Author Topic: Bulldog modification log .328 porting and more (Read 39852 times - 1 votes)
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oldpro · « **Reply #100 on:** October 20, 2018, 07:35:37 PM »

Quote from: Ironman482 on October 20, 2018, 05:21:18 PM

I have a question for you david, my JSA bulldog vavle is not sealing after one shot, sounds like its burping or bouncing , I've talked to travis and he said to blow through the holes in the poppet stem to clear it , tried that didn't help, whats weird is it worked fine for about 50 shots while testing diff. Ammo, you stated yours was sticking earlier and you changed the jet in the valve, where did you find those jets , are they common carb jets?

Were you using the stock spring?

PCPhack · « **Reply #101 on:** October 20, 2018, 08:15:50 PM »

I have only seen or heard that with way too much hammer spring, or too low of a reservoir pressure for the current hammer spring setting. If you are using the factory spring instead of the one JSAR shipped with the valve, then you need to cut at least 2 loops off of the spring, because the factory spring is way too strong.

Ironman482 · « **Reply #102 on:** October 20, 2018, 09:18:05 PM »

Travis I'm using the spring that came with the valve, 2 turns in past flush with the back of the receiver, ported to .295 , I did notice a slight ni k in the rear oring on the poppet assy.barely feel it with a fingernail using a magnifying glass i can't see any damage but can feel it . Almost ready to put the stock valve back in but am afraid the poppet seal won't seal because of going past .277 on the porting

Ironman482 · « **Reply #103 on:** October 20, 2018, 09:23:21 PM »

I also polished the poppet stem with 1500 sand paper because it was binding when i first installed it. Wish the bulldog wasn't so difficult to take apart to work on ,hope the stock screws don't strip out from removing them so many times LOL

PCPhack · « **Reply #104 on:** October 21, 2018, 12:13:27 AM »

The screws shouldn't strip. I have had mine apart probably 20 times. Also, the porting will not impact your ability the use the factory valve, unless you damaged the seat area somehow, in which case you would have a leak already.

oldpro · « **Reply #105 on:** October 21, 2018, 01:22:18 AM »

Quote from: Ironman482 on October 20, 2018, 09:18:05 PM

Travis I'm using the spring that came with the valve, 2 turns in past flush with the back of the receiver, ported to .295 , I did notice a slight ni k in the rear oring on the poppet assy.barely feel it with a fingernail using a magnifying glass i can't see any damage but can feel it . Almost ready to put the stock valve back in but am afraid the poppet seal won't seal because of going past .277 on the porting

Is the valve leaking when you cock the gun and air it up if so the valve will behave poorly and we need to fix the leak before any more usage.

Lani52 · « **Reply #106 on:** October 21, 2018, 11:00:06 AM »

And if the screws strip or more likely the threaded insert will pull out, McMaster Carr sells a package of inserts.

tkerrigan · « **Reply #107 on:** October 21, 2018, 01:17:18 PM »

Quote from: Ironman482 on October 20, 2018, 09:23:21 PM

I also polished the poppet stem with 1500 sand paper because it was binding when i first installed it. Wish the bulldog wasn't so difficult to take apart to work on ,hope the stock screws don't strip out from removing them so many times LOL

The Bulldog is a joy to take apart, try a Hatsan Carnivore .3 or .357, then you will really appreciate the Bulldog. Regards, Tom

Ironman482 · « **Reply #108 on:** October 21, 2018, 06:18:39 PM »

Travis ,no the gun airs up fine. I only get one or two shots then it burps (the best i can describe the sound) and the vel drops off by 50 fps or so. Ive inspected all the parts can't see any foreign material or damage, guess I'll try the stock valve for deer season then return to the troubleshooting of the jsa valve,really liked the results I was getting before the problem

oldpro · « **Reply #109 on:** October 21, 2018, 10:33:45 PM »

Quote from: Ironman482 on October 21, 2018, 06:18:39 PM

Travis ,no the gun airs up fine. I only get one or two shots then it burps (the best i can describe the sound) and the vel drops off by 50 fps or so. Ive inspected all the parts can't see any foreign material or damage, guess I'll try the stock valve for deer season then return to the troubleshooting of the jsa valve,really liked the results I was getting before the problem

Before you waste a lot of time swaping valves i would call me at the shop its likely a simple problem we can address.

PCPhack · « **Reply #110 on:** November 28, 2018, 06:58:12 AM »

Quote from: PCPhack on October 17, 2018, 09:47:21 PM

Though I am having excellent success with the NSA 130gr slugs, I have ordered some 165gr MrHollowpoint slugs, and will test them with the higher power tune (300+ FPE), along with 178gr NSA slugs (single loaded). I also have the replacement Pitbull air tube in hand, so will put that on while retuning. I can always come back to the existing tune, if accuracy is an issue. Stay tuned.

I am back after another short break. I will pick up from here in the coming days to test these new slugs and I might move back to using the longer reservoir. Another hunt is coming up in a week and a half.

PCPhack · « **Reply #111 on:** December 04, 2018, 09:03:52 PM »

First up on this round of work will be making a longer linkage piece for the lever mechanism so that the slugs will seat fully and the bolt fully retract from the .328 porting. I am not sure it will add much difference, but with .328 porting, those two conditions definitely exist.

PCPhack · « **Reply #112 on:** December 04, 2018, 11:53:59 PM »

This one is .075" hole to hole longer than factory. It may be a few thousandths less as I did this prototype quickly. It probably should be a hair longer. You can see the test slug mostly seated, but still just peaking out from the TP hole. This is better than before though.

rsterne · « **Reply #113 on:** December 05, 2018, 12:35:14 AM »

David, I don't understand how a longer link can allow the bolt to retract further as well as load the bullet deeper.... Please explain....

Bob

PCPhack · « **Reply #114 on:** December 05, 2018, 12:47:51 AM »

Bob, by itself it will not, but the plan is to adjust the angles on the lever as well (yeah I might foul it all up lol). The arm and pivot point at the end of that link needs to swing further past the centerline for more retraction. I will fiddle with it more tomorrow, as I had limited time tonight.

PCPhack · « **Reply #115 on:** December 05, 2018, 10:04:28 AM »

Here is a not so good picture of the bolt, flipped over to show the scalloped area of the bolt, with the cocking lever seated. This hole is the same diameter as the transfer port below it. As the new linkage seats the slug deeper, I now plan to reshape and grind this scalloped area to allow better air flow, rather than change the lever mechanics to retract the bolt further.

PCPhack · « **Reply #116 on:** December 05, 2018, 10:16:25 AM »

I probably have taken around 800 shots with this Bulldog, and this is a shot of the cocking arm pin hole. It is a bit concerning that it is already wallowed out of round. This part should be steel or otherwise reinforced, rather than plain aluminum.

PCPhack · « **Reply #117 on:** December 05, 2018, 11:02:28 AM »

Much deeper scoop...

PCPhack · « **Reply #118 on:** December 05, 2018, 11:07:14 AM »

Here is the new clearance view. I think that I will stop here for now with this linkage and bolt mod.

PCPhack · « **Reply #119 on:** December 05, 2018, 11:51:01 AM »

Eh...good enough. This is slightly thinner metal than the factory link, so I will put a washer on either side. That will also keep it centered and from rubbing this paint off.

If this works well enough, I may not even bother to have a proper stainless link made.

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Bulldog modification log .328 porting and more

Author Topic: Bulldog modification log .328 porting and more (Read 39852 times - 1 votes) )

Author Topic: Bulldog modification log .328 porting and more (Read 39852 times - 1 votes)
)