PCP on order

[jsizemore]

I got the replacement Avenge-x classic today. Spent the past 5 hours cleaning the barrel off and on. The interior finish of the barrel is way better than the original. Still had plenty of crude in the bore but after each layer was removed the finish would shine more and more. The end of the barrel looked exactly like Randy described EDM wire cutting. Where the transfer port enters the chamber is clear of the leade. It didn't shave any lead from the pellet skirt when chambered. I got the scope mounted and cheek rest adjusted. I'm gonna leave the rest of the gun as received except for gassing the cylinder/tank. Tomorrow is a high setting over the region so shouldn't be any winds. High's in the low 80's. The last target I shot is still stapled to the target backer so I'll have a direct comparison with the returned gun. It'll be a poor day for deer hunting but really great for bull's eye hunting.

[jsizemore]

I had about an hour before lunch to get some shooting in. Mounted the scope same position as the first. 1" left and 5" high at 30 yards. The Hawke Vantage had enough internal adjustment to handle the difference. I'll do a 2 or 3 MOA box test another day to check. I had the last 30 JSB 18's in the tin to get zero and get used to the rifle. Gotta work on the trigger. Reg set pressure started at 2250 and ended at 2000 when I finished the 30 JSB's. Shot a few CP dome 14's and they were 1 MOA high like the 1st rifle. Degassed the rifle, turned the reg all the way down and backed off 1/8 turn which gave me 1250 on the 1st rifle. This time it was 1750 and would creep, like the first rifle, 125 psi while I reloaded the magazine. The first rifle slung the first shot. This one didn't. 1st 2 shots were in the same hole. Sometimes the hole was so small I thought the pellet hadn't got to the target or just plain missed. This was shooting 14 gr CP domes. Did a tune at 1750 psi with 6 hammer spring settings. All were .4-.6" for 9 10 shot groups. Best was .42 at 1/2 turn in on the hammer spring. That's .1" bigger than the JSB 18's in the first rifle. Since I was near the end of the cylinder/tank fill, I set the hammer spring to + 1/2 and shot the last 3 groups. Finish pressure on each successive group was 1750, 1500, and 1250. All 3 groups were just under or over 1/2". That was a total of 70 shots above the reg set point and a total of 90 going to the same POA. Stuck the Teslong down the barrel and I need to do some more cleaning and possible polishing on the barrel. I'm trying to restrain myself from sticking a cleaning rod down the barrel and go slow. It took about an hour to clean the barrel after 150 pellets. This rifle likes a firm hold, my favorite.

Tomorrow and Sunday will be a fresh tin of JSB JH 18's and scare the chrony time. This rifle is fun too.

[jsizemore]

I finally got back to the Avenge-x. Last weekend I shot JSB 18's on Sat. and CPD 14's on Sun.The wind was cooperative both days. I was looking at different hammer spring settings with the reg pressure a constant. Both pellets liked the HS set at half a turn in. All the groups were between 3/8" and 1/2". What set the half turn groups apart besides size was they were very round. Just as wide as they were high.

Today I shot with the reg set at 1750 and the HS turned in half a turn. Tried some old JSB 18 and a new lot that came in Friday. I shot the last 6 CPD I had and the CPHP I got at Walmart ($7/500 tin). I shot them all over the chrony.

I checked the tank/cylinder pressure after every 10 shot mag. Tank pressure dropped 250 psig each mag. Reg pressure was real steady when I paused to tend to the chrony and refill the mag.When shooting the JSBs the Avg. velocities were :


876.8 FPS 4.9 ES
876 FPS 25.4 ES
881.3 FPS 19.4 ES
878.2 FPS 11.3 ES

The worst ES shot the smallest group @ .33.

The CPD (6 pellets) 967.3 FPS 6.6 ES and .342" group.

