HW/Weihrauch Bad barrel run around

[Mycapt65]

I bought a used 22 cal Hw95 Field Pro. I kitted it with a Vortek kit. It struggled to make expected power. I tried different kits and springs. The best it would do is around 16 fpe. It shot fairly nicely with some of the spring/guide combinations but the rifle should be making around 17 as outfitted.

I recently added a plastic piston sleeve to reduce twang and new seal. The power dropped. I thought the piston sleeve was too tight so I removed it. I inspected the new VAC seal for damage and there was none. The seal had more drag than desired but it has less than a 300 shots on it and it should loosen with use.

Currently in 22 without a liner and with the fresh seal
FTTs 14.66 = 15.05 fpe
JSB 15.89 = 13.78 fpe

Not happy with these numbers I slugged the barrel and it had very tight chokes at the breech and muzzle. I replaced the barrel with a 20 cal barrel and the power output jumped to way more normal levels.

FTTs 11.42 = 16.27
JSB 13.73 = 15.85

Its been my experience with (with no other changes) 22 cal usually makes about a pound more energy than 20 cal in the same Weihrauch rifle. That's due to increased efficiency from the larger bore diameter. That's reversed on this rifle. It's making a solid pound more in 20. Unless something odd changed during the swap there's something wrong with the 22 barrel. The only way to be sure is to put it back on.

Or maybe put it on my 22 R1 and see what happens to it's power levels. I was hoping it wasn't the barrel because I like the looks of the sightless Karbine Field Pro.

I'm contemplating lapping the chokes looser. Has anyone tried this? I'm open to suggestions.

 

[Bedrock Bob]

Seems like scrubbing a spot with valve grinding paste and polishing it out good with JB would do it. I've read lots of posts where guys have done it. If you knew exactly where to scrub and took it slow it seems like it would work fine.

I think a hard rubber rod or slug of the right diameter and valve grinding paste of the right viscosity would straighten out a constriction pretty quickly.

I've never done it. But if you have a barrel choked at both ends there isn't much to loose.

 

[Mycapt65]

Seems like scrubbing a spot with valve grinding paste and polishing it out good with JB would do it. I've read lots of posts where guys have done it. If you knew exactly where to scrub and took it slow it seems like it would work fine.

I think a hard rubber rod or slug of the right diameter and valve grinding paste of the right viscosity would straighten out a constriction pretty quickly.

I've never done it. But if you have a barrel choked at both ends there isn't much to loose.

All the weihrauchs are choked at both ends. Some more than others. Too much ckoke at the breech maybe why that barrel is more efficient with larger head sizes and stiffer skirts. I'm always hesitant to do things that require metal removal. I've already polished the bore with JB paste but its hardly more abrasive than toothpaste. I have 240, 320 and 600 lapping compound. Maybe I'll start with the 600?

 

[Star7]

I have successfully lapped with 800. It was adequate but have never used anything coarser.

 

[Mycapt65]

I have successfully lapped with 800. It was adequate but have never used anything coarser.

What were you lapping? Was it a weihrauch barrel? Sorry to ask but lapping barrels to smooth then out is common. Lapping them to loosen a choke isn't and would require more metal removed. I'm asking a lot of details because I'd rather not ruin it trying to fix it.
Thanks

 

[Mycapt65]

Before I try lapping it to loosen the chokes. I'll chronograph my R1 before and after installing this suspect barrel. Then I'll know for sure if this barrels bad. If it does come out significantly lower on power I'll lapp it.

 

[Bedrock Bob]

All the weihrauchs are choked at both ends. Some more than others. Too much ckoke at the breech maybe why that barrel is more efficient with larger head sizes and stiffer skirts. I'm always hesitant to do things that require metal removal. I've already polished the bore with JB paste but its hardly more abrasive than toothpaste. I have 240, 320 and 600 lapping compound. Maybe I'll start with the 600?

I think they use button rifled barrels. The "choke" comes from forming the dovetail for the front sight, the threads for the muzzle and the profile at the pivot block. There shouldn't be much "choke" at the pivot block if any. I think it's just knurled and pressed into the block with that funky breech nut.

At least that is what I have been able to gather from my inquiries. I could be wrong.

I have 2 hw barrels and I don't feel any "choke" at the breech. The 97 is a bit difficult to tell. But the 95 is glass smooth from the breech to the sight dovetail where it constricts a bit.

