Jump to content
Brian Enos's Forums... Maku mozo!

Blitzkrieg Hydraulic Buffer question, lots of recoil


Recommended Posts

My PCC recoils quite a bit with lots of barrel jump. I'm running the Blitzkrieg AR-15 9mm Hydraulic Buffer with their recommended recoil spring, Spinta precision 9mm bolt, 16" barrel and comp. Initially I shot it a few times without the comp. Everything runs great. But recoil for this thing is severe in my opinion. People talk about their dot hardly moving. Mine jumps all over the place and seems to be getting a little worse than better now that I have a comp on it. Does the hydraulic buffer have any hydraulic tension on it when you collapse the piston? Mine seems to not have much tension or resistance. It doesn't just slide haphazardly when you tilt it, but there isn't much resistance at all. Wondering if I have a defective one? My empties are ejecting approximately 15 feet between 3 and 4 o'clock. Power factor is running about 135 on these loads. 

Link to comment

I just pulled my Blitzkrieg out of the gun to see how much tension was involved.

When I hold the buffer between my thumb and forefinger it compresses relatively easily, but you can still feel the hydraulic action as you compress and decompress the plunger. That's a good thing.

By comparison I grabbed my new MBX spring driven plunger and found it to be at least twice as stiff as the Blitzkrieg, when I compressed it. That, however, may be due to it's being new.

 

First, check and see if there is a small puddle of oil under the back of your gun. Second, hold the plunger twixt thumb and forefinger and actuate it back and forth. If it compresses and returns, in one continuous motion, I'd say you were good to go. If it compresses and sticks, or doesn't return properly, then it's time for a change.

I like mine just fine, but I'm also anxious to give the MBX a go. If nothing else, there's a few less things to go wrong with it.

 

Also, if you're shooting what were once pistol loads through a sixteen inch barrel you can probably back off on the powder charge and still get the same PF. Less powder means less recoil. Good luck. :)

 

Link to comment

You have to realize the speed that the bolt/buffer travel, before you assume how stiff the valving on the buffer should be.  While you can barely feel it at speeds you reach while compressing it with your finger, that same resistance increases significantly when you try to move it at the speed the bolt/buffer travel. 

 

I have seen where Blitzkrieg usually recommends the rifle length spring, but JP recommends the carbine length spring.  I ordered both springs and the rifle length spring makes pulling back the charging handle feel like a weight training exercise.  The gun cycled, but there was too much spring and recoil with my loads.  I replaced that with the carbine spring and that felt great and much lighter to pull back. 

 

If you have the rifle spring, I can understand your observation, but it should not be THAT bad.

Edited by L9X25
Link to comment
26 minutes ago, MikieM said:

On the Blitzkrieg website they show a list of springs suitable for 9 mm carbines.  I'm currently using the blue spring and it's working fine. 

 

With pistols springs, the major manufacturers have gone with the compressed length pressure as the rating for the springs.  Regardless of if you are looking at an IMSI, Woolf, etc., you can be reasonably sure of how stiff each spring will be.  With AR-15s, everyone has chosen colors or percentages which make it practically impossible to know what you are getting, or how to compare them to other brands, or even other springs within the same brand.  I went to Blitzkrieg and they referenced Springco.  I went to springco and they tell you practically nothing about the spring, other than potential uses.   

Link to comment

I checked my order and it is a carbine length JP spring that they recommended for my build. Now, when I said recoil was bad, I was talking about compared to the 9 mm pistols I shoot. Not as in like a 308 or 30-06! I did not have a lot of time to shoot it yesterday. But, at 40 yards, double taps were a good 24" high with the second shot when I pulled the trigger as fast as I could. As reference, I shot Expert in IDPA when I used to shoot it. I'm not speedy gonzalez but I'm not in slow motion either. If I had to guess, muzzle is jumping a good 3" with not a rock solid hold, but a firm more relaxed hold

Edited by Gary H.
Link to comment

There is something up in your technique if the muzzle is “jumping” 3”. Again...if you can post a video of you shooting your PCC, Folks here might be able to help you and recommend some shooting pointers.

 

Myself, I use my weak hand to pull the rig tight into my shoulder and to aim/point the rig. I grab the hand guard pretty far forward. My strong hand has a firm grip, but is mainly used for running the trigger not holding or strearing the rig.

 

 I can really see on the targets when I start loosing my weak hand grip. My double taps open up. Even close in...10 yards....my double taps go from 1-2” to 3-4” just on grip alone.

