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All about Short Stroking. $2.75 to increase accuracy


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Less than $3.00 to improve accuracy

Thought I'd share this. Tuning up my Berserker for level 2's. Wanted to experiment on Short Stroking the bolt. 

 

20 yards, hard cover. 

 

Here are my findings. Current load is 147grain, 3.2 grains of Bullseye. 152pf. Before the short stroke feature, felt recoil was mild. My point of aim was at the lower left corner of the alpha zone. Double tap Recoil impulse brought the red dot 1 o'clock, almost pass the right shoulder. 

After adding 11 quarters, in the back of my taccom buffer, it cycles enough to where it resets the trigger and catches a new round reliably.

 

Grouping got a lot tighter. Felt recoil increased but the red dot hovered around the low left corner. Will be lessening the weight on the bolt and increasing the spring weight.

 

Short stroking alone does not increase splits. The trigger does this. You also need to stay around 145 to 155 pf to really benefit from this. I shot a short stroke grouping with 115s at 132pf and dot rise was still significant

 

Overall, this cut time for me as I would always bring the dot back to zero at further targets. Now I can just send it.

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Short stroking increases felt recoil.  IMO, you are better off with the heavier bolt and standard spring.  You do not have to stay at 145 to 155 PF, in fact, that is a problem for dot bounce.  Short stroking decreases splits as long as you have everything else set up correctly.

 

If you are shooting USPSA you want somewhere between 135 and 145 PF.  135 to 140 is better.  To minimize dot bounce you have to tune your buffer and spring.  The idea is to not have the bolt slam home and raise the muzzle.  As an example, a 147 @ 985 load in my 5.5" PCC barrel will put shot after shot on top of each other at 50 yards.  That's great for outlaw steel matches, or USPSA which I don't shoot with a PCC.

 

Now I'm trying to set the gun up to shoot 124s at 140 PF.  That is the load I use for SCSA Open.  You wouldn't think that 4-5 PF difference would make a difference, but it does.

 

As far as accuracy goes, my PCC shoots Berry's plated and some JHPs very accurately.   It shoots Lawman factory ammo with acceptable accuracy, and Summers Industries poly coated bullets with the same accuracy.  It absolutely does not like J-Ames bullets.  Group size at 25 yards is larger than a dinner plate, and they smoke horribly.

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23 minutes ago, zzt said:

Short stroking increases felt recoil.  IMO, you are better off with the heavier bolt and standard spring.  You do not have to stay at 145 to 155 PF, in fact, that is a problem for dot bounce.  Short stroking decreases splits as long as you have everything else set up correctly.

 

If you are shooting USPSA you want somewhere between 135 and 145 PF.  135 to 140 is better.  To minimize dot bounce you have to tune your buffer and spring.  The idea is to not have the bolt slam home and raise the muzzle.  As an example, a 147 @ 985 load in my 5.5" PCC barrel will put shot after shot on top of each other at 50 yards.  That's great for outlaw steel matches, or USPSA which I don't shoot with a PCC.

 

Now I'm trying to set the gun up to shoot 124s at 140 PF.  That is the load I use for SCSA Open.  You wouldn't think that 4-5 PF difference would make a difference, but it does.

 

As far as accuracy goes, my PCC shoots Berry's plated and some JHPs very accurately.   It shoots Lawman factory ammo with acceptable accuracy, and Summers Industries poly coated bullets with the same accuracy.  It absolutely does not like J-Ames bullets.  Group size at 25 yards is larger than a dinner plate, and they smoke horribly.

I actually got the recipe from Max. At the time, I was using my carry optics load to try out the short stroke feature. But the explanation of using lighter bullets means more propellant to help utilize the comp better. Which proved the concept when I used my light 115 gr loads. It was 132 pf. Dot rise was still significant.

 

Also measured my splits before and after the short stroke was put in, .02 was the difference. I expected this because my current trigger doesnt have enough reset pressure like a hiperfire does. Leads me to slapping the trigger...which is inneficient.

