Does this 20 Cal barrel bore look normal???

[searcher]

One thing I'd suggest is using loaded cartridge overall length as cited in the Hornady manual for your V-max bullets. I have loaded tons of those things in the small bullet category for .17, 20 and .224 caliber and my experience has been (for me), they like to jump more than they like to be run up close to the lands. Because there is so little bearing surface - it is important to keep the entire bearing surface inside the neck of the brass on the A/R's, as you more often than not end up with big concentricity problems when the bullet strikes the ramp if you don't. If you have any LT-32 powder - try a bit with those V=-Max bullets. All the .20's I've tried so far like that combo. I never had fantastic results with TAC. My results were similar to what you are getting. I like to test until a barrel is about toast - but I find it enjoyable. I tried about every powder recommended and many not. Most of the results I got ran from about 1/2" to around 1 1/4" in size for 5 shots. The best (with LT32) ran closer to just about 1/4". Pays to test until magic is found. Skim turning your necks helps tremendously with the .20's. Good luck!

 

[Bachekermooni]

One thing I'd suggest is using loaded cartridge overall length as cited in the Hornady manual for your V-max bullets. I have loaded tons of those things in the small bullet category for .17, 20 and .224 caliber and my experience has been (for me), they like to jump more than they like to be run up close to the lands. Because there is so little bearing surface - it is important to keep the entire bearing surface inside the neck of the brass on the A/R's, as you more often than not end up with big concentricity problems when the bullet strikes the ramp if you don't. If you have any LT-32 powder - try a bit with those V=-Max bullets. All the .20's I've tried so far like that combo. I never had fantastic results with TAC. My results were similar to what you are getting. I like to test until a barrel is about toast - but I find it enjoyable. I tried about every powder recommended and many not. Most of the results I got ran from about 1/2" to around 1 1/4" in size for 5 shots. The best (with LT32) ran closer to just about 1/4". Pays to test until magic is found. Skim turning your necks helps tremendously with the .20's. Good luck!

Thanks. I have no LT32, but I do 2230. I have had very good luck with TAC and 50 Vmax in 223 Rem in the same CZ rifle before it got re-barreled. I have also good luck with Hornady 68 bthp in my Kimber Montana on 223.
The entire bearing surface in in the neck already.

 

[L.Sherm]

I have very good luck with AA2230 in mine

 

[Bachekermooni]

finally got a chance to take a closer look at the LabRadar data. WOW. The first two 40 vmax groups had an ES of 77 and SD of 27. The last three shot group (the vertical one with worst grouping) had ES of 29 and SD of 14.5.
The 32vmax were really bad. ES of 159 and SD of 50.6; another ES of 150 and SD of 44.6. The 8-shot group with only 6 getting recorded, had an ES of 203 and SD of 72.6.

The 32 Vmax powder was thrown by the Hornady LnL Powder Measure; the 40 Vmax by RCBS ChargeMaster Lite.

 

[Bachekermooni]

I have very good luck with AA2230 in mine

how far off lands with which bullets?

 

[L.Sherm]

34g V- nitemare bullet from midsouth.
Not sure how far off but its close thats were ive had those bullets shoot the best even touch or in just a tad in multiple 20 cals.

 

[Bachekermooni]

34g V- nitemare bullet from midsouth.
Not sure how far off but its close thats were ive had those bullets shoot the best even touch or in just a tad in multiple 20 cals.

thanks

 

[searcher]

finally got a chance to take a closer look at the LabRadar data. WOW. The first two 40 vmax groups had an ES of 77 and SD of 27. The last three shot group (the vertical one with worst grouping) had ES of 29 and SD of 14.5.
The 32vmax were really bad. ES of 159 and SD of 50.6; another ES of 150 and SD of 44.6. The 8-shot group with only 6 getting recorded, had an ES of 203 and SD of 72.6.

The 32 Vmax powder was thrown by the Hornady LnL Powder Measure; the 40 Vmax by RCBS ChargeMaster Lite.

Moving to a faster powder should get your ES down.

 

[Bachekermooni]

AA2230 is next.

 

[JohnD]

I’ve got several barrels from your top tier list. One broke in at about 8-9 rounds and became an absolute laser. Another looked like a copper mine and was very inaccurate on a very nice custom rifle with a high end rust blue finish. The manufacturer took it back, replaced the barrel and when asked about bluing the barrel, they took care of that so well I couldn’t tell the finish was any different than was on the action. I would think things will work out.

John

 

[Bachekermooni]

Waiting for the weather to break...

 

[Bachekermooni]

One thing I'd suggest is using loaded cartridge overall length as cited in the Hornady manual for your V-max bullets. I have loaded tons of those things in the small bullet category for .17, 20 and .224 caliber and my experience has been (for me), they like to jump more than they like to be run up close to the lands. Because there is so little bearing surface - it is important to keep the entire bearing surface inside the neck of the brass on the A/R's, as you more often than not end up with big concentricity problems when the bullet strikes the ramp if you don't. If you have any LT-32 powder - try a bit with those V=-Max bullets. All the .20's I've tried so far like that combo. I never had fantastic results with TAC. My results were similar to what you are getting. I like to test until a barrel is about toast - but I find it enjoyable. I tried about every powder recommended and many not. Most of the results I got ran from about 1/2" to around 1 1/4" in size for 5 shots. The best (with LT32) ran closer to just about 1/4". Pays to test until magic is found. Skim turning your necks helps tremendously with the .20's. Good luck!