 

 

Link to comment

I can't speak to 40 yard doubles, that is not part of my routine.   I usually test in the 12-15 yard range and can keep fast doubles in a 2" circle when I do my part.  That should extrapolate into a ~6" group at ~40 yds, If I were to dare to try it at that range.  

Link to comment

I just checked the compensator. Forgot about that Aircooled, but it's not hitting. Next time I get a chance to go to the range, I'll try pulling the weight. But does that sound about right for the distance of the ejected shells to land about 15' at the shortest? That's where they landed, not where they bounced to. I'm 6'2. Seems to me that this is very strong ejection, but I'm new to the PCC's.  I don't have a video shooting it.  I live in the city. I just can't pull it out and shoot. I have to go to the country or local range

 

 

 

 

Edited by Gary H.
Link to comment

and just to mention it, my AR15 has almost no muzzle rise compared to this and I can double tape with it a whole lot more efficiently. And the 40 yards is not something I work on. It was just at the range we were messing with things at the last time we shot.

 

Edited by Gary H.
Link to comment

Gary,

 

An AR-15 has a light bullet and a TON of gas to work the comp and the gas system keeps the bolt locked until the bullet is almost out of the barrel and pressure is lower. Only a small amount of pressure is left to transfer to the bult/buffer.  With the loads that most shoot in 9mm (3-4grs of powder) there is not much pressure left at the end of the barrel to work the comp.  The AR-9 is also direct Blowback, so all of the energy is directly put into the bolt/buffer and has to be absorbed by the recoil system.   They are different animals to tune.

Link to comment

It seems that you have enough mass with the bolt that weighs  15.5 ounces and the buffer at 6.1 ounces. Have you done the plunk test? Your bullets might be jammed into the riflings. Along with too much powder will give horrible recoil. Especially if you use something like Power Pistol. What is your load and oal? 

Edited by TheTodd
Link to comment

A couple things I have noticed since I just jumped into the PCC world about a month ago trying to develop some loads for a client is that the ammo plays a huge part in it along with the buffer system in regards to felt recoil. Over the past two weeks I have tried four  different buffers, three different springs and about 15 iterations of load development. If you run factory ammo, you are going to have some powerful stuff. I know people running 4.8 grains of Tightgroup with a 115 grain FMJ screaming at over 1440 fps. Thats major power factor! Considering most store bought ammo has a 135ish PF in handguns with 4"-5" barrels, thats high velocity with a 14.5 or 16" barrel. 

 

Originally I had a rifle length setup with a fixed low-pro stock and an old A2 buffer that weighed 5.0. I was having problems with the cases not wanting to eject. It would start to chamber the next round while the spent case was still in the chamber. With this set-up the gun was super soft to shoot. But the malfunctions were killing me, and I wanted to get that fixed since I was shooting matches with it. So I started with the cheap stuff.

 

So off I went trying different buffer setups. I switched to a carbine length buffer system with an H2 buffer at 5.5. The gun seemed to run ok. It was bit more "perky" and direct as far as cycling went, but I still was getting problems every so often. So I switched again to a custom 6.8 buffer and thought that would do the trick since I knew that system worked in another PCC carbine. It failed me too however. I was miffed. I couldn't figure it out. I knew the BCG was clean and  I thought it wasn't damaged, but I could be wrong. Start with the cheap stuff first, right?

 

Lastly I took the mass out of the bolt and took the buffer plunger out and stuck a JP SCS in. It functioned a friends JP GMG13 fine. Zero malfunctions over a 200-400 round session with many different loads through it. His softer 135ish PF loads and my factory loads that were much hotter both ran flawlessly. Once I put the JP SCS in, the gun began to cycle very fast. It took my super soft shooting gun that was kind of mushy feeling and turned it into a jack hammer that shot brass to the next county. I shot the last competition with it and had zero malfunctions but it still gave me hiccups in practice. Not to mention my accuracy started to suffer due to the recoil impulse. It didn't help that I was still running my factory loads either though. I was pushing close to major PF because I didn't have the time to load my own. 

 

I am switching to the Blitz system this week though. I am curious to see how it feels in my carbine. After testing with it in JP carbine it was buttery smooth. To the OP, I really can't see how the recoil in your carbine would be bad. I know its a long reply but I wanted to give you my feedback on what all I have tried. The dot literally didn't move for me. Double taps at 25 yards were almost connecting. To be far I ran specific PCC ammo through it to do that. But even with my factory stuff it wasn't nearly as bad as my rifle with the JP setup. I know you can tune the JP system to a specific load, but after feeling that Blitz system, I don't think I would choose another. I hope you figure out your issue. But like others are saying, I think it might just be your ammo and/or your positioning while shooting. If you load your own, go load a few batches and chrono' them. I think you will be surprised at what a difference that will make alone. Good luck!

