1911 barrel diameters

Being I've decided to make a barrel testing fixture and looking at other designs I'm trying to determine the best way to hold the barrel. Wiseman uses a block that has the barrel radius on the top and bottom plus a slot for the lower lug. Not sure if it's a one size fits all, I see another is made for ramped barrel only difference is the slot extends to the very end of the bottom block. Problem is only about 2" of the rear of the barrel is supported. The Clark and Atalanta Arms testers seem to have the support extend to the end of the barrel. Adam said the AMU unit is similar to the Atlanta tester but they have 2 screws that are use to hold the barrel on the end and the unit is mounted on linear bearings to absorb recoil. I can use 2 or 4 brass or brass tipped set screw for the end. Linear rails and carriages on the way.
 I have 2 new Kart gunsmith fit barrels diameter near the breach is .6945" and .6955" near the first lug. Then .5765" just ahead of first lug to .5785" near the end/muzzle of the barrel. Benson drawing has .696" +.000/-.004" for the breech side and .580" +000/-.002" at muzzle end.
 Wiseman made a comment that barrel can be tested at 15 or 25 yards, odd coming from an ex Marine smith. However when testing results are listed in magazines the range is 15, 20 or 25 yards!
 Atlanta and Clark were testing at 50 yards, I know the AMU tests at 50 yards. I intend to test at 50 yards.
 My micrometer is tested on Starrett A1 grade gauge block accuracy +/- .000006"
 I'm wondering what others might have as barrel dimensions so I can determine how to make the barrel holding fixture.
 Being I'm working on .22 conversion the test fixture will start with a .22 holder for Nelson/Marvel/Advantage Arms barrels. Holder will be easier since they are fixed just above the slidestop pin. Barrels I made are .625" wide.

If this can help…

Wobbley; That's the Benson drawing I referred to. I have the complete set of all the drawings.

I would make the barrel “holding” part of the fixture interchangeable. More flexibility down the line if you have reason to test something other than a 1911 barrel or something more specialized such as a coned barrel.

I like the Wiseman design in that he has interchangeable blocks for different types of barrels. I don't like that he only uses the rear of the barrel to hold it in the fixture. So instead of making it short like he did to make it 5" long. Also have the idea to get a 1911 slide, remove the rear and use it in the tester so as to test the barrel as held in the 1911. Plus one to accept the Nelson type barrel that will probably work with Marvel and Advantage Arms barrels. In addition put it on linear rails to absorb recoil. What I want is barrel dimensions of different barrels to determine how to make the 1911 45acp barrel adapter.

 sort of like this.... my removable solution to supporting the front of the barrel with actual bushings. The unit simply slides on and the two screws hold it down.. zero modification to the Sams unit. to date we haven't used it much but testing to follow.

I understand using the bushing. I'm sure when I get one made friends at the club will want barrels tested. They can supply their bushing but the outside dimmers of the bushing might be different. I'm sure most barrels are made to a dimension that's an industry standard at the lug side. Benson drawing has .696" +.000/-.004 inches. But the barrel end is what I'm concerned about. Any movement will change group size but not the barrels fault. If bushing is provided it may not be done right and make a great barrel shoot bad group. Or at least larger than if correct fit bushing is used. By adding recoil absorption with linear rails so tendency of the barrel to move is lessened. Since my first Wiseman like insert (much better fit than what I seen in the videos) will be for .22 Nelson and similar barrels. However I want to get as much info on barrel size so that I can probably build a few 45acp barrel holder inserts. Maybe one like the Wiseman, another with set screws to hold the end. I'm even thinking that I make an insert so that is a slide has a scope mount it can be inserted in fixture so that the entire assembly can be tested.
 Possibly instead of a half round the top insert, one made with a Vee so all diameters will fit perfect. Barrel with bushing can be put is so bushing is in a slightly larger hole with 4 set screw to adjust so the bushing is held from movement, bushing can be removed and set screw hold the barrel to check bushing fit.
 My concern is making a base that will do all and not find it should have been 1/2" longer later, sort of measurer twice cut once. In this case explore all possibilities prior to making the item. However overkill may not be worth the effort so simple is better!

Here are dimensions from a Kart .45 ACP barrel. 

Muzzle   .5805"
Behind Muzzle  .5742"  .5745"  (oval)
Near Breech   .5730" .5726" (oval)

Certified, calibrated Micrometer.

I have another Kart and a KKM I will try to get to later this evening.

