Fixing Hard to Load TX200 Breach by Chamfering

[Fred J]

First off: I would like to thank Roadworthy for this easy tip!

My TX200 has always been hard to load. The breach did not have enough chamfer (bevel) for the pellet to easily slide into the barrel. There were sharp lands on the rifling that would grab the pellet head and skirt. The only pellet that would load easily were JSB 10.3gr. The hardest to load were JSB 8.4. These pellets would simply not seat all the way into the breach. When I closed the action, part of the pellet skirt would get trimmed off, making a mess out of the breach seal and loading port, and most important, messing with the accuracy of the 8.4gr pellet.

I went out on GTA to find a solution to the problem. That is when I found Roadworthy's tip: Use a Dremel stone (No. 953) to add a slight amount of chamfer (bevel) to the breach. The proceed is real simple:

1. Cut the cotton ball off a swab and insert the swab into the breach.
2. Insert the 953 Dremel stone into the breach as you would a pellet.
3. Rotate the stone in the breach manually until you cannot feel any sharp edges of the rifling lands.
4. Pop the cotton ball out of the breach by running a 1/8" wooden dowel down the barrel muzzle.
5. Clean the barrel to make sure there are no metal particles in the barrel.

I didn't like the idea of having my fingers in the loading port with the gun cocked, so I removed the mainspring first. I needed to do this anyway, since I need to add a power washer to my Vortek spring kit to bump up the power a bit (from 12.3 fpe to 13.5 fpe).

Now I can load all pellets easily into the breach. Even the JSB 8.4gr load easily, with no damage to the skirts when the action is closed. In fact, it looks like the JSB 8.4gr pellets may be the best pellet in my TX200.

[AmBraCol]

Nice fix.  Thanks for sharing that!

[Motorhead]

Yup ... thats how ya do it.
Good info to get out there "IF" you have any leade that is abrupt to get a pellet started into.

[Fred J]

Thank you, Scott, for providing the qualifier. My breach was very abrupt. If your TX200 does not have an abrupt breach, this procedure is not necessary.

[Frank in Fairfield]

Not an issue for mine.
Load blind-folded...Scope covers loading port..

[TonyL]

That could have ruined the lead in and pellet seal, the pellets have to seal in the end of the barrel. The fact the guns probably fac masks the issue but thats not a good idea. The barrel needs a tiny 45 or 60deg lead, around 0.5mm long for the skirt of the pellet to seal against, the pellet acts as a valve blocking the barrel and port and allowing pressure to build, eventually the pellet will let go and accelerate down the barrel.

The fix will be to pull the barrel out, shroud off, reface the barrel and cut a new correct lead in, then cut the shoulder further back, glue the shroud back on and refit...

Hope its still ok...

[Artie]

"That could have ruined the lead in and pellet seal, the pellets have to seal in the end of the barrel."
I thought the rifling anchored the pellet at the leade and the immediate force of the released gas expanded the skirt around the chamfer, creating the seal.
So.. Do a before and after chrony test

[Fred J]

Not to worry: Everything is fine with the leade.

I have to admit that I was a bit paranoid about doing this. I proceeded very cautiously, lest I compromised my beloved TX200.

This is an operation that should to be done very carefully.

First, only do this if you cannot get the pellet into the leade all the way. In my case, the pellet skirts were hanging up on the lands of the rifling where the lands met the leade. Second, only turn the stone by hand, and do not exert much pressure: The goal is to smooth sharp edges of the rifling lands in the leade that are catching on the pellet skirt.

The power output of the rifle was 13.5 fpe before and after removing the sharp edges. The accuracy of the rifle was greatly improved for the JSB 8.4gr pellets (no longer clipping the skirts when the action was closed). I did not see any change in accuracy for the JSB 10.3gr pellets, which did not previously have a problem with the skirts catching on the sharp edges of the lands inside the leade.

I checked the chamfer of the leade with a magnifier before and after turning the stone. The chamfer was about 0.5 mm before and after turning the stone. The only part of the leade that was touched by the stone was the sharp edges of rifling lands just inside the leade. 

[Yogi]

That could have ruined the lead in and pellet seal, the pellets have to seal in the end of the barrel. The fact the guns probably fac masks the issue but thats not a good idea. The barrel needs a tiny 45 or 60deg lead, around 0.5mm long for the skirt of the pellet to seal against, the pellet acts as a valve blocking the barrel and port and allowing pressure to build, eventually the pellet will let go and accelerate down the barrel.

The fix will be to pull the barrel out, shroud off, reface the barrel and cut a new correct lead in, then cut the shoulder further back, glue the shroud back on and refit...

