Pressure Trace II

[Blood Trail]

For those of you who have this, what are your thoughts? I’m about to “pull the trigger” and purchase this system.

Just wanna here your thoughts first.


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[megasupermagnum]

I was just shooting with it today. It's a great system. There is only one load that I've had pressure tested by Tom Armbrust, and also shot in the PTII. It's worth noting Tom tested at 80 degrees, and I tested at about 65. In this particular load Tom got a MAP of 12,600 psi. I got right at 12,000 psi. I see no reason to question the accuracy of the system, there are other people who did comparisons, and found PTII as good or better than other pressure testing equipment. I knew I would never be able to do what I wanted by sending loads to Tom or Precision for pressure testing. It's too slow and costly. PTII has already paid for itself there.

The system is very portable. It's just a small yellow box, plus you need a laptop. Where some might not like it is that the strain gages are glued to your barrel. You can remove them, but it ruins the gage. The easy solution for shotguns is to use a separate barrel. If that's not an option, you can usually find a dirt cheap gun of some type. The gages are low profile, and do not get in the way.

Gluing the gages on a barrel can be a trick, someone with better dexterity may have no problems. Once glued on, the system is plug and play. Don't get lazy, make sure the wire is held good. I shot a few times letting the wire dangle, and it ripped the wires off the strain gage. The system comes with a velcro strap, but I prefer to use a small piece of duct tape instead. Getting the PTII box to link with my laptop the first time was a chore, although now it links instantly.

I can't think of any reason not to get it. Any question I ever had was answered by the instructions. There is a ton of info in there.

[Blood Trail]

I was just shooting with it today. It's a great system. There is only one load that I've had pressure tested by Tom Armbrust, and also shot in the PTII. It's worth noting Tom tested at 80 degrees, and I tested at about 65. In this particular load Tom got a MAP of 12,600 psi. I got right at 12,000 psi. I see no reason to question the accuracy of the system, there are other people who did comparisons, and found PTII as good or better than other pressure testing equipment. I knew I would never be able to do what I wanted by sending loads to Tom or Precision for pressure testing. It's too slow and costly. PTII has already paid for itself there.

The system is very portable. It's just a small yellow box, plus you need a laptop. Where some might not like it is that the strain gages are glued to your barrel. You can remove them, but it ruins the gage. The easy solution for shotguns is to use a separate barrel. If that's not an option, you can usually find a dirt cheap gun of some type. The gages are low profile, and do not get in the way.

Gluing the gages on a barrel can be a trick, someone with better dexterity may have no problems. Once glued on, the system is plug and play. Don't get lazy, make sure the wire is held good. I shot a few times letting the wire dangle, and it ripped the wires off the strain gage. The system comes with a velcro strap, but I prefer to use a small piece of duct tape instead. Getting the PTII box to link with my laptop the first time was a chore, although now it links instantly.

I can't think of any reason not to get it. Any question I ever had was answered by the instructions. There is a ton of info in there.

MM,

I just ordered it along with a three pack of strain gauges. Tell me, will pressure readings be different going from a rifled barrel to smoothbore if using the same load?

Any pointers or tips you could share will greatly be appreciated. What measurements do you enter when setting it up? I know you have to input barrel OD (at the muzzle?), but I saw a field to input chamber ID. How and where do you measure that? Micrometer, I suppose?


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[bikerbeans]

BT,

You could do a chamber cast using Cerrosafe to get the dimensions.

BB

[megasupermagnum]

MM,

I just ordered it along with a three pack of strain gauges. Tell me, will pressure readings be different going from a rifled barrel to smoothbore if using the same load?

Any pointers or tips you could share will greatly be appreciated. What measurements do you enter when setting it up? I know you have to input barrel OD (at the muzzle?), but I saw a field to input chamber ID. How and where do you measure that? Micrometer, I suppose?


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I have no idea if rifling will have an effect. I have strain gauges on a 10, 12, and 16 gauge, and all three are smooth bore.

The instructions can be a bit... overwhelming at first, but they are a phenomenal resource. They did a great job writing it, every question I ever had was answered in there. Both ID and OD measurements are supposed to be where you want the mid point of the strain gauge to be. OD is simple, I use a calipers. A micrometer would be more precise, although I think unnecessary. In the directions, I seem to remember it recommended that ideally you take a chamber cast, although measuring a fired case is acceptable. That's great for rifle, but doesn't help much on a plastic cased shotgun. Despite that, all that I have done is measure near the top of the metal head of a fired shotgun shell. I have also tried to use a bore gauge, and found the same measurement.

One feature of the program is that you can compensate for differences, but you have to be careful with this. Say you have a load you had tested by Tom Armbrust, and it read 10,000 psi, that's in his tight bored test gun. Now you shoot it in your factory gun, and PTII is saying it is only 9,200 psi. Is PTII reading low? I'm not so sure. To be safe, you can then enter a "correction factor" if 800, and your system will now read that load as 10,000 psi. You could then send that same load to Precision Reloading, and they could find it to be 11,500 psi in their gun, so there is variability.

Hopefully as I play with this more, I can have better answers.

[Blood Trail]

I have no idea if rifling will have an effect. I have strain gauges on a 10, 12, and 16 gauge, and all three are smooth bore.

The instructions can be a bit... overwhelming at first, but they are a phenomenal resource. They did a great job writing it, every question I ever had was answered in there. Both ID and OD measurements are supposed to be where you want the mid point of the strain gauge to be. OD is simple, I use a calipers. A micrometer would be more precise, although I think unnecessary. In the directions, I seem to remember it recommended that ideally you take a chamber cast, although measuring a fired case is acceptable. That's great for rifle, but doesn't help much on a plastic cased shotgun. Despite that, all that I have done is measure near the top of the metal head of a fired shotgun shell. I have also tried to use a bore gauge, and found the same measurement.

One feature of the program is that you can compensate for differences, but you have to be careful with this. Say you have a load you had tested by Tom Armbrust, and it read 10,000 psi, that's in his tight bored test gun. Now you shoot it in your factory gun, and PTII is saying it is only 9,200 psi. Is PTII reading low? I'm not so sure. To be safe, you can then enter a "correction factor" if 800, and your system will now read that load as 10,000 psi. You could then send that same load to Precision Reloading, and they could find it to be 11,500 psi in their gun, so there is variability.

Hopefully as I play with this more, I can have better answers.

How do you mount the strain gage if your barrel has a vent rib?


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[megasupermagnum]

I believe the best option would be to glue it on the bottom of the barrel, if it can not be glued under the rib. It is ideal to have the gauge over the center of the chamber, but near the end of the chamber is acceptable too.

[missionary5155]

Good morning
Is this "PTII" only available from the factory and what is the rough cost of the unit with lets say 3 packs of gauges..
Mike in Peru

[megasupermagnum]

The full system comes with one gauge I believe. $600.

3 pack gauges $109

6 pack gauges with glue $196

[curioushooter]

Any input on use in metallic cartridges?

[Blood Trail]

Any input on use in metallic cartridges?

It works great for metallic cartridges. Actually, this system was used to developed the .45 Raptor and 6.5 Grendel.

A lot of AR guys uses them to develop subsonic loads as well.


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