The Rifle Documented Here — September 2026

Volumes 1 to 7 describe the pattern — what each M40 was, how its action works, how it is kept working, and how a clone is built. This volume describes one rifle: a Remington 700 SPS Varmint in .308 Winchester that its owner is building as an M40A1 clone. It is the volatile part of the dive, and it is written that way: every statement about the rifle is as documented in September 2026, from the owner’s inventory record (last modified 17 September 2026) and the owner’s answers of 19 September 2026, and parts are kept strictly in three categories — installed, on hand but not installed, and pending. A part on hand is not fitted, and nothing here should be read as saying otherwise.

Where the record is silent, this volume says so. The one inference it draws — about the donor’s era — is labelled as one.

8.1 The Designation — Why “A1”

The owner’s standing decision, made on 18 September 2026, is that this rifle is an M40A1 clone. That decision stands in this dive and is not second-guessed here.

It needs one paragraph of context, because the parts list alone would suggest otherwise. The owner’s own inventory tab for the rifle is named for the M40A3, and several parts on hand are A3-pattern: the McMillan A-4 stock is the A3/A5 stock, and the Harris notched-leg bipod with its KMW Pod-Loc matches the published description of the A3’s (Volume 3).¹ The build has evolved over years, and its owner has settled on the A1 designation for the rifle as a whole.

The pattern-versus-unit split exists for exactly this case. The A1 pattern is fixed and is documented in Volume 2. The unit is a clone in McMillan’s sense of the word — “built to the basic specs as the M40a1” and meant to be shot, taking the easier choice where fidelity and practicality conflict (Volume 7).² A clone of the A1 that carries A3-pattern parts is a coherent thing to build; it is simply not a replica of either, and this volume does not describe it as one.

8.2 The Donor Rifle

Table 1 — The Donor Rifle

	As recorded	Note
Model	Remington 700 SPS Varmint
Calibre	.308 Winchester / 7.62×51 mm
Barrel	26 in, the factory barrel, not cut (confirmed by the owner, 19 September 2026)	26 in is the SPS Varmint’s factory length in both the 2016 and 2026 listings34
Twist	not recorded	1:12 on the legacy Remington .308; 1:10 (5R) on the current RemArms .308. The unthreaded factory barrel points to the former — see below
Muzzle	Threaded in the builder’s own shop, on a lathe; the barrel came from the factory unthreaded (owner, 19 September 2026). Pitch 5/8×24 per the Suppressors by Caliber dive	See “The Barrel and the Muzzle” below
Trigger	not recorded	The legacy rifle shipped with the X-Mark Pro
Stock	The factory SPS Varmint stock — still fitted (owner, 19 September 2026)	The McMillan A-4 is on hand, not fitted
Date of manufacture	not recorded	Decides the twist, the trigger and the recall question

The date of manufacture is the one that decides the others, and it can be answered from the rifle’s paperwork. Volume 7 sets out why: a legacy Remington .308 SPS Varmint was listed with a 1:12 twist and an X-Mark Pro trigger and no factory thread;³ the current RemArms .308 is listed with 1:10 5R rifling and a factory 5/8×24 thread.⁴ A legacy rifle made between 1 May 2006 and 9 April 2014 is also inside Remington’s X-Mark Pro recall population (Volume 6).⁵

8.3 Configuration as Documented, September 2026

8.3.1 Installed

Table 2 — Installed

Part	Detail on the record	What it is
Kinetic Research Group Bolt Lift	”KRG bolt lift”; which of KRG’s two versions is not recorded	A clamp-on oversize knob that fits over the factory 700 knob with a screw and reinforcing pins; owner-installed; reversible unless epoxied.6 It does not alter the bolt handle (Volume 6)
Harris 6–9 in notched-leg swivel bipod	”HBRMS” on the record	Shared between rifles. Matches the published description of the M40A3’s bipod (Volume 3)
KMW Pod-Loc	on the Harris	Moves with the bipod; shared

None of the three alters the rifle. The rifle otherwise stands on its factory SPS Varmint stock and its factory barrel, threaded by the builder; everything that would change that is in the next table.

