Others Sub-MOA Barrels

[American Air Arms]

Is my second barrel the newer method?

Yes, absolutely.

 

[Billm]

Yes, absolutely.

Thanks for the information. Well, the tighter bore might explain why my resizing my swaged slugs to sub .300” has increased the velocity by 30fps. Now, I just have to find the bore size that produces the most accuracy. Maybe I’ll try resizing my pellets too LOL.

 

[American Air Arms]

Thanks for the information. Well, the tighter bore might explain why my resizing my swaged slugs to sub .300” has increased the velocity by 30fps. Now, I just have to find the bore size that produces the most accuracy. Maybe I’ll try resizing my pellets too LOL.

Twist ?

 

[Billm]

Twist ?

It is 1:26 .30

 

[American Air Arms]

It is 1:26 .30

Optimized for pellets. Light slugs like the RMR are very good. Any, slug over .300 is going to be very tight.

 

[Pumacarl]

That in-stock Paradigm had been there quite a while, and I'm surprised that it stayed on the shelf that long. Because it did sit without selling for so long was probably the reason for discontinuing that particular model.

I find this to be really sad. Totally awesome gun! The design of the gun itself, the materials it is made of, and the machining are first rate, simple, and tough. I think this gun was kind of let down by the blocky (though damn good looking) stock. I hope if there is another hunting model produced that it has a lighter, slimmer stock. Oh yeah, and in .25!

 

[Airgun-hobbyist]

Optimized for pellets. Light slugs like the RMR are very good. Any, slug over .300 is going to be very tight.

They both do shoot well! It is nice to see a manufacturer making a 30 caliber bore tight and optimized for the standard 30 caliber diameter ammo. Thank you, Tom.

 

[Billm]

Optimized for pellets. Light slugs like the RMR are very good. Any, slug over .300 is going to be very tight.

My Corbin press produces a slug right at .300” not taking into consideration how accurate a measurement with a micrometer is . My 52gr slugs were 30fps slower than AEA 52.2 gr slugs and were shooting scattered groups in comparison. The AEA slugs mic at around .298-.289” and so I’ve been resizing them to .298” and now the Corbin swaged slugs of the same weight are about 3-5fps faster, but still sporadic. I’m thinking that maybe I’m not getting a 100% seal and getting blow by and maybe .299” might help. I’ve tried almost every weight between 44gr and 55gr without much success. It seems that if I go below 48gr the slugs are very unstable due to the shorter length. That’s a guess. The Sonoran struggles to push a 52gr slug over 855fps. I do understand that the twist is a compromise for slugs and that the AEA 52.2gr slug quite possibly produces the optimum accuracy that you might expect from these barrels. I’ve shot several .75-.9” 5 shot groups at 101yds with them. I’m just confounded why I can’t do the same or even get relatively consistent 1.5” groups with similar slugs that I swage. The one difference that I can’t easily duplicate is that the AEA slugs have drive bands to reduce the friction and that might also possibly alter the rear weight and CP. I love a challenge, but maybe I’m chasing my tail lol. Going back to the point of the thread: the accuracy of the AEA slug with this Sub-MOA barrel, is arguably better than a lot of barrels can do with pellets. I do wish there were a larger variety of pellets in .30 to try.

 

[Billm]

Corbin did ask me if I was measuring my slugs/barrels with an air gap measuring device and hinted that a micrometer might not be accurate/consistent enough.

 

[Solo1]

Corbin did ask me if I was measuring my slugs/barrels with an air gap measuring device and hinted that a micrometer might not be accurate/consistent enough.

Bill i have 2 thoughts along the same line. First you seem to be typically shooting at a high reg pressure have you triied shooting your slugs at say 150 bar? Also if that doesn’t work perhaps you should try some type of muzzle break maybe your destabilizing your slugs with too much air exiting the barrel ?

 

[Pumacarl]

Corbin did ask me if I was measuring my slugs/barrels with an air gap measuring device and hinted that a micrometer might not be accurate/consistent enough.

I just checked out an airgagingllc video on YT, as I had never heard, or seen, one of those before. Very cool, looks expensive!