What loads do you use with lt-32 and 32&40 Vmax? I found some LT-32.

 

[Bachekermooni]

I also took off the scope and replaced it with a T36. I use it when developing loads for accuracy. Nice thing about CZ 527: two screws and the mount with the scope are off the action. Put it back on and it is back to zero.

 

[msalm]

I am not an expert on what custom barrel finishes should look like. So I need your help.
I have attached the pics of a super clean bore - only 8 rounds. I have two other custom barrels - one from Lilja and one from Pac-Nor. Both 6mm, 8 twist. Never seen these types of machining marks perpendicular to the bore line on custom or factory (TC, Ruger, Howa, Kimber, ...) factory rifles.

The marks are all on one of the three grooves.

Your feedback is greatly appreciated.

If that barrel doesn’t shoot, I don’t think it’ll be because of the bore finish. Looks like a cut rifles barrel with light residual reamer marks from the bore reamer. In your last picture, those marks are of a different spacing and are likely from the bushing/screw your gunsmith used on the chamber reamer as that looks like the breech end with the powder discoloration. Take a couple more pictures at the throat and see if it’s perfectly concentric along with a clean crisp crown. IMO those two things would have a greater impact on your accuracy than the what I see of the bore finish. And yes, I have lapped 20 and 224 cal barrels, and the 20’s are a PITA. Not a barrel maker, but I know and hang out with a few.

bottom line is you really need to shoot it some more, try the Sierra 39 BK’s, those have always shot very well for me. Those groups aren’t terrible, but obviously we all want to see better when we spend that kind of $ on a custom. I think that barrel will do so assuming a good chamber and crown.

 

[L.Sherm]

My moneys on button barrel, and its certainly not a knock on button barrels.
Wether it shoots up to expectations do we buy a custom barrel expecting tooling marks in it, I dont.

 

[B23]

My moneys on button barrel, and its certainly not a knock on button barrels.
Wether it shoots up to expectations do we buy a custom barrel expecting tooling marks in it, I dont.

I thought it looked like a button rifled barrel as well.

 

[6MMsteve]

I bought a Kreiger from Bruno's looked like shit inside but I did keep it cause I didn't know any better at the time, but it shot great...right off the bat, I would really like to try a American they look pristine inside

 

[Bachekermooni]

It is button rifled.

 

[searcher]

What loads do you use with lt-32 and 32&40 Vmax? I found some LT-32.

As always - work up to these loads. These may not be the fastest - but I strive for accuracy more than velocity. These loads all use either Remington brass (just what I had at the time) and Lake City. If using the Remington brass - increase powder 2/10 to 3/10 grain to get same velocity (with my lots of brass, anyway).
For the 32 V-Max, I run 23.6 grains LT32 for 3,825 FPS. The accuracy window allows for more powder, but I like the significant brass life with this 'reduced' load as I turn my necks, etc.. For the 39 Blitz King or 40 V-Max, I use 22.7 grains Lt32 for 3,528 fps. Using40 V-max, I use 22.3 grains to get many 5-shot groups under .200" MOA. That and the Blitz king load are stellar. Regarding primers, I use a lot of Tula and Wolff Russian primers (standard and magnum), Federal A/R Match, and Remington 7 1/2. Over the chrono - they are all within 20 FPS - so I interchange primers based on what I have. I might have to bump powder or drop powder up to 3/10th of a grain to get back to my FPS - but all work very well and produced excellent accuracy. Good luck!

 

[Bachekermooni]

As always - work up to these loads. These may not be the fastest - but I strive for accuracy more than velocity. These loads all use either Remington brass (just what I had at the time) and Lake City. If using the Remington brass - increase powder 2/10 to 3/10 grain to get same velocity (with my lots of brass, anyway).
For the 32 V-Max, I run 23.6 grains LT32 for 3,825 FPS. The accuracy window allows for more powder, but I like the significant brass life with this 'reduced' load as I turn my necks, etc.. For the 39 Blitz King or 40 V-Max, I use 22.7 grains Lt32 for 3,528 fps. Using40 V-max, I use 22.3 grains to get many 5-shot groups under .200" MOA. That and the Blitz king load are stellar. Regarding primers, I use a lot of Tula and Wolff Russian primers (standard and magnum), Federal A/R Match, and Remington 7 1/2. Over the chrono - they are all within 20 FPS - so I interchange primers based on what I have. I might have to bump powder or drop powder up to 3/10th of a grain to get back to my FPS - but all work very well and produced excellent accuracy. Good luck!

Thanks. AR or bolt? Barrel length?