The CPHP from Wamart shot a bit over half inch groups but the chrony numbers looked good:

966.3 FPS 7.4 ES
963.2 FPS 13 ES
958.2 FPS 7.4 ES

After that last group the tank pressure was down to reg pressure, 1750 psig. I decided to call it quits and head inside to look at the numbers. This rifle is consistent and shoots with plenty of power. I'm gonna take in down to the 100 yard range to see how it fares at 50 & 100.

[brokeasajoke]

Just got a Kratos PCP. I'm going to try those JSB and some air arms.

[jsizemore]

AEA guy did a tour of the JSB and H&N factories on Youtube. They make a bunch of the pellets for other folks like air arms. The JSB manager said they used the dies from the individual companies to make their pellets.

That JSB group that had the 19.4 ES had a pellet with a bent skirt that produced the slowest speed, 870.3 fps, but still went into the middle of the group.

[dverna]

Nice report!!

Those PCP's are amazing guns. Like you, I have had very good results with the cheapo Crosman's and for my needs, at 1/2 to 1/3 the cost of JSB's, are the only pellet I use in both rifles.

[brokeasajoke]

I will save the crossmans for others to shoot and get myself some top shelf pellets and then sort by weight and visual though good pellets may or may not need that. I sampled 25 Crossman premier yesterday and found a spread of 14.1-14.6gn. will that make a difference? Only the target will tell.

[jsizemore]

I went to Pyramyd to get my JSB 18's. Buy 3 get 1 free. That freebie paid for tax and shipping. They were about $21/500. Ordered on Sunday, got here Friday.

The crosman's I got from Walmart were bounced around a bit. Maybe I should do the exam and sort thing. I figure the swage from chambering, and the pressure applied to the bent skirt will take care of most of it. Misalignment at the initial seating may account for some dispersion. I've been through sorting mid level 22lr and ultimately isn't worth the time for fine accuracy. If you want to shoot small go with consistent ammo that fits the rifle correctly from the start. The rest is up to the shooter.

[alamogunr]

I went to Pyramyd to get my JSB 18's. Buy 3 get 1 free. That freebie paid for tax and shipping. They were about $21/500. Ordered on Sunday, got here Friday.

The crosman's I got from Walmart were bounced around a bit. Maybe I should do the exam and sort thing. I figure the swage from chambering, and the pressure applied to the bent skirt will take care of most of it. Misalignment at the initial seating may account for some dispersion. I've been through sorting mid level 22lr and ultimately isn't worth the time for fine accuracy. If you want to shoot small go with consistent ammo that fits the rifle correctly from the start. The rest is up to the shooter.

I've been doing the same thing and was about to ask about the advisability of continuing to shoot them or cull out. So far my abilities haven't been able to discern a difference in accuracy. Mine weren't Crosmans but JSB's

[dverna]

I will save the crossmans for others to shoot and get myself some top shelf pellets and then sort by weight and visual though good pellets may or may not need that. I sampled 25 Crossman premier yesterday and found a spread of 14.1-14.6gn. will that make a difference? Only the target will tell.

I sorted 200 CP HP's when I was doing my tests.

ES was .3 gr (14.2-14.5)
SD was .071 gr

I fired 10 shot groups at 25 yards and got the following:

14.2 gr - one group .597" (only 12 pellets so could not fire more groups)
14.3 gr - two groups .663" and .529"
14.4 gr - two groups .501" and .553"
14.5 gr - one groups .515" (only 13 pellets so could not fire more groups)

I fired unsorted pellets. Five 10 shot groups averaged .547"

I added 20 drops of Ballistol to a tin of 500 pellets and averaged .491" for 15 groups with unsorted pellets.

I do not call "fliers". Every shot counts. As a result, I get larger groups than those who are more 'selective' in doing accuracy tests. IMO it is too easy to dismiss a 'bad' shot and that is not reality. I get caught by wind gusts as well...again that is reality.

