Thomas HPX and some 50y BR

[thomasair]

I

It’s been clear that my gun could use some more plenum volume do the higher power stuff. The first iteration was just a longer valve block...but this obviously made the gun longer. The second version had an single external tube that went under the main tube. That required cutting a pocket out of the bottom of the stock so I could drop the plenum through when installing the action. I really didn’t like that idea because I wanted to be able to use this in a FT stock in case someone wanted to use a bipod for the 100y stuff.

Take 3....I designed 1” titanium dual plenum boosters and a yoke that positions them up alongside the barrel. This will fit in any stock, and can be fitted onto existing 25m guns. This also gave the gun a less flippy recoil pulse since the extra weight was in line with the pellet travel along the barrel.

With plenty of regulated volume on tap, now...power is much easier to come by and efficiency climbed as well.


My friend Darrin came by this morning to do something we haven’t done in a while....shoot some benchrest. Since I have moved, we now live in the same town so it’s much easier to do. Today was a 50y session. Wind was 6-8 mph most of the time and began the morning direction switch as things warmed up. Darrin has not shot for years now, but he got back in the groove pretty quickly. We are upgrading his rifle to the HPX as well.


When the dust settled, Darrin shot a 725 18x and I shot a 738 34x. Both scores qualified as new 50y usarb records and will be sent off for verification. My best card was a 249 14x...so close....yet so far. We both shot JSB Redesigned 25.4 gr Monsters at around 940-950.


We held around the 5-6 ring for the majority of shots. We both tried to shoot some of the lulls and were rewarded with unexpected pellet landings. It was best to wait for the tails of the flags to push out solid than to throw the dice. I did my best to be patient, but fell victim to the desire to shoot instead of wait a little. It was a lot of fun. We are gonna try to make this a regular thing again.


Mike 

 

[Altair-uy]

Hi Mike! If I buy the barrel and plenums, Will this work in a sub 12ft/lb thomas? Maybe the reg must be adjusted I will believe

either way, will this typically outperform the 16gr in .177 at around 860 fps?

Andres

 

[thomasair]

This gun can go from 20fpe up to about 80 or more. I’m not sure how it would do on a short barreled 12 fpe gun like the 18”. This is all new to me, too. This is mostly geared toward 24” barreled BR guns.

You could likely get 860 from a 16.3 with just a reg pressure increase.

Mike 

 

[zx10wall]

Absolutely fantastic shooting. Cool to hear about the evolution of the rig. 

 

[nomojo65]

That’s an awesome rig! And shooting! And looks truly well engineered And manufactured unlike some!

 

[thomasair]

Thanks guys, nice of you to say. 


Mike 

 

[Davec107]

Nice shooting Mike and high quality work as usual. Can't wait to see whats next....

Dave

 

[nomojo65]

Something caught my attention after reading post again, you said shooting in lulls bit ya!, ( they have bit me to, many times especially when impatient! ) I’ve said before on this forum the condition that looks the hardest to shoot In may not be! Pick the condition that’s predictable and let em’ fly!

 

[Guest]

Mmmmm

 

[Arzrover]

Very nice shooting , Mike. I look forward to seeing it in person some time.

Bob

 

[mark404]

Great shooting Mike, nice upgrade

 

[thomasair]

Thanks again, guys.

Im working with the slugs today. Shooting indoors at 25m. The pellets still get a slight nod in the accuracy dept.

The smallest group is 25 shots with 25.4 RD monsters...and the slightly larger is 25 shots of the 25.4 knockout slugs. I then shot a 25m card with the slugs and it was as I suspected it might be from the group size. I think this should put to bed the notion that slugs are not accurate at short ranges. Although the pellets are a little better....having half the wind drift would sure come in handy most days. I may be able to get outside towards the evening when things cool down (low 90s now) to shoot at 50y with the slugs.


