Tuning Fix impact pin probe vs. Huma pin probe

[madeintheuk]

Reading on the Huma website, it states the fx adjustable pin probe that comes with the slug power kit is not advisable to use with pellets. However, the Huma pin probe is said to work well with both. Does anyone have any experience with both of these side by side? What differences are there that make the fx probe not work with pellets, and the Huma to work fine?

I know with my fx pin probe, seating deep skirted pellets was a chore. Does the Huma have some different magic going on?

 

[Bigragu]

The FX slug kit pins are not as beefy as the Huma pins are. Not too long ago there was a thread like this asking for comparisons, and Centercut piped in and said his slug kit pin was already bent. 

Chuck has had great results with the Huma pin shooting the fix hybrid 30 cal slugs. Me, not so much. But, on my 25 cal the Huma pin works well with the pellets I shoot.

 

[kiba]

I agree the FX pin probe is rather fragile. The huma is stronger, and the Nielsen is stronger still and it's depth adjustable.

Being the limitation on how far any probe can be adjusted forward is it can't obstruct the magazine opening when the bolt is open, a pin probe will seat any dish base projectile shallower than a pellet probe which pushes at the outer circumference. It will only match a pellet probe for seating depth with a flat based projectile. (An exception for this would be if you're shooting a boat tail or rebated boat tail slug, then the pin probe might seat the projectile deeper than the pellet probe if the boat tail fits inside the pellet probe.)

If you're going to use a pin probe with dish based projectiles (slugs or pellets) you need to seat one and then make sure the projectile is seated deep enough to clear the transfer port if you want to get maximum performance.

I originally installed a nielsen pin probe in my M3, and while it worked well with Nielsen flat base and shallow dish slugs and seated them deep enough to clear the transfer port, it did not seat pellets deep enough to clear the transfer port. I switched to a huma high flow pellet probe, which gave up 15 fps on my slug tune and required another couple clicks on the hammer micro wheel to get back to where the slugs are happy, but the rifle now seats pellets deep enough to clear the transfer port without issues and I can switch from slugs to pellets without changing the probe.

Another issue of note, with the pin probe installed occasionally a round would be rough chambering from the magazine and it would usually be a flyer-- this happened most often with pellets. With the Huma pellet probe installed that hasn't happened anymore.

 

[2muchair4leyla]

Well poop I just removed my huma and installed a Nielsen on my 22cal guess it be a slug only sniper.

 

[kiba]

Well poop I just removed my huma and installed a Nielsen on my 22cal guess it be a slug only sniper.

Maybe, maybe not. Adjust the probe as far forward as it will go without blocking the magazine opening and then chamber the pellet you plan on using. Then pull the barrel and see if it's seated forward far enough to clear the transfer port. If it is, that pellet is good to go with the pin probe and you can easily switch back and forth between pellets and slugs without switching the probe. The deeper the skirt on the pellet, the more likely it is that the pin probe won't seat it deep enough to clear the transfer port.

 

[madeintheuk]

I have the factory pellet probe, and the huma high flow pellet probe. I went from the pin probe with 34 grain pellets to the factory pellet probe, and lost almost 30fps. Didn’t think it would be THAT much. So it sounds like the major difference is in girth for the huma probe. Does it have the adjustable pin? I guess it really doesn’t matter if I’m sticking to pellets, I was just intrigued why huma would tout their as being good with pellets, and not the fx. 

 

[kiba]

The Huma pin probe isn't adjustable for depth like the FX or Nielsen.

FYI, the Huma .22 high flow pellet probe restricts about 11% more cross sectional area of the chamber that the nielsen .22 pin probe. I lost 15fps at the same settings going from the Nielsen pin probe to the Huma high flow pellet probe. Should say I'm also using one of Ernest's high flow dual transfer ports, it lines up perfectly with the Huma high flow pellet probe.

 

[Glem.Chally]

I'll stick to a modded factory part.

 

[madeintheuk]

The Huma pin probe isn't adjustable for depth like the FX or Nielsen.

FYI, the Huma .22 high flow pellet probe restricts about 11% more cross sectional area of the chamber that the nielsen .22 pin probe. I lost 15fps at the same settings going from the Nielsen pin probe to the Huma high flow pellet probe. Should say I'm also using of of Ernest's high flow dual transfer ports, it lines up perfectly with the Huma high flow pellet probe.