8.3.2 On hand — not yet installed

Table 3 — On hand — not yet installed

Part	Detail on the record	Pattern it belongs to
Badger Ordnance 20 MOA Picatinny rail	which of Badger’s 20 MOA short-action rails (steel #6-48, aluminium, or steel #8-40) is not recorded	Neither. The A1 had no rail; the A3/A5 rail was 30 MOA with a clip slot and #8-40 screws (Volume 3).7 A 20 MOA rail is a practical clone choice
TPS 1-in rings	height not recorded	A1-era scopes were steel-tubed Unertls; the A3/A5’s Schmidt & Bender was 34 mm. 1-in rings take only 1-in tubes
McMillan A-4 stock	which A-4 — the Marine “Mod 1”, the “Mod 2”, or McMillan’s current A-4 — is not recorded	A3/A5 stock (Volume 3).2 The A1’s was the McMillan HTG
Surgeon Rifles bottom metal, detachable magazine	part number recorded as 100-004-303WB; not verified against Surgeon’s own site during this work	A3/A5 function (detachable magazine). The A1 had Winchester-pattern steel with a floorplate

8.3.3 Pending

Table 4 — Pending

Work	Detail on the record
Inletting the stock for the Surgeon bottom metal	Pending; by whom is not recorded

Volume 7 covers the inletting job — the drawing the inlet is cut to, a fixture that references the action’s axis, and a skim of bedding for the final fit — and it applies directly to this step.

8.3.4 Undecided

Table 5 — Undecided

Item	As recorded
Scope	”Bushnell Scope ???” — the choice has not been made

8.3.5 Considered and not chosen

The record notes two alternatives the owner considered for the stock: a Manners T2A stock and an MDT HS3 chassis. Neither is an M40 pattern; both are recorded here because they show the build’s direction was open.

8.4 Measured Against the Pattern

Table 6 — Measured Against the Pattern

	M40A1 pattern (Vol 2)	M40A3 pattern (Vol 3)	The rifle documented here, September 2026
Action	Rem 700 SA, trued, lug welded	Rem 700 SA	Rem 700 SA (SPS Varmint); truing not recorded
Barrel	24 in stainless, 1:12, 6 grooves	24 in, 1:12, 5 grooves (USMC)	26 in factory barrel, carbon steel (the SPS Varmint’s, per both maker listings); twist not recorded
Muzzle	bare, recessed crown	recessed crown	threaded 5/8×24, cut by the builder — an A5-era feature
Stock	McMillan HTG	McMillan A-4	factory SPS Varmint stock fitted; A-4 on hand, not fitted
Bottom metal	Win 70-pattern steel, floorplate	D.D. Ross, then Badger DM	Surgeon DM on hand; inletting pending
Scope base	one-piece, hand-fitted, no rail	M1913 rail, 30 MOA	Badger 20 MOA rail on hand
Scope	Unertl 10×	Unertl 10× → S&B 3–12×50	undecided (a Bushnell is being considered)
Bipod	none in the A1 fact file	Harris 6–9 in + KMW Pod-Loc	Harris 6–9 in + KMW Pod-Loc installed, shared
Bolt knob	factory	factory	KRG Bolt Lift installed
Ammunition	M118, 173 gr, 2,550 ft/s	M118LR, 175 gr	175 gr at 2,550–2,600 ft/s on the record

Read across, the table says what the owner’s decision already says: an A1 by designation, with its fitted parts and its parts on hand drawn mostly from the A3’s era.

8.5 The Barrel and the Muzzle

Three facts were confirmed by the owner on 19 September 2026, and they settle what the inventory record left open.

1. The barrel is 26 in — the factory SPS Varmint barrel, not cut. It is therefore a carbon-steel heavy-contour barrel,³⁴ two inches longer than the M40A1’s and not stainless. An earlier edition of this hub’s Suppressors by Caliber dive gave 24 in; that dive has since been corrected to 26 in.
2. The muzzle was threaded in the builder’s own shop, on a lathe. The barrel left the factory unthreaded. The thread is 5/8×24, as the Suppressors by Caliber dive records it. A bare muzzle is the A1 and A3 pattern; a thread is an A5 feature (Volume 3). The thread’s value depends on its concentricity to the bore, which How Suppressors Work covers.
3. The factory stock is still on the rifle. The McMillan A-4 is on hand and not fitted, and inletting it for the Surgeon bottom metal is pending.