Hope its still ok...

Tony,

Agreed, but the Dremel 953 stone has a chamfer.  Pellets need to fit in the leade just right for really good permormance.

-Y

[TonyL]

That could have ruined the lead in and pellet seal, the pellets have to seal in the end of the barrel. The fact the guns probably fac masks the issue but thats not a good idea. The barrel needs a tiny 45 or 60deg lead, around 0.5mm long for the skirt of the pellet to seal against, the pellet acts as a valve blocking the barrel and port and allowing pressure to build, eventually the pellet will let go and accelerate down the barrel.

The fix will be to pull the barrel out, shroud off, reface the barrel and cut a new correct lead in, then cut the shoulder further back, glue the shroud back on and refit...

Hope its still ok...

Tony,

Agreed, but the Dremel 953 stone has a chamfer.  Pellets need to fit in the leade just right for really good permormance.

-Y

people will try this and wreck their barrels, seen it to many times, even seen stones pushed down muzzles to ease the choke...

Honestly if you have a tight barrel unless you machine precision guides to sit in the action and use a precision ground rod to hold the tool which you know is going to spin true to the bore...take the barrel out and ease the lead in with a tapered reamer on a lathe. in fact use the reamer mounted to the rod over a stone if you must.

Barrels are so easy to wreck...

Regards needing a taper I feel they do not, they just need that slight angle for the skirt to sit into/onto to form a seal. I have rebarreled an LGU and B40 recently, the LGU is a .22 now, BSA barrel, no tapered lead, the B40 has a 177 HW barrel, again no taper, both have a 45deg cut for the skirt on the face and this is then polished, pellet seal is near 100%, performance is spot on, and the pellets in both are easy to feed.

[LSK]

Do it careful and it has only improved every rifle I've done it on. One of my most inaccurate air rifles needed this done to the muzzle. So accurate it impressed my nephew so I gave it to him. Another convert to air Gunndom
I'm tempted to do the muzzle of more of my air rifle's
The same way.
All the tests I've seen and done shows that the muzzle is most sensitive to this work. But after all the positive I've had
Will never hesitate just slow easy and test;)

PS
if they are going to do the above-mentioned they ProBably should not be shooting.
THINK ABOUT IT.

[LSK]

Frank that's very sweet 😳😮

[Yogi]

Fred,

Did you ever consider using a pellet sizer?  That way you could make at least the pellet head fit much easier into the leade.
Just wondering....

-Y

[Fred J]

I currently size my pellets with Pellet Gauge. All pellets head sizes shoot accurately, but the velocities and POI are a bit different for each head size. If I shoot unsorted pellets I see some vertical stringing at 45-55 yards.

What was the cause of pellet hanging up in the leade was the pellet skirt catching on a sharp edge of the rifling in the leade. Pellet heads would just slide right in. I tested the leade smoothness with a q tip, and I could feel the sharp edges catching on the Q-tip. After lightly rotating the dremel bit, I tested with the Q-tip to determine if the sharp edges were gone.

Just an update: My TX200 is shooting great now. Pellets load easy, rifle is real accurate (more accurate than my Marauder). I installed Tinbum spring guides in the gun when my 3rd Vortek kit died. I am using the stock spring with this kit. I shot 3/8" 5 shot groups on two consecutive days. The rifle is currently shooting JSB 10.3gr pellets at 825 fps.

Can't wait until Field Target season starts!

[LSK]

 Fred J
Great to hear
I've been so close to getting one of those vortec kits glad I haven't though

[Yogi]

I currently size my pellets with Pellet Gauge. All pellets head sizes shoot accurately, but the velocities and POI are a bit different for each head size. If I shoot unsorted pellets I see some vertical stringing at 45-55 yards.

What was the cause of pellet hanging up in the leade was the pellet skirt catching on a sharp edge of the rifling in the leade. Pellet heads would just slide right in. I tested the leade smoothness with a q tip, and I could feel the sharp edges catching on the Q-tip. After lightly rotating the dremel bit, I tested with the Q-tip to determine if the sharp edges were gone.

Just an update: My TX200 is shooting great now. Pellets load easy, rifle is real accurate (more accurate than my Marauder). I installed Tinbum spring guides in the gun when my 3rd Vortek kit died. I am using the stock spring with this kit. I shot 3/8" 5 shot groups on two consecutive days. The rifle is currently shooting JSB 10.3gr pellets at 825 fps.

Can't wait until Field Target season starts!

Glad you are not in my FT region!
Stock springs are underrated.

-Y