.25 cal replacement barrel for my 350 Mag finally here!

[Toxylon]

Early last May I contacted Mike Melick to purchase a .25 cal replacement barrel for my 350 Mag. Lo and behold, 4 months and 8 days later, the barrel arrived! (Mike sent it promptly, as Priority Mail, but the USPS took their sweet time, Grrrr).

On first inspection, the barrel and the bore is true and clean, thanks to prep work by Mike. The barrel is also a pretty faithful clone of the 350 Mag line - no fitting, or esthetic issues.

There is zero choke in the bore. .25 cal FTTs exhibit some resistance while inside the breech block section of the bore, then little resistance with no change until the muzzle. My original 350 Mag barrel's bore has a definitive choke starting app. 1" from the muzzle.

There are no stampings or markings of any kind on the barrel. I was expecting Made in China there, but hey, I like the anonymity 

China-flavored features include the scratched pivot joint breech shims, the uneven cocking shoe profile, and the very generously fitted cocking arm joint at the breech. None of these is a dealbreaker, for sure.

After all the expenses, S&H, taxes etc., I'm looking at a price tag of 144 USD for this hunk of Chinese steel. Ironically, I could've bought an original Diana barrel for less money from Germany. Alas they don't sell .25 cal replacements. Buying overseas is neither fast nor cheap, but hey, I wanted a .25 cal 350 Mag and now I'm getting there, even if at a glacial pace.

Just looking at the manly sized muzzle makes me want to go out and lob some .25 cal pellets down the range!

[Yogi]

Cool.   glad you are happy.

Wondering what the pellet drop between 25 and 35 yards is?
What are your FPS expectations?

-Y

[Mark 611]

Ya I'm also waiting on those results! I have a Ruger Air Mag .22cal another 1 of OC's rifles, I have tried lot of pellets thru it and cannot get consistent groups, But OC did put a sticker on the gun that says 21gn H&N Barracuda's, this rifle is also stroked with a I assume lesser powered spring but still jumps like a jackhammer! when fired with the 14 to 18gn pellets!

[Toxylon]

My FPS expectations is based on reports by people who did the same conversion as I. Here are some examples, off this forum, by veteran shooters:

350 Mag .25 cal @ 1.23 g (19.91 gr.): 229 m/s (751 fps)
350 Mag .25 cal @ 1.65 g (25.4 gr.): 212 - 216 m/s (696 - 709 fps)
XS-28 (350 Mag copy) .25 cal @ 1.23 g (19.91 gr.): 220 m/s (722 fps)
XS-28 (350 Mag copy) .25 cal @ 1.23 g (19.91 gr.): 229 m/s (751 fps)

I keep hearing whispers how the .25 cal pellets "will drop like a rock after 25 yards". But that's fighting basic ballistics / physics. Heavy pellets traveling around 600 fps at 25 yards will not drop any more than lighter / smaller pellets shot from medium-power airguns. What they do is retain their KE and Momentum better than the smaller ones. They also have bigger wind resistance, which muddies the waters a little. .25 cal users state downrange ballistics is precisely where the bigger caliber wins, let alone in windy conditions. Paper punchers they are not, but neither am I.

[Mark 611]

OH they do! and wait until u try a shot at longer ranges at an up angle shooting at a bird up in a tree!

[Toxylon]

They also have bigger wind resistance

Oops. Meant air resistance, of course.

[Toxylon]

OK, major setback. The replacement barrel doesn't fit the 350 Mag, after all. Properly assembled and locked, the breech and the barrel sit at a pronounced downward angle. It's like the breech block is a half-millimeter or so too long, preventing the breech and barrel from reaching level.

I contacted Mike and explained the situation, and he IMMEDIATELY returned the 144 USD. He then proceeded to explain two ways to deal with correcting the barrel. He's a stand up guy that I will be happy to do business with again.

Now I'm facing the semi-daunting task of filing the breech block end down to fit the 350 Mag receiver. I'm an experienced woodworker, less so with precision metalwork. Now that the financial strain of an expensive, defective barrel is off me, I'll breathe more freely, taking my time to not screw things up.

[subscriber]

Duke,

Perhaps once you start filing, you can use the time tested smoke method for identifying high spots to preferentially file those?  See this video: 

You could also use a black Sharpie pen instead of smoke.

[uglymike]

Duke, what type of small game will you hunting using your .25?   

[dave2288]

Duke,

Perhaps once you start filing, you can use the time tested smoke method for identifying high spots to preferentially file those?  See this video: 

You could also use a black Sharpie pen instead of smoke.