I have the same dual transfer port. The issue I was having with the huma high flow pellet probe was the cocking would get hard right at the end of the stroke, like the pellet was being pushed too far into the rifling. I had it adjusted to the transfer port, so it’ll they lined up perfectly, but this caused resistance. When I switched to the factory probe, the resistance almost went away completely. When I put them next to each other, the huma is noticeably longer. In another post about this issue, a member told me it wasn’t a good thing to have that resistance because it would cause excessive wear on the linkage, so I swapped to factory probe. This obviously caused me to lose a substantial amount of speed, and on max. The gun sounds louder than it did before, almost like it’s more inefficient. I started looking on the huma site to see if their transfer port was somehow different to the Ernest dual port when I stumbled on this info about the huma pin probe. Thought it was interesting that one pin probe could be better with pellets than another. I know my pin probe wouldn’t advance the hades enough past the transfer port to be worth using. As being as I only use pellets, this is why I bought the pellet probes. I just didn’t realize I’d lose so much speed with a simple probe swap. Amazing what effects these guns!!

 

[kiba]

Weird, my Huma pellet probe is only 0.007" longer than the stock probe when measuring from the front face of the probe block. Mine does not bind on the breech end of the liner when the handle cams over and didn't require any adjustments compared to the factory probe.

Ernest's dual transfer port is shaped differently with more "flare" on the port and is very slightly larger than the Huma dual transfer port. I haven't done a comparison between the two to see if there is any velocity advantage to Ernest's port.

With the pellet probe, you can adjust the effective probe length, seating depth, and transfer port alignment by removing the top plate of the rifle and tightening or loosening the probe block mounting plate on the threaded linkage to move it forward or back, but if you swap probes for caliber changes that's not something you want to do every time you switch calibers. If the transfer port is aligned but it's still binding in the cam over when closing the bolt you might have to shorten the tip of the probe.

 

[madeintheuk]

Weird, my Huma pellet probe is only 0.007" longer than the stock probe when measuring from the front face of the probe block. Mine does not bind on the breech end of the liner when the handle cams over and didn't require any adjustments compared to the factory probe.

Ernest's dual transfer port is shaped differently with more "flare" on the port and is very slightly larger than the Huma dual transfer port. I haven't done a comparison between the two to see if there is any velocity advantage to Ernest's port.

With the pellet probe, you can adjust the effective probe length, seating depth, and transfer port alignment by removing the top plate of the rifle and tightening or loosening the probe block mounting plate on the threaded linkage to move it forward or back, but if you swap probes for caliber changes that's not something you want to do every time you switch calibers. If the transfer port is aligned but it's still binding in the cam over when closing the bolt you might have to shorten the tip of the probe.

I don’t believe the binding is being caused by the probe contacting anything based on the measurements I made during install to make sure it was lined up with the transfer port. I think the resistance is the pellet engaging the rifling because using knockout slugs, there was zero resistance with the same probe. If ernests port is larger than the Huma, then maybe I have some room to back the probe out a little to stop the resistance without hurting velocity touch. I guess testing is the only way. 

 

[kiba]

If the probe doesn't bind during the bolt handle cam over when not chambering any projectile, then it's not set so deep that the tip of the probe is bottoming out on the breech end of the liner. If it binds a bit only when chambering a slug, then it's the slug engaging the rifling, and that's where an adjustable pin probe would come in handy (or shorten the tip of the pellet probe to maintain transfer port alignment, but to seat the projectile less deep.)

 

[madeintheuk]

If the probe doesn't bind during the bolt handle cam over when not chambering any projectile, then it's not set so deep that the tip of the probe is bottoming out on the breech end of the liner. If it binds a bit only when chambering a slug, then it's the slug engaging the rifling, and that's where an adjustable pin probe would come in handy (or shorten the tip of the pellet probe to maintain transfer port alignment, but to seat the projectile less deep.)

Without shortening the tip, will I definitively cause excessive wear on the cocking assembly? Or am I being too cautious?

 

[kiba]

I would not be worried about a slight increase in effort at the very end of the bolt closing when the bolt handle cams over provided that slight increase is effort is only from the slug seating into the rifling and not from mechanical binding. Keep in mind the linkage gets a pretty good jolt every time the rifle is fired and the chamber and probe gets pressurized, which is probably more stress on the linkage and pins than a little bit of effort from pushing a slug slightly into the rifling.

What you do not want is the bolt closing effort increasing and the handle binding during the cam over without loading a projectile-- that means the probe is far enough forward to be hitting the breech end of the liner and binding. Besides being really hard on the bolt linkage since the barrel is a hard obstruction that won't move, you may also damage the tip of the probe and the breech and lead in of the liner.

If you're worried about the slight "bump" on cam over from the slug engaging the rifling putting undue stress and wear on the linkage, your only real options are to shave the nose of the probe down, back off the probe if it's adjustable, or loosen the probe block mounting plate on the linkage to move it rearwards.