 

Chris

Link to comment

Chief,

 

I currently have the Blitzkrieg/carbine spring combo in my gun and it works great with 130pf reloads.  The same loads functioned with the rifle spring, but the recoil was much softer with the carbine spring.  

 

I purchased the all of the SCS springs that JP sells, along with extra tungsten and steel weights to test.  My initial set-up was heavy buffer/light spring and, while it felt much better than the stock JP config, it was not nearly as good as the Blitzkrieg/carbine combo.  Many people have read my posts and asked me how much better the Blitzkrieg was and, without testing every possible combination of the SCS, I could not honestly answer the question.  Since then I have been trying other set-ups with the SCS to see how good it can be.   Following Eric's (Aircooled6racer's) recommendations, I went with a much lighter buffer and the light 85% spring.  I am getting pretty close to the Blitzkrieg combo "feel" with that, close enough that I could easily shoot either without feeling that I am "missing out" on anything.  It throws the brass a country mile, but the rifle seems to function 100% and feels really good. 

 

I can say that the Blitzkrieg works really well with my combination and, other than choosing the carbine spring over the rifle spring, there were no decisions or settings that I needed to choose, or could choose.  On the other hand, the JP SCS can also work very well, but it will require each individual to test out various combinations of weights and springs to find what works best for them. I am pretty sure that a properly set-up SCS is not giving up much (if anything) to a Blitzkrieg.  The advantage of the Blitzkrieg is that you can simply drop it in and go, with no testing required.        

Link to comment

When talking about rifle versus carbine springs, is that .308 (heavy) versus 5.56 (standard)?  I like the lighter (5.56) spring in my PCCs so far.  Also, would there be a difference if a flat spring were used?

 

I am having no trouble hitting where I want, but I would like to be able to do double taps like I see posted.  Has anyone ever analysed or compared a heavier buffer that utilizes different weights with the rubber spacers?  I understand that those work similar to a dead blow effect.

Link to comment

When I purchased the Blitzkrieg Buffer, they offered two primary options, the JP AR-10 Rifle spring or the JP AR-10 Carbine Spring.  

 

The buffer with the interchangeable weights, interchangeable captured spring and rubber spacers in the JP SCS (Silent Captured Spring).  

It gives you the ability to tune the rifle to your load and how you like for it to feel.  

 

Link to comment

I've read about people putting quarters in the end of their extension tubes to stop the rearward bolt travel after ~1/4" or so past the bolt hold open.  Would short-stopping the bolt like that help minimize dot movement?  In my current setup, the bolt can move several inches beyond the BHO.

Link to comment

I think the "quarter trick" is more about protecting your BHO latch than reducing recoil.

 

I would expect that more travel gives the spring more time to stop the bolt smoothly, if sprung properly. 

I think that you might not have as much over-travel as you think, since the bolt cannot travel that far beyond

the BHO catch before the fake gas tube manifold hits the charging handle.  Even a rifle length buffer tube

cannot add more travel because of the gas tube manifold.  My carbine length recoil system has a bumper

to limit travel and protect the rifle from damage.

Link to comment

To my way of thinking the correct tune on a PCC should be as follows, and in this order:

1. Determine what bullet, bullet weight, powder, case, and primer you intend to use, along with the desired power factor. Chronograph this load, if necessary to verify PF.

2, With the desired PF established choose a spring/buffer/bolt combination that will allow the gun to function reliably.

3. Generally speaking a heavy bolt, buffer, and heavy spring will create more problems than a lighter set-up so my recommendation is to choose a buffer in the 5 ounce range with a standard .556 AR spring to start and work from there. Personally I think the .308 carbine spring, in combination with a heavy bolt (15.7 oz, say), is too much.

You might even start with the mass weight out along with the .556 spring and a bone stuck plunger.

My two cents.

 

Edited by MikieM
Link to comment

Hello: Since I have been asked about a cheaper setup than either the Blitzkrieg buffer or the JP tuned buffer setups, here you go. If you are using reloads in the 131-138PF range this should work with your setup. I have tried this with Colt lowers and also Glock lowers. Use a standard bolt with weight installed or a JP bolt. Use a 223 carbine spring, 4.3oz carbine buffer and a New Frontier Armory stop(or make your own). This is to be used in a carbine buffer tube. If you wish you can take out the weight and split pin and try it that way. For me the sweet spot for buffers is in the 4.3-5.2oz range with a bolt around 14ozs. Thanks, Eric

Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...