What the unthreaded factory barrel suggests — an inference, not a finding. Remington’s own listing of the SPS Varmint in January 2016 showed no factory thread on the .308, with a 1:12 twist and the X-Mark Pro trigger; RemArms’s current listing shows the .308 factory-threaded 5/8×24 with 1:10 5R rifling.³⁴ A barrel that arrived unthreaded is therefore consistent with a Remington-era rifle rather than a RemArms one — and if so, its twist would be 1:12, the M40A1’s own,⁸ and its trigger would have shipped as an X-Mark Pro. That chain rests on two listings, not on this rifle’s paperwork. The date of manufacture has not been confirmed, and until it is, the twist and the trigger remain unrecorded here, and so does whether the rifle falls in the X-Mark Pro recall window (Volume 6).

A note on the pattern. Some clone literature, including an earlier edition of the Suppressors by Caliber dive, treats the M40A1’s twist as contested between 1:12 and 1:11. The Marine Corps’s own sniping manual gives the service M40A1 as 1 turn in 12 inches, right hand, six grooves (Volume 2).⁸

The rifle as a suppressor host. With a threaded muzzle the rifle is a suppressor host, and everything about that belongs to the Suppressors by Caliber dive, including the point that a 1:12 or 1:10 .308 is a supersonic rifle behind a can. The law, federal and Michigan, is in the Suppressor Law dive. A bolt-action .308 rifle with a 26-inch barrel raises no National Firearms Act question of its own.

8.6 Ammunition

The record gives 175-grain ammunition at a muzzle velocity of 2,550–2,600 ft/s. It does not say whether that range is a chronograph measurement from this barrel or a published figure, or which load it is.

For comparison, from the sources in Volumes 1 to 3: the Marine Corps’s M118 Match was a 173-grain boat-tail at 2,550 ft/s, the figure its fact file also gives as the M40A1’s muzzle velocity; the later M118LR load (the Lake City “AA11”) used a 175-grain Sierra MatchKing, described in 2001 as running “at up to 2680 fps”.⁸⁹¹⁰ A 175-grain load at 2,550–2,600 ft/s is squarely inside the envelope the M40’s 1:12 twist was specified for. Loading it is the business of The Reloading Bench.

8.7 The Scope — Decisions That Are Already Made

The scope is undecided, but two parts already on hand narrow the choice, and they are worth stating before a scope is bought.

• The rings are 1-in. A 1-in ring set takes only a scope with a 1-in main tube. Many long-range variable scopes use 30 mm or 34 mm tubes; the A3/A5’s Schmidt & Bender did (Volume 3). If the scope chosen is not a 1-in tube, the TPS rings on hand will not fit it.
• The rail is 20 MOA. A canted rail helps only if the scope has enough internal elevation travel to reach a 100-yard zero with the cant in place. Badger gives its 20 MOA short-action rail as “20 MOA bias (5.81 mils)”.⁷ The scope’s published elevation travel should be checked against that before purchase. The general theory is in the Types of Scopes dive.

An A1-faithful choice would be a fixed 10× in the Unertl style on a one-piece base, which is a different mounting system from the Badger rail entirely (Volume 2). The parts on hand point toward a modern variable on a rail, which is a clone decision in the sense of Volume 7.

8.8 The Trigger

The trigger fitted to the rifle is not recorded. Because an SPS Varmint of legacy manufacture shipped with the X-Mark Pro,³ and X-Mark Pro rifles made from 1 May 2006 to 9 April 2014 are in Remington’s recall population,⁵ the trigger’s identity and history belong on the record before the rifle is used further — whether it is the original, a recall replacement, a settlement retrofit, or an aftermarket unit (Volume 6). Whatever it is, the maker’s ten-times bolt test and the trigger checks in Volume 5 apply to it.