I have got a barrel that's choked at the breech and has a loading chamfer at the muzzle. The crown is cut on the loading end. You can hardly chamber a pellet. Once it gets 2" down it will free fall out the muzzle. Obviously the blank was turned backwards in the machining process. It's not an HW but I can see how that error might happen.

 

[boscoebrea]

Try a cam with more lift,what your talking 1lb. difference?Maybe start with a higher power springer,I like my springers to be in the 14-16# range I would suggest you get a AGt Hornet spring kit that will get you more power,iLapping is not going to get you more power..STOP,get the AGT hornet kit.I had a .22 24ft#spriner, had a spring made for it to bring the power down to 16 ft# much better at the power level.

 

[Bear-of-Grayling]

If you believe it could be to much choke, then size down a few pellets and see if the numbers go up. Could be the breech seal on the 22 barrel is not as aligned as the 20. Easy to check. Put some dental floss or pipe tape under the breech seal.

 

[Bedrock Bob]

I played with my HW97k in .22 this morning. I patched the barrel both ways with a tight patch. Pushed a pellet from the muzzle. There is only one choke that I can find. It's up on the business end of the rifle.

Took it out this morning and fired 15 shots through it. 5 went in the .40 cal dot on the top target. I took it out to 50 and shot 5 more off the first hash mark under the crosshair (top target, lower group). There was a steady 5-7 mph breeze from the right. I adjusted my poa for windage and elevation and shot 5 more at 50 at the bottom target.

I chronographed every shot. Avg. 673 fps with a 15 fps variance. 4000 fas at 78 degrees.

Factory spring and seal. No "tuning" or modification. About 6-7k shots through the rifle. H&N 14.66 FTT. Shot sitting in a lawn chair resting on a camera tripod.

I think this represents the average performance from this rifle as well as my HW95. They both seem to be almost identical in accuracy. The 95 is shooting pretty slow (645-650) and has a little bit more drop at range but not much.

I honestly tried to find that choke in the breech but it's simply not there. I've had 3 HW95's and one 97, all .22 cal. They have all had their issues but in my very limited experience accuracy has never been one.

 

[Mycapt65]

Ok it's confirmed. This 22 Field Pro barrel has an issue.

I put it on the R1 minutes after chronographing it with it's regular 22 barrel. All readings from 10 shot strings after 10 fouling shots.
R1 with its regular barrel
JSB 15.89 - 698fps = 17.2 fpe
FTT 14.66 - 724fps= 17.1 fpe


With the 95 Field Pro barrel
JSB 15.89 - 662fps= 15.5 fpe
FTT 14.66 - 675fps= 14.8 fpe



Simpler results with the 95 Field Pro barrel on R1
JSBs lost 1.7 fpe
FTT lost 2.3 fpe

That's a considerable loss in my book. Now I can stop chasing my tail looking for something wrong in the power plant. Now I'll have to figure out if I want another 20 caliber 95 family rifle or wrestle with I this 22 barrel.

Btw I had a weak 20 caliber barrel I bought new with similar defects. Weihrauch replaced with the barrel that's on the Field Pro 95 now. I guess it's no longer a "Field Pro" in this arrangement. Oh well.

Thank you everyone for your responses. I'm gonna address some them in a separate thread about Weihrauch barrel idiosyncrasies. It'll be done in my typical lengthy detailed fashion. Read at your own risk of boredom. I learn things the hard way and then write it up so you don't have to.

 

[Mycapt65]

I fiddled with my HW97k in .22. Patched the barrel both ways with a tight patch. Pushed a pellet from the muzzle. There is only one choke that I can find. It's up on the business end of the rifle.

Took it out this morning and fired 15 shots through it. 5 went in the .40 cal dot on the top target. I took it out to 50 and shot 5 more off the first hash mark under the crosshair. There was a steady 5-7 mph breeze from the right. I adjusted my poa for windage and elevation and shot 5 more.

View attachment 501467

I chronographed every shot. Avg. 673 fps with a 15 fps variance. 4000 fas at 78 degrees.

Factory spring and seal. About 6-7k shots through the rifle. H&N 14.66 FTT. Shot sitting in a lawn chair resting on a camera tripod.

I think this represents the average performance from this rifle as well as my HW95. They both seem to be almost identical in accuracy. The 95 is shooting pretty slow (645-650) and has a little bit more drop at range but not much.

I honestly tried to find that choke in the breech but it's simply not there on my guns. And from my limited window of experience with them accuracy has never been an issue.

