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Bullet setback in PPC


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Hey guys, just got my first PPC in last night, a Foxtrot Mike sure charging rifle. I was starting to plunk my reloads in it (115gr RMR plated and 147 Brazos coated) and both round plunk tested fine, but I was getting setback in both of these rounds.

 

The 115s has setback on the first chambering of about 0.01”, and then 0.005-0.01” each time it was chambered after that. Rounds were loaded to ~1.14” over titegroup. Crimped you’re have just a light mark on the plating (have never had any problems with this slight mark on the bullet).

 

The 147s has no setback the first chambering, on each chambering that they elongated by about 0.001” each time. Loaded at 1.10” over Titegroup. I’m not so much worried about this round, as rounds will normally only be chambered once, maybe twice for the rounds that are in the chamber at the end of stage after “showing clear”.

 

So, for those of you that have had similar problems what is the easiest solution? There is not a feed ramp in the gun, the mag sits almost flush with the chamber and feeds the rounds directly into the semi sharp edged chamber. I saw there is a feed ramp you can put into the gun, but with where the mag sits I’m not sure there would be room for it and I also don’t want to mill slots into my receiver for them.

 

I haven’t tested any factory ammo as I wasn’t at the range and didn’t to have live ammo in the gun. Maybe I’ll take the firing pin out tonight and try it though.

 

I can upload some pictures of the gun and chambered rounds tonight after work if that would help.

 

Thanks guys

 

 

 

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Your 115s are to long shorten them to 1.135 and re test

the growing length is somewhat normal. thanch of it as the same action as a hammer 

type bullet puller.

if 1.135 still hits then try 1.130 etc

as long as you can unload without a bullet sticking you really are ok.

Edited by AHI
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Just now, AHI said:

Your 115s are to long shorten them to 1.135 and re test

the growing length is somewhat normal. thanch of it as the same action as a hammer 

type bullet puller.

if 1.135 still shortins then try 1.130

as long as you can unload without a bullet sticking you really are ok.

And that bullet-puller type action is exacerbated by the heavy bolt in the blowback Foxtrot Mike upper.  There's a weight in the bolt that makes it considerably heavier than a standard AR BCG.  

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Your 115s are to long shorten them to 1.135 and re test
the growing length is somewhat normal. thanch of it as the same action as a hammer 
type bullet puller.
if 1.135 still hits then try 1.130 etc
as long as you can unload without a bullet sticking you really are ok.

What do you mean still hits? Both of the bullets did contact that chamber of the rifle while loading, the 115s were just down from the top of the bullet, but the 147s has dents in them as well. Seeing as the 147s did better in the test I do agree that I think a shorter OAL will help. Will also have more bullet in the case to help with retention?


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