Daisy Powerline 408 barrel shim mod - gains 50fps!

[Tom Tucker]

So I was tinkering with my new favorite action pistol, the Daisy Powerline 408.  Velocity was pretty good for what it was - about 430fps with light lead pellets.  I wasn't really even expecting 400.  Even though I was happy with it, I couldn't get over how much CO2 was blasting out from the breech area with every shot, so I decided to do a little digging.

It turned out that the rotary magazine wasn't even close to coming in contact with the barrel.  I did a little experimenting with making gaskets out of foil tape, and it turned out that it needed about 0.020 to 0.025 worth of gasket to make a decent seal.  This made a big difference in velocity - it was getting over 460fps with the tape.  Unfortunately, the foil tape would blow out after a few shots, so I went on McMaster-Carr and bought some shims of various sizes in order to figure out what would work best.

It turned out that 1/4" OD, 3/16" ID, 0.020" thick was perfect.  I JB-welded it in place and this did a lot better than the tape, about 480fps average with 7.3 grain lead!

I never even heard of this pistol until I bought it on impulse, and I don't know why that is... everyone should own one!

[JnJHess]

Congrats for that discovery, it really paid of good times. And thanks a lot for letting us all now.
Looked at that Daisy 408 for a long time since they came out, looks like a nice little Pistol. What sounds really interesting on it, is that cam CO2 piercing system on it. And also reminds me a little on the Crosman 1008 Pistol, i had one a long time ago, but the Crosman was not very accurate either with pellets nor with BB's. Now you can't find them 1008's anymore.

[Tom Tucker]

The cartridge piercing system works very well.  The lever is metal and feels solid.  I think it also transfers heat from the shooters hand to the powerlet, which may help the gun recover between shots.  It's a cool design.  The only downside is that you can't install a powerlet without piercing it.

Speaking of guns that are no longer being made, I've been trying to find a used Daisy 622X.

[JnJHess]

Sorry, i haven't seen to much of them Daisy's 622 X around either. I have seen some older Daisy's like 15X and others on ebay, but that was about 2 month back. So i guess checking there might turn up one maybe somtime.

[Rob M]

good Mod Tom ..
the crosman 2210 was from the same era, 22 cal repeatair.. similar to the daisy 622. all hard to find or overpriced nowadays.. i do like the little cleips from the 1008 and the daisy models.. they were relaible.. I made a crosman 1008 with 9 inch barrel off a chopped 1077.. as i recall it shot low 500s with 7.4 s

[Tom Tucker]

It would be great if Daisy or Crosman brought a new .22 cal action pistol to market.  Did they forget that MO' POWER is what sells?

I thought about converting the 408 to .22 - lord knows this thing dumps enough CO2 per shot to use it.  The barrel would be easy, but the only problem is that these 8-shot clips don't have enough meat to be drilled out to .22.  Maybe .20 cal, LOL.

Oh well, I'll keep checking e-bay.  It seems like I always come across rare items when I DON'T want them...

[AndyKunz]

Tom,

I love my 408 as well, and I noticed the same thing with lost power.

Now that you've had this mod for a while, are you having any issue with the action rotating the next pellet into position?  Did you continue the ramp that is there already, or did you add a smaller one just around the shim?

I was just on McMaster.com to order a set myself and figured it might be a good idea to check out the long-term results first.

Thanks.

Andy

[Tom Tucker]

Hi Andy.  The most important thing is to use pellets that are a snug fit.  The modification makes it more easy for a loose pellet to jam the action.  What can happen is the force of recoil causes them to shift back and forth and the pellet tail can stuck on the valve side.  I did use JB weld to extend the ramp at the forcing cone to surround the shim, but that didn't make much of a difference  I get great results with JBL Express RS, H&N Econ II, and Daisy hollow points.

[AndyKunz]

I did the mod last night and then cleaned it up before work this morning.  I extended the ramp as well.  Figured it's  better to have it than not.

My pistols all use Crosman 7.9gr Premium round nose.

The first mag definitely had more whack on the cans than I had in the past, and I noticed no puff around my hand.  I knew we had something!

For the second mag I took it outside with the ProChrono DLX.  It recorded 539, 451, 450, 424, 443, 441.  This was about 5 seconds between shots.

I compared it to the last time I had this gun on the chrony.  Back then it was 359, 362, 364, 343, 335, 335.

If we throw out that first 539, it looks like a pretty solid 442 vs. 349.  We're looking at 100 fps boost!

I have another 408 on order at Pyramyd now, but they're not due until October.  That's fine, it'll make a nice "change of season" gift to myself

Tom, I have to thank you again for posting this simple mod.  You made a great gun that much better!

Andy

[Tom Tucker]

I'm glad it worked out for you!

[AndyKunz]

I noticed I started having more misfires since making this mod, where the pellet wasn't perfectly centered behind the barrel.  They would catch on the edge of the shim and try to fire sideways.

I decided to recrown it to get a bit of a bevel on the shim, and it made a huge difference.  I shot 80 rounds (1 cartridge) with 5 that misfired, and only 1 of those was similar to the problem I was trying to solve.

Not a bad improvement for a 15-minute start-to-finish job.

The other problem appears to be caused by a pellet that isn't flush at the back side, snagging something as it rotates into position.  I can prevent it by seating the pellets a smidgen deeper but not so deep that the nose is out.

You can see in the photo that there's also some clean-up I want to do on the ramp.

Andy

[Longbob]

Ok, now the juices are really flowing.

I'd ordered a couple of tins of:

Winchester 7420 .177 Cal. Hyper Velocity Pellet - 250 Tin


This is a 4.4 gr alloy pellet made of tin. It has the same shape as my favorite 'go to' pellet for my hot rodded 1377; the 7.8 gr Gamo Pro Magnum.