 

[Billm]

I just checked out an airguagingllc video on YT, as I had never heard, or seen, one of those before. Very cool, looks expensive!

Ok now I have to look for that video lol. I have to admit before I told them no I wasn’t using an “Air gap measuring device” I had to look up what one was lol.

 

[Pumacarl]

Ok now I have to look for that video lol. I have to admit before I told them no I wasn’t using an “Air gap measuring device” I had to look up what one was lol.

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[Billm]

Bill i have 2 thoughts along the same line. First you seem to be typically shooting at a high reg pressure have you triied shooting your slugs at say 150 bar? Also if that doesn’t work perhaps you should try some type of muzzle break maybe your destabilizing your slugs with too much air exiting the barrel ?

I’ve done pellets all the way down to like 140-145 bar. The Sonoran really seems to do well with Pellets in the 159-165bar range. I’m not sure if I’ve tried slugs below below 155bar. I do know that the AOA power tune had the hammer set for max velocity. As soon as I lowered it to 3-5% tune, it tightened up, increased the shot count and reduced the bark. Due to hearing loss and tinnitus, I didn’t think that I could hear too much air leaving the barrel, like others talk about. But, now I can somewhat tune it by sound alone. It helped the AEA slugs, but mine will put 2 or 3 slugs on top of each other and then throw a flyer that is 3-5” away, and then put one near the first group and then throw one 2 or 3” up/down/sideways in a different direction.
What you’re suggesting is kind of why I wish the Sonoran had a little more power. I think when it’s tuned for the average slugs that are available, you are very limited in the max velocity attainable without producing a turbulent muzzle blast. Of course it’s all conjecture on my part.

 

[Solo1]

I’ve done pellets all the way down to like 140-145 bar. The Sonoran really seems to do well with Pellets in the 159-165bar range. I’m not sure if I’ve tried slugs below below 155bar. I do know that the AOA power tune had the hammer set for max velocity. As soon as I lowered it to 3-5% tune, it tightened up, increased the shot count and reduced the bark. Due to hearing loss and tinnitus, I didn’t think that I could hear too much air leaving the barrel, like others talk about. But, now I can somewhat tune it by sound alone. It helped the AEA slugs, but mine will put 2 or 3 slugs on top of each other and then throw a flyer that is 3-5” away, and then put one near the first group and then throw one 2 or 3” up/down/sideways in a different direction.
What you’re suggesting is kind of why I wish the Sonoran had a little more power. I think when it’s tuned for the average slugs that are available, you are very limited in the max velocity attainable without producing a turbulent muzzle blast. Of course it’s all conjecture on my part.

Well the reason i was thinking that was i was able to get good velocity at much lower pressure with the ghost and sub moa 30. What you describe here makes me think of my fx m3 before i put a airmarksman top rail on it. It was more of a harmonics thing with the fx perhaps you should try a barrel tunner?

 

[Billm]

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Thanks, I watched a couple of their videos. Why do I suspect that system costs more than all of my airguns. Each probe is custom made for caliber, twist rate, #lands and left or right hand twist.

 

[Billm]

Well the reason i was thinking that was i was able to get good velocity at much lower pressure with the ghost and sub moa 30. What you describe here makes me think of my fx m3 before i put a airmarksman top rail on it. It was more of a harmonics thing with the fx perhaps you should try a barrel tunner?

I wondered about that too. I also wondered if I should try a moderator not designed by me lol. I have shot it with no moderator, but it is horribly loud. Another thing that I’ve wondered about is how the shroud affects it? On the Alpha the shroud acts as a barrel tensioner. It made me wonder if the shroud has an affect on the harmonics.

 

[Solo1]

I wondered about that too. I also wondered if I should try a moderator not designed by me lol. I have shot it with no moderator, but it is horribly loud. Another thing that I’ve wondered about is how the shroud affects it? On the Alpha the shroud acts as a barrel tensioner. It made me wonder if the shroud has an affect on the harmonics.

I have seen an accuracy change with certain moderators.

