250Z Are these dings on the entering bevel of the barrel anything to be concerned with?

[GAJoe]

My pellets (JSB Match Diablo Exact King Mk II Heavy 33.95 Domed) and my Tipton cleaning rod arrived at lunch today so I was able to push a couple pellets through to see how they feel. It was tight starting, then moved very easily, almost freely (Yet I was able to tell that the pellet was turning with the rifling.), two to three inches from the end of the barrel it stopped and required added force to get it to exit the barrel. I'll try to measure that force required tomorrow to see if it is too much for a slug barrel.

 

[cosmic]

It should start out somewhat tight and then It should be the same all the way through..

 

[Billm]

My pellets (JSB Match Diablo Exact King Mk II Heavy 33.95 Domed) and my Tipton cleaning rod arrived today so I was able to push a couple pellets through to see how they feel. It was snug starting and slightly choked near the end; no resistance in between. That good?

Considering that the 250z barrel is not supposed to be choked, technically that’s not good. But, that is common for the 250z and part of what started all of the commotion. If I were you, I would not take it for granted that any of this means your barrel will not shoot well. I suggest that you push a slug through. Then post a closeup photo of your slug on here. Take a look at the side of the slug, while you slowly rotate it. Do it with two slugs. Push the first one in about 6 inches from the breech and then push it out of the breech, by pushing from the muzzle. Push the second one all the way out of the barrel, starting from the breech and exiting the muzzle. It’s normal for there to be sticky spots in airgun barrels, even in $2500 rifles and a good polishing will generally fix that.

1. The shiny band near the base of the first slug will tell you the groove diameter of your barrel. The same band on the second slug will tell you if your barrel is choked.
2. You should be able to see where the rifling contacts the slug.
3. You may be able to see damage on the base if the Leade is really bad.

Barra told me that my barrel was not actually choked, but improperly (varying diameter) rifled. My 250z would shoot pellets really well, but not any slugs that I tried. It in all honesty it just really peed me off that @Pumacarl and @Cantona256 both had 250z that performed beyond well with slugs.
I could be wrong, but I sense that you’re second guessing your purchase. If you are, please don’t (yet). Give it a polish and a try and see how it actually does and sometimes it takes more than one polish. The 250z is a really fun rifle to shoot and if it does what you want/expect it to do, you’ll be very happy. Keep posting your questions. There are a great bunch of knowledgeable airgunners on here that are always willing to share their knowledge.

 

[GAJoe]

Considering that the 250z barrel is not supposed to be choked, technically that’s not good. But, that is common for the 250z and part of what started all of the commotion. If I were you, I would not take it for granted that any of this means your barrel will not shoot well. I suggest that you push a slug through. Then post a closeup photo of your slug on here. Take a look at the side of the slug, while you slowly rotate it. Do it with two slugs. Push the first one in about 6 inches from the breech and then push it out of the breech, by pushing from the muzzle. Push the second one all the way out of the barrel, starting from the breech and exiting the muzzle. It’s normal for there to be sticky spots in airgun barrels, even in $2500 rifles and a good polishing will generally fix that.

1. The shiny band near the base of the first slug will tell you the groove diameter of your barrel. The same band on the second slug will tell you if your barrel is choked.
2. You should be able to see where the rifling contacts the slug.
3. You may be able to see damage on the base if the Leade is really bad.

Barra told me that my barrel was not actually choked, but improperly (varying diameter) rifled. My 250z would shoot pellets really well, but not any slugs that I tried. It in all honesty it just really peed me off that @Pumacarl and @Cantona256 both had 250z that performed beyond well with slugs.
I could be wrong, but I sense that you’re second guessing your purchase. If you are, please don’t (yet). Give it a polish and a try and see how it actually does and sometimes it takes more than one polish. The 250z is a really fun rifle to shoot and if it does what you want/expect it to do, you’ll be very happy. Keep posting your questions. There are a great bunch of knowledgeable airgunners on here that are always willing to share their knowledge.

Thanks for the thorough clear instructions! It just so happened that I just finished doing that with a pellet. Franco just emailed me that the slugs shipped today. So I will when they arrive. My reasoning for doing that with a pellet was that if at any point the rifling didn't have a "grip" on the pellet there would be different rifling traces between the two. They both came out with the same 12 distinct grooves as they should. and the pellets didn't touch the rough part when inserted front or back first. I understand that I am looking for any sign of a bad chambering with a slug when I try them. My compressor will be arriving in a week so I'll go ahead with the polishing and see how it shoots. My Dad just gave me his old home-made rifle vice that should hold it exactly the same POI if it's shooting well after getting it tuned so that it's traveling the same speed. I'll keep "pluggin' away". If it shoots so well that I don't want to part with it, I may try my hand at polishing the lead. Thanks again for the encouragement!