You wont feel the choke with a patch. You need to slug the barrel. That means you have to physically push a pellet through it. Trust me its there. If it's not that'd be the first I've seen without one.

 

[Star7]

What were you lapping? Was it a weihrauch barrel? Sorry to ask but lapping barrels to smooth then out is common. Lapping them to loosen a choke isn't and would require more metal removed. I'm asking a lot of details because I'd rather not ruin it trying to fix it.
Thanks

Sorry for late reply. I have a flock of HW and do not recall ever having a tight breech. I was lapping a hatsan. 800 garnet compound has worked well for me.

 

[Bedrock Bob]

You wont feel the choke with a patch. You need to slug the barrel. That means you have to physically push a pellet through it. Trust me its there. If it's not that'd be the first I've seen without one.

As I said I pushed pellets through them all. No hint of a choke back there that I can tell.

It's not a matter of trusting you. I believe every HW barrel you have seen is choked in the rear. I'm asking you to trust me when I tell you mine are not.

A button rifled barrel is choked after its rifled. The button sizes it the same all the way down. The choke is reduced afterward by rolling or stamping (if I understand the process correctly and I may not). There just isn't a "choke" on the breech end. If there is a diameter change the breech was deformed knurling it or pressing it in the block. That may very well be a problem. But I don't believe they intentionally "choked" the breech end.

Just my ramblings. I'm just an internet weirdo that knows very little about the subject. I may be totally wrong.

...but I don't think so.

 

[Bedrock Bob]

Sorry for late reply. I have a flock of HW and do not recall ever having a tight breech. I was lapping a hatsan. 800 garnet compound has worked well for me.

You can start about 50 grit and work your way down with a Hatsan barrel. Inside AND out.

 

[Star7]

You can start about 50 grit and work your way down with a Hatsan barrel. Inside AND out.

yes, I have found that to be true
thanks

 

[TG59]

Some center fire rifle shooters use fire lapping to smooth out barrels using polishing compound in grease grooves of cast lead bullets. These are shot at lower velocities.

May be a crazy idea for air rifles.

 

[Mycapt65]

Nah. People have fire lapped airguns. It's an option but I'll probably lapp the barrel by hand. I think pushing the compound through by hand gives you a better feel for things and more control.

 

[Mycapt65]

Against my better judgment to leave things well enough alone, I removed the muzzle weight on this barrel and found 6mm jag fits through the barrel. With a thin rimfire patch it went tightly through the bore from the breech until it hit the last ~3/8" at the muzzle. Then it stopped dead. Same as slugging it. The breech area felt fine. I'll have to find a way to reduce only the muzzle choke. Maybe some sort of adjustable reamer. I'll have to recrown the muzzle if I go in through the muzzle. I'm open to suggestions here.

 

[Bedrock Bob]

Against my better judgment to leave things well enough alone, I removed the muzzle weight on this barrel and found 6mm jag fits through the barrel. With a thin rimfire patch it went tightly through the bore from the breech until it hit the last ~3/8" at the muzzle. Then it stopped dead. Same as slugging it. The breech area felt fine. I'll have to find a way to reduce only the muzzle choke. Maybe some sort of adjustable reamer. I'll have to recrown the muzzle if I go in through the muzzle. I'm open to suggestions here.

It sounds like you have learned that a tight patch can feel a choke. And that there is no choke in the breech after all.

How did you determine that the choke at the muzzle needs to be reduced? Is "a 6mm jag on a thin rimfire patch" supposed to pass through the muzzle? How does this indicate any problem with the barrel?

It sounds like you are having some other problem to me. You've done lots of modifications. There has been some tinkering with the engineering. I would wager your problem has nothing to do with the choke.

Just a hunch. I have no idea what it may be. But I'll bet you a new rifle it has nothing to do with the choke. Before changing the choke dimensions make sure you really have a problem.

Put a pellet in the breech 2". Tap it back out the breech. Measure it. Observe the engraving with a magnifier. Push a pellet through the bore and out the muzzle. Measure that. Compare them visually and dimensionally very carefully.

The difference will be (an approximate) measurement of choke. Unless it is definitely more choke than your other rifles I think it best to keep searching for the problem.

Have you looked in the barrel with a borescope? Take the barrel to a gunsmith who has an inside micrometer suitable for measuring a rifled bore. Have him give you an opinion. At least have him scope it before deciding you have found the problem.