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 Post subject: How much PSI??
PostPosted: Tue Jul 18, 2017 7:05 pm 
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Joined: Fri May 05, 2017 11:41 pm
Posts: 48
Location: Western NV
Guys,
I did an experiment this afternoon.
I wanted to check the bbl and expansions of pellets in my new QB 79, 22 cal, Co2 AR.

I just installed an above ground swimming pool that is 5'+ deep, 90* outside,
grabbed the AR and a sample of 14 different weights/brands of pellets,
and then proceeded to shoot these pellets into the pool, pellet speeds runs 575+ fps.

Then I took a dip (had to cool off after all this ballistic work) LOL,
and recovered all these pellets etc, and found this info out,
all of these pellets failed to expand at all, impact distance was less than 18",
and none of these pellets show any rifling groves, except the pointed HP, :shock:
which shows very very light engraving on the nose/skirt areas etc.

This bbl does not show any great accuracy trends, about +1" at 25 yds, nothing smaller etc,
with all the pellets I have shot so far.
It will shoot a couple into touching side by side then fling a couple out to 1-2", high left,
then come back and plant the rest with in 1" or so of the first couple shots.

I am just about finished with the 88 grm cylinder, and then I'll start with the mods etc.

I would believe that 550-575 fps should have blown out the pellets skirts to engage the rifling's,
I don't have very good VIBES for this bbl.........
Any thought suggestions or Ideas?

Tia,
Don

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"Speeds fine, but accuracy is final"

QB-79, 22 cal
Airforce Condor 22 cal - pending


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 Post subject: Re: How much PSI??
PostPosted: Tue Jul 18, 2017 8:28 pm 
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Joined: Sat Apr 23, 2011 10:13 pm
Posts: 201
Have you tried any oversized pellets?

Like 5.53 etc?

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Don't take life too serious... It's not like you're gonna make it out alive.


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 Post subject: Re: How much PSI??
PostPosted: Wed Jul 19, 2017 4:19 pm 
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Joined: Fri May 05, 2017 11:41 pm
Posts: 48
Location: Western NV
Thanks,

I haven't taken the bbl off, for the pellet push test, when I start the complete mods for HPA/SSG, I'll check the bbl out,
but from what I have found so far, as for the rifling marks left on fired pellets etc, it don't sound good for this bbl etc.

FWIW, here is a list of pellets fired so far, using a 20x lupe, here is new info found,
I had to get the sun lite on these pellets to see the rifling marks, almost all are very lightly engraved on either the head or skirt,
only the Crosman Pointed Expanding showed decent rifling marks, on the head/skirt areas.

JSB Diabolo Exact Jumbo Heavy = 18.1gr -5.52mm = very light rifling marks on skirt only
JSB Diabolo Exact Jumbo Monster = 25.4gr -5.52mm = very very lite/shallow rifling marks on skirt
JSB Diabolo Exact Jumbo RS = 13.4gr -5.52mm, very lite/shallow rifling marks on skirt
JSB Diabolo Straton Jumbo = 15.9gr -5.50mm, very lite/shallow rifling marks on skirt,

Crosman
Super Point = 14.3 gr - 5.5mm, very lite rifling marks on skirt,
Domed Magnum = 14.3 -5.5mm, very lite rifling marks on head/skirt
Pointed Expanding = 14.3 gr- 5.5mm, This pellet showed deep rifling marks all the way around the head/skirt.
HP = 14.3gr-5.45mm, very light/shallow rifling marks on head/skirt

There were several other pellets, that I don't know the make/spec's on,
all were from the late 80's/early 90's, I think they were Beeman brands.

I know how to shoot, have shot lots of 1-1/4" groups @ 300yds with my various PB pistols etc,
This trigger pull is down to the 1-1/2 lb range etc, the fps seems to be very uniform, using Co2,
just shot a 50 rd test @ 1100psi, 90* temps,
Av = 575 fps,
H = 585 fps,
L = 568 fps,
Sd 4.7.

This bbl does not show any great accuracy trends, about +1" at 25 yds,
is the best so far for 5 shot groups using a 15x scope.

So, I will have to test other pellets to hopefully find a couple of good shooters,
any suggestions on which other pellet sizes to try?

Tia,
Don

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"Speeds fine, but accuracy is final"

QB-79, 22 cal
Airforce Condor 22 cal - pending


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 Post subject: Re: How much PSI??
PostPosted: Mon Sep 04, 2017 4:55 pm 
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Joined: Sat Aug 13, 2016 1:26 am
Posts: 4
I noticed a marked improvement on engaging the lands of the rifling when using the sniper pellets from H&N. they have a markedly thin skirt at the outter edge which the air expands with little effort. I also use whatever diameter the barrel tells me to, from 449-453 or 550-554. I slug the new barrels first first and then play with the pressure ranges for best groups.
1.5 in at 300 yds eh? well done.
I learned a long time ago to pamper the pellets in order to reduce the fliers. so I wash them with soap and water, dry them thoroughly, apply a light coat of silicone oil/wax and examine each pellet for weight variance and damage. then I know what my base line is with each new gun.


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 Post subject: Re: How much PSI??
PostPosted: Mon Sep 04, 2017 5:37 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1271
Location: United States
That pressure won;t do much if anything to the pellets, and that velocity against water won;t do anything either. You need something that will stop the pellet in a inch or less to see it deform. Clay probably won't even work but or duct seal or even ballistic putty might, which I think some places still sell. Even then you won't see them deform much at that speed. Crosman pellets are very tough so you could probably shoot those at clay at that speed and reuse them over and over.
Chinese barrels tend to be oversize which is why you're barely getting rifling marks. I think it's very frustrating that they can't make a barrel right but it is what it is.
You can also try shooting at Ivory bar soap, or heavier soap. Then there's phone books.
I suppose you could buy another barrel and see if you get lucky, but might end up with the same or worse.
There's also the possibility of choking the barrel, which I've yet to try and I don't know how well it'll work on a chinese barrel, which needs it the most, but if you're willing to try... Google it and look for a pipe cutter tool where the blade is exchanged with a roller. It's a redneck fix but the easiest and only one size fits all I know of. You could also hammer it, carefully, but obviously more prone to ruining it.
Best of luck :)


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 Post subject: Re: How much PSI??
PostPosted: Mon Sep 04, 2017 9:06 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 6015
Location: P.G. B.C.
Rsterne gets good results with his soap tests.

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Best Wishes
Daryl


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 Post subject: Re: How much PSI??
PostPosted: Mon Sep 04, 2017 11:06 pm 
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Joined: Sat Nov 03, 2007 4:19 pm
Posts: 8977
Location: Coalmont BC
Penetration in melt-and-pour soap for a .22 cal Non-PAL gun that was close to the 500 fps MV limit with 14.3 gr. pellets, impacting the soap at 25 yards, varied from 3/4" for wadcutters to 1-1/2" for heavy round-nose pellets.... NONE of the pellets, even the large cavity Hollowpoints, showed any expansion in the soap, even point blank at Non-PAL velocities.... Once impact velocities got up to about 600 fps expansion started to occur for HPs with large cavities.... Smaller HPs required more velocity, but all were showing some expansion by 700 fps.... and dramatic expansion in soap at 900 fps as expected....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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