-facing surface is aft of an aft end of a barrel (figure 2);
the improved firearm assembly further comprising:
a barrel as claimed (figure 2, barrel);
a barrel extension defining a threaded inner surface, wherein the threaded inner surface of the barrel extension is configured to engage the threaded outer surface of the barrel (figure 2, barrel extension).
Thus, Mather discloses the claimed invention, except for (A) the inner surface of the barrel engagement portion being tapered, as claimed, and an outer surface of the barrel extension being tapered, as claimed, and configured to engaged the tapered inner surface of the barrel engagement portion. Further, Mather fails to disclose (B) an opening that extends from the external surface of the upper receiver to the tapered inner surface, wherein the opening is configured to allow a pin to be positioned therein.
Regarding (A), Farquhar teaches it is known to form an inner surface of a barrel engagement portion of a receiver as a tapered (frustoconical) inner surface (7c) configured engage a tapered outer surface (8a) of a breech end (8a+8b) of a barrel, in order to form a slidable, plug-wise connection that promotes barrel centering and mitigates radial and/or axial play, which may develop via wear (figures 2 and 3). It is noted that in Mather, the barrel extension effectively serves as the breech end portion of the barrel and engages the barrel engagement portion of the upper receiver (figure 7).
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to form the inner surface of the barrel engagement portion of Mather as a tapered inner surface, as claimed, configured to engage a tapered outer surface of a barrel extension, and to form the barrel extension with such a tapered outer surface, as claimed, with a reasonable expectation of success, in order to form a slidable, plug-wise connection that promotes barrel centering and mitigates radial and/or axial play, which may develop via wear.
Regarding (B), it is noted that Mather discloses a pin that extends from the barrel assembly into engagement with the receiver, in order to index the barrel assembly relative to the receiver (paragraph 6). Thus, Mather employs a configuration that constitutes a reversal of parts relative to Applicant’s.
However, Aalto teaches that Applicant’s configuration is also known in the prior art, and is also used to index a barrel extension relative to an upper receiver. Specifically, Aalto teaches a pin engaged with an improved receiver, wherein the upper receiver defines an opening on a barrel end side of the ejection port, wherein the opening extends from an external surface of the upper receiver to a portion of the bore defined by the barrel engagement portion, wherein the pin is installed in the opening and is configured to extend into engagement with a slot in the barrel extension (figure 5, receiver 20, pin 208, barrel extension 35, slot 358).
Thus, it would have been obvious to one of ordinary skill in the art to substitute the claimed configuration, as clearly taught by Aalto, for the configuration of Mather to provide predictable indexing of the barrel extension relative to the upper receiver. Further, it is noted that a mere reversal of the essential working parts of a device involves only routine skill in the art. Further, it is noted that the barrel engagement portion of the proposed upper receiver of Mather, Farquhar, and Aalto is a tapered inner surface, as set forth above.
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Marked-up Figure 2 of Mather
In reference to claim 2, Mather in view of Farquhar and further in view of Aalto (the modified Mather) makes obvious the claimed invention, as set forth above.
In reference to claim 4, the modified Mather makes obvious the claimed invention (Mather, figure 2; paragraphs 5 and 6; see marked-up figure 2, above).
In reference to claim 13, the modified Mather makes obvious the claimed invention, as set forth above (also see Mather, paragraphs 5 and 6).
In reference to claim 14, the modified Mather makes obvious the claimed invention, as set forth above in the reference to claim 1 (pin taught by Aalto).
In reference to claim 15, The modified Mather make obvious the claimed invention, as set forth above in the reference to claims 1 and 12 (the slot is taught by Aalto to be positioned at a breech end of the barrel extension, extending between the outer surface and an inner bore thereof).
In reference to claim 17, the modified Mather makes obvious the claimed invention, as set forth above in the reference to claim 4.
In reference to claims 21 and 22, the modified Mather makes obvious the claimed invention, since the proposed modification would place the slot at the breech end of the barrel extension and the opening/pin at a location to engage the slot. Looking at figure 2 of Mather, this would locate the opening as claimed.
In reference to claim 23, the modified Mather makes obvious the claimed invention, as set forth above in the reference to claims 1 and 12 (the modification of Mather via Farquhar renders the inner surface of Mather, which extends from the aft-facing surface to the forward-facing surface, as a tapered inner surface).
In reference to claim 24, the modified Mather makes obvious the claimed invention, as set forth above in the references to claims 1, 12, and 23.
In reference to claim 25, the modified Mather makes obvious the claimed invention, as set forth above in the reference to claims 1 and 12 (the degree of tapering taught by Farquhar, applied to the barrel extension of Mather, would result in the claimed invention; see Farquhar, figure 2).