 

[Airgun-hobbyist]

I’ve done pellets all the way down to like 140-145 bar. The Sonoran really seems to do well with Pellets in the 159-165bar range. I’m not sure if I’ve tried slugs below below 155bar. I do know that the AOA power tune had the hammer set for max velocity. As soon as I lowered it to 3-5% tune, it tightened up, increased the shot count and reduced the bark. Due to hearing loss and tinnitus, I didn’t think that I could hear too much air leaving the barrel, like others talk about. But, now I can somewhat tune it by sound alone. It helped the AEA slugs, but mine will put 2 or 3 slugs on top of each other and then throw a flyer that is 3-5” away, and then put one near the first group and then throw one 2 or 3” up/down/sideways in a different direction.
What you’re suggesting is kind of why I wish the Sonoran had a little more power. I think when it’s tuned for the average slugs that are available, you are very limited in the max velocity attainable without producing a turbulent muzzle blast. Of course it’s all conjecture on my part.

A few additional things come to mind reading about your posted results. First is the ammo. I'd suggest weight sorting the different ammo into .100 grain piles, at least for testing purposes. When I started doing this, I all but eliminated wild fliers and improved group size consistency. Sorting projectiles, then testing over a chronograph for fps speed consistency, and target group size will give you an idea of whether the consistency or lack thereof is the gun or the ammo.

Also, the gun's shot-to-shot consistency and the subsequent changing harmonics could be what is throwing things off from having consistent good groups. A consistent and tight extreme spread will help more than adding power, (unless adding the power through regulator pressure tightens up the extreme spread). All PCP's do tend to have a sweet spot in their settings.

As for the diameter size of the ammo... I buy my swaging die sets .001" or slightly more oversized of the bore. Then I get a Lee or NOE sizing die -.001" smaller than bore size, and size the slugs through it and test them for accuracy. If they can push through the bore fairly easily and groups are big, then I sand and polish a little material out of the sizing die to open it up some. This will tighten up the slug in the bore some and usually improve the group size. I repeat this sanding, polishing, and testing process until the sizing die and slug's match what the bore and down range results dictate.

 

[Billm]

A few additional things come to mind reading about your posted results. First is the ammo. I'd suggest weight sorting the different ammo into .100 grain piles, at least for testing purposes. When I started doing this, I all but eliminated wild fliers and improved group size consistency. Sorting projectiles, then testing over a chronograph for fps speed consistency, and target group size will give you an idea of whether the consistency or lack thereof is the gun or the ammo.

Also, the gun's shot-to-shot consistency and the subsequent changing harmonics could be what is throwing things off from having consistent good groups. A consistent and tight extreme spread will help more than adding power, (unless adding the power through regulator pressure tightens up the extreme spread). All PCP's do tend to have a sweet spot in their settings.

As for the diameter size of the ammo... I buy my swaging die sets .001" or slightly more oversized of the bore. Then I get a Lee or NOE sizing die -.001" smaller than bore size, and size the slugs through it and test them for accuracy. If they can push through the bore fairly easily and groups are big, then I sand and polish a little material out of the sizing die to open it up some. This will tighten up the slug in the bore some and usually improve the group size. I repeat this sanding, polishing, and testing process until the sizing die and slug's match what the bore and down range results dictate.

Just to be clear I’m only having these wild flyers with my own swaged slugs using the Corbin .300 dies. Pellets and AEA 52.2gr slugs do very good. I weigh my cores before swaging and weigh and sort the slugs down to .05gr with the assumption that my cheap scales are probably really only accurate to .1gr at best. When they are swaged they mic at exactly .300”. Swaged to the same exact weight as the AEA slugs using a dish base or a cup base similar to the AEA, my slugs are 30fps slower. Slugging my Sub-MOA barrel indicates a .299” bore. I started resizing them to .298” and my slugs are now 3-5fps faster than the same weight AEA slugs. The dies have to be custom ordered for .299” and so I will order one. I only went with .298” because there were some available from a custom overrun. But, I believe that I can hear some blow by with .298”. Part of my problem is that I have 10-15mph winds almost daily, which makes testing difficult. My SD is pretty good with the Sonoran. The SD is usually between 1.7 and 2.5 with either slugs, unless I start playing with the hammer. Right now I’ve been shooting 45gr pellets at 150bar and I’d have to swage 44gr slugs to get any kind of velocity over 800fps lol.