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Thread Protector Caps

Thread Caps

CNC machined stainless steel muzzle thread protector caps. In stock in a variety of sizes. These are made in-house on our own CNC lathe (as well as our own patented/registered NZ muzzle brakes). Stainless is better and more durable than soft aluminium, and with a bit of grease on the threads they won’t rattle loose.

If you require a cap for a non-standard thread we may be able to do it as a custom or short production run, but note that minimum costs for this service do apply due to machine set-up costs, and extra time involved.

Some thread caps for AR rifles are available in Flat black (GunKote) for an extra $5.00 (i.e. $25.00 , usually 0.735″ to 0.746″ diameter, in 1/2-28 or 5/8-24 only).

Thread and diameter options (usually in stock in 0.020″ or 0.5mm diameter increments) are as follows (RH threads only):

1/2-20 0.570″ – 0.670″, 0.870”
1/2-28 0.570″ – 0.746″

M13X1.0mm  – 0.580” only
M14x1.0mm – 0.620” to 0.746”

9/16-24 – 0.620″ to 0.746″, 0.830”

9/16-28 – 0.620”, 0.660”
M15x1.0mm – 0.660″ to 0.746″
5/8-24 – 0.685″ to 0.935″

5/8-28 – 0.685” only

M17x1.0mm – 0.760”, 0.800”
M18x1.0mm – 0.770″ to 0.935″
3/4-28 – 0.830″ to 0.930″
M20x1.0mm – 0.930″, 0.950”
7/8-28 – 0.970″, 1.010”, 1.130”

Standard thread cap length is 0.583″ long. (14.8mm) approx. Note that some sizes are produced in a longer 0.650″ length (16.5mm) only. Please enquire for specific details.

*Please specify thread size and cap diameter and length required when ordering or asking questions. PLEASE BE AWARE THAT SOME GUNSMITH THREADED BARRELS MAY HAVE SLIGHTLY OVERSIZE THREADS. As such we cannot guarantee 100% that our ‘correct spec’ thread caps will fit YOUR barrel if it was not threaded by us. We can exchange if required, but may have to charge for any extra admin time, etc. as we literally only make a few dollars on the sale of these caps, so cannot really afford to absorb the cost of excessive amount of admin time or freight costs on very small sales.

We can ship multiple thread caps together if required. Dealer/gunsmith inquiries welcome for larger orders as well.


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