In reference to claim 26, the modified Mather makes obvious the claimed invention, as set forth above in the references to claims 1 and 12 (the first axial location need only be aft of the aft end of the barrel, but not necessarily at the very aft end of the inner surface).
In reference to claim 27, the modified Mather makes obvious wherein:
the upper receiver further defines a flat forward-facing surface located at a forward end of the upper receiver, the flat forward-facing surface extending between the threaded outer surface and the tapered inner surface and oriented perpendicular to the axis extending between the barrel end and the buttstock end (see above-reference to claims 1 and 12, 4, and 17),
the barrel extension defines an aft-facing surface that is oriented perpendicular to the axis and a flange that is located forward of the tapered outer surface (see above-reference to claims 1 and 12, 4, and 17),
the tapered inner surface of the upper receiver tapers continuously from the flat forward-facing surface to the aft-facing surface, the tapered inner surface being a frustoconical inner surface (see above-reference to claims 1 and 12, 4, and 17; also see figure 2 of Mather, the cylindrical inner surface that receives the barrel extension is replaced by a tapered inner surface, as set forth above),
the tapered outer surface of the barrel extension tapers continuously from the flange to the aft-facing surface, the tapered outer surface being a frustoconical outer surface (see above-reference to claims 1 and 12, 4, and 17; also see figure 2 of Mather, the cylindrical outer surface of the barrel extension is replaced by a tapered outer surface, as set forth above),
the barrel extension defines lugs that are configured to engage a bolt of an action of a firearm when a cartridge is chambered and the firearm is ready to fire (Mather, figure 2, bolt locking lugs),
during assembly, tightening the barrel nut draws the barrel extension rearward such that the tapered outer surface and the tapered inner surface are placed in compressive engagement and the flange of the barrel extension is drawn toward the flat forward-facing surface of the upper receiver (see Mather, figure 2; also note, a conical connection, like that of Farquhar, inherently provides compressive wedging), and
in an installed condition the tapered outer surface of the barrel extension engages the tapered inner surface of the upper receiver at at least a first axial location that is aft of a second axial location of an aft end of the barrel (see figure 2 of Mather, picture the cylindrical connection between the receiver and the barrel extension as replaced by a conical, tapered connection, and it is clear that a portion of said connection would be aft of the aft end of the barrel).
In reference to claim 28, the modified Mather makes obvious the claimed invention, as set forth above in the references to claims 1 and 12, 14, 15, 21, and 22; also see Aalto, figure 5, which shows the slot is in a valley between lugs 350 of the barrel extension 35).
Response to Arguments
Applicant's arguments filed 25 February 2026 have been fully considered but they are not persuasive.
Specifically, Applicant argues that the examiner’s rationale to modify Mather in view of Farquhar is flawed, since it assumes that Mather suffers from radial or axial play that develops during wear. Applicant states that Mather does not identify, suggest, or implies the existence of such a problem. The examiner respectfully disagrees, but also notes that Applicant’s argument is moot considering the fact the examiner provides multiple motivations for making the proposed modification, NOT just the mitigation of radial or axial play that could develop via wear.
The examiner clearly states that one of the motivations to modify Mather to form the inner surface of the barrel engagement portion as a tapered inner surface, as claimed, configured to engage a tapered outer surface of a barrel extension, and to form the barrel extension with such a tapered outer surface, as claimed, is to form a slidable, plug-wise connection that promotes barrel centering. This is the first listed motivation to combine, since the examiner considers such to be the primary motivation to modify Mather via Farquhar. Applicant addresses this rationale, but only in passing, stating there is no indication in Mather (FIG. 2) that “centering through wedging engagement would be desirable.”
However, the examiner does not make such an overly narrow statement as that which is immediately above-quoted. In fact, the term “wedging” or “wedge,” or any synonym thereof, does not appear anywhere in the above-rejection. If anything, Applicant’s instant recognition that wedging occurs in a conical connection only bolsters the fact that a person of ordinary skill in the art would be apprised of the various benefits and advantages associated therewith. Wedging provides a compressive fit that is more axially robust vis-à-vis a purely cylindrical connection, like that of Mather. Moving forward, the examiner notes that prima facie case of obvious has clearly been established.
The examiner asserts that the following rationale has been properly applied:
Mather provides a finding of a base device upon which the claimed invention can be seen as an improvement. FIG. 2 shows the base device, having a cylindrical connection between the receiver and barrel extension, as set forth above. The claimed invention includes a tapered connection between the receiver and the barrel extension, which can be seen as an improvement. It is noted that the advantages and benefits of a conical connection between mechanical parts are within the knowledge-base of a person having ordinary skill in the art, since such a connection is a purely mechanical, simple, and well-understood element of basic mechanical engineering, e.g., a conical connection promotes centering.