Hmm...i may try this on my crosman g1 extreme...i have a similar issue with it.  With a droop compensating scope mount i am still maxed out to get it close to sighted in

[Mark 611]

I have a suggestion u might try, try removing the new cocking arm and using the old arm that came on the rifle! and see if that doesn't change things?

[Yogi]

OK, major setback. The replacement barrel doesn't fit the 350 Mag, after all. Properly assembled and locked, the breech and the barrel sit at a pronounced downward angle. It's like the breech block is a half-millimeter or so too long, preventing the breech and barrel from reaching level.

I contacted Mike and explained the situation, and he IMMEDIATELY returned the 144 USD. He then proceeded to explain two ways to deal with correcting the barrel. He's a stand up guy that I will be happy to do business with again.

Now I'm facing the semi-daunting task of filing the breech block end down to fit the 350 Mag receiver. I'm an experienced woodworker, less so with precision metalwork. Now that the financial strain of an expensive, defective barrel is off me, I'll breathe more freely, taking my time to not screw things up.

Duke,

You sound like the kind of guy who wants to fit a square peg in a round hole.     Good luck with that!
and welcome to the club.

-Y

[subscriber]

I have a suggestion u might try, try removing the new cocking arm and using the old arm that came on the rifle! and see if that doesn't change things?

Yes Duke,

At least makes sure the cocking arm is free, and not the limiting factor for breech closure.  Makes sure that the breech face is actually making contact near the bottom - should be obvious looking straight down - especially with a thin feeler gauge pinched in between.

Now, if you have to remove a lot of steel (actually going to go very fast as you approach full closure), the breech cone may end up smaller.  That could require re-cutting the breech cone too - if it ends up too small...

[subscriber]

Hmm...i may try this on my crosman g1 extreme...i have a similar issue with it.  With a droop compensating scope mount i am still maxed out to get it close to sighted in

If the detent is locking properly, then removing metal from the barrel breech face may end up unloading the detent.  Then your barrel will be sloppy when closed, and leak at the breech seal.  Also, if you cut away the cone at the rear of the bore, that will need to be restored.  So, proceed with caution.

In terms of difficulty and risk, bending your barrel up slightly is the usual rout.  In Duke's case, his breechblock is clearly not "home".  So barrel bending won't solve his problem.

[dave2288]

Hmm...i may try this on my crosman g1 extreme...i have a similar issue with it.  With a droop compensating scope mount i am still maxed out to get it close to sighted in

If the detent is locking properly, then removing metal from the barrel breech face may end up unloading the detent.  Then your barrel will be sloppy when closed, and leak at the breech seal.  Also, if you cut away the cone at the rear of the bore, that will need to be restored.  So, proceed with caution.

In terms of difficulty and risk, bending your barrel up slightly is the usual rout.  In Duke's case, his breechblock is clearly not "home".  So barrel bending won't solve his problem.

My crosman looks just like this when in lockup, very clear that the breech block is not in line with the chamber tube.  The barrel is so "dang" accurate with 8.44 g jsb exacts that i didnt wanna mess with it but i got sick of having to shim the *(&^ out of the rear scope ring to sight it in

[subscriber]

My crosman looks just like this when in lockup, very clear that the breech block is not in line with the chamber tube.  The barrel is so "dang" accurate with 8.44 g jsb exacts that i didnt wanna mess with it but i got sick of having to shim the *(&^ out of the rear scope ring to sight it in

It sounds like you have a plan.   I am eager to see how much breech face actually needs to come off to fix it.

[Toxylon]

OK, lots of good commentary. I won't go through the quote dance this time, but try to address the raised points.

I actually used the original Diana cocking arm (the outermost part with the cocking shoe) when mounting the new barrel. No help from there.

The Xisico breech block face was tight against the receiver end all along, as in the photo below. There is simply no way for the slanted breech block to advance downwards into a level position, short of taking metal off.

Very good point about the cone and the detente and the possible mangling of them. Those are the big issues to look out for.

Last night I started the filing down process, using the familiar-to-me method of using bright background light and a steel straight edge to look for high / low spots when filing the breech block face down. The situation is already improving, slowly. We'll see.

If the Chinese barrel doesn't make it, I'll just order a .22 cal OEM barrel from Germany with the money I got from the refund, and get on with my airgunning life.

[subscriber]

Jolly good, Duke.  Carry on.  If the detent does not work, we will have that info for future reference.

If you are brave, you can bore out the .177 barrel and sleeve it to .25 with a proper liner

[HectorMedina]

Peter;

You beat me to it. Thanks, my friend!

Keep  well  and shoot straight!





HM