ACCU 22 break in questions

[bald1]

After checking to ensure no barrel obstructions I put about 2 dozen pellets through then rifle and then moved to see what the chrony had to say.



Not particularly pleased with the fps let alone the extreme spread and standard deviation.  I had expected to see 650 and 680 fps rather than 591 and 602 respectively. This is supposed to be a 15fpe class rifle.

Am I wrong here?

How much shooting does it take to fully break in a new air rifle?

[grimeszee]

My gamo accu .177 is dead on 15fpe from 7 grain to 10.5 grain pellets. Something is wrong with the gun. Maybe a piston seal.

[bald1]

Something is wrong with the gun. Maybe a piston seal.

Anyway to tell for sure or just arrange an RMA?

[grimeszee]

That extreme spread and low fpe are indicators to me. I would RMA the gun.

[bald1]

That extreme spread and low fpe are indicators to me. I would RMA the gun.

Guess I'll be talking to AirGunDepot Monday

[bhh]

I received an Accu .22 this week also. I shot less than 50 pellets through it this week. After reading your report, I took it out this morning and shot a few over the chrono. I actually used two chronos - a Competition ProChrono and a Caldwell.

Results with CPHP 14.3gr:

ProChrono  ---  Caldwell
Err                  643
696                 686
Err                  697
626                 620
711                 697
Err                  672
643                 637
678                 670
758                 750
684                 669
Err                  545
684                 Err3
903                 Did not use for this shot.
668                 Did not use for this shot.

The ProChrono was in front and I think the errors were from the cloud of smoke produced from all the dieseling.

Then I shot JSB 15.89gr pellets over the ProChrono only.
Results:
616
617
647
643
640
607
657
620
641
659

I shot a couple of groups with the JSB pellets earlier this week and it looks like this rifle is going to be extremely accurate.

The breech is oozing black oil and the smoke cloud shows no sign of abating soon. I think this is another case of getting a rifle kit. I like everything else about it so I'm going to tear it down and tune it myself.

[bald1]

bhh,

   At least mine never evidenced any black cloud or dieseling.  Still, the performance here is abysmal.

   As a near septuagenarian I don't feel anywhere close to having the skill set to do what you have planned for a self-tune.  Heck the trek to a FedEx location to return the ACCU will be challenging enough.

   Oh and as an aside the chony here was a Pact 1.

ADDENDUM:

   With your report reflecting another less than stellar QC example I'm beginning to rethink my RMA request for a replacement.  I'm simply ill equipped to deal with another defective rifle.  I don't want to have to deal with over packed grease, piston seal, or any number of other bad defect situations.

[bhh]

Well, sorry to have discouraged you.  I just wanted to add another data point as you were deciding what to do.

I'm new to airguns and have found that doing the final QA has been left to me for most of the rifles I've bought.  I haven't purchased any German guns, however. My son has a RWS 34 that has been good to go right out of the box.

[bald1]

Understood bhh 

Last night I put a bunch more pellets through it on my indoor 10m setup hoping things might settle down a bit.  This morning I set up the chrony again and got this.  WTH?  This is crazy.  Throw out the few lows and you have very respectable numbers albeit way above the rated 15 fpe of this rifle (e.g  Exact Jumbos would average 778 fps).  Of course the SD and ES are pretty poor
 
Probably need to redo as maybe the air ejected from the barrel skewed things.  Then again I also chronied my old vintage Webley at the same time and the results looked spot on (I've posted them in my vintage thread on the Hawk MKIII:  http://www.gatewaytoairguns.org/GTA/index.php?topic=116994.msg1125381#new).

[bald1]

Okay, went and conducted a sanity check.  Increased the normal 24" spacing between barrel and first chony sensor to 48".  Fired a few "control" shots from my Crosman P1322 which perfectly matched the results I posted in the Crosman subforum in my thread (http://www.gatewaytoairguns.org/GTA/index.php?topic=117044.0).

Shooting from my dining room through the chrony screens set up on the porch into the lawn in back.  4000' elevation, 68 degrees.



Still shaking my head.  Here were the "re-do" results.  FWIW the Gamo pellets seemed to be the tightest and most consistent fit, which frankly was a suprise.  What should I make of all this?  Is this rifle really defective?  Again the fpe is way up there for what is supposed to be a 15 fpe class rifle (using the AOA calculator).  No dieseling, smoking, whatever.



Summary:
Crosman Premier Domed 14.3g -- 808.5 fps
RWS 14.5g  --  781 fps
Gamo Match 15.43g  -- 850 fps
JSB Exact Jumbo 15.89g  -- 760.4 fps

[grimeszee]

According to the numbers of 900 fps for light .22 ammo that would be around 19.1fpe so your gun is doing what it should. You must have been to close to the chrony or the lighting was poor over the sensors. The only time mine did this I was only a foot from the chrony.

