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Guy Neill

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About Guy Neill

  • Birthday 09/04/1951

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  1. You may consider the 9x25 was over gassed since it would drive the gun down, as I understand.
  2. Try test groups with each and see if there is a notable difference.
  3. Recoil is historically reported as the kinetic energy of the gun. Reference: Hatcher's Notebook SAAMI (as taken from the British Textbook of Small Arms 1929)
  4. He's in the Portland, OR area. He has a website, but I don't know about videos. Tyler Firearms Instruction | Competitive Shooting
  5. Since the powder gas works the comp. the powder with the heaviest charge weight will deliver the most gas at a target power factor.
  6. Recoil is looked at as the kinetic energy of the gun, with the gun velocity found with a momentum balance, as shown in the numbers given earlier that include the gas momentum. The gas jet does do something, but to what degree is unknown. If it did nothing compensators would not work. Finding the thrust cannot be accomplished easily, and since we are already using the gas momentum in the momentum balance, it may be unnecessary. Thrust requires the mass flow rate and the gas velocity at the muzzle, at least. A muzzle gas velocity can be approximated only if we know the actual chamber pressure, and varies shot to shot just as the chamber pressure does. We normally do not know this. Even with chamber pressure values from a pressure gun, and approximate muzzle pressure. I am also not certain what time element would be used in determining the mass flow rate. Thereby, historically, any jet effect adding to recoil is ignored.
  7. Most PCC's I've seen have compensators. Compensators work better with more gas, so the lighter weigh bullets, with more powder, give more gas. I've not shot a lot of PCC, but that's the way I would approach it, leaning to using the 124 grain bullets as the middle ground.
  8. Power factor is a momentum value. Definitely, if you are shooting the bullets at the same velocity, the heavier will recoil more. However, you are normally shooting the bullets at the same power factor so that the recoil is the same. The heavier bullet, going slower for a given power factor, will take longer to exit the barrel (though not by much), so the recoil is delivered over a longer period of time. Most will not likely notice the time difference. The choice comes down to what feels best to the shooter, delivering quicker follow-up shots and accuracy. Other factors include the moment arm and the amount of powder. Since the powder charge plays a part in recoil, and the heavier bullets normally use less to make a power factor, the resultant feel is different since the force on the gun changes. As an example, taking some charge weights from one of the reloading manuals, we have, for 9mm, Bullet Velocity Charge Recoil Force PF 115 1130 5.2 2.52 6.4 130 124 1048 4.9 2.47 5.9 130 147 884 4.0 2.34 5.6 130
  9. How about these? D45 - Black Lacquer Gun Stock (herrettstocks.com)
  10. If ruling out anything to do with the comp, bullet tumbling would relate to the bullet, the velocity and the twist. What is your barrel twist and bullet velocity? For a 124gr making a 170 power factor. a 1:10" twist will normally give almost 100,000 RPM. A slower twist rate will, of course, give less RPM. What RPM is needed for bullet stability would need to be determined. Does your friends gun have the same twist rate as yours? The most common cause of tumbling is low velocity (giving low RPM). Causes of low velocity can be bullet diameter, barrel bore diameter or load. Assuming the ammunition shoots well in your friends gun, it suggests a problem with your barrel. Larger bore diameter, less rifling or slower twist rate. Thus, a number of things to investigate.
  11. i had understood that the "Glock bulge" had to do with the case head that expanded such that the sizer die could not totally iron it out. Thus the various roll sizers and push through sizers. Nothing to do with the primer that I have heard.
  12. With regard to ambi thumb safeties, it's mostly what lever/paddle size and shape you like, and what method of joining the two sides. The EGW mentioned used an extended sear pin to keep the two sides together, as I recall. Others may use the original Swenson method of the through pin joining in the middle with a tongue in groove sort of arrangement. Some say the tongue in groove is prone to breakage, but I have never seen it, though I expect it has happened. Regarding the front sight. I believe the only way to really "fix" the two holes is to weld them, then proceed with the new sight installation. Talk to you gunsmith.
  13. Look at the inside of the slide where the sight is mounted. If there are two holes, replacement will be difficult as those are no longer made. If there is a single staking hole, then replacement is to find a suitable tenon sight to replace it. I think Series 70's had the narrow tenon. The two hole mounting was to provide greater strength. Alternate is to have a dovetail milled into the slide to take one of the various dovetail type sights. Will you be changing the rear sight as well? The problem with larger front sights (larger than teh factory) is that the tenon may not hold as well. This is a primary reason dovetail sights became popular. Why do you want to change it?
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