Mike 

 

[Centercut]

Looks very good! I think it should also put to bed the old wive's tale that slugs get "more accurate" the further out they go. I'm pretty sure what shooters see is that the wind affects them less, so the accuracy remains less affected the further out you go. Many many BS posts on here that shooters get better groups at longer range than at shorter range, which of course is physically impossible. Hopefully you can help dispel that nonsense...

PS., great idea on the space shuttle booster rocket plenums! Very cool!!!

 

[bubblerboy64]

Mike, LOL Some times I shoot better groups at longer yards. Two possible explanations The wind died down or I missed the target completely.
I’ve given up on slugs at least temporarily. I really have no interest in shooting beyond 100 yards and it just got frustrating. I have several air rifles that shoot pellets really well out to 75 yards and if there is no wind out to 100. This morning I was shooting my RAW 30 cal at 100 yards and tagging a 1 inch swinger 3 out of 5 times. I’m a believer on slugs it’s just more then I care to mess with. I hunt some. I have two spots for pigeons. One is about 50 yards and the other is 65. I’ve hit too many pigeons with 25 cal and even 30 cal at those distances and not made clean kills. So for myself I limit my use of my air guns. I have plenty of powder burners for longer ranges.

 

[Scotchmo]

Looks very good! I think it should also put to bed the old wive's tale that slugs get "more accurate" the further out they go. I'm pretty sure what shooters see is that the wind affects them less, so the accuracy remains less affected the further out you go. Many many BS posts on here that shooters get better groups at longer range than at shorter range, which of course is physically impossible. Hopefully you can help dispel that nonsense...

PS., great idea on the space shuttle booster rocket plenums! Very cool!!!

I don't think it's an old wives tale.

For user induced error, the center-to-center distance is proportional to target distance. But, if by "more accurate", you mean tighter MOA, the projectile might be "more accurate" at longer distances.

Precession and nutation, which might be causing some inaccuracy, may be constant (or even decreasing) as the distance increases.

 

[nomojo65]

Wait what? I thought slugs didn’t stabilize until 50yds then got more accurate from there!

 

[Centercut]

I don't think it's an old wives tale.

For user induced error, the center-to-center distance is proportional to target distance. But, if by "more accurate", you mean tighter MOA, the projectile might be "more accurate" at longer distances.

Precession and nutation, which might be causing some inaccuracy, may be constant (or even decreasing) as the distance increases.

Maybe you misunderstood. I’m saying that your groups at 100 yards can’t physically be better (smaller) than your groups are at 50 yards. Farther is never MORE accurate than nearer, you fill in the distances. It can be close, if you have a supremely accurate gun that shoots one hole groups (5 shots minimum, less is not a “group”) at 50 yards and gets close to that at 100 yards. But unless the slug, pellet or bullet has a built in homing correctional system to return it to the middle, it’s physically not possible.

 

[nomojo65]

Disregard! 

 

[kellycr97]

Great shooting Mike,I love seeing the new stuff that you come up with. Can't wait to see it at a upcoming match.

 

[Scotchmo]

I don't think it's an old wives tale.

For user induced error, the center-to-center distance is proportional to target distance. But, if by "more accurate", you mean tighter MOA, the projectile might be "more accurate" at longer distances.

Precession and nutation, which might be causing some inaccuracy, may be constant (or even decreasing) as the distance increases.

Maybe you misunderstood. I’m saying that your groups at 100 yards can’t physically be better (smaller) than your groups are at 50 yards. Farther is never MORE accurate than nearer, you fill in the distances. It can be close, if you have a supremely accurate gun that shoots one hole groups (5 shots minimum, less is not a “group”) at 50 yards and gets close to that at 100 yards. But unless the slug, pellet or bullet has a built in homing correctional system to return it to the middle, it’s physically not possible.

I understand. Of course the group won't get smaller as the distance increases. But group size as an accuracy measure is meaningless without knowing the distance to target.

Which is the more accurate?:

1" group ( at 50yds)

Or

1.5" group ( at 100yds)

The 1.5" group may not be smaller, but it is better.