Position dependant point of impact shift with Swiss Arms PE90?

[Steve Janes]

I'd question the validity of anyone's comments who have indicated they have trigger time on this gun and have claimed they have not seen a poi change....either that or all their shooting is done inside 50m.....

I shoot out to 250-300m with my Swiss Arms quite regularly and do not experience this poi shift, and in the past have taken it out to 400m still with no noticeable POI shift. In fact I started a thread on how my first Swiss Rifle did at 400m when I originally got it. http://www.canadiangunnutz.com/forum/showthread.php?t=602130 I think that was April of this year..... That Rifle has seen over 2500 rounds since then with no issues, including POI shift.

Why you have to refute what someone else has told you is there personnel experience is beyond me.

It does not matter that you question this, I have multiple witness's, and don't need to prove anything to you

I have said my piece as far as this thread goes, the OP can take it or leave it, I'm done arguing! It's always the same on CGN nothing but arguing

 

[J996]

I'm expecting around 1-2" high at 100 yards when firing off the bi-pod in comparison to a magazine rest.

And that to me is an acceptable result, that is still well within center mass (not worth stressing over In the least).
To some I'm sure such a result would be a disaster and they would sell the rifle.

I would love to see you do such a test AR180, I always enjoy reading your writeups.

I will add that everyones idea of what is accurate will vary. Mine is blowing the guts out of Fig 11's and 12's out to 400m and my rifles do that no problem at all. If someone is expecting to consitently hit a loonie, better get a bolt gun.

 

[Steve Janes]

And that to me is an acceptable result, that is still well within center mass (not worth stressing over In the least).
To some I'm sure such a result would be a disaster and they would sell the rifle.

I would love to see you do such a test AR180, I always enjoy reading your writeups.

Agreed!

 

[NavyShooter]

We had one guy on the Bisley team bring a Grip-pod with him...he tried it during a 300/200/100m match (shooter stationary with pop-up targets at various distances out to 300m) and he was missing high with every shot.

It didn't get used much after that....

NS

 

[beltfed]

I shoot out to 250-300m with my Swiss Arms quite regularly and do not experience this poi shift, and in the past have taken it out to 400m still with no noticeable POI shift. In fact I started a thread on how my first Swiss Rifle did at 400m when I originally got it. http://www.canadiangunnutz.com/forum/showthread.php?t=602130 I think that was April of this year..... That Rifle has seen over 2500 rounds since then with no issues, including POI shift.

Why you have to refute what someone else has told you is there personnel experience is beyond me.

It does not matter that you question this, I have multiple witness's, and don't need to prove anything to you

Right, I call bull####.

 

[greentips]

Right, I call bulls**t.

I second that - however, if he was shooting 18" steel plates, he won't exactly know where the rounds were hitting either.

Also, I doubt he is using a center hold at 400m. If he is using a 6 o'clock hold at 400m and center hold at 200m, the rise due to pressure on the barrel actually helped him to add the 2MOA back to the difference in POA and get the rounds back to the center of the target.

 

[zupermann]

I do alot of shooting with sling and since the SA's sling mounting point is at the 9 O'clock position it is clear to me that the barrel will be pulled to the left when slung up.

I decided not to attempt sling use with mine for that reason. If I did I would try aiming off to the right until I walked the rounds into target.
As it sits this rifle is not well suited for sling use.

Was the sling mounting point relocated to the underside of the rifle in line with the bore? If not, I can well imagine that there was a major POI shift.

My experience with my "classic green" (in it's stock configuration--no change in sling attachment point) is a major POI shift. When using the bipod alone, impacts were 5" high and approx 1 3/4" to the right versus my sling prone zero.

So, yes, you get a windage and elevation POI change. Theoretically, a sling attachment point on the underside of the rifle should help cut down on the windage change (but not elevation) when using the sling, but one would still be exerting some sideways force I would think, which is bound to manifest itself. We just have to either compensate or live with it

 

[zupermann]

That is what I did but I still want to find out what cause that. Probably me but heh...lol

Individual rifle designs like the AR15/M16 A1's with the "pencil" barrels were real "barrel flexers".

Still, I've experienced noticeable POI changes with AR's and other rifles that had free floating forearms. For a long time I couldn't figure out why, except that your shooting position (prone, sitting, standing, kneeling) affects your follow through on recoil, and obviously the different holds will affect this as well.

Anyone else have any theories/observations on this?

 

[scottm]

Individual rifle designs like the AR15/M16 A1's with the "pencil" barrels were real "barrel flexers".

Still, I've experienced noticeable POI changes with AR's and other rifles that had free floating forearms. For a long time I couldn't figure out why, except that your shooting position (prone, sitting, standing, kneeling) affects your follow through on recoil, and obviously the different holds will affect this as well.

Anyone else have any theories/observations on this?

Could be due to changes in cheekweld due to different shooting positions. Unless you have parallax adjusted for the exact target distance, slight changes in eye position will change your aim point and ultimately your bullet impact point.

 

[Ar180shooter]

And that to me is an acceptable result, that is still well within center mass (not worth stressing over In the least).
To some I'm sure such a result would be a disaster and they would sell the rifle.