 

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I have mine 'semi-stroked', if you will, so that I still get LRBHO, but it still quickens the cycle and although it may have a bit more jolt to the shoulder, it gets the dot back on target quicker.  I had a friend fashion a spacer out of nylon after I measured how many quarters.  A Blitzkrieg buffer helps cushion the ends/extremes of buffer travel a bit.

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11 hours ago, MoRivera said:

I have mine 'semi-stroked', if you will, so that I still get LRBHO, but it still quickens the cycle and although it may have a bit more jolt to the shoulder, it gets the dot back on target quicker.  I had a friend fashion a spacer out of nylon after I measured how many quarters.  A Blitzkrieg buffer helps cushion the ends/extremes of buffer travel a bit.

What gran bullet are you shooting?

 

The jolt on the shoulder is real. Im definitely going to need the chiropractor after a few thousand

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10 hours ago, Jcgatus said:

The jolt on the shoulder is real. Im definitely going to need the chiropractor after a few thousand

 

Then go a lot lower.  I've shot 115s as low as 950 fps for steel.  You can barely feel the recoil.  Dot bounce is minimal.  This is with a bolt/buffer/spring system that weighs 21 ounces.  BTW, this load was good for ringing steel only.  It will not drop a popper.  For USPSA you might try 147gr bullets.  I'm working down from 144 PF right now to see what happens.

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5 hours ago, zzt said:

 

Then go a lot lower.  I've shot 115s as low as 950 fps for steel.  You can barely feel the recoil.  Dot bounce is minimal.  This is with a bolt/buffer/spring system that weighs 21 ounces.  BTW, this load was good for ringing steel only.  It will not drop a popper.  For USPSA you might try 147gr bullets.  I'm working down from 144 PF right now to see what happens.

So ive been using the 147s for both my pcc and carry optics in uspsa. 

 

I used to use 115 then i preferred the soft felt recoil. However, after 6 months, I noticed my accuracy has suffered. Went back to the drawing board and realized that I was double tapping most targets I see. This was a habit I formed when I had my limcat tron with a blitzkrieg buffer. It was tuned perfectly to shoot hot 115s with minimal bounce. I sold it since then.

 

 

As i was messing with the short stroke feature, I noticed a few things. The 147s at 152pf hit harder than normal...expeccted with the short stroke. But i also recorded the movement pattern of the dot, 20 yard hardcover. My dot would stay in the a zone going 1 o'clock

 

When I shot the recommended load for the ideal short stroke ammo, the hot 115s made my dot hover in the a zone during double taps due to the faster cycle speed. How i was explained to was... More powder=faster cycle speed + short stroke=less movement in receiver set=minimized dot movement.

 

A few times I went full auto due to a combination of the triggertech and the 308 spring.

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4 hours ago, Jcgatus said:

The extra powder will also create more gas to help activate the comp

 

One of the things you can do to reduce the recoil you feel is go to a shorter barrel.  I went to a Wiland USA LLW 9mm barrel.  It is a 5.5" rifled section with a light 4140 steel shroud welded on to get it to 16.1"  All of the weight is in your hands, and it transitions like lightning.  That is the bonus.  The primary reason I bought it was it doesn't add the extra 200 fps to a 'standard' pistol load that a 16" barrel does.  You don't need a comp to minimize dot bounce.

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18 hours ago, zzt said:

 

One of the things you can do to reduce the recoil you feel is go to a shorter barrel.  I went to a Wiland USA LLW 9mm barrel.  It is a 5.5" rifled section with a light 4140 steel shroud welded on to get it to 16.1"  All of the weight is in your hands, and it transitions like lightning.  That is the bonus.  The primary reason I bought it was it doesn't add the extra 200 fps to a 'standard' pistol load that a 16" barrel does.  You don't need a comp to minimize dot bounce.

Interesting. I'll look into it. I used to own a taccom shrouded barrel and it really affected my 100 yard groupings so I steered away from uml matches. Have you had any luck with the wiland barrel with further distances?

