How To Adjust Feed Lips on Your Detachable Magazine Feeding System

When you are changing your feeding system to a different caliber, experiencing feeding issues, or you have a specific caliber you are starting to use such as a wildcat cartridge – adjusting the feed lips may be necessary. This simple tutorial will walk you through how to flawlessly feed the caliber you’re wanting to use quickly without having to purchase a new magazine box.

What you’ll need:

When is adjusting the feed lips on your detachable magazine feeding system necessary?

  • Changing to a different caliber
  • You have a caliber that is not listed on our website such as wildcat cartridges
  • You’re experiencing feeding issues

The H-S Precision adjustment tool is constructed of aluminum which prevents scratches to the magazine finish. The milled slot with a beveled edge slips over the feed lips so you can confidently adjust the front and rear widths to the caliber-specific dimensions (below).

Simply slide the tool with the beveled side towards the inside of the magazine over the rail. Then, apply slight amounts of pressure inwards to tighten the gap and outwards to widen. Be sure to adjust both sides equally to keep the original center feed, center stack design.

The adjustment tool does come with an attached ruler guide. However, for best results, we suggest using a pair of calipers. Measure the rear gap and then the front gap (as close as possible to the ends of the magazine box) to take current measurements of your feeding system. 

Next, you will want to find the caliber listed on your instruction sheet (or below) to find the correct adjustment measurements needed. Determine the amount needed to open or close the feeding system gap and use your adjustment tool accordingly to bend into place; then, measure the changes with calipers. Repeat these steps until your gap dimensions are correct according to the specification guide.

Once your dimensions have been reached, load the cartridges outside of your rifle to ensure uniformity and proper feeding. 

If you have any more questions on adjusting the feed lips on your detachable magazine feeding system, contact us here or give us a call at 605-341-3006.



Setting Feed Gap

  1. Place the adjustment tool over the rail with the beveled side towards the inside of the magazine. Fig. 1
  2. Angle bender along rail diagonally as shown to widen or reduce front gap. Bend both rails the same amount. Fig. 2
  3. Angle bender along rail diagonally as shown to widen or reduce rear gap. Bend both rails the same amount. Fig. 3
  4. Check straightness by placing the straight edge of the bending tool against each rail. Fig 4.
  5. Check front and rear gaps with a Vernier caliper for best results. The scale on the bending tool can be used but will only give approximate results.

Feed Gap Specifications 

NOTE: Feed Gap specifications below are a close starting point. Small adjustments may be necessary for best performance. If large adjustments have been made and it’s still feeding improperly, check the clearance between the bolt and the top of the magazine feed rails. There should be roughly 1/32” to 1/16” clearance while pushing UP on the magazine. Excessive clearance will cause feeding malfunction.

Short Action CartridgeMagazine #Magazine #Magazine #Front GapRear Gap

Low CapMed CapHigh Cap
Remington: 17, 222, 223
204 Ruger
73697527.325.312
350 Legend73695727.325.312
6.5 Grendel, 6mm ARC73697527.360.370
22 Nosler75567554.360.370
224 Valkyrie75567554.360.370
300 AAC Blackout7369.325.312
22-250 Rem7368.380.380
220 Swift7371See Fig. 5See Fig. 5
6mm Rem
257 Roberts
73727384.400.420
284 Win737373757393.435.425
Short Action Ultra Mag SAUM:
6.5mm, 7mm, 300
737273757376.485.490
Winchester Short Mag WSM:
7mm, 270, 300, 325
737273757376.485.490
Ruger Compact Mag RCM:
300, 338
737273847393.450.480
35 Rem7372.395.410
Remington Magnum:
6.5mm, 350
737273847393.460.445
Creedmoor: 6mm, 6.5mm, 22
Remington: 7mm-08, 260
Winchester: 243, 308, 358
338 Federal
6 GT
6.5 Lapua
6 XC
737273847376.410.420
Long Action CartridgeMagazine #Magazine #Front GapRear Gap

Low CapHigh Cap
7×57 Mauser, 6.5×55, 6.5×55 Swedish7377 (< 3.061 COAL).415.425
7381 (> 3.061 COAL).395.410
6.5 PRC7390 (< 3.061 COAL).450.480
7379 (> 3.061 COAL).440.450
240 Wby Mag7377.395.410
6.5×284 Norma7390 (< 3.061 COAL).450.430
7380 (> 3.061 COAL).440.450
(> 3.061 COAL) 7367.395.410
300 H&H Mag7380.420.460
300 Win Mag73797382.440.450
7mm STW
8mm Rem Mag
73797367.440.450
338 Lapua73817382.475.440
Norma Magnum: 300, 33873817396.475.440
Remington Magnum: 7mm
Winchester Magnum: 264, 338
Norma Magnum: 308, 358
73797367.440.450
Weatherby Magnum: 7mm, 257, 270, 300, 34073797367.440.450
Remington: 25-06, 280, 280 Ackley Improved
30-06 Springfield
35 Whelen
270 Winchester
73817396.395.410
Nolser: 26, 27, 28, 30, 3373797367.460.460
375 H&H Mag7379.420.460
7396.395.410
7mm LRM, 300 PRC , 375 Ruger73817396.440.450
Remington Ultra Magnum RUM:
7mm, 338, 300, 375
73797367.460.460
Weatherby magnum: 30-378, 3787381.490.490
416 Rigby7381.490.500
416 Rem Mag, 458 Lott7379.440.450
458 Win Mag73797367.440.450