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How would you handle this?

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Ten-X

Ten-X

Member
Jul 24, 2023
44
29
Fort Worth, TX, USA
I bought a Daystate Revere and finally had the opportunity to get a scope mounted and shoot it this past weekend. I have a Huma Mod30 mounted to it and it wouldn't group

I took the Huma off and it shoots dimes. Great, it must be clipping. Next step was to take the Huma apart and all the baffles are spotless, just as I was putting it back together I noticed this on the end cap.

Is this something that Huma should be responsible for or is it easier to just widen the port a few thousandths and get back to shooting?

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I seriously doubt it. I have a lot of their mods. ALL of mine are perfectly square. They used to make their bores a lot tighter. But as we all know, not all guns, threads, shrouds are square. I've had to square some of the thread adapters or shrouds on my guns. Basically I know the mods are straight as an arrow. They mount perfectly in line with bore on my fx Crown. If they don't on any of my other guns. I fix the gun. I want to say my original mod 30 has a bore of 6.5mm. It is used for 22 cal, 5.5mm

I'm willing to bet if you put another mod on the gun with the same bore size, the same thing will happen.
 
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gendoc said:
yes that ^^^^
try another moderator and see if same thing happens....
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I spent $150 on the Huma. I don't have others lying around and I would rather not buy another. If we believe it's an issue with the rifle, what can be done to fix this? It seems to me that the issue would be with the squareness of the threads on either the rifle or the moderator.

For those recommending a larger caliber, I checked all the baffles and they are fine, but I'm getting a small amount of clipping on the end cap so it seems like opening the port slightly would have the same effect as going with a larger size.

What I'm asking is, is there a larger issue that needs to be addressed or can I fix this with a drill bit and move on?
 
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Ten-X said:
I spent $150 on the Huma. I don't have others lying around and I would rather not buy another. If we believe it's an issue with the rifle, what can be done to fix this? It seems to me that the issue would be with the squareness of the threads on either the rifle or the moderator.

For those recommending a larger caliber, I checked all the baffles and they are fine, but I'm getting a small amount of clipping on the end cap so it seems like opening the port slightly would have the same effect as going with a larger size.

What I'm asking is, is there a larger issue that needs to be addressed or can I fix this with a drill bit and move on?
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Does the gun have a shroud? If so, the moderator could be heavy enough to bend it down enough to cause the clipping. Is the shroud loose?
 
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You probably won't believe this but many barrels have a OD to bore concentricity variation of about .003" to .005". I've seen upto .025" on cheap imports. And as low as .0003" on finer stuff. I make quite a few barrels every year (avg 30+). Also, a lot of makers don't make their cuts after dialing in on the bore along the axis. They'll dial in on a gauge pin placed in the bore, using an independent 4 jaw chuck. But if you were to move the indicator away from the muzzle on that gayge pin, you'd see the co centricity deviate. In this condition, the threads would be cut out of concentricity and out of parallel to the bore. .003" out over an inch gets magnifies with a 6" muzzle device. This would result in an .018" off center in a system that has about .015 clearance.
 
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This alignment issue is hit or miss with some guns. Curious how often it occurs.
There’s a very simple cure for it if manufacturers would agree to set a design agreement.
If in addition to muzzle threads there was a slightly larger diameter portion (often referred to as a pilot) that was a tight tolerance, maybe .550” to .5505. If the moderator had a counterbore of .449 to .4495. Which would make the worst case of .0015 clearance between the muzzle pilot and moderator counterbore pilot.
I have noticed, especially 3D printed moderator without metallic thread inserts, that the threads are very piss poor. Very sloppy.
When male and female threads are sloppy, or even when they are both in tolerance, at the last moment as the two join together there is a slight shift that throws the two parts off center from each other. A male and female pilot prevents that. But I don’t see the industry doing that. It may be too late for that.

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subscriber said:

rcs9250,​


How about a conical pilot, rather than cylindrical?
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Yep, conical works very well too. Except, it’s harder to gage accurately in manufacturing. It takes due diligence on the part of the machine, the operator and the inspector. The cylindrical pilot primarily requires one dimension to be within tolerance to work.
Yes, the cylindrical has a tiny bit of a slip fit required but nothing compared to the sloppiness of the current method.
I will admit all of my seven different moderators do not clip but I don’t know how close they might be to clipping. I have read that if the projectile is off center as it travels through a moderator can affect the ballistic trajectory. Don’t know how true that is. I do know some of the threads on the moderators are pretty sloppy. That can be from a female thread being on the high limit and the male thread being on the low limit. Or, one or both being out of tolerance to create even more slop.
A while back I took my .223 Tikka T3x to a gunsmith to thread the barrel for a suppressor. He wanted the suppressor so he could make the thread a perfect fit for the suppressor threads. The only problem with that is if you have some other device like a muzzle brake or thread protector, it might not fit. In my case it worked out OK for my brake and protector and the suppressor is a perfect fit.
I used to make and assemble small shock absorber like assemblies for GE lighting. They were quite similar to a shock absorber or small air cylinder. When we screwed the end cap on that the rod came through it, it would shift the end cap over very slightly off center and it would not slide back and forth freely. Loosen it ever so slightly and it worked perfect. We would have to put a tiny piece of shim stock on one side under the end cap where the faces met and it would work perfectly.
 
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I have had problems with my shroud shifting and causing clipping. There is a recess that runs the length of the shroud that corresponds with the air tube. If it gets shifted, it will cause clipping. Sucks the only thing holding the shroud in place is 2 tiny set screws. It is easy to shift the shroud when you tighten a moderator on the end. Loosen the moderator adaptor and slide the shroud back into place. If you twist it, you can feel where it hits the air tube. Get it in the middle as much as possible and tighten the set screws down. Now you can tighten the mod adaptor down. Double check the barrel band to make sure it is evenly spaced around the shroud. There are 3 tiny setscrews keeping it in place.

I think I will drill a blind hole for the set screws to fit into so the shroud stays in place better. I clipped my @OldSpook moderator and blasted some of the plastic out of the front cap. Dangit.
 
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Ten-X said:
I bought a Daystate Revere and finally had the opportunity to get a scope mounted and shoot it this past weekend. I have a Huma Mod30 mounted to it and it wouldn't group
View attachment 394442
I took the Huma off and it shoots dimes. Great, it must be clipping. Next step was to take the Huma apart and all the baffles are spotless, just as I was putting it back together I noticed this on the end cap.
View attachment 394443
Is this something that Huma should be responsible for or is it easier to just widen the port a few thousandths and get back to shooting?

View attachment 394440

View attachment 394441
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Huma won’t be responsible. Rifles with shrouds can have this problem with misalignment. Talking to a moderator manufacturer about this with his moderator, he blamed my Impact and misalignment when I had this similar issue. He did offer to bore it out larger. That being said, I tried several other manufacturer’s moderators and didn’t have the issue at all. While the rifle is the cause, it doesn’t mean you will have the issue with all moderators. Oddly enough, the lightest moderator by far is the one I had alignment issues with, so it wasn’t because the weight of the moderator was too much.

You said you didn’t want to buy another moderator, so one option is to increase the bore size as you mentioned. I’m not an expert on this, so I won’t suggest just getting a drill bit. I’m not sure if Huma offers it, but you could purchase a larger end cap too.
 
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