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42 minutes ago, Jcgatus said:

Interesting. I'll look into it. I used to own a taccom shrouded barrel and it really affected my 100 yard groupings so I steered away from uml matches. Have you had any luck with the wiland barrel with further distances?

 

My groups depend on what I am feeding it.  The zero dot bounce 147gr @ 985 load groups into 2" at 50 yards shooting offhand.  So do various handloads of 147gr Everglades ammo plated and Berry's plated.  Berry's HBRNHP bullets in 115 and 124 group well also.  Sommers Enteprizes 124s shoot accurately, but not as accurate as the 147 JHPs.  Federal Syntec 150 gr ammo shoots superbly.  Speer Lawman 115 and 124, along with Blazer 115 and 124 are not as accurate.

 

Several of the poly coated bullets I bought or had laying around were not as accurate.  Groups were often 3 or 4 inches at 25 yards.  The worst were the 124 and 135 J-Ames bullet I bought because several on these threads raved about them.  The 25 yards groups with either could not be covered with a dinner plate.  The smoked horribly to boot.  I will be giving the 975 124s I have left and the 475 135s away.  What a waste of time and money.

 

The farthest I've shot was at an 8" steel plate at 100 yards.  With my 115 steel challenge load I could hit it 7 out of 10 trys standing offhand once I figured out how much hold over I needed.  My 12 MOA dot was bigger than the plate, so it took some experimenting.  This load is not as accurate as the 147 JHP load.

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One of the things you can do to reduce the recoil you feel is go to a shorter barrel.  I went to a Wiland USA LLW 9mm barrel.  It is a 5.5" rifled section with a light 4140 steel shroud welded on to get it to 16.1"  All of the weight is in your hands, and it transitions like lightning.  That is the bonus.  The primary reason I bought it was it doesn't add the extra 200 fps to a 'standard' pistol load that a 16" barrel does.  You don't need a comp to minimize dot bounce.

Is this true?
I was under the impression that the shorter the barrel the more perceived recoil and you don’t have a heavy barrel out from pulling the muzzle down with gravity
That was the theory behind the original GMR-15, heavy heavy gun just soaks up the recoil.

Doesn’t seem to have worked so well in practice though as most people have moved away from ultra light, and ultra heavy and are somewhere in between now.


Regarding the short stroking, I’ve been running a 14.5 gmr for a year now with the short stroke buffer.
I need to do more testing with different powder loads to see what is best. I have just stuck to one load because it was acceptable and extremely reliable.

But I think that’s the next step to tuning down the recoil for me.
The dot movement isn’t bad on the JP, but it’s not laser like.
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9 hours ago, hello0o0o0o said:

Is this true?

 

Yes, for normal loads.  If you shoot your typical Production load in a 16"  PCC barrel you gain between 100 and 200 fps, depending on the powder used.  Here is one example.  One of my shooting buddy's Production load makes 132 PF over the chrono.  Out of his 16" PCC it makes 155 PF.  That's almost 200 fps faster. 

 

The faster the powder, the less velocity gain.  Some mouse fart pistol loads are actually slower out of a 16" barrel, because there is not enough gas generated to accelerate the bullet all the way down the barrel.  So it is actually slowing down before it exits.

 

My PCC weighs 5 lb. 7.5 oz. unloaded.  Set up as it currently is there is virtually no dot bounce with a 147 gr @ 985 fps load (144 PF).  I literally can hit the same spot at 50 yards as fast as I can pull the trigger.  I definitely feel the recoil, but it is straight back.  BTW, the gun is short stroked by 3/4".

