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Discussion Starter · #1 ·
New XCR owner and really like it. However, after 400+ rounds, I'm getting light strikes...with all brands (Federal, PMC, Privi Part. ..all 55 gr). In today's outing, I had 6 of 80 rounds not firing (at least 1 of each brand). The attached photo shows the more pronounced dimple in the round that fired and the smaller one for the light strike. With almost 500 rounds, I'm expecting better by now. Advice?

Also (and forgive the ignorance of 5.56/.223 ballistic traits). My rounds keep rising depending on the distance to target. My shooting is confined to a 150' indoor range, which may not be a fair distance to draw conclusions, but the POI rises from 50' to 100' and again to 150' (in each case the POA is the middle if the black dot...I had zeroed at 100'). As above, this happens with Fed, PMC and PP, but the spread varies. Is it normal for the POI to keep rising like this?

Thanks in advance for your responses.
 

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New XCR owner and really like it. However, after 400+ rounds, I'm getting light strikes...with all brands (Federal, PMC, Privi Part. ..all 55 gr). In today's outing, I had 6 of 80 rounds not firing (at least 1 of each brand). The attached photo shows the more pronounced dimple in the round that fired and the smaller one for the light strike. With almost 500 rounds, I'm expecting better by now. Advice?

Also (and forgive the ignorance of 5.56/.223 ballistic traits). My rounds keep rising depending on the distance to target. My shooting is confined to a 150' indoor range, which may not be a fair distance to draw conclusions, but the POI rises from 50' to 100' and again to 150' (in each case the POA is the middle if the black dot...I had zeroed at 100'). As above, this happens with Fed, PMC and PP, but the spread varies. Is it normal for the POI to keep rising like this?

Thanks in advance for your responses.


Speaking broadly from my target experiance, and I am by no means a great shooter or "Snipa", but POI and POA are only identical at two points of a bullet arch. Everything inbetween requires some degree of calcuation for maximum precision.

The barrel of a gun is not straight, when zero'ed. If so the bullet would begin dropping as soon as it left the barrel and you'd be striking low at anything over 50 yards. You have to angle the barrel slightly up, hence, rising POI compared to POA the farther you move from the barrel. However, the bullet will eventually start to drop and eventually POI/POA will be the same again for a brief moment.

It's up to the shooter to know the bullet path and know at which point POI and POA are the same. Generally speaking, a 16" barreled XCR zero'ed at 50 yards will have identical POI and POA at 50 yards and 200 yards. You're going to have to compensate for shots inbetween.
 

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To verify, you have the 5.56 model?

Have you had any trigger work done to the rifle, either by yourself or someone else?
 

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Discussion Starter · #4 ·
variablebinary - good tutorial, thank you. I assume that the practical answer to my question is that "yes, it climbs in the early feet from the muzzle (including within the first 150')." I'll note with respect that my outstanding Arsenal 7.62x39 does not demonstrate anywhere near the same climb differential (anticpiating a "mass-of-bullet" reply). I suppose I was expecting a simpler "it's normal, stupid, don't worry about it" response.

Tarra - VERY responsive, as per your normal monitoring of this Forum. Yes, it's a 5.56N and no trigger work has been done whatsoever...straight from the factory in late June. This is one awesome rifle and I plan to post a photo soon of my tweaking; but I need to resolve this reliability question (spoiled with an AK that's been zero-defect for over 4K rounds).

This is a great forum.
 

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Well, we can fix this two ways. I can have it sent in for inspection or you can quick-fix it and have a heavy hammer put in instead. Let me know what you would like to do.
 

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For the light hammer strikes you could try bending the hammer spring just a bit.If you remove the hammer via the pin it rides on,Take the spring off the hammer ,you will notice the spring has a shallow v shape.Take the spring and try to make that v more shallow.This should make the spring stronger.You may just have gotten a weak hammer spring.

VB as usual very good info.I would add that with a hundred yard zero,with the 55 grain load with a velocity of 3250 fps ,then your maximum rise point should be at about 180 yards,with a maximum point blank range of 357 yards.This is assuming a 5 inch kill zone.



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Just to verify, but you have gone thru the gun and cleaned and checked and locktited all the bolts since break in was completed right? also make sure your barrel bolt is torqued in pretty good as well.
 

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Discussion Starter · #8 ·
Cleaned & lubricated thoroughly after every trip to the range, yes. Have inspected bolts but not detected a need to use Locktite (for the example, the infamous ejector seems as tight as day one). Barrell bolt did loosen slightly, but detected and corrected previously.
 

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zero your rifle for 50 yards-it gives the most usable trajectory. buis on the xcr start with a 3" poa/poi difference at the muzzle rather than a 2.6" difference of an ar, but the 50yard zero is still best.



this is for a 16" barrel w 55g amax from an xcr.

here is the difference for the 50y zero between ar and xcr:

 

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Magik,
Do you have a smilar chart for the 6.8 110 grain bullet? I haven't had a chance to shoot my XCR yet but plan to soon. It would be great to start off right and save time and ammo.

Thanks, Col Maddog
 

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Discussion Starter · #12 ·
LIGHT-STRIKE PROBLEM SOLVED! Thanks to Terra for sending the heavy hammer, which was quite easy to install. Fired 110 rounds this morning and function was 100% perfect, including re-firing 10 "retreads" from previous light-strikes.

Also, the tutorials on POI vs. POA were superb, thanks to all. The graphics were copied and are kept with the rifle for future reference.
 

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For the best zero distance to give you a useable range you need to knkow a few things:

Bullet type, make model etc... this lets you work out the drag
Velocity from the gun you are shooting
sight height over the muzzle, lets you work out sight offset
Zero range

With this you can then work out point blank ranges and the POI/POA offset for each range.

A 50 yard zero does make most sense, but you need the specifics to be able to adjust for drops beyond the PBR.
 

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LIGHT-STRIKE PROBLEM SOLVED! Thanks to Terra for sending the heavy hammer, which was quite easy to install. Fired 110 rounds this morning and function was 100% perfect, including re-firing 10 "retreads" from previous light-strikes.

Also, the tutorials on POI vs. POA were superb, thanks to all. The graphics were copied and are kept with the rifle for future reference.
Let us know about your accuracy now that everything is squared away.
 

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That was quick less than 2 weeks and you recieved your heavy hammer had it installed and tested. Damn border its been 2.5 weeks for me I still don't have my heavy hammer. But my light strike problem has definitely been alot less frequent as I put more rounds downrange. I will post my results as well when I get mine.
 
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