I just fired my 1st sub 1 inch group w/ the 7420's & my 408. 4 shots went into a half inch & the last shot opened the group to an inch.

Unfortunately, these pellets are now 'Currently unavailable' at Amazon.

As light as these 7420's are, I don't imagine they're effective much at over 10 yards. Which is fine for snake protection while fishing.

[AndyKunz]

I noticed I started having more misfires since making this mod, where the pellet wasn't perfectly centered behind the barrel.

I've been reworking the mod on this for several days.  I spent a lot more time on it than I had earlier.

My further mods required disassembly of the barrel assembly down to just the raw parts.  I polished inside the barrel breach using a Q-Tip with buffing compound spun my by trust Dremel 8220 at moderate speed, only briefly. 

I noted that the difficulty in rotation noticed earlier was due to the shim causing too much friction, and the plastic ratchet parts on the mag flexing away.  As I pulled the trigger slowly I could see the barrel deflecting downward slightly.  To prevent this, I ground down the added shim by just a few thou, then rebuilt (JB Weld) and polished the ramp to make it a straight transition (there were a few irregularities I had not completely eliminated earlier).  The thinned shim meant I needed to recrown the breach as well.

I just finished 96 shots and had 3 misfires, and they were all "loose" pellets that didn't want to stay in the mag.  I can write that off to the bulk-buy Crosman pellets I get (boxes of 1250).  This is exactly what Tom mentioned a few posts back.  Those pellets won't go to waste - my SA10 holds them just fine.  (BTW, I finally got my extra SA10 mags - I had to get a friend in the UK send me them from JS Ramsbottoms).

It's still shooting in the 440fps range with 7.9gr pellets.  Plenty of power for ventilating Coke cans in my indoor range.

Andy

[Longbob]

I noticed I started having more misfires since making this mod, where the pellet wasn't perfectly centered behind the barrel.

It's still shooting in the 440fps range with 7.9gr pellets.  Plenty of power for ventilating Coke cans in my indoor range.

Andy

It's been my experience w/ the 1377 that once the velocity gets up to 450 fps or so w/ the 7.9gr pellets, I can get some real killing done on several pest species at 10 yards & under, should you ever want to nail something other than a can.

I'm going to start keeping my own 408 in my tackle box for snakes, it'll do just fine for those.

[AndyKunz]

I live in Illinois.

Snakes here are your friends.  They eat mice.  Mice eat grain, and grain is what makes Illinois money.  Unless you're in politics, in which case it's corruption.  Here when the governor leaves office, he goes to the big house and makes license plates.  I guess that means he's still a state employee...

Besides, a shovel is a better tool for dispatching "bad" snakes.  And I'm not much into fishing - don't even have a pole.

Andy

[Longbob]

I live in Illinois.

Snakes here are your friends.

Besides, a shovel is a better tool for dispatching "bad" snakes.  And I'm not much into fishing - don't even have a pole.

Andy

Quote:
There are four species of venomous snakes found in Illinois—Copperhead (Agkistrodon contortrix), Cottonmouth (Agkistrodon piscivorus), Timber Rattlesnake (Crotalus horridus) and Massasauga (Sistrurus catenatus). In Illinois, the Timber Rattlesnake is listed as a threatened species and the Massasauga is listed as endangered.

https://www.wildlifeillinois.org/gallery/amphibians-and-reptiles/snakes/venomous-snakes/

Seems like you and your shovel can get quite a workout on what's available in Illinois.

I think I'll stay back from their striking distance rather than get a shovel length away from them.

Daisy 408 can fill them full of pellets nicely from a safe distance.

We have timber rattlers here in East Texas too. TR's are one of Gods exceedingly foul creatures.

[Longbob]

Andy, you're an engineer?

That's what you do for a living?

See, this math of yours seems a little odd.

Quote from Andy Kunz:
gain = 100 * (new - old) / old

Doing the substitutions:

gain = 100 * (442 - 349) / 349

gain = ~26%

Wouldn't that be ... 349/442 X 100 % = 78.8% ... round if off to 79% and your supposed gain is 21% not 26%.

This website backs up my math.

349 ... is what percentage of ...442 - Answer 78.96%

https://percentagecalculator.mes.fm

[AndyKunz]

I have reported your harassment that has moved from PMs to open forum.

FYI,  442 is 126.6% of 349.

You're still doing the math wrong.

Andy

[Rocker1]

 One and only Warning guys and that means STOP!!!!  David

[AndyKunz]

I've been reworking the mod on this for several days.  I spent a lot more time on it than I had earlier.
...
It's still shooting in the 440fps range with 7.9gr pellets.  Plenty of power for ventilating Coke cans in my indoor range.

During earlier polishing of the internals, I noticed there was a magnet which is located in the top of the barrel cover.  The magnet came out once or twice, and I had just popped it back in.  While cleaning up the rest of the gun, I realized there was a mating magnet in the frame right adjacent to this first magnet.  Turns out the polarity is important there.  With a little more polishing and the magnets in proper orientation to attract one another, I no longer have any misfires and the FPS is still consistent in the 440 range, with 90+ shots per CO2 cartridge.

For the past several weeks I've also been working on improving the feel by replacing the grips.  What a difference it makes in shooting when your gun fits your hands!  The new grips are 1/8" thicker per side (3/8" vs. 1/4"), and the shape was modified to fit my hands correctly.  It's also now a right-handed gun, not ambi, which also improves the hold and aim.  They are walnut, finished with 30% boiled linseed oil.  I'll be doing the checkering after Christmas, when I get my tools from Dem-Bart.

Andy