8.9 The Build From Here

Using the sequence in Volume 7, with the recorded state of each step:

Table 7 — Using the sequence in [Volume 7](/actual-firearms/rifles/remington-700-m40a1/vol-7/), with the recorded state of each step

Step	State, September 2026
Replica or clone; A1 or A3 parts	Decided: an M40A1 clone (owner, 18 September 2026), with A3-pattern parts on hand
Donor established: date, trigger, twist, muzzle	Not recorded
Scope chosen, then rail and rings to suit	Scope undecided; 20 MOA rail and 1-in rings on hand
Action trued; lugs lapped; recoil lug	Not recorded
Barrel: length, crown, thread, headspace	26 in factory barrel, uncut; threaded 5/8×24 in the builder’s shop (confirmed); headspace not recorded
Trigger verified or replaced	Not recorded
Bottom metal and stock: inlet, bed, torque	A-4 and Surgeon DM on hand; inletting pending
Rail and rings fitted	On hand, not fitted
Function test; accuracy proof	Not recorded

8.10 What Is Owed

• Photographs, in order of value: the rifle full-length as it stands; the muzzle and barrel roll marks; the on-hand parts together; the trigger; then each stage of the build as it happens.
• A chronograph string from this barrel with the 175-grain load.
• The donor’s date of manufacture, and with it the twist and the trigger. (Barrel length, muzzle and stock were confirmed by the owner on 19 September 2026.)

8.11 Bibliography

Footnotes

1. “M40 rifle”, English Wikipedia, wikitext consulted 2026-09-19 — the M40A3’s “6–9” Harris notched swivel type bipod, model S-BRM, with a KMW Pod-Loc”. ↩

2. McMillan, “M40a1 and M40a3/5 Specific Stocks”, company blog, 10 August 2017. Archived at https://web.archive.org/web/2020id_/https://mcmillanusa.com/m40a1-m40a35-specific-stocks/ ↩ ↩²

3. Remington Arms, “Model 700 SPS Varmint”, product page archived 20 January 2016 — .308 Win order no. 84218, 26 in, 1:12, X-Mark Pro externally adjustable trigger, hinged floorplate. https://web.archive.org/web/20160120193845/http://www.remington.com:80/rifles/bolt-action/model-700/model-700-sps-varmint ↩ ↩² ↩³ ↩⁴ ↩⁵

4. RemArms, “Model 700 SPS Varmint”, product page consulted 2026-09-19 — .308 Win R84223, 26 in, 1:10, 5R rifling, “Threaded Muzzle: … 5/8 x 24 (.308 Win & 6.5 Creedmoor)”. https://www.remarms.com/rifles/bolt-action/model-700/model-700-sps-varmint ↩ ↩² ↩³ ↩⁴

5. Remington Arms Company, LLC, “Product Safety Warning and Recall Notice” (X-Mark Pro), archived — https://web.archive.org/web/2014id_/http://xmprecall.remington.com/ (consulted 2026-09-19). ↩ ↩²

6. Kinetic Research Group, “Bolt Lift”, product page consulted 2026-09-19. https://kineticresearchgroup.com/product/bolt-lift/ ↩

7. Badger Ordnance, Remington short-action scope rails, product pages consulted 2026-09-19 (306-06, 306-06a, 306-06-8 at 20 MOA; 306-06-A3 USMC at 30 MOA). https://www.badgerordnance.com/shop/mounts/manufacturer/remington.html ↩ ↩²

8. Headquarters, U.S. Marine Corps, FMFM 1-3B, Sniping, 1981, reissued as MCWP 3-15.3 (2004) — the M40A1’s tabulated data (24 in, six grooves, one turn in 12 in right hand) and M118 Match (173 gr, 2,550 ft/s). Internet Archive item mcwp-3-15.3-sniping-2004. ↩ ↩² ↩³

9. Headquarters, U.S. Marine Corps, Fact File, “M40A1 Sniper Rifle”, last modified 15 December 1995 — muzzle velocity 2,550 ft/s. Archived at https://web.archive.org/web/20070225004953/http://www.hqmc.usmc.mil/factfile.nsf/7e931335d515626a8525628100676e0c/03ae5c82962bc0f48525627b006d3126?OpenDocument ↩

10. Brian C. Sheetz and Doug Wicklund, “Long-Range Warriors: The USMC M40 Rifles”, American Rifleman, February 2001 — the AA11 load, 175-grain Sierra MatchKing “at up to 2680 fps”. https://www.americanrifleman.org/content/long-range-warriors-the-usmc-m40-rifles/ ↩