 

[Billm]

Thanks for the thorough clear instructions! It just so happened that I just finished doing that with a pellet. Franco just emailed me that the slugs shipped today. So I will when they arrive. My reasoning for doing that with a pellet was that if at any point the rifling didn't have a "grip" on the pellet there would be different rifling traces between the two. They both came out with the same 12 distinct grooves as they should. and the pellets didn't touch the rough part when inserted front or back first. I understand that I am looking for any sign of a bad chambering with a slug when I try them. My compressor will be arriving in a week so I'll go ahead with the polishing and see how it shoots. My Dad just gave me his old home-made rifle vice that should hold it exactly the same POI if it's shooting well after getting it tuned so that it's traveling the same speed. I'll keep "pluggin' away". If it shoots so well that I don't want to part with it, I may try my hand at polishing the lead. Thanks again for the encouragement!

The difference between using a slug and a pellet, is that the slug has a larger bearing surface and shows more of the contact. That’s just my opinion and so Also usually do both. Don’t just polish the leade, I’d polish the full length, unless the pellet is literally falling through the barrel in the center- some have reported having that happen.

 

[Pumacarl]

I have been fortunate in my experience with airguns that my bores have been good to outstanding, at all price levels. Now the Barra barrel had issues that I corrected or didn't matter but the bore diameter was consistent. I don't think that you should feel a choke at the end, mine doesn't have one. That doesn't mean that it won't shoot well, especially with pellets, but slugs need a very consistent bore, it seems to me. @Billm was right to be really peeved at both myself and @Cantona256, our guns shot, and shoot Great! Sorry Bill, I couldn't resist!

 

[Cantona256]

So if you feel a choke in the bore, which the gun should NOT there are a few options.

1) Barra customer support: You will probably get a good barrel eventually.

2) Get ahold of one of the Lothar barrels: Costs money.

3) Polish barrel: Airgunners fall into two camps on this one. Those who polish and those who do not. Why? Some argue that polishing can lead to losing FPS. Do your own research on this.

I will (and have!) machined my own barrel but I’ve never polished one. No plans on changing that.

4) Knurled Slugs: My adventures in slug tuning .303 and .306 barrels has taught me the value of knurled slugs. They will collapse down to the size of the bore. I even got my buddy to shot .3025 slugs out of his Gauntlet. A gun that famously narrow in the slug hole …

Get some slugs knurled in .219 and .218… you might even find that they shoot even better than expected because of an improved barrel seal and rifling engagement… remember Over-engaging the rifling is just as bad as Under-engaging.

 

[Madhatter]

I picked up around 20 fps after polishing the bore in my Diane 48. I also picked up fps in my Liberty but don't remember how much.

 

[GAJoe]

Barra told me that my barrel was not actually choked, but improperly (varying diameter) rifled.

That sounds like a manufacturer defect; should have gotten you a new barrel under warranty! You didn't get one? I guess you missed the 30 day return window? I'll get mine back together and see how it shoots next week when my compressor and slugs arrive.

 

[Billm]

They offered me the choice of a new barrel or rifle. I chose a new rifle and they ended up just giving me a refund. They don’t usually argue there’s an issue with some of their barrels - it’s too well documented.

 

[Cantona256]

I picked up around 20 fps after polishing the bore in my Diane 48. I also picked up fps in my Liberty but don't remember how much.

I believe it… I’m not against it per se but I’ve seen a lot of horror stories. As a dedicated slug shooter losing FPS is my nightmare

 

[Solo1]

I believe it… I’m not against it per se but I’ve seen a lot of horror stories. As a dedicated slug shooter losing FPS is my nightmare

But if you loose 10-15 fps but gain accuracy which is better? Not to mention longer cleaning cycles

 

[Cantona256]

But if you loose 10-15 fps but gain accuracy which is better? Not to mention longer cleaning cycles

That’s totally fair… if you can guarantee only losing that much fps…

Also maybe I’ve just gotten lucky with barrels? I’m not lucky at anything else so maybe this is my version of hitting a few hundred bucks off a scratcher

 

[Billm]

I haven’t lost any velocity so far. I have gained accuracy/consistency on at least two barrels.

 

[GAJoe]

Good news for now! Barra Help sent me an email telling me to send the bad barrel back and they would send a replacement. I just drove an hour to get it on the road. I'll keep you posted on the quality of the new barrel. Hopefully they'll have a look at it before sending another bad one.