The JSB's and Air Arms pellets shoot into tighter groups. After shooting 100's of groups, I cannot justify spending three times as much to gain a 15% reduction in group size. I am too lazy to sort pellets that get the job done by adding 20 drops of Ballistol to a tin of pellets.
I am shooting for fun and not good enough to appreciate that little edge premium pellets provide.

You are correct. Only the target will tell you what matters. It takes a lot of targets to get the "truth". At least for me.

[brokeasajoke]

Seems a touch of ballistol is the ticket for you. I've heard of others lubing pellets but I guess one must be careful not to diesel.

[dverna]

Seems a touch of ballistol is the ticket for you. I've heard of others lubing pellets but I guess one must be careful not to diesel.

Dieseling is caused by rapid compression of air in a springer.

In a PCP, the air is compressed in the tube and released on firing. The expansion causes a "cooling" effect instead of a heating effect.

PCP's do not diesel.

[brokeasajoke]

Dieseling is caused by rapid compression of air in a springer.

In a PCP, the air is compressed in the tube and released on firing. The expansion causes a "cooling" effect instead of a heating effect.

PCP's do not diesel.

Thanks for that. So I dont have to use just a strait silicone based oil to lube/rust prevention my barrel. I've had it happen in my springer but this PCP thing is a new world to me and I'm liking it

[dverna]

Thanks for that. So I dont have to use just a strait silicone based oil to lube/rust prevention my barrel. I've had it happen in my springer but this PCP thing is a new world to me and I'm liking it

I do not lube my barrels, but I would not hesitate to use a petroleum based lube in a PCP barrel.

[jsizemore]

I looked at the SDS of ballistol. Seems the biggest part is mineral oil. I haven't found anything on the net that tells at what pressure mineral oil will combust. Maybe somebody has that number?

[W.R.Buchanan]

Size: Don explained this above but I can put a finer point on it. A PCP can't diesel no matter what the pressure is behind it. The Pressure is dropping from the tank to the barrel. Air under pressure drops in temp when released. Go let the air out of a tire and you will see that it is cold.

A Springer is Compressing the air behind the pellet, that air is rising in temp. Hence how the Diesel Engine works by Compression Ignition.

Randy.

[jsizemore]

Are you saying the pressure doesn't increase behind the pellet in a PCP?

[chutesnreloads]

Think of it this way. The PCP is already at pressure before the sear is released.
The spring piston starts building pressure when the sear is released and as the pellet goes down the barrel.

[jsizemore]

Think of it this way, the pressurized air is held in a plenum and then released by a poppet valve into the transfer port that dumps the high pressure into the chamber behind the pellet/slug in a PCP. The spring piston compresses air in the cylinder to high pressure passes through a transfer port to the chamber behind the pellet/slug. The air from the PCP has been fed from a tank and possibly given up some of it's heat when pressurized. Springer hasn't had a chance to lose it's heat. I figure it matters how much the pressure builds behind the pellet/slug before it ebbs as the pellet/slug moves down the barrel. Typical diesel engine runs 300-500 psi. Does a PCP get that high behind the pellet/slug? Or only springers? Is it only going to happen when the fuel/air mixture 18/1 or 70/1?

I've never seen the pressure behind the pellet listed for either rifle. Curious to know the details.

[W.R.Buchanan]

You are over thinking this, what we are telling is the absolute fact!!. There is no Dieseling in PCP's, Period! Put some Ballistol on a pellet and shoot it,,, it won't diesel. That way you can see for yourself.

The PCP doesn't "recompress the air" behind the pellet. The pressure is decaying from the tank to the muzzle. As the pellet moves the pressure is decreasing. If the pellet is seeing 2200psi the instant when the valve opens, it is seeing less every inch it moves down the barrel. Released Air is Cold ! period! Air only gets hot as it is being compressed.

There is a saying I know about, You can make anything work in your Head. Making it work in the Real World is much harder, and that is all that counts..

My Father was the perfect example of this in action, as he tried many times to make impossible things work, that he could only make work in his head. Wasted a lot of money doing it too!

Randy