 

It is generally accepted that you need between 135 and 145 PF to minimize dot bounce, assuming you have everything set up correctly.  For me that was 144.  That load is great for falling steel matches, especially the fall forward poppers.  It is not ideal for steel challenge.  I'm experimenting with lighter loads to see if I can get reduced recoil and still no appreciable dot bounce.  I just tried a 147 over 2.8gr e3.  It was super soft with minimal dot bounce, but it stove piped.  I'll try a little more powder and see if that works.  If not I'll have to take the 3 oz. weight out of the bolt for the light load.  I'd rather not, because I might forget to put it back in for the falling steel matches.  That would be a disaster for recoil and dot bounce.  

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59 minutes ago, zzt said:

 

Yes, for normal loads.  If you shoot your typical Production load in a 16"  PCC barrel you gain between 100 and 200 fps, depending on the powder used.  Here is one example.  One of my shooting buddy's Production load makes 132 PF over the chrono.  Out of his 16" PCC it makes 155 PF.  That's almost 200 fps faster. 

 

The faster the powder, the less velocity gain.  Some mouse fart pistol loads are actually slower out of a 16" barrel, because there is not enough gas generated to accelerate the bullet all the way down the barrel.  So it is actually slowing down before it exits.

 

My PCC weighs 5 lb. 7.5 oz. unloaded.  Set up as it currently is there is virtually no dot bounce with a 147 gr @ 985 fps load (144 PF).  I literally can hit the same spot at 50 yards as fast as I can pull the trigger.  I definitely feel the recoil, but it is straight back.  BTW, the gun is short stroked by 3/4".

 

It is generally accepted that you need between 135 and 145 PF to minimize dot bounce, assuming you have everything set up correctly.  For me that was 144.  That load is great for falling steel matches, especially the fall forward poppers.  It is not ideal for steel challenge.  I'm experimenting with lighter loads to see if I can get reduced recoil and still no appreciable dot bounce.  I just tried a 147 over 2.8gr e3.  It was super soft with minimal dot bounce, but it stove piped.  I'll try a little more powder and see if that works.  If not I'll have to take the 3 oz. weight out of the bolt for the light load.  I'd rather not, because I might forget to put it back in for the falling steel matches.  That would be a disaster for recoil and dot bounce.  

If it helps on your search for a powder puff load with minimal bounce, I have found that around 105PF I can get it settled down pretty well. 

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10 minutes ago, hello0o0o0o said:

Wouldn’t you not be able to compete with 105 pf though?

 

For steel challenge there is no power factor requirement, so yes you can compete.  USPSA has a 125 PF floor, and most go to 132 to be sure of making minor at the chrono station.  I've tried a 115 at 109 PF and it was okay.  The light 147gr load I mentioned above is way softer.  It would definitely work for steel challenge, but there is no way it, or any 105~120 PF load is going to reliably knock down steel.  I've tried all the 115 and 124 variations, plus a dabble at 135.  So now I'm experimenting with 147s to see if I can find one load that will do both and still have minimal dot bounce.  If I cannot, I'll set the gun up to run the powder puff loads and then reconfigure the bolt for the three or four falling steel matches I shoot a year.

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On 5/30/2020 at 11:12 PM, Jcgatus said:

What gran bullet are you shooting?

 

The jolt on the shoulder is real. Im definitely going to need the chiropractor after a few thousand

For me this is mainly with 115-gr factory stuff.  I've tried some 124 and 147 that's softer, but then in comparison it feels like the bolt and buffer are kind of 'lingering' during the cycle and then the gun wants to lift more, and the overall cycle is slower.  I'll take sharper and quicker over softer and slower.

 

 

That last part sounded weird.

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18 hours ago, MoRivera said:

For me this is mainly with 115-gr factory stuff.  I've tried some 124 and 147 that's softer, but then in comparison it feels like the bolt and buffer are kind of 'lingering' during the cycle and then the gun wants to lift more, and the overall cycle is slower.  I'll take sharper and quicker over softer and slower.

 

 

That last part sounded weird.

Haha. Thats funny. Yeah, i'll take faster and accurate over soft, slow, and comfortable. Im switching to 115s. Also, i have also messed eith 135s and they do a good job without tuning and short stroking.

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