Thanks Da/SA! Will help if breach end was measured too as I listed in my first post. Wiseman tester holds the barrel on that end. jglenn21 posted this link  https://www.youtube.com/watch?v=P_6P5eVSaaA&t=22s  in my topic 1911 barrel testing fixture. I also found more Wiseman videos that show more details on how the tester is made. That method will be great for testing the Nelson/Marvel/Advantage Arms/FCW  .22 barrels.

The breech end is all over the place from horizontal to vertical and front to rear.

It would have to be mapped out to make any sense.

I would think that clamping a .45 barrel in a barrel tester in a manner other than that in which it is supported in 1911 pistol would tend to skew the "real world" results.

Interesting! The barrel I have don't change more than .001", yeah near the small barrel diameter the larger diameter is tapered on the bottom but sides remain constant. I agree a better hold should be more like the barrel is held in the pistol so when I make the tester the barrel support end will be longer and insert more like the 1911 slide end.
 Looking at other Wiseman videos he claims he no longer makes the manual firing pin release model. Has two on the bench that have been ordered by Hornady and Winchester. I suspect his testers are primarily for ammo makers. Most of the test results posted in the magazines are at 15 or 25 yards!

Greetings,

My tester clamps the breech end of the barrel.

Nominal dimension is 0.695".

Very few barrels I have tested have uniform dimensions.

One runs into machining mismatch where the lower lug is and just behind the lug near the chamber mouth.

I use a three point "tripod" to secure/stabilize the muzzle and as long as the barrel is round, not square, clamping is easy. (Three brass screws with lock nuts.)

I have been thinking of redesigning my rest to make use of an ER 40 collet to clamp on the main body of the barrel.

Since I have two years of unfinished projects for other people this effort is still a work in progress.

Cheers,

Dave

I'll try Vee instead of radius for top and bottom halves near the breach and 4 brass tipped set screws with lock-nuts for muzzle end. Also thinking about ER-25 collet, they are available up to 5/8"

Just thinking, but an "octagonal" design instead of a circle or vee would yield several more edges to contact the barrel. I'm sure you know that a little undersized radius would be helpful also.

Just an idea; how about a two piece block at the muzzle that has an O-ring groove machined in it? This would allow an O-ring to be inserted around the barrel and then the top block bolted down. This would allow for different barrel diameters and maybe help absorb harmonics.
Engineers?

I'm not convinced "Barrel Harmonics" are a real issue in short pistol barrels.  In a 1911 style pistol, where the barrel is supported at the rear & the front, I think barrel flexing when firing is a concern.  That why I always liked the idea of the spherical bearing front bushing Briley sells, but I've never seen any real test data to say how much it helps.  It probably depends a lot on the barrel & how well it is fitted in the rear, so it would be difficult to get good data without a ton of testing.

Back to the original issue:  The usual approach for hanging onto round things is Vee blocks.  Again, you have two points of support, and barrel diameter (and apparently, roundness) variations.  When you clamp it down, it will be difficult to avoid stressing the barrel due to misalignment of the front & rear supports, no matter how careful you are.  The O-ring is a nice idea in that it provides some support, but it's not a hard mount.  Then again, it doesn't duplicate the real-world support of a well fitted pistol.  You certainly don't want to have to carefully fit the barrel & fixture together for every test.

My conclusion:  it's tricky...

The planned Vee will be for top and bottom that would create a square opening. But the shape of the Vee I had in mind will be octagonal, No need for the Vee to come to sharp points. Barrel diameters at the breech end will only change a few thousandths so octagonal shape will save space but barrel contact will only be in 4 places. 8 will require exact size.
 O-Ring might help with used barrels to compensate for wear. Various materials are available, I've seen some made from Nylon, possibly the type with square cross -section. What I like about the Wiseman design is inserts are made to hold the barrels, as time permits different types can easily be made to determine the best method or have flexibility in holding methods.
 I don't know the sequence of machining operations used to make a slide, it might be possible to buy one that had the firing pin side seriously screwed-up so much it can't be sold as they do seconds at Perry. I could cut it off at the hood and fit it in the Wiseman type insert opening so as to test the barrel as used. I like and use Briley bushings. The outer part can be fitted to the slide like insert and few insides used that fit barrel tested, if a barrel tested that used Briley bushing the inner ring can be used with the outer that fit the holder.
 Wiseman design offers greater flexibly in barrel holding methods.