Farquhar provides a finding that the prior art contained a comparable device that has been improved in the same way as the claimed invention (see above, page 4, regarding A).
Further, Farquhar provides a finding that one of ordinary skill in the art could have applied the known improvement in the same way to the base device and the results would have been predictable. Specifically, Farquhar demonstrates that the improvement can be applied in a straightforward, predictable manner by forming the inner, barrel engagement portion of a receiver as a tapered inner surface, and by forming the breech or cartridge chamber end of a barrel with a corresponding outer tapered surface, in order to form a slidable plug-wise, conical connection.
Looking at Mather, FIG. 2, it is clear that the base device includes an inner, barrel engagement portion of a receiver and a corresponding breech or cartridge chamber end of a barrel assembly, wherein said end is formed as a barrel extension analogous to the breech or cartridge chamber end of Farquhar. Thus, the improvement taught by Farquhar could clearly be applied to Mather in the same straightforward, predictable manner noted above. Further, a person of ordinary skill in the art would be apprised of the benefits and advantages of making such a modification, as set forth above.
It is noted that Mather need not disclose or imply that the base device is need of such an improvement. That being said, a person of ordinary skill in the art would be apprised of the advantages and benefits of such an improvement, since a conical connection between mechanical parts would be well-understood by a person having a basic understanding of mechanical engineering. Within the context of firearm design and engineering, the examiner asserts that a person of ordinary skill in the art indeed possess at least basic, mechanical engineering knowledge.
Regarding claim 12, in response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). In Mather, the inner surface of the barrel engagement portion extends to an aft-facing surface of the upper receiver (FIG. 2). Modifying Mather in view of the teaching of Farquhar renders the inner surface as a tapered inner surface, and, thus, the result is a tapered inner surface that extends to the aft-facing surface of the receiver. Further, modifying Mather via the teaching of Farquhar, as set forth above, results in a tapered outer surface of the barrel extension that mates with a tapered inner surface of the receiver. In Mather, the aft end of the barrel is forward of at least a portion of the outer surface of the barrel extension, and, thus, said aft end of the barrel would be forward of at least a portion of the tapered outer surface of barrel extension modified as proposed.
Regarding claim 21, Applicant argues that the examiner fails to establish an obviousness rationale placing the opening aft of the threaded outer surface, as claimed. Applicant argues that the examiner makes a conclusory statement regarding such. The examiner respectfully disagrees. Aalto clearly teaches a barrel assembly and receiver, similar to that of Mather (set forth above; locking piece 35 fits the art recognized definition of a barrel extension). Further, Aalto teaches a slot formed in an end of the barrel extension and a pin extending through the receiver at the location of the slot, in order to form an indexing arrangement (figure 5; see above-rejection).
The examiner asserts that Mather could be reasonably modified to have an indexing arrangement, as taught by Aalto, in lieu of the indexing arrangement explicitly disclosed by Mather (paragraph 6), since such a substitution would provide predictable indexing; the proposed modification represents the mere substitution of one known indexing arrangement for another in an analogous art setting. It is of no consequence that the firearm of Aalto is not an AR-pattern firearm, since the firearm of Aalto is sufficiently similar to that of Mather, and the indexing arrangement could clearly be applied to Mather (i.e., it has a barrel assembly having a barrel with a barrel extension 35 that mates with a barrel engagement portion of a receiver 20 and includes an indexing arrangement, wherein the barrel held in the receiver compressively via a clamping arrangement 356, 366, 36, and 37 analogous to the flange and barrel nut of Mather). There is no indication in Mather that would preclude the application of Aalto’s indexing arrangement thereto.
The examiner asserts that such a modification, which is supported via all of the above, would result the barrel extension of Mather having a slot formed in its aft end, since this is what Aalto teaches. Looking at figure 2 of Mather, it is clear that the aft end of the barrel extension is at a location position aft of the threaded outer surface of the barrel nut engagement portion of the receiver. Thus, it is clear that a pin opening located at the slot in the aft end of the barrel extension, as taught by Aalto, would place said opening aft of the threaded outer surface. Thus, replacing the indexing arrangement of Mather with that of Aalto would clearly result in the claimed positioning of parts.
Thus, the examiner concludes that the above-rejections render obvious each and every limitation of the claimed invention.
Allowable Subject Matter
Claims 29-31 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Conclusion
Applicant's amendment necessitated any new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to GABRIEL J KLEIN whose telephone number is (571)272-8229. The examiner can normally be reached 11:30am-8pm.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Troy Chambers can be reached at 571-272-6874. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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GABRIEL J. KLEIN
Examiner
Art Unit 3641
/Gabriel J. Klein/Primary Examiner, Art Unit 3641
Prosecution Insights