I would love to see you do such a test AR180, I always enjoy reading your writeups.

I will add that everyones idea of what is accurate will vary. Mine is blowing the guts out of Fig 11's and 12's out to 400m and my rifles do that no problem at all. If someone is expecting to consitently hit a loonie, better get a bolt gun.

No doubt, but those are the people who usually expect something like the Swiss Arms to shoot 1/2 MOA at 500 yards with bulk ammo too.

You just have to be realistic with your expectations. A 1-2 MOA shift is acceptable to me as well, but since you can't use bi-pods in ORA service conditions matches anyway, to me that point is moot.

I shoot out to 250-300m with my Swiss Arms quite regularly and do not experience this poi shift, and in the past have taken it out to 400m still with no noticeable POI shift. In fact I started a thread on how my first Swiss Rifle did at 400m when I originally got it. http://www.canadiangunnutz.com/forum/showthread.php?t=602130 I think that was April of this year..... That Rifle has seen over 2500 rounds since then with no issues, including POI shift.

Why you have to refute what someone else has told you is there personnel experience is beyond me.

It does not matter that you question this, I have multiple witness's, and don't need to prove anything to you

I have said my piece as far as this thread goes, the OP can take it or leave it, I'm done arguing! It's always the same on CGN nothing but arguing

You may not have noticed the POI shift, but I guarantee you that it's there. As to weather it makes a significant difference in engaging a figure 11 sized target, in field conditions out to 400 yards, that is a different topic of discussion.

 

[Bolivar]

I shoot out to 250-300m with my Swiss Arms quite regularly and do not experience this poi shift, and in the past have taken it out to 400m still with no noticeable POI shift. In fact I started a thread on how my first Swiss Rifle did at 400m when I originally got it. http://www.canadiangunnutz.com/forum/showthread.php?t=602130 I think that was April of this year..... That Rifle has seen over 2500 rounds since then with no issues, including POI shift.

Steve

Are you consistently using the bi-pod for this shooting or switching back and forth between resting on the mag or another type of hold. Your post above does not really say.

 

[J996]

I am going to try something with the Classic green this weekend.

During my recent vacation, I got to fire the Stgw57. It was very accurate, hit the bull every time and we were shooting it using the bipod with no issues at all.

The interesting thing is its bipod is mounted at the REAR. Nothing is contacting the rifle from the bipod forward which is mounted further back where the barrel is thicker and just ahead of the receiver.

I am going to take my PE90's bipod out of the spare parts bin, jerry-rig it to the very rear of the handguard and go shoot it this weekend.

If it works (in theory it makes sense) there should be no group shift issue even if the bipod is loaded since no contact is being made with the front end of the rifle.

Changing the bipod mounting location to the rear of the handguard could easily be done by buying a spare handguard and mounting a QD stud to it to use the bipod of your choice.

Here's the 57 we shot.

 

[Pooker]

J996, how are you going to mount it at the back? If you wouldn't mind taking some photos to cure my curiosity that'd be really cool.

 

[J996]

J996, how are you going to mount it at the back? If you wouldn't mind taking some photos to cure my curiosity that'd be really cool.

I am going to tape it on with gun tape just to see if this works. For a permanent attachment point my idea is to use something like a Sadlak reinforced QD post assembly (for M14 usgi stock), grind the spacers down to match the thickness of the SA handguard and then epoxy it in addition to the bolted together plates.

htt p://www.sadlak.com/si_qd_post_assy.html

Any QD bipod could then be used.
I will not attempt this until I have a spare handguard. I will not drill my original.

 

[Kampfhamster]

Even the Swiss Military mentions the shift of POI when using the bipod in the manual.

It's not much and the bipod's rarely used anyway.

/edit: I must correct myself: it isn't in the manual, but it was mentioned during the NCO-course 2003 and also at the small arms instructors course two months ago. We even tried it out.

 

[KevinB]

Problem with mounting the bipod near the magwell is that any minor movments at the rear are much larger than if the bipod was out front, and also magnify any jump when fired due to a poor position for leverage.
(hence the whole reasons bipods are out front...).

Its a service gun not a benchrest gun.
Either make a FF Forened for it - or accept that you will get POI deviation from sling and bipod usage.

 

[Kampfhamster]

The only reason the original Stgw90 aka 550 has a bipod is because the 300m-targetshooters wanted it. For everything else, it's useless.

 

[greentips]

The only reason the original Stgw90 aka 550 has a bipod is because the 300m-targetshooters wanted it. For everything else, it's useless.

It is good for leaving the rifle up while you are lining up for lunch.

 

[J996]

Problem with mounting the bipod near the magwell is that any minor movments at the rear are much larger than if the bipod was out front, and also magnify any jump when fired due to a poor position for leverage.
(hence the whole reasons bipods are out front...).

Excellent point.
I tried to temporarily attach it to the rear this weekend, way too unstable so abandoned the idea.
As I've said I don't use the bipod much and it is currently off the rifle. Resting on mag has always worked best for me.