[bald1]

Been handloading for over 50 years and using a chrony for the better part of them.  But as noted in my intro post health issues have dampened my ability to enjoy my powder burners so I've turned to airguns for some fun. 

The chrony set up showed my vintage Webley as expected as well as my new Crosman P1322 (links posted above).  As said I also increased the interval between the muzzle and first sensor from 2 feet to 4.  So I sincerely doubt we're looking at a set up error compounding results. 

When it came to this ACCU 22 I wasn't sure what to expect.  Not much online in the way of chrony results.  I have read where a standard deviation of 20 or better is a good sign in general.  But again not much guidance for other chrony results in evaluating a new air rifle.  The factory rating of 950 fps as embossed on the gun's receiver is with ultra light Gamo PBA 9.7gr pellets for a fpe of 19.44.  Apparently the notion of a 15 fpe class rifle is with the .177 version and not the .22 which is more powerful.  Of the few reviews out there of the .22 version none show the results I'm seeing.  The extreme spreads I still find bothersome save the Gamo Match pellet results.  It'd be nice to see more results like those from bhh.

[grimeszee]

Pellet picky, the Gamo brand got closer but you find better quality pellets will get you below the 20 fps ES.

[bald1]

Pellet picky, the Gamo brand got closer but you find better quality pellets will get you below the 20 fps ES.

 I hear you!   I have the following on hand and will move to sanity check accuarcy now that it appears the rifle is NOT defective. 

Crosman Premier HP  14.3g
Crosman Premier Domed 14.3g
Crosman Premium Pointed 14.3g
RWS Superpoint Extra Field 14.5g
Gamo Match Diabolo Wadcutter 15.43g
JSB Exact Jumbo Diabolo Domed 15.89gr

Looking at acquiring and trying:
RWS Super H Point Field Line 14.2g
H&N Field Target Trophy (5.53) 14.66g
H&N Excite Spike 15.74g ( aka Beeman Silver Sting)

I'm open to other suggestions.  That said I've read where the ACCU and older CFX did not benefit from pellets in excess of 16gr.

[grimeszee]

Try the 14.66 H&N FTT pellets for sure. Pointed pellets will not be good for accuracy beyond 15-20 yards. RWS Superdomes are also one that would be on my list, the fact that your getting over 20fpe means that it should handle 16-19 grain like the H&N BARACUDA Extremes.

[bald1]

Thanks for the recommendations.


The old bracketed by the new

[bhh]

Glad to see it's coming around. How is the accuracy?

[bald1]

Glad to see it's coming around. How is the accuracy?

That's my next challenge.  Just got the scope zeroed last night while I was running all that ammo through to see if I could settle the rifle down.  But I will say what I got last night "informally" was very encouraging.

BTW something I find interesting.  It is said that the ACCU uses the same power plant as the CFX.  Yet the CFX was factory rated at 850 fps.  Then when the ACCU22 was introduced it was rated at 900fps (the .177 was 1200fps).  Now my ACCU22 sample shows 950fps embossed on the receiver.  (Obviously all these fps is with their "uber" light 9.7g fodder.)  I'm wondering if Gamo tweaked things and the revision isn't showing on outlet web sites.  Certainly my chrony results significantly eclipse those of Rick Eutsler in his May '16 video review.  Granted I'm at 4000' too but still....

What does yours show on the receiver?  900 or 950?

[wahoowad]

Here are my numbers from a new one earlier this year. I was disappointed in the continued dieseling and overall quality and returned mine to PA. Plenty of new guns to enjoy without going on a roller coaster ride trying to sort out the problems with a poorly QA'd production process.

This rifle has been hit and miss. Some love it. Others sent it right back. How many shots have you put through it so far? It isn't a matter of the results varying from different pellet designs, you just want it consistent when you shoot multiple strings with the same pellet.

[bald1]

Here are my numbers from a new one earlier this year. I was disappointed in the continued dieseling and overall quality and returned mine to PA.

Oh yes I read your thread when evaluating my purchase choice.   Seems one of the big bugaboos with Gamo is the over-greasing and lubing resulting in situations such as you've encountered.  As previously noted my sample was not plagued by those issues.

Right now I figure I've run somewhere between 200 and 300 pellets through mine.  And yes, when running strings through the chrony I endevour to be consistent with my form and execution.  That said I am not weighing and sorting pellets.  They are what they are.

Hoping to see SD and ES come down with more usage and determination of what ammo this rifle prefers for accuracy.