A Nurse with a Gun

Saturday, December 24, 2005

Getting 18.5 Inches

First.......18 inches. That is the number. 18.5 inches is fine & dandy. 17.98 inches is bad legal juju. Cement that in your head.

Next, you need to know how the boys in blue measure barrels so you can be compliant. They close the bolt. Then they drop a dowel marked at 18 inches into the muzzle. If their 18 inch mark ends up outside the muzzle, a trip to the pokey is in order. So.....how do you achieve this nirvana, the shortest legal length without going under?

First, settle on 18.5 inches to give you a little room for error. Get a dowel that will drop into a shotgun barrel. I use a 3/8 inch dowel. Next, mark 18.5 inches on your dowel. Close the bolt of your gun. Drop in the dowel, 18.5 inch measurement first. Now, mark the dowel again at the end of the muzzle. This is your present barrel length. Let's suppose for the moment that is 28 inches.

Now remove the dowel, and subtract the 18.5 from 28, ie the least legal length from the present length. Our result is 9.5 inches. Now, measure back from the muzzle 9.5 inches and mark the measurement on the barrel. Check it again. Put everything down, go have a cup of coffee and check it a third time. When you are totally satisfied that you are of legal length, make your cut.

I like to use a pipe cutter, but a chop saw could also be used. The key is to get a 90 degree cut. Many barrels have a taper, and that can throw you off on a chop saw table unless you compensate for it. Once your cut is made, remove the burred metal, burnish the area of the muzzle, and cold blue it. Finally, drill and tap a hole for a bead. I prefer a big brass bead.

Congratulations! You have now lowered the monetary value of your shotgun, but increased it's versatility markedly as a defensive weapon.

A couple of considerations:
1. The overall length of the shotgun must remain over 26 inches. If not, bad legal juju. As long as you have a full stock, no worries here. Be careful if you decide to make your own pistol grip.
2. Many magazine extensions need more than 18.5 inches of barrel for support. If you are going to use a magazine extension, install it first!

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Anonymous Windaria said...

The question is... what are you going to make pink?

11:27 AM  
Blogger Grampapinhead said...

Thank you, Thank you, an excellent answer to my inquiry.

Great instructions, you sure should be writing all the destruction manuals for my electronic toys.

Although, I have been wanting one for a long time, I am still reluctant to chop; down my daddy's model 1897. As much as I prefer a hammer on my guns, I think I may be
shopping for a mossberg soon.

4:47 PM  
Anonymous freddyboomboom said...

Mossberg markets a version of the 500 with both 28" and 18" barrels... And and 8 round magazine... :)

I sure wish I had gotten that when I bought mine several years ago. That would have saved me from ordering the 28" barrel for shooting clay pidgeons during the mating season.

2:05 PM  
Blogger Mr. Completely said...

I found a great way to get the muzzle absolutely square. Most automotive machine shops have a valve facing (grinding) machine, and most of them have a gizmo for grinding the end of valve stems square. You can clamp the barrel in the v-block where the valve stem would go, make a couple of passes across the grinding wheel, and it's dead on the money square. Works slick!

Mr. C.

11:24 AM  
Blogger Xavier said...

Cool idea Mr. C! I'm going to have to get another shooty just so can try that!

12:06 PM  
Blogger Ravenwood said...

I would add that when you close the bolt, you need to have chambered the longest shell the gun will fire. So if you have a shotgun that fires 2 3/4" or 3" shells, you need to chamber a 3" shell and then take your measurement.

Otherwise you'll end up a few inches short.

8:30 AM  
Blogger Xavier said...

In measuring barrel length you do it from the closed breech to the muzzle, see 27 CFR sec. 179.11. "the length of the barrel having an integral chamber(s) on a shotgun or rifle shall be determined by measuring the distance between the muzzle and the face of the bolt, breech, or breech block when closed and when the shotgun or rifle is cocked."
To measure overall length do so along, "the distance between the extreme ends of the weapon measured along a line parallel to the center line of the bore." 27 CFR sec. 179.11.


8:57 AM  
Blogger Ravenwood said...

Okay. I stand corrected.

8:02 PM  
Blogger 007 said...

I chopped my Mossberg with great success today. After putting the cold blue on it, it looks like I bought it this way. I gave myself 18.5" just in case.

12:44 PM  
Blogger 007 said...

I chopped my Mossberg with great success today. After putting the cold blue on it, it looks like I bought it this way. I gave myself 18.5" just in case.

12:45 PM  
Anonymous Anonymous said...

When chopping a semi auto is there any consideration needed so as not to render it inop due to gas pressures etc??? Can I safely go ahead and go 18.5" on a Remington semi? thanks

10:32 PM  
Blogger Xavier said...

I don't think so anon, but I have never chopped a semi, so I can't say for certain.

12:20 AM  
Anonymous Anonymous said...

Hi do you have any suggestions / instructions regarding cutting the wooden stock? I have a 30" squibman that I am thinking of cutting the barrel down to 20" and I have to saw the stock as well to get a nice fit on me. My question is how do I get a perfect stock "fit" on my shoulder. How long is too long and how short is too short? Thanks!

7:51 AM  
Anonymous mistery man said...

I was just wondering ok 18.5 with a shell or without. i know its a dumb question but thats ok .id rather ask a dumb question now than look like a dumb a- later THANK YOU in advance....

6:37 PM  
Blogger andson jhon said...

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10:41 AM  
Anonymous john jay said...


please do not put a loaded shell in the chamber of the shotgun, and then be handling it, period.

for any reason. you are liable to blow your head off, or take a hand or a major portion of it.

and, as the man says, the regulations provide for measuring the length of the barrel against the breach face/bolt face